diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index c02c5c37..c42d0fab 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -17,7 +17,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        PYTHON_VERSION: ['3.8']
+        PYTHON_VERSION: ['3.9']
     timeout-minutes: 10
     steps:
       - uses: actions/cache@v1
diff --git a/.github/workflows/static.yml b/.github/workflows/static.yml
index 6ec4345d..881a0aa6 100644
--- a/.github/workflows/static.yml
+++ b/.github/workflows/static.yml
@@ -30,9 +30,7 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-python@v5
         with:
-          # TODO: check with Python 3, but need to fix the
-          # errors first
-          python-version: '3.8'
+          python-version: '3.9'
           architecture: 'x64'
       - run: python -m pip install --upgrade pip setuptools jsonschema
       # If we don't install pycodestyle, pylint will throw an unused-argument error in pylsp/plugins/pycodestyle_lint.py:72
diff --git a/.github/workflows/test-linux.yml b/.github/workflows/test-linux.yml
index 89277d67..7a7f2f6e 100644
--- a/.github/workflows/test-linux.yml
+++ b/.github/workflows/test-linux.yml
@@ -24,7 +24,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        PYTHON_VERSION: ['3.10', '3.9', '3.8']
+        PYTHON_VERSION: ['3.11', '3.10', '3.9']
     timeout-minutes: 10
     steps:
       - uses: actions/cache@v4
diff --git a/.github/workflows/test-mac.yml b/.github/workflows/test-mac.yml
index d9e4818f..a92c82a8 100644
--- a/.github/workflows/test-mac.yml
+++ b/.github/workflows/test-mac.yml
@@ -24,7 +24,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        PYTHON_VERSION: ['3.10', '3.9', '3.8']
+        PYTHON_VERSION: ['3.11', '3.10', '3.9']
     timeout-minutes: 10
     steps:
       - uses: actions/cache@v4
diff --git a/.github/workflows/test-win.yml b/.github/workflows/test-win.yml
index 1db41154..8ecd3429 100644
--- a/.github/workflows/test-win.yml
+++ b/.github/workflows/test-win.yml
@@ -24,7 +24,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        PYTHON_VERSION: ['3.10', '3.9', '3.8']
+        PYTHON_VERSION: ['3.11', '3.10', '3.9']
     timeout-minutes: 10
     steps:
       - uses: actions/cache@v4
diff --git a/.well-known/funding-manifest-urls b/.well-known/funding-manifest-urls
new file mode 100644
index 00000000..dc9cf163
--- /dev/null
+++ b/.well-known/funding-manifest-urls
@@ -0,0 +1 @@
+https://www.spyder-ide.org/funding.json
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4a5a5c2d..146f6730 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,15 @@
 # History of changes
 
+## Version 1.12.2 (2025/02/07)
+
+### Pull Requests Merged
+
+* [PR 608](https://github.com/python-lsp/python-lsp-server/pull/608) - Fix putting `extra_paths` in front of `sys.path`, by [@cmashinho](https://github.com/cmashinho)
+
+In this release 1 pull request was closed.
+
+----
+
 ## Version 1.12.1 (2025/02/06)
 
 ### Issues Closed
diff --git a/CONFIGURATION.md b/CONFIGURATION.md
index 0609169b..ec2a9a6c 100644
--- a/CONFIGURATION.md
+++ b/CONFIGURATION.md
@@ -42,6 +42,7 @@ This server can be configured using the `workspace/didChangeConfiguration` metho
 | `pylsp.plugins.jedi_symbols.enabled` | `boolean` | Enable or disable the plugin. | `true` |
 | `pylsp.plugins.jedi_symbols.all_scopes` | `boolean` | If True lists the names of all scopes instead of only the module namespace. | `true` |
 | `pylsp.plugins.jedi_symbols.include_import_symbols` | `boolean` | If True includes symbols imported from other libraries. | `true` |
+| `pylsp.plugins.jedi_type_definition.enabled` | `boolean` | Enable or disable the plugin. | `true` |
 | `pylsp.plugins.mccabe.enabled` | `boolean` | Enable or disable the plugin. | `true` |
 | `pylsp.plugins.mccabe.threshold` | `integer` | The minimum threshold that triggers warnings about cyclomatic complexity. | `15` |
 | `pylsp.plugins.preload.enabled` | `boolean` | Enable or disable the plugin. | `true` |
@@ -75,5 +76,7 @@ This server can be configured using the `workspace/didChangeConfiguration` metho
 | `pylsp.plugins.yapf.enabled` | `boolean` | Enable or disable the plugin. | `true` |
 | `pylsp.rope.extensionModules` | `string` | Builtin and c-extension modules that are allowed to be imported and inspected by rope. | `null` |
 | `pylsp.rope.ropeFolder` | `array` of unique `string` items | The name of the folder in which rope stores project configurations and data.  Pass `null` for not using such a folder at all. | `null` |
+| `pylsp.signature.formatter` | `string` (one of: `'black'`, `'ruff'`, `None`) | Formatter to use for reformatting signatures in docstrings. | `"black"` |
+| `pylsp.signature.line_length` | `number`  | Maximum line length in signatures. | `88` |
 
 This documentation was generated from `pylsp/config/schema.json`. Please do not edit this file directly.
diff --git a/SECURITY.md b/SECURITY.md
new file mode 100644
index 00000000..eb6e57df
--- /dev/null
+++ b/SECURITY.md
@@ -0,0 +1,17 @@
+# Security Policy
+
+
+## Supported Versions
+
+We normally support only the most recently released version with bug fixes, security updates and compatibility improvements.
+
+
+## Reporting a Vulnerability
+
+If you believe you've discovered a security vulnerability in this project, please open a new security advisory with [our GitHub repo's private vulnerability reporting](https://github.com/python-lsp/python-lsp-server/security/advisories/new).
+Please be sure to carefully document the vulnerability, including a summary, describing the impacts, identifying the line(s) of code affected, stating the conditions under which it is exploitable and including a minimal reproducible test case.
+Further information and advice or patches on how to mitigate it is always welcome.
+You can usually expect to hear back within 1 week, at which point we'll inform you of our evaluation of the vulnerability and what steps we plan to take, and will reach out if we need further clarification from you.
+We'll discuss and update the advisory thread, and are happy to update you on its status should you further inquire.
+While this is a volunteer project and we don't have financial compensation to offer, we can certainly publicly thank and credit you for your help if you would like.
+Thanks!
diff --git a/pylsp/__main__.py b/pylsp/__main__.py
index 44aa3cfa..760f8829 100644
--- a/pylsp/__main__.py
+++ b/pylsp/__main__.py
@@ -20,7 +20,7 @@
     start_ws_lang_server,
 )
 
-LOG_FORMAT = "%(asctime)s {0} - %(levelname)s - %(name)s - %(message)s".format(
+LOG_FORMAT = "%(asctime)s {} - %(levelname)s - %(name)s - %(message)s".format(
     time.localtime().tm_zone
 )
 
@@ -40,7 +40,7 @@ def add_arguments(parser) -> None:
         "--check-parent-process",
         action="store_true",
         help="Check whether parent process is still alive using os.kill(ppid, 0) "
-        "and auto shut down language server process when parent process is not alive."
+        "and auto shut down language server process when parent process is not alive. "
         "Note that this may not work on a Windows machine.",
     )
 
@@ -50,7 +50,7 @@ def add_arguments(parser) -> None:
     )
     log_group.add_argument(
         "--log-file",
-        help="Redirect logs to the given file instead of writing to stderr."
+        help="Redirect logs to the given file instead of writing to stderr. "
         "Has no effect if used with --log-config.",
     )
 
@@ -98,7 +98,7 @@ def _configure_logger(verbose=0, log_config=None, log_file=None) -> None:
     root_logger = logging.root
 
     if log_config:
-        with open(log_config, "r", encoding="utf-8") as f:
+        with open(log_config, encoding="utf-8") as f:
             logging.config.dictConfig(json.load(f))
     else:
         formatter = logging.Formatter(LOG_FORMAT)
diff --git a/pylsp/_utils.py b/pylsp/_utils.py
index b96df5a9..dfe84b14 100644
--- a/pylsp/_utils.py
+++ b/pylsp/_utils.py
@@ -7,9 +7,11 @@
 import os
 import pathlib
 import re
+import subprocess
+import sys
 import threading
 import time
-from typing import List, Optional
+from typing import Optional
 
 import docstring_to_markdown
 import jedi
@@ -57,7 +59,7 @@ def run():
 
 
 def throttle(seconds=1):
-    """Throttles calls to a function evey `seconds` seconds."""
+    """Throttles calls to a function every `seconds` seconds."""
 
     def decorator(func):
         @functools.wraps(func)
@@ -78,7 +80,7 @@ def find_parents(root, path, names):
 
     Args:
         path (str): The file path to start searching up from.
-        names (List[str]): The file/directory names to look for.
+        names (list[str]): The file/directory names to look for.
         root (str): The directory at which to stop recursing upwards.
 
     Note:
@@ -198,7 +200,7 @@ def wrap_signature(signature):
 SERVER_SUPPORTED_MARKUP_KINDS = {"markdown", "plaintext"}
 
 
-def choose_markup_kind(client_supported_markup_kinds: List[str]):
+def choose_markup_kind(client_supported_markup_kinds: list[str]):
     """Choose a markup kind supported by both client and the server.
 
     This gives priority to the markup kinds provided earlier on the client preference list.
@@ -209,8 +211,96 @@ def choose_markup_kind(client_supported_markup_kinds: List[str]):
     return "markdown"
 
 
+class Formatter:
+    command: list[str]
+
+    @property
+    def is_installed(self) -> bool:
+        """Returns whether formatter is available"""
+        if not hasattr(self, "_is_installed"):
+            self._is_installed = self._is_available_via_cli()
+        return self._is_installed
+
+    def format(self, code: str, line_length: int) -> str:
+        """Formats code"""
+        return subprocess.check_output(
+            [
+                sys.executable,
+                "-m",
+                *self.command,
+                "--line-length",
+                str(line_length),
+                "-",
+            ],
+            input=code,
+            text=True,
+        ).strip()
+
+    def _is_available_via_cli(self) -> bool:
+        try:
+            subprocess.check_output(
+                [
+                    sys.executable,
+                    "-m",
+                    *self.command,
+                    "--help",
+                ],
+            )
+            return True
+        except subprocess.CalledProcessError:
+            return False
+
+
+class RuffFormatter(Formatter):
+    command = ["ruff", "format"]
+
+
+class BlackFormatter(Formatter):
+    command = ["black"]
+
+
+formatters = {"ruff": RuffFormatter(), "black": BlackFormatter()}
+
+
+def format_signature(signature: str, config: dict, signature_formatter: str) -> str:
+    """Formats signature using ruff or black if either is available."""
+    as_func = f"def {signature.strip()}:\n    pass"
+    line_length = config.get("line_length", 88)
+    formatter = formatters[signature_formatter]
+    if formatter.is_installed:
+        try:
+            return (
+                formatter.format(as_func, line_length=line_length)
+                .removeprefix("def ")
+                .removesuffix(":\n    pass")
+            )
+        except subprocess.CalledProcessError as e:
+            log.warning("Signature formatter failed %s", e)
+    else:
+        log.warning(
+            "Formatter %s was requested but it does not appear to be installed",
+            signature_formatter,
+        )
+    return signature
+
+
+def convert_signatures_to_markdown(signatures: list[str], config: dict) -> str:
+    signature_formatter = config.get("formatter", "black")
+    if signature_formatter:
+        signatures = [
+            format_signature(
+                signature, signature_formatter=signature_formatter, config=config
+            )
+            for signature in signatures
+        ]
+    return wrap_signature("\n".join(signatures))
+
+
 def format_docstring(
-    contents: str, markup_kind: str, signatures: Optional[List[str]] = None
+    contents: str,
+    markup_kind: str,
+    signatures: Optional[list[str]] = None,
+    signature_config: Optional[dict] = None,
 ):
     """Transform the provided docstring into a MarkupContent object.
 
@@ -232,7 +322,10 @@ def format_docstring(
             value = escape_markdown(contents)
 
         if signatures:
-            value = wrap_signature("\n".join(signatures)) + "\n\n" + value
+            wrapped_signatures = convert_signatures_to_markdown(
+                signatures, config=signature_config or {}
+            )
+            value = wrapped_signatures + "\n\n" + value
 
         return {"kind": "markdown", "value": value}
     value = contents
diff --git a/pylsp/config/config.py b/pylsp/config/config.py
index 815f8fd2..7b201824 100644
--- a/pylsp/config/config.py
+++ b/pylsp/config/config.py
@@ -3,8 +3,9 @@
 
 import logging
 import sys
+from collections.abc import Mapping, Sequence
 from functools import lru_cache
-from typing import List, Mapping, Sequence, Union
+from typing import Union
 
 import pluggy
 from pluggy._hooks import HookImpl
@@ -32,7 +33,7 @@ def _hookexec(
         methods: Sequence[HookImpl],
         kwargs: Mapping[str, object],
         firstresult: bool,
-    ) -> Union[object, List[object]]:
+    ) -> Union[object, list[object]]:
         # called from all hookcaller instances.
         # enable_tracing will set its own wrapping function at self._inner_hookexec
         try:
diff --git a/pylsp/config/schema.json b/pylsp/config/schema.json
index 18248384..a0caa38a 100644
--- a/pylsp/config/schema.json
+++ b/pylsp/config/schema.json
@@ -270,6 +270,11 @@
       "default": true,
       "description": "If True includes symbols imported from other libraries."
     },
+    "pylsp.plugins.jedi_type_definition.enabled": {
+      "type": "boolean",
+      "default": true,
+      "description": "Enable or disable the plugin."
+    },
     "pylsp.plugins.mccabe.enabled": {
       "type": "boolean",
       "default": true,
@@ -511,6 +516,24 @@
       },
       "uniqueItems": true,
       "description": "The name of the folder in which rope stores project configurations and data.  Pass `null` for not using such a folder at all."
+    },
+    "pylsp.signature.formatter": {
+      "type": [
+        "string",
+        "null"
+      ],
+      "enum": [
+        "black",
+        "ruff",
+        null
+      ],
+      "default": "black",
+      "description": "Formatter to use for reformatting signatures in docstrings."
+    },
+    "pylsp.signature.line_length": {
+      "type": "number",
+      "default": 88,
+      "description": "Maximum line length in signatures."
     }
   }
 }
diff --git a/pylsp/hookspecs.py b/pylsp/hookspecs.py
index 41508be1..e7e7ce42 100644
--- a/pylsp/hookspecs.py
+++ b/pylsp/hookspecs.py
@@ -38,6 +38,11 @@ def pylsp_definitions(config, workspace, document, position) -> None:
     pass
 
 
+@hookspec(firstresult=True)
+def pylsp_type_definition(config, document, position):
+    pass
+
+
 @hookspec
 def pylsp_dispatchers(config, workspace) -> None:
     pass
diff --git a/pylsp/plugins/_resolvers.py b/pylsp/plugins/_resolvers.py
index 44d6d882..dcfd06ab 100644
--- a/pylsp/plugins/_resolvers.py
+++ b/pylsp/plugins/_resolvers.py
@@ -88,7 +88,7 @@ def resolve(self, completion):
 def format_label(completion, sig):
     if sig and completion.type in ("function", "method"):
         params = ", ".join(param.name for param in sig[0].params)
-        label = "{}({})".format(completion.name, params)
+        label = f"{completion.name}({params})"
         return label
     return completion.name
 
@@ -115,7 +115,7 @@ def format_snippet(completion, sig):
         snippet_completion["insertTextFormat"] = lsp.InsertTextFormat.Snippet
         snippet = completion.name + "("
         for i, param in enumerate(positional_args):
-            snippet += "${%s:%s}" % (i + 1, param.name)
+            snippet += "${{{}:{}}}".format(i + 1, param.name)
             if i < len(positional_args) - 1:
                 snippet += ", "
         snippet += ")$0"
diff --git a/pylsp/plugins/_rope_task_handle.py b/pylsp/plugins/_rope_task_handle.py
index 8bc13c1d..5e278ee5 100644
--- a/pylsp/plugins/_rope_task_handle.py
+++ b/pylsp/plugins/_rope_task_handle.py
@@ -1,7 +1,8 @@
 from __future__ import annotations
 
 import logging
-from typing import Callable, ContextManager, List, Optional, Sequence
+from collections.abc import Sequence
+from typing import Callable, ContextManager
 
 from rope.base.taskhandle import BaseJobSet, BaseTaskHandle
 
@@ -19,13 +20,13 @@ class PylspJobSet(BaseJobSet):
     _report_iter: ContextManager
     job_name: str = ""
 
-    def __init__(self, count: Optional[int], report_iter: ContextManager) -> None:
+    def __init__(self, count: int | None, report_iter: ContextManager) -> None:
         if count is not None:
             self.count = count
         self._reporter = report_iter.__enter__()
         self._report_iter = report_iter
 
-    def started_job(self, name: Optional[str]) -> None:
+    def started_job(self, name: str | None) -> None:
         if name:
             self.job_name = name
 
@@ -42,7 +43,7 @@ def finished_job(self) -> None:
     def check_status(self) -> None:
         pass
 
-    def get_percent_done(self) -> Optional[float]:
+    def get_percent_done(self) -> float | None:
         if self.count == 0:
             return 0
         return (self.done / self.count) * 100
@@ -66,8 +67,8 @@ def _report(self) -> None:
 
 class PylspTaskHandle(BaseTaskHandle):
     name: str
-    observers: List
-    job_sets: List[PylspJobSet]
+    observers: list
+    job_sets: list[PylspJobSet]
     stopped: bool
     workspace: Workspace
     _report: Callable[[str, str], None]
@@ -77,7 +78,7 @@ def __init__(self, workspace: Workspace) -> None:
         self.job_sets = []
         self.observers = []
 
-    def create_jobset(self, name="JobSet", count: Optional[int] = None):
+    def create_jobset(self, name="JobSet", count: int | None = None):
         report_iter = self.workspace.report_progress(
             name, None, None, skip_token_initialization=True
         )
@@ -89,7 +90,7 @@ def create_jobset(self, name="JobSet", count: Optional[int] = None):
     def stop(self) -> None:
         pass
 
-    def current_jobset(self) -> Optional[BaseJobSet]:
+    def current_jobset(self) -> BaseJobSet | None:
         pass
 
     def add_observer(self) -> None:
diff --git a/pylsp/plugins/definition.py b/pylsp/plugins/definition.py
index 67abfb71..1ddc03a0 100644
--- a/pylsp/plugins/definition.py
+++ b/pylsp/plugins/definition.py
@@ -3,7 +3,7 @@
 from __future__ import annotations
 
 import logging
-from typing import TYPE_CHECKING, Any, Dict, List
+from typing import TYPE_CHECKING, Any
 
 import jedi
 
@@ -23,7 +23,7 @@
 
 
 def _resolve_definition(
-    maybe_defn: Name, script: Script, settings: Dict[str, Any]
+    maybe_defn: Name, script: Script, settings: dict[str, Any]
 ) -> Name:
     for _ in range(MAX_JEDI_GOTO_HOPS):
         if maybe_defn.is_definition() or maybe_defn.module_path != script.path:
@@ -43,8 +43,8 @@ def _resolve_definition(
 
 @hookimpl
 def pylsp_definitions(
-    config: Config, document: Document, position: Dict[str, int]
-) -> List[Dict[str, Any]]:
+    config: Config, document: Document, position: dict[str, int]
+) -> list[dict[str, Any]]:
     settings = config.plugin_settings("jedi_definition")
     code_position = _utils.position_to_jedi_linecolumn(document, position)
     script = document.jedi_script(use_document_path=True)
diff --git a/pylsp/plugins/flake8_lint.py b/pylsp/plugins/flake8_lint.py
index 74e2664c..0ac91855 100644
--- a/pylsp/plugins/flake8_lint.py
+++ b/pylsp/plugins/flake8_lint.py
@@ -135,7 +135,7 @@ def run_flake8(flake8_executable, args, document, source):
         cmd = [flake8_executable]
         cmd.extend(args)
         p = Popen(cmd, stdin=PIPE, stdout=PIPE, stderr=PIPE, **popen_kwargs)
-    except IOError:
+    except OSError:
         log.debug(
             "Can't execute %s. Trying with '%s -m flake8'",
             flake8_executable,
@@ -165,9 +165,9 @@ def build_args(options):
             arg = "--{}={}".format(arg_name, ",".join(arg_val))
         elif isinstance(arg_val, bool):
             if arg_val:
-                arg = "--{}".format(arg_name)
+                arg = f"--{arg_name}"
         else:
-            arg = "--{}={}".format(arg_name, arg_val)
+            arg = f"--{arg_name}={arg_val}"
         args.append(arg)
     return args
 
diff --git a/pylsp/plugins/hover.py b/pylsp/plugins/hover.py
index ca69d1b3..daaae90b 100644
--- a/pylsp/plugins/hover.py
+++ b/pylsp/plugins/hover.py
@@ -10,6 +10,7 @@
 
 @hookimpl
 def pylsp_hover(config, document, position):
+    signature_config = config.settings().get("signature", {})
     code_position = _utils.position_to_jedi_linecolumn(document, position)
     definitions = document.jedi_script(use_document_path=True).infer(**code_position)
     word = document.word_at_position(position)
@@ -46,5 +47,6 @@ def pylsp_hover(config, document, position):
             definition.docstring(raw=True),
             preferred_markup_kind,
             signatures=[signature] if signature else None,
+            signature_config=signature_config,
         )
     }
diff --git a/pylsp/plugins/jedi_completion.py b/pylsp/plugins/jedi_completion.py
index 2796a093..51c3589c 100644
--- a/pylsp/plugins/jedi_completion.py
+++ b/pylsp/plugins/jedi_completion.py
@@ -40,8 +40,9 @@ def pylsp_completions(config, document, position):
     """Get formatted completions for current code position"""
     settings = config.plugin_settings("jedi_completion", document_path=document.path)
     resolve_eagerly = settings.get("eager", False)
-    code_position = _utils.position_to_jedi_linecolumn(document, position)
+    signature_config = config.settings().get("signature", {})
 
+    code_position = _utils.position_to_jedi_linecolumn(document, position)
     code_position["fuzzy"] = settings.get("fuzzy", False)
     completions = document.jedi_script(use_document_path=True).complete(**code_position)
 
@@ -88,6 +89,7 @@ def pylsp_completions(config, document, position):
             resolve=resolve_eagerly,
             resolve_label_or_snippet=(i < max_to_resolve),
             snippet_support=snippet_support,
+            signature_config=signature_config,
         )
         for i, c in enumerate(completions)
     ]
@@ -103,6 +105,7 @@ def pylsp_completions(config, document, position):
                     resolve=resolve_eagerly,
                     resolve_label_or_snippet=(i < max_to_resolve),
                     snippet_support=snippet_support,
+                    signature_config=signature_config,
                 )
                 completion_dict["kind"] = lsp.CompletionItemKind.TypeParameter
                 completion_dict["label"] += " object"
@@ -118,6 +121,7 @@ def pylsp_completions(config, document, position):
                     resolve=resolve_eagerly,
                     resolve_label_or_snippet=(i < max_to_resolve),
                     snippet_support=snippet_support,
+                    signature_config=signature_config,
                 )
                 completion_dict["kind"] = lsp.CompletionItemKind.TypeParameter
                 completion_dict["label"] += " object"
@@ -137,7 +141,11 @@ def pylsp_completions(config, document, position):
 
 
 @hookimpl
-def pylsp_completion_item_resolve(config, completion_item, document):
+def pylsp_completion_item_resolve(
+    config,
+    completion_item,
+    document,
+):
     """Resolve formatted completion for given non-resolved completion"""
     shared_data = document.shared_data["LAST_JEDI_COMPLETIONS"].get(
         completion_item["label"]
@@ -152,7 +160,12 @@ def pylsp_completion_item_resolve(config, completion_item, document):
 
     if shared_data:
         completion, data = shared_data
-        return _resolve_completion(completion, data, markup_kind=preferred_markup_kind)
+        return _resolve_completion(
+            completion,
+            data,
+            markup_kind=preferred_markup_kind,
+            signature_config=config.settings().get("signature", {}),
+        )
     return completion_item
 
 
@@ -207,13 +220,14 @@ def use_snippets(document, position):
     return expr_type not in _IMPORTS and not (expr_type in _ERRORS and "import" in code)
 
 
-def _resolve_completion(completion, d, markup_kind: str):
+def _resolve_completion(completion, d, markup_kind: str, signature_config: dict):
     completion["detail"] = _detail(d)
     try:
         docs = _utils.format_docstring(
             d.docstring(raw=True),
             signatures=[signature.to_string() for signature in d.get_signatures()],
             markup_kind=markup_kind,
+            signature_config=signature_config,
         )
     except Exception:
         docs = ""
@@ -228,6 +242,7 @@ def _format_completion(
     resolve=False,
     resolve_label_or_snippet=False,
     snippet_support=False,
+    signature_config=None,
 ):
     completion = {
         "label": _label(d, resolve_label_or_snippet),
@@ -237,7 +252,9 @@ def _format_completion(
     }
 
     if resolve:
-        completion = _resolve_completion(completion, d, markup_kind)
+        completion = _resolve_completion(
+            completion, d, markup_kind, signature_config=signature_config
+        )
 
     # Adjustments for file completions
     if d.type == "path":
diff --git a/pylsp/plugins/pylint_lint.py b/pylsp/plugins/pylint_lint.py
index 722e831b..f3415c8a 100644
--- a/pylsp/plugins/pylint_lint.py
+++ b/pylsp/plugins/pylint_lint.py
@@ -287,7 +287,7 @@ def _run_pylint_stdio(pylint_executable, document, flags):
         cmd.extend(flags)
         cmd.extend(["--from-stdin", document.path])
         p = Popen(cmd, stdin=PIPE, stdout=PIPE, stderr=PIPE)
-    except IOError:
+    except OSError:
         log.debug("Can't execute %s. Trying with 'python -m pylint'", pylint_executable)
         cmd = [sys.executable, "-m", "pylint"]
         cmd.extend(flags)
diff --git a/pylsp/plugins/rope_autoimport.py b/pylsp/plugins/rope_autoimport.py
index 12f5d80b..8ba951f7 100644
--- a/pylsp/plugins/rope_autoimport.py
+++ b/pylsp/plugins/rope_autoimport.py
@@ -2,7 +2,8 @@
 
 import logging
 import threading
-from typing import Any, Dict, Generator, List, Optional, Set, Union
+from collections.abc import Generator
+from typing import Any, Optional, Union
 
 import parso
 from jedi import Script
@@ -36,7 +37,7 @@ def reload_cache(
         self,
         config: Config,
         workspace: Workspace,
-        files: Optional[List[Document]] = None,
+        files: Optional[list[Document]] = None,
         single_thread: Optional[bool] = True,
     ):
         if self.is_blocked():
@@ -45,7 +46,7 @@ def reload_cache(
         memory: bool = config.plugin_settings("rope_autoimport").get("memory", False)
         rope_config = config.settings().get("rope", {})
         autoimport = workspace._rope_autoimport(rope_config, memory)
-        resources: Optional[List[Resource]] = (
+        resources: Optional[list[Resource]] = (
             None
             if files is None
             else [document._rope_resource(rope_config) for document in files]
@@ -65,7 +66,7 @@ def _reload_cache(
         self,
         workspace: Workspace,
         autoimport: AutoImport,
-        resources: Optional[List[Resource]] = None,
+        resources: Optional[list[Resource]] = None,
     ) -> None:
         task_handle = PylspTaskHandle(workspace)
         autoimport.generate_cache(task_handle=task_handle, resources=resources)
@@ -76,7 +77,7 @@ def is_blocked(self):
 
 
 @hookimpl
-def pylsp_settings() -> Dict[str, Dict[str, Dict[str, Any]]]:
+def pylsp_settings() -> dict[str, dict[str, dict[str, Any]]]:
     # Default rope_completion to disabled
     return {
         "plugins": {
@@ -180,13 +181,13 @@ def _handle_argument(node: NodeOrLeaf, word_node: tree.Leaf):
 
 
 def _process_statements(
-    suggestions: List[SearchResult],
+    suggestions: list[SearchResult],
     doc_uri: str,
     word: str,
     autoimport: AutoImport,
     document: Document,
     feature: str = "completions",
-) -> Generator[Dict[str, Any], None, None]:
+) -> Generator[dict[str, Any], None, None]:
     for suggestion in suggestions:
         insert_line = autoimport.find_insertion_line(document.source) - 1
         start = {"line": insert_line, "character": 0}
@@ -220,7 +221,7 @@ def _process_statements(
             raise ValueError(f"Unknown feature: {feature}")
 
 
-def get_names(script: Script) -> Set[str]:
+def get_names(script: Script) -> set[str]:
     """Get all names to ignore from the current file."""
     raw_names = script.get_names(definitions=True)
     log.debug(raw_names)
@@ -233,7 +234,7 @@ def pylsp_completions(
     workspace: Workspace,
     document: Document,
     position,
-    ignored_names: Union[Set[str], None],
+    ignored_names: Union[set[str], None],
 ):
     """Get autoimport suggestions."""
     if (
@@ -251,7 +252,7 @@ def pylsp_completions(
     word = word_node.value
     log.debug(f"autoimport: searching for word: {word}")
     rope_config = config.settings(document_path=document.path).get("rope", {})
-    ignored_names: Set[str] = ignored_names or get_names(
+    ignored_names: set[str] = ignored_names or get_names(
         document.jedi_script(use_document_path=True)
     )
     autoimport = workspace._rope_autoimport(rope_config)
@@ -303,9 +304,9 @@ def pylsp_code_actions(
     config: Config,
     workspace: Workspace,
     document: Document,
-    range: Dict,
-    context: Dict,
-) -> List[Dict]:
+    range: dict,
+    context: dict,
+) -> list[dict]:
     """
     Provide code actions through rope.
 
@@ -317,9 +318,9 @@ def pylsp_code_actions(
         Current workspace.
     document : pylsp.workspace.Document
         Document to apply code actions on.
-    range : Dict
+    range : dict
         Range argument given by pylsp. Not used here.
-    context : Dict
+    context : dict
         CodeActionContext given as dict.
 
     Returns
diff --git a/pylsp/plugins/rope_completion.py b/pylsp/plugins/rope_completion.py
index b3a1f066..dc94ddea 100644
--- a/pylsp/plugins/rope_completion.py
+++ b/pylsp/plugins/rope_completion.py
@@ -22,7 +22,7 @@ def _resolve_completion(completion, data, markup_kind):
     except Exception as e:
         log.debug("Failed to resolve Rope completion: %s", e)
         doc = ""
-    completion["detail"] = "{0} {1}".format(data.scope or "", data.name)
+    completion["detail"] = "{} {}".format(data.scope or "", data.name)
     completion["documentation"] = doc
     return completion
 
diff --git a/pylsp/plugins/symbols.py b/pylsp/plugins/symbols.py
index 4e1890c1..3a7beb07 100644
--- a/pylsp/plugins/symbols.py
+++ b/pylsp/plugins/symbols.py
@@ -2,6 +2,7 @@
 # Copyright 2021- Python Language Server Contributors.
 
 import logging
+import re
 from pathlib import Path
 
 from pylsp import hookimpl
@@ -19,6 +20,9 @@ def pylsp_document_symbols(config, document):
     symbols = []
     exclude = set({})
     redefinitions = {}
+    pattern_import = re.compile(
+        r"^\s*(?!#)\s*(from\s+[.\w]+(\.[\w]+)*\s+import\s+[\w\s,()*]+|import\s+[\w\s,.*]+)"
+    )
 
     while definitions != []:
         d = definitions.pop(0)
@@ -27,7 +31,8 @@ def pylsp_document_symbols(config, document):
         if not add_import_symbols:
             # Skip if there's an import in the code the symbol is defined.
             code = d.get_line_code()
-            if " import " in code or "import " in code:
+
+            if pattern_import.match(code):
                 continue
 
             # Skip imported symbols comparing module names.
diff --git a/pylsp/plugins/type_definition.py b/pylsp/plugins/type_definition.py
new file mode 100644
index 00000000..5fe0a890
--- /dev/null
+++ b/pylsp/plugins/type_definition.py
@@ -0,0 +1,38 @@
+# Copyright 2021- Python Language Server Contributors.
+
+import logging
+
+from pylsp import _utils, hookimpl
+
+log = logging.getLogger(__name__)
+
+
+def lsp_location(name):
+    module_path = name.module_path
+    if module_path is None or name.line is None or name.column is None:
+        return None
+    uri = module_path.as_uri()
+    return {
+        "uri": str(uri),
+        "range": {
+            "start": {"line": name.line - 1, "character": name.column},
+            "end": {"line": name.line - 1, "character": name.column + len(name.name)},
+        },
+    }
+
+
+@hookimpl
+def pylsp_type_definition(config, document, position):
+    try:
+        kwargs = _utils.position_to_jedi_linecolumn(document, position)
+        script = document.jedi_script()
+        names = script.infer(**kwargs)
+        definitions = [
+            definition
+            for definition in [lsp_location(name) for name in names]
+            if definition is not None
+        ]
+        return definitions
+    except Exception as e:
+        log.debug("Failed to run type_definition: %s", e)
+        return []
diff --git a/pylsp/py.typed b/pylsp/py.typed
new file mode 100644
index 00000000..e69de29b
diff --git a/pylsp/python_lsp.py b/pylsp/python_lsp.py
index ba41d6aa..36265890 100644
--- a/pylsp/python_lsp.py
+++ b/pylsp/python_lsp.py
@@ -7,7 +7,7 @@
 import threading
 import uuid
 from functools import partial
-from typing import Any, Dict, List
+from typing import Any
 
 try:
     import ujson as json
@@ -117,6 +117,8 @@ def start_ws_lang_server(port, check_parent_process, handler_class) -> None:
         ) from e
 
     with ThreadPoolExecutor(max_workers=10) as tpool:
+        send_queue = None
+        loop = None
 
         async def pylsp_ws(websocket):
             log.debug("Creating LSP object")
@@ -146,14 +148,20 @@ def send_message(message, websocket):
             """Handler to send responses of  processed requests to respective web socket clients"""
             try:
                 payload = json.dumps(message, ensure_ascii=False)
-                asyncio.run(websocket.send(payload))
+                loop.call_soon_threadsafe(send_queue.put_nowait, (payload, websocket))
             except Exception as e:
                 log.exception("Failed to write message %s, %s", message, str(e))
 
         async def run_server():
+            nonlocal send_queue, loop
+            send_queue = asyncio.Queue()
+            loop = asyncio.get_running_loop()
+
             async with websockets.serve(pylsp_ws, port=port):
-                # runs forever
-                await asyncio.Future()
+                while 1:
+                    # Wait until payload is available for sending
+                    payload, websocket = await send_queue.get()
+                    await websocket.send(payload)
 
         asyncio.run(run_server())
 
@@ -276,6 +284,7 @@ def capabilities(self):
             "documentRangeFormattingProvider": True,
             "documentSymbolProvider": True,
             "definitionProvider": True,
+            "typeDefinitionProvider": True,
             "executeCommandProvider": {
                 "commands": flatten(self._hook("pylsp_commands"))
             },
@@ -382,7 +391,7 @@ def watch_parent_process(pid):
     def m_initialized(self, **_kwargs) -> None:
         self._hook("pylsp_initialized")
 
-    def code_actions(self, doc_uri: str, range: Dict, context: Dict):
+    def code_actions(self, doc_uri: str, range: dict, context: dict):
         return flatten(
             self._hook("pylsp_code_actions", doc_uri, range=range, context=context)
         )
@@ -412,6 +421,9 @@ def completion_item_resolve(self, completion_item):
     def definitions(self, doc_uri, position):
         return flatten(self._hook("pylsp_definitions", doc_uri, position=position))
 
+    def type_definition(self, doc_uri, position):
+        return self._hook("pylsp_type_definition", doc_uri, position=position)
+
     def document_symbols(self, doc_uri):
         return flatten(self._hook("pylsp_document_symbols", doc_uri))
 
@@ -471,7 +483,7 @@ def _lint_notebook_document(self, notebook_document, workspace) -> None:
         random_uri = str(uuid.uuid4())
 
         # cell_list helps us map the diagnostics back to the correct cell later.
-        cell_list: List[Dict[str, Any]] = []
+        cell_list: list[dict[str, Any]] = []
 
         offset = 0
         total_source = ""
@@ -762,6 +774,11 @@ def m_text_document__definition(self, textDocument=None, position=None, **_kwarg
             return self._cell_document__definition(document, position, **_kwargs)
         return self.definitions(textDocument["uri"], position)
 
+    def m_text_document__type_definition(
+        self, textDocument=None, position=None, **_kwargs
+    ):
+        return self.type_definition(textDocument["uri"], position)
+
     def m_text_document__document_highlight(
         self, textDocument=None, position=None, **_kwargs
     ):
diff --git a/pylsp/uris.py b/pylsp/uris.py
index cba5b290..8ebd8e31 100644
--- a/pylsp/uris.py
+++ b/pylsp/uris.py
@@ -61,7 +61,7 @@ def to_fs_path(uri):
 
     if netloc and path and scheme == "file":
         # unc path: file://shares/c$/far/boo
-        value = "//{}{}".format(netloc, path)
+        value = f"//{netloc}{path}"
 
     elif RE_DRIVE_LETTER_PATH.match(path):
         # windows drive letter: file:///C:/far/boo
diff --git a/pylsp/workspace.py b/pylsp/workspace.py
index d8f1bfd6..290b95ee 100644
--- a/pylsp/workspace.py
+++ b/pylsp/workspace.py
@@ -7,9 +7,10 @@
 import os
 import re
 import uuid
+from collections.abc import Generator
 from contextlib import contextmanager
 from threading import RLock
-from typing import Callable, Generator, List, Optional
+from typing import Callable, Optional
 
 import jedi
 
@@ -436,7 +437,7 @@ def lines(self):
     @lock
     def source(self):
         if self._source is None:
-            with io.open(self.path, "r", encoding="utf-8") as f:
+            with open(self.path, encoding="utf-8") as f:
                 return f.read()
         return self._source
 
@@ -460,7 +461,8 @@ def apply_change(self, change):
         end_col = change_range["end"]["character"]
 
         # Check for an edit occuring at the very end of the file
-        if start_line == len(self.lines):
+        lines = self.lines
+        if start_line == len(lines):
             self._source = self.source + text
             return
 
@@ -469,7 +471,7 @@ def apply_change(self, change):
         # Iterate over the existing document until we hit the edit range,
         # at which point we write the new text, then loop until we hit
         # the end of the range and continue writing.
-        for i, line in enumerate(self.lines):
+        for i, line in enumerate(lines):
             if i < start_line:
                 new.write(line)
                 continue
@@ -493,10 +495,11 @@ def offset_at_position(self, position):
 
     def word_at_position(self, position):
         """Get the word under the cursor returning the start and end positions."""
-        if position["line"] >= len(self.lines):
+        lines = self.lines
+        if position["line"] >= len(lines):
             return ""
 
-        line = self.lines[position["line"]]
+        line = lines[position["line"]]
         i = position["character"]
         # Split word in two
         start = line[:i]
@@ -599,9 +602,9 @@ def sys_path(
         )
         path.extend(environment.get_sys_path())
         if prioritize_extra_paths:
-            path += extra_paths + path
+            path = extra_paths + path
         else:
-            path += path + extra_paths
+            path = path + extra_paths
 
         return path
 
@@ -623,7 +626,7 @@ def __init__(
     def __str__(self):
         return "Notebook with URI '%s'" % str(self.uri)
 
-    def add_cells(self, new_cells: List, start: int) -> None:
+    def add_cells(self, new_cells: list, start: int) -> None:
         self.cells[start:start] = new_cells
 
     def remove_cells(self, start: int, delete_count: int) -> None:
diff --git a/pyproject.toml b/pyproject.toml
index f9c6a521..7b0c205b 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -2,7 +2,7 @@
 # Copyright 2021- Python Language Server Contributors.
 
 [build-system]
-requires = ["setuptools>=61.2.0", "setuptools_scm[toml]>=3.4.3"]
+requires = ["setuptools>=69.0.0", "setuptools_scm[toml]>=3.4.3"]
 build-backend = "setuptools.build_meta"
 
 [project]
@@ -11,7 +11,7 @@ authors = [{name = "Python Language Server Contributors"}]
 description = "Python Language Server for the Language Server Protocol"
 readme = "README.md"
 license = {text = "MIT"}
-requires-python = ">=3.8"
+requires-python = ">=3.9"
 dependencies = [
     "docstring-to-markdown",
     "importlib_metadata>=4.8.3;python_version<\"3.10\"",
@@ -19,6 +19,7 @@ dependencies = [
     "pluggy>=1.0.0",
     "python-lsp-jsonrpc>=1.1.0,<2.0.0",
     "ujson>=3.0.0",
+    "black"
 ]
 dynamic = ["version"]
 
@@ -58,6 +59,7 @@ test = [
     "matplotlib",
     "pyqt5",
     "flaky",
+    "websockets>=10.3",
 ]
 
 [project.entry-points.pylsp]
@@ -66,6 +68,7 @@ folding = "pylsp.plugins.folding"
 flake8 = "pylsp.plugins.flake8_lint"
 jedi_completion = "pylsp.plugins.jedi_completion"
 jedi_definition = "pylsp.plugins.definition"
+jedi_type_definition = "pylsp.plugins.type_definition"
 jedi_hover = "pylsp.plugins.hover"
 jedi_highlight = "pylsp.plugins.highlight"
 jedi_references = "pylsp.plugins.references"
@@ -120,8 +123,8 @@ exclude = [
 line-length = 88
 indent-width = 4
 
-# Assume Python 3.8
-target-version = "py38"
+# Assume Python 3.9
+target-version = "py39"
 
 [tool.ruff.lint]
 # https://docs.astral.sh/ruff/rules/
diff --git a/test/plugins/test_autoimport.py b/test/plugins/test_autoimport.py
index dbad8d02..cbe3dde1 100644
--- a/test/plugins/test_autoimport.py
+++ b/test/plugins/test_autoimport.py
@@ -1,6 +1,6 @@
 # Copyright 2022- Python Language Server Contributors.
 
-from typing import Any, Dict, List
+from typing import Any
 from unittest.mock import Mock, patch
 
 import jedi
@@ -26,14 +26,14 @@
 DOC_URI = uris.from_fs_path(__file__)
 
 
-def contains_autoimport_completion(suggestion: Dict[str, Any], module: str) -> bool:
+def contains_autoimport_completion(suggestion: dict[str, Any], module: str) -> bool:
     """Checks if `suggestion` contains an autoimport completion for `module`."""
     return suggestion.get("label", "") == module and "import" in suggestion.get(
         "detail", ""
     )
 
 
-def contains_autoimport_quickfix(suggestion: Dict[str, Any], module: str) -> bool:
+def contains_autoimport_quickfix(suggestion: dict[str, Any], module: str) -> bool:
     """Checks if `suggestion` contains an autoimport quick fix for `module`."""
     return suggestion.get("title", "") == f"import {module}"
 
@@ -78,7 +78,7 @@ def should_insert(phrase: str, position: int):
     return _should_insert(expr, word_node)
 
 
-def check_dict(query: Dict, results: List[Dict]) -> bool:
+def check_dict(query: dict, results: list[dict]) -> bool:
     for result in results:
         if all(result[key] == query[key] for key in query.keys()):
             return True
diff --git a/test/plugins/test_completion.py b/test/plugins/test_completion.py
index b8de8912..3ba8dbdd 100644
--- a/test/plugins/test_completion.py
+++ b/test/plugins/test_completion.py
@@ -5,7 +5,7 @@
 import os
 import sys
 from pathlib import Path
-from typing import Dict, NamedTuple
+from typing import NamedTuple
 
 import pytest
 
@@ -66,7 +66,7 @@ class TypeCase(NamedTuple):
 
 
 # fmt: off
-TYPE_CASES: Dict[str, TypeCase] = {
+TYPE_CASES: dict[str, TypeCase] = {
     "variable": TypeCase(
         document="test = 1\ntes",
         position={"line": 1, "character": 3},
diff --git a/test/plugins/test_flake8_lint.py b/test/plugins/test_flake8_lint.py
index e7b6b001..d8199d63 100644
--- a/test/plugins/test_flake8_lint.py
+++ b/test/plugins/test_flake8_lint.py
@@ -125,20 +125,20 @@ def test_flake8_respecting_configuration(workspace) -> None:
 def test_flake8_config_param(workspace) -> None:
     with patch("pylsp.plugins.flake8_lint.Popen") as popen_mock:
         mock_instance = popen_mock.return_value
-        mock_instance.communicate.return_value = [bytes(), bytes()]
+        mock_instance.communicate.return_value = [b"", b""]
         flake8_conf = "/tmp/some.cfg"
         workspace._config.update({"plugins": {"flake8": {"config": flake8_conf}}})
         _name, doc = temp_document(DOC, workspace)
         flake8_lint.pylsp_lint(workspace, doc)
         (call_args,) = popen_mock.call_args[0]
         assert "flake8" in call_args
-        assert "--config={}".format(flake8_conf) in call_args
+        assert f"--config={flake8_conf}" in call_args
 
 
 def test_flake8_executable_param(workspace) -> None:
     with patch("pylsp.plugins.flake8_lint.Popen") as popen_mock:
         mock_instance = popen_mock.return_value
-        mock_instance.communicate.return_value = [bytes(), bytes()]
+        mock_instance.communicate.return_value = [b"", b""]
 
         flake8_executable = "/tmp/flake8"
         workspace._config.update(
@@ -187,7 +187,7 @@ def test_flake8_multiline(workspace) -> None:
 
     with patch("pylsp.plugins.flake8_lint.Popen") as popen_mock:
         mock_instance = popen_mock.return_value
-        mock_instance.communicate.return_value = [bytes(), bytes()]
+        mock_instance.communicate.return_value = [b"", b""]
 
         doc = workspace.get_document(doc_uri)
         flake8_lint.pylsp_lint(workspace, doc)
diff --git a/test/plugins/test_hover.py b/test/plugins/test_hover.py
index 9674b872..b507acd2 100644
--- a/test/plugins/test_hover.py
+++ b/test/plugins/test_hover.py
@@ -10,7 +10,7 @@
 DOC_URI = uris.from_fs_path(__file__)
 DOC = """
 
-def main():
+def main(a: float, b: float):
     \"\"\"hello world\"\"\"
     pass
 """
@@ -79,13 +79,47 @@ def test_hover(workspace) -> None:
 
     doc = Document(DOC_URI, workspace, DOC)
 
-    contents = {"kind": "markdown", "value": "```python\nmain()\n```\n\n\nhello world"}
+    contents = {
+        "kind": "markdown",
+        "value": "```python\nmain(a: float, b: float)\n```\n\n\nhello world",
+    }
 
     assert {"contents": contents} == pylsp_hover(doc._config, doc, hov_position)
 
     assert {"contents": ""} == pylsp_hover(doc._config, doc, no_hov_position)
 
 
+def test_hover_signature_formatting(workspace) -> None:
+    # Over 'main' in def main():
+    hov_position = {"line": 2, "character": 6}
+
+    doc = Document(DOC_URI, workspace, DOC)
+    # setting low line length should trigger reflow to multiple lines
+    doc._config.update({"signature": {"line_length": 10}})
+
+    contents = {
+        "kind": "markdown",
+        "value": "```python\nmain(\n    a: float,\n    b: float,\n)\n```\n\n\nhello world",
+    }
+
+    assert {"contents": contents} == pylsp_hover(doc._config, doc, hov_position)
+
+
+def test_hover_signature_formatting_opt_out(workspace) -> None:
+    # Over 'main' in def main():
+    hov_position = {"line": 2, "character": 6}
+
+    doc = Document(DOC_URI, workspace, DOC)
+    doc._config.update({"signature": {"line_length": 10, "formatter": None}})
+
+    contents = {
+        "kind": "markdown",
+        "value": "```python\nmain(a: float, b: float)\n```\n\n\nhello world",
+    }
+
+    assert {"contents": contents} == pylsp_hover(doc._config, doc, hov_position)
+
+
 def test_document_path_hover(workspace_other_root_path, tmpdir) -> None:
     # Create a dummy module out of the workspace's root_path and try to get
     # a definition on it in another file placed next to it.
diff --git a/test/plugins/test_symbols.py b/test/plugins/test_symbols.py
index c00ab935..242a38a1 100644
--- a/test/plugins/test_symbols.py
+++ b/test/plugins/test_symbols.py
@@ -30,6 +30,17 @@ def main(x):
 
 """
 
+DOC_IMPORTS = """from . import something
+from ..module import something
+from module import (a, b)
+
+def main():
+    # import ignored
+    print("from module import x")  # string with import
+    return something
+
+"""
+
 
 def helper_check_symbols_all_scope(symbols):
     # All eight symbols (import sys, a, B, __init__, x, y, main, y)
@@ -73,6 +84,24 @@ def sym(name):
     assert sym("main")["location"]["range"]["end"] == {"line": 12, "character": 0}
 
 
+def test_symbols_complex_imports(config, workspace):
+    doc = Document(DOC_URI, workspace, DOC_IMPORTS)
+    config.update({"plugins": {"jedi_symbols": {"all_scopes": False}}})
+    symbols = pylsp_document_symbols(config, doc)
+
+    import_symbols = [s for s in symbols if s["kind"] == SymbolKind.Module]
+
+    assert len(import_symbols) == 4
+
+    names = [s["name"] for s in import_symbols]
+    assert "something" in names
+    assert "a" in names or "b" in names
+
+    assert any(
+        s["name"] == "main" and s["kind"] == SymbolKind.Function for s in symbols
+    )
+
+
 def test_symbols_all_scopes(config, workspace) -> None:
     doc = Document(DOC_URI, workspace, DOC)
     symbols = pylsp_document_symbols(config, doc)
diff --git a/test/plugins/test_type_definition.py b/test/plugins/test_type_definition.py
new file mode 100644
index 00000000..b433fc63
--- /dev/null
+++ b/test/plugins/test_type_definition.py
@@ -0,0 +1,96 @@
+# Copyright 2021- Python Language Server Contributors.
+
+from pylsp import uris
+from pylsp.plugins.type_definition import pylsp_type_definition
+from pylsp.workspace import Document
+
+DOC_URI = uris.from_fs_path(__file__)
+DOC = """\
+from dataclasses import dataclass
+
+@dataclass
+class IntPair:
+    a: int
+    b: int
+
+def main() -> None:
+    l0 = list(1, 2)
+
+    my_pair = IntPair(a=10, b=20)
+    print(f"Original pair: {my_pair}")
+"""
+
+
+def test_type_definitions(config, workspace) -> None:
+    # Over 'IntPair' in 'main'
+    cursor_pos = {"line": 10, "character": 14}
+
+    # The definition of 'IntPair'
+    def_range = {
+        "start": {"line": 3, "character": 6},
+        "end": {"line": 3, "character": 13},
+    }
+
+    doc = Document(DOC_URI, workspace, DOC)
+    assert [{"uri": DOC_URI, "range": def_range}] == pylsp_type_definition(
+        config, doc, cursor_pos
+    )
+
+
+def test_builtin_definition(config, workspace) -> None:
+    # Over 'list' in main
+    cursor_pos = {"line": 8, "character": 9}
+
+    doc = Document(DOC_URI, workspace, DOC)
+
+    defns = pylsp_type_definition(config, doc, cursor_pos)
+    assert len(defns) == 1
+    assert defns[0]["uri"].endswith("builtins.pyi")
+
+
+def test_mutli_file_type_definitions(config, workspace, tmpdir) -> None:
+    # Create a dummy module out of the workspace's root_path and try to get
+    # a definition on it in another file placed next to it.
+    module_content = """\
+from dataclasses import dataclass
+
+@dataclass
+class IntPair:
+    a: int
+    b: int
+"""
+    p1 = tmpdir.join("intpair.py")
+    p1.write(module_content)
+    # The uri for intpair.py
+    module_path = str(p1)
+    module_uri = uris.from_fs_path(module_path)
+
+    # Content of doc to test type definition
+    doc_content = """\
+from intpair import IntPair
+
+def main() -> None:
+    l0 = list(1, 2)
+
+    my_pair = IntPair(a=10, b=20)
+    print(f"Original pair: {my_pair}")
+"""
+    p2 = tmpdir.join("main.py")
+    p2.write(doc_content)
+    doc_path = str(p2)
+    doc_uri = uris.from_fs_path(doc_path)
+
+    doc = Document(doc_uri, workspace, doc_content)
+
+    # The range where IntPair is defined in intpair.py
+    def_range = {
+        "start": {"line": 3, "character": 6},
+        "end": {"line": 3, "character": 13},
+    }
+
+    # The position where IntPair is called in main.py
+    cursor_pos = {"line": 5, "character": 14}
+
+    assert [{"uri": module_uri, "range": def_range}] == pylsp_type_definition(
+        config, doc, cursor_pos
+    )
diff --git a/test/test_python_lsp.py b/test/test_python_lsp.py
new file mode 100644
index 00000000..b7b9daec
--- /dev/null
+++ b/test/test_python_lsp.py
@@ -0,0 +1,161 @@
+import asyncio
+import json
+import os
+import socket
+import subprocess
+import sys
+import threading
+import time
+
+import pytest
+import websockets
+
+NUM_CLIENTS = 2
+NUM_REQUESTS = 5
+TEST_PORT = 5102
+HOST = "127.0.0.1"
+MAX_STARTUP_SECONDS = 5.0
+CHECK_INTERVAL = 0.1
+
+
+@pytest.fixture(scope="module", autouse=True)
+def ws_server_subprocess():
+    cmd = [
+        sys.executable,
+        "-m",
+        "pylsp.__main__",
+        "--ws",
+        "--host",
+        HOST,
+        "--port",
+        str(TEST_PORT),
+    ]
+
+    proc = subprocess.Popen(
+        cmd,
+        stdout=subprocess.PIPE,
+        stderr=subprocess.PIPE,
+        env=os.environ.copy(),
+    )
+
+    deadline = time.time() + MAX_STARTUP_SECONDS
+    while True:
+        try:
+            with socket.create_connection(
+                ("127.0.0.1", TEST_PORT), timeout=CHECK_INTERVAL
+            ):
+                break
+        except (ConnectionRefusedError, OSError):
+            if time.time() > deadline:
+                proc.kill()
+                out, err = proc.communicate(timeout=1)
+                raise RuntimeError(
+                    f"Server didn’t start listening on port {TEST_PORT} in time.\n"
+                    f"STDOUT:\n{out.decode()}\nSTDERR:\n{err.decode()}"
+                )
+            time.sleep(CHECK_INTERVAL)
+
+    yield  # run the tests
+
+    proc.terminate()
+    try:
+        proc.wait(timeout=2)
+    except subprocess.TimeoutExpired:
+        proc.kill()
+
+
+TEST_DOC = """\
+def test():
+    '''Test documentation'''
+test()
+"""
+
+
+def test_concurrent_ws_requests():
+    errors = set()
+    lock = threading.Lock()
+
+    def thread_target(i: int):
+        async def do_initialize(idx):
+            uri = f"ws://{HOST}:{TEST_PORT}"
+            async with websockets.connect(uri) as ws:
+                # send initialize
+                init_request = {
+                    "jsonrpc": "2.0",
+                    "id": 4 * idx,
+                    "method": "initialize",
+                    "params": {},
+                }
+                did_open_request = {
+                    "jsonrpc": "2.0",
+                    "id": 4 * (idx + 1),
+                    "method": "textDocument/didOpen",
+                    "params": {
+                        "textDocument": {
+                            "uri": "test.py",
+                            "languageId": "python",
+                            "version": 0,
+                            "text": TEST_DOC,
+                        }
+                    },
+                }
+
+                async def send_request(request: dict):
+                    await asyncio.wait_for(
+                        ws.send(json.dumps(request, ensure_ascii=False)), timeout=5
+                    )
+
+                async def get_json_reply():
+                    raw = await asyncio.wait_for(ws.recv(), timeout=60)
+                    obj = json.loads(raw)
+                    return obj
+
+                try:
+                    await send_request(init_request)
+                    await get_json_reply()
+                    await send_request(did_open_request)
+                    await get_json_reply()
+                    requests = []
+                    for i in range(NUM_REQUESTS):
+                        hover_request = {
+                            "jsonrpc": "2.0",
+                            "id": 4 * (idx + 2 + i),
+                            "method": "textDocument/definition",
+                            "params": {
+                                "textDocument": {
+                                    "uri": "test.py",
+                                },
+                                "position": {
+                                    "line": 3,
+                                    "character": 2,
+                                },
+                            },
+                        }
+                        requests.append(send_request(hover_request))
+                    # send many requests in parallel
+                    await asyncio.gather(*requests)
+                    # collect replies
+                    for i in range(NUM_REQUESTS):
+                        hover = await get_json_reply()
+                        assert hover
+                except (json.JSONDecodeError, asyncio.TimeoutError) as e:
+                    return e
+                return None
+
+        error = asyncio.run(do_initialize(i))
+        with lock:
+            errors.add(error)
+
+    # launch threads
+    threads = []
+    for i in range(1, NUM_CLIENTS + 1):
+        t = threading.Thread(target=thread_target, args=(i,))
+        t.start()
+        threads.append(t)
+
+    # wait for them all
+    for t in threads:
+        t.join(timeout=50)
+        assert not t.is_alive(), f"Worker thread {t} hung!"
+
+    assert not any(filter(bool, errors))
diff --git a/test/test_utils.py b/test/test_utils.py
index 966c469e..7ed6214f 100644
--- a/test/test_utils.py
+++ b/test/test_utils.py
@@ -6,7 +6,7 @@
 import sys
 import time
 from threading import Thread
-from typing import Any, Dict, List
+from typing import Any
 from unittest import mock
 
 from docstring_to_markdown import UnknownFormatError
@@ -19,7 +19,7 @@
 CALL_TIMEOUT_IN_SECONDS = 30
 
 
-def send_notebook_did_open(client, cells: List[str]) -> None:
+def send_notebook_did_open(client, cells: list[str]) -> None:
     """
     Sends a notebookDocument/didOpen notification with the given python cells.
 
@@ -31,7 +31,7 @@ def send_notebook_did_open(client, cells: List[str]) -> None:
     )
 
 
-def notebook_with_python_cells(cells: List[str]):
+def notebook_with_python_cells(cells: list[str]):
     """
     Create a notebook document with the given python cells.
 
@@ -61,7 +61,7 @@ def notebook_with_python_cells(cells: List[str]):
     }
 
 
-def send_initialize_request(client, initialization_options: Dict[str, Any] = None):
+def send_initialize_request(client, initialization_options: dict[str, Any] = None):
     return client._endpoint.request(
         "initialize",
         {