DataDog · nikita-tkachenko-datadog · May 30, 2025 · May 30, 2025 · Jun 2, 2025
@@ -100,5 +100,7 @@ public final class GeneralConfig {
   public static final String APM_TRACING_ENABLED = "apm.tracing.enabled";
   public static final String JDK_SOCKET_ENABLED = "jdk.socket.enabled";
 
+  public static final String STACK_TRACE_LENGTH_LIMIT = "stack.trace.length.limit";
+
   private GeneralConfig() {}
 }
@@ -27,8 +27,7 @@
 import datadog.trace.bootstrap.instrumentation.api.ErrorPriorities;
 import datadog.trace.bootstrap.instrumentation.api.ResourceNamePriorities;
 import datadog.trace.bootstrap.instrumentation.api.Tags;
-import java.io.PrintWriter;
-import java.io.StringWriter;
+import datadog.trace.core.util.StackTraces;
 import java.util.Collections;
 import java.util.List;
 import java.util.Map;
@@ -350,9 +349,9 @@ public DDSpan addThrowable(Throwable error, byte errorPriority) {
         // or warming up - capturing the stack trace and keeping
         // the trace may exacerbate existing problems.
         setError(true, errorPriority);
-        final StringWriter errorString = new StringWriter();
-        error.printStackTrace(new PrintWriter(errorString));
-        setTag(DDTags.ERROR_STACK, errorString.toString());
+        setTag(
+            DDTags.ERROR_STACK,
+            StackTraces.getStackTrace(error, Config.get().getStackTraceLengthLimit()));
       }
 
       setTag(DDTags.ERROR_MSG, message);

@@ -0,0 +1,145 @@
+package datadog.trace.core.util;
+
+import java.io.BufferedReader;
+import java.io.PrintWriter;
+import java.io.StringReader;
+import java.io.StringWriter;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+import java.util.stream.Collectors;
+
+public final class StackTraces {
+  private StackTraces() {}
+
+  public static String getStackTrace(Throwable t, int maxChars) {
+    StringWriter sw = new StringWriter();
+    t.printStackTrace(new PrintWriter(sw));
+    String trace = sw.toString();
+    try {
+      return truncate(trace, maxChars);
+    } catch (Exception e) {
+      // If something goes wrong, return the original trace
+      return trace;
+    }
+  }
+
+  static String truncate(String trace, int maxChars) {
+    if (trace.length() <= maxChars) {
+      return trace;
+    }
+
+    trace = abbreviatePackageNames(trace);
+    if (trace.length() <= maxChars) {
+      return trace;
+    }
+
+    trace = removeStackTraceMiddleForEachException(trace);
+    if (trace.length() <= maxChars) {
+      return trace;
+    }
+
+    /* last-ditch centre cut to guarantee the limit */
+    String cutMessage = "\t... trace centre-cut to " + maxChars + " chars ...";
+    int retainedLength = maxChars - cutMessage.length() - 2; // 2 for the newlines
+    int half = retainedLength / 2;
+    return trace.substring(0, half)
+        + System.lineSeparator()
+        + cutMessage
+        + System.lineSeparator()
+        + trace.substring(trace.length() - (retainedLength - half));
+  }
+
+  private static final Pattern FRAME = Pattern.compile("^\\s*at ([^(]+)(\\(.*)$");
+
+  private static String abbreviatePackageNames(String trace) {
+    StringBuilder sb = new StringBuilder(trace.length());
+    new BufferedReader(new StringReader(trace))
+        .lines()
+        .forEach(
+            line -> {
+              Matcher m = FRAME.matcher(line);
+              if (m.matches()) {
+                sb.append("\tat ").append(abbreviatePackageName(m.group(1))).append(m.group(2));
+              } else {
+                sb.append(line);
+              }
+              sb.append(System.lineSeparator());
+            });
+    return sb.toString();
+  }
+
+  /**
+   * Abbreviates only the package part of a fully qualified class name with member. For example,
+   * "com.myorg.MyClass.myMethod" to "c.m.MyClass.myMethod". If there is no package (e.g.
+   * "MyClass.myMethod"), returns the input unchanged.
+   */
+  private static String abbreviatePackageName(String fqcnWithMember) {
+    int lastDot = fqcnWithMember.lastIndexOf('.');
+    if (lastDot < 0) {
+      return fqcnWithMember;
+    }
+    int preClassDot = fqcnWithMember.lastIndexOf('.', lastDot - 1);
+    if (preClassDot < 0) {
+      return fqcnWithMember;
+    }
+    String packagePart = fqcnWithMember.substring(0, preClassDot);
+    String classAndAfter = fqcnWithMember.substring(preClassDot + 1);
+
+    StringBuilder sb = new StringBuilder(fqcnWithMember.length());
+    int segmentStart = 0;
+    for (int i = 0; i <= packagePart.length(); i++) {
      if (i == packagePart.length() || packagePart.charAt(i) == '.') {
+        sb.append(packagePart.charAt(segmentStart)).append('.');
+        segmentStart = i + 1;
+      }
+    }
+    sb.append(classAndAfter);
+    return sb.toString();
+  }
+
+  private static final int HEAD_LINES = 8, TAIL_LINES = 4;
+
+  /**
+   * Removes lines from the middle of each exception stack trace, leaving {@link
+   * StackTraces#HEAD_LINES} lines at the beginning and {@link StackTraces#TAIL_LINES} lines at the
+   * end
+   */
+  private static String removeStackTraceMiddleForEachException(String trace) {
+    List<String> lines =
+        new BufferedReader(new StringReader(trace)).lines().collect(Collectors.toList());
+    List<String> out = new ArrayList<>(lines.size());
+    int i = 0;
+    while (i < lines.size()) {
+      out.add(lines.get(i++)); // "Exception ..." / "Caused by: ..."
+      int start = i;
+      while (i < lines.size() && lines.get(i).startsWith("\tat")) {
+        i++;
+      }
+
+      int total = i - start;
+
+      int keepHead = Math.min(HEAD_LINES, total);
+      for (int j = 0; j < keepHead; j++) {
+        out.add(lines.get(start + j));
+      }
+
+      int keepTail = Math.min(TAIL_LINES, total - keepHead);
+      int skipped = total - keepHead - keepTail;
+      if (skipped > 0) {
+        out.add("\t... " + skipped + " trimmed ...");
+      }
+
+      for (int j = total - keepTail; j < total; j++) {
+        out.add(lines.get(start + j));
+      }
+
+      // "... n more" continuation markers
+      if (i < lines.size() && lines.get(i).startsWith("\t...")) {
+        out.add(lines.get(i++));
+      }
+    }
+    return String.join(System.lineSeparator(), out) + System.lineSeparator();
+  }
+}
@@ -0,0 +1,188 @@
+package datadog.trace.core.util
+
+
+import spock.lang.Specification
+
+class StackTracesTest extends Specification {
+
+  def "test stack trace truncation: #limit"() {
+    given:
+    def trace = """
+Exception in thread "main" com.example.app.MainException: Unexpected application failure
+    at com.example.app.Application\$Runner.run(Application.java:102)
+    at com.example.app.Application.lambda\$start\$0(Application.java:75)
+    at java.base/java.util.Optional.ifPresent(Optional.java:178)
+    at com.example.app.Application.start(Application.java:74)
+    at com.example.app.Main.main(Main.java:21)
+    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
+    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
+    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
+    at java.base/java.lang.reflect.Method.invoke(Method.java:566)
+    at com.example.launcher.Bootstrap.run(Bootstrap.java:39)
+    at com.example.launcher.Bootstrap.main(Bootstrap.java:25)
+    at com.example.internal.\$Proxy1.start(Unknown Source)
+    at com.example.internal.Initializer\$1.run(Initializer.java:47)
+    at com.example.internal.Initializer.lambda\$init\$0(Initializer.java:38)
+    at java.base/java.util.concurrent.Executors\$RunnableAdapter.call(Executors.java:515)
+    at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
+    at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
+    at java.base/java.util.concurrent.ThreadPoolExecutor\$Worker.run(ThreadPoolExecutor.java:628)
+    at java.base/java.lang.Thread.run(Thread.java:834)
+    at com.example.synthetic.Helper.access\$100(Helper.java:14)
+Caused by: com.example.db.DatabaseException: Failed to load user data
+    at com.example.db.UserDao.findUser(UserDao.java:88)
+    at com.example.db.UserDao.lambda\$cacheLookup\$1(UserDao.java:64)
+    at com.example.cache.Cache\$Entry.computeIfAbsent(Cache.java:111)
+    at com.example.cache.Cache.get(Cache.java:65)
+    at com.example.service.UserService.loadUser(UserService.java:42)
+    at com.example.service.UserService.lambda\$loadUserAsync\$0(UserService.java:36)
+    at com.example.util.SafeRunner.run(SafeRunner.java:27)
+    at java.base/java.util.concurrent.Executors\$RunnableAdapter.call(Executors.java:515)
+    at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
+    at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
+    at java.base/java.util.concurrent.ThreadPoolExecutor\$Worker.run(ThreadPoolExecutor.java:628)
+    at java.base/java.lang.Thread.run(Thread.java:834)
+    at com.example.synthetic.UserDao\$1.run(UserDao.java:94)
+    at com.example.synthetic.UserDao\$1.run(UserDao.java:94)
+    at com.example.db.ConnectionManager.getConnection(ConnectionManager.java:55)
+Suppressed: java.io.IOException: Resource cleanup failed
+    at com.example.util.ResourceManager.close(ResourceManager.java:23)
+    at com.example.service.UserService.lambda\$loadUserAsync\$0(UserService.java:38)
+    ... 3 more
+Caused by: java.nio.file.AccessDeniedException: /data/user/config.json
+    at java.base/sun.nio.fs.UnixException.translateToIOException(UnixException.java:90)
+    at java.base/sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:111)
+    at java.base/sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:116)
+    at java.base/sun.nio.fs.UnixFileSystemProvider.newByteChannel(UnixFileSystemProvider.java:219)
+    at java.base/java.nio.file.Files.newByteChannel(Files.java:375)
+    at java.base/java.nio.file.Files.newInputStream(Files.java:489)
+    at com.example.util.FileUtils.readFile(FileUtils.java:22)
+    at com.example.util.ResourceManager.close(ResourceManager.java:21)
+    ... 3 more
+"""
+
+    expect:
+    StackTraces.truncate(trace, limit) == expected
+
+    where:
+    limit | expected
+    1000  | """
+Exception in thread "main" com.example.app.MainException: Unexpected application failure
+	at c.e.a.Application\$Runner.run(Application.java:102)
+	at c.e.a.Application.lambda\$start\$0(Application.java:75)
+	at j.b.u.Optional.ifPresent(Optional.java:178)
+	at c.e.a.Application.start(Application.java:74)
+	at c.e.a.Main.main(Main.java:21)
+	at s.r.NativeMethodAccessorImpl.invoke0(Native Method)
+	at s.r.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
+	at s.r.Delegat
+	... trace centre-cut to 1000 chars ...
+ToIOException(UnixException.java:90)
+	at j.b.n.f.UnixException.rethrowAsIOException(UnixException.java:111)
+	at j.b.n.f.UnixException.rethrowAsIOException(UnixException.java:116)
+	at j.b.n.f.UnixFileSystemProvider.newByteChannel(UnixFileSystemProvider.java:219)
+	at j.b.n.f.Files.newByteChannel(Files.java:375)
+	at j.b.n.f.Files.newInputStream(Files.java:489)
+	at c.e.u.FileUtils.readFile(FileUtils.java:22)
+	at c.e.u.ResourceManager.close(ResourceManager.java:21)
+    ... 3 more
+"""
+    2500  | """
+Exception in thread "main" com.example.app.MainException: Unexpected application failure
+	at c.e.a.Application\$Runner.run(Application.java:102)
+	at c.e.a.Application.lambda\$start\$0(Application.java:75)
+	at j.b.u.Optional.ifPresent(Optional.java:178)
+	at c.e.a.Application.start(Application.java:74)
+	at c.e.a.Main.main(Main.java:21)
+	at s.r.NativeMethodAccessorImpl.invoke0(Native Method)
+	at s.r.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
+	at s.r.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
+	... 8 trimmed ...
+	at j.b.u.c.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
+	at j.b.u.c.ThreadPoolExecutor\$Worker.run(ThreadPoolExecutor.java:628)
+	at j.b.l.Thread.run(Thread.java:834)
+	at c.e.s.Helper.access\$100(Helper.java:14)
+Caused by: com.example.db.DatabaseException: Failed to load user data
+	at c.e.d.UserDao.findUser(UserDao.java:88)
+	at c.e.d.UserDao.lambda\$cacheLookup\$1(UserDao.java:64)
+	at c.e.c.Cache\$Entry.computeIfAbsent(Cache.java:111)
+	at c.e.c.Cache.get(Cache.java:65)
+	at c.e.s.UserService.loadUser(UserService.java:42)
+	at c.e.s.UserService.lambda\$loadUserAsync\$0(UserService.java:36)
+	at c.e.u.SafeRunner.run(SafeRunner.java:27)
+	at j.b.u.c.Executors\$RunnableAdapter.call(Executors.java:515)
+	... 3 trimmed ...
+	at j.b.l.Thread.run(Thread.java:834)
+	at c.e.s.UserDao\$1.run(UserDao.java:94)
+	at c.e.s.UserDao\$1.run(UserDao.java:94)
+	at c.e.d.ConnectionManager.getConnection(ConnectionManager.java:55)
+Suppressed: java.io.IOException: Resource cleanup failed
+	at c.e.u.ResourceManager.close(ResourceManager.java:23)
+	at c.e.s.UserService.lambda\$loadUserAsync\$0(UserService.java:38)
+    ... 3 more
+Caused by: java.nio.file.AccessDeniedException: /data/user/config.json
+	at j.b.n.f.UnixException.translateToIOException(UnixException.java:90)
+	at j.b.n.f.UnixException.rethrowAsIOException(UnixException.java:111)
+	at j.b.n.f.UnixException.rethrowAsIOException(UnixException.java:116)
+	at j.b.n.f.UnixFileSystemProvider.newByteChannel(UnixFileSystemProvider.java:219)
+	at j.b.n.f.Files.newByteChannel(Files.java:375)
+	at j.b.n.f.Files.newInputStream(Files.java:489)
+	at c.e.u.FileUtils.readFile(FileUtils.java:22)
+	at c.e.u.ResourceManager.close(ResourceManager.java:21)
+    ... 3 more
+"""
+    3000  | """
+Exception in thread "main" com.example.app.MainException: Unexpected application failure
+	at c.e.a.Application\$Runner.run(Application.java:102)
+	at c.e.a.Application.lambda\$start\$0(Application.java:75)
+	at j.b.u.Optional.ifPresent(Optional.java:178)
+	at c.e.a.Application.start(Application.java:74)
+	at c.e.a.Main.main(Main.java:21)
+	at s.r.NativeMethodAccessorImpl.invoke0(Native Method)
+	at s.r.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
+	at s.r.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
+	at j.b.l.r.Method.invoke(Method.java:566)
+	at c.e.l.Bootstrap.run(Bootstrap.java:39)
+	at c.e.l.Bootstrap.main(Bootstrap.java:25)
+	at c.e.i.\$Proxy1.start(Unknown Source)
+	at c.e.i.Initializer\$1.run(Initializer.java:47)
+	at c.e.i.Initializer.lambda\$init\$0(Initializer.java:38)
+	at j.b.u.c.Executors\$RunnableAdapter.call(Executors.java:515)
+	at j.b.u.c.FutureTask.run(FutureTask.java:264)
+	at j.b.u.c.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
+	at j.b.u.c.ThreadPoolExecutor\$Worker.run(ThreadPoolExecutor.java:628)
+	at j.b.l.Thread.run(Thread.java:834)
+	at c.e.s.Helper.access\$100(Helper.java:14)
+Caused by: com.example.db.DatabaseException: Failed to load user data
+	at c.e.d.UserDao.findUser(UserDao.java:88)
+	at c.e.d.UserDao.lambda\$cacheLookup\$1(UserDao.java:64)
+	at c.e.c.Cache\$Entry.computeIfAbsent(Cache.java:111)
+	at c.e.c.Cache.get(Cache.java:65)
+	at c.e.s.UserService.loadUser(UserService.java:42)
+	at c.e.s.UserService.lambda\$loadUserAsync\$0(UserService.java:36)
+	at c.e.u.SafeRunner.run(SafeRunner.java:27)
+	at j.b.u.c.Executors\$RunnableAdapter.call(Executors.java:515)
+	at j.b.u.c.FutureTask.run(FutureTask.java:264)
+	at j.b.u.c.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
+	at j.b.u.c.ThreadPoolExecutor\$Worker.run(ThreadPoolExecutor.java:628)
+	at j.b.l.Thread.run(Thread.java:834)
+	at c.e.s.UserDao\$1.run(UserDao.java:94)
+	at c.e.s.UserDao\$1.run(UserDao.java:94)
+	at c.e.d.ConnectionManager.getConnection(ConnectionManager.java:55)
+Suppressed: java.io.IOException: Resource cleanup failed
+	at c.e.u.ResourceManager.close(ResourceManager.java:23)
+	at c.e.s.UserService.lambda\$loadUserAsync\$0(UserService.java:38)
+    ... 3 more
+Caused by: java.nio.file.AccessDeniedException: /data/user/config.json
+	at j.b.n.f.UnixException.translateToIOException(UnixException.java:90)
+	at j.b.n.f.UnixException.rethrowAsIOException(UnixException.java:111)
+	at j.b.n.f.UnixException.rethrowAsIOException(UnixException.java:116)
+	at j.b.n.f.UnixFileSystemProvider.newByteChannel(UnixFileSystemProvider.java:219)
+	at j.b.n.f.Files.newByteChannel(Files.java:375)
+	at j.b.n.f.Files.newInputStream(Files.java:489)
+	at c.e.u.FileUtils.readFile(FileUtils.java:22)
+	at c.e.u.ResourceManager.close(ResourceManager.java:21)
+    ... 3 more
+"""
+  }
+}
@@ -575,6 +575,8 @@ public static String getHostName() {
 
   private final boolean jdkSocketEnabled;
 
+  private final int stackTraceLengthLimit;
+
   // Read order: System Properties -> Env Variables, [-> properties file], [-> default value]
   private Config() {
     this(ConfigProvider.createDefault());
@@ -2024,6 +2026,13 @@ PROFILING_DATADOG_PROFILER_ENABLED, isDatadogProfilerSafeInCurrentEnvironment())
 
     this.jdkSocketEnabled = configProvider.getBoolean(JDK_SOCKET_ENABLED, false);
 
+    int defaultStackTraceLengthLimit =
+        instrumenterConfig.isCiVisibilityEnabled()
+            ? 5000 // EVP limit
+            : Integer.MAX_VALUE; // no effective limit (old behavior)
+    this.stackTraceLengthLimit =
+        configProvider.getInteger(STACK_TRACE_LENGTH_LIMIT, defaultStackTraceLengthLimit);
+
     log.debug("New instance: {}", this);
   }
 
@@ -3646,6 +3655,10 @@ public boolean isJdkSocketEnabled() {
     return jdkSocketEnabled;
   }
 
+  public int getStackTraceLengthLimit() {
+    return stackTraceLengthLimit;
+  }
+
   /** @return A map of tags to be applied only to the local application root span. */
   public Map<String, Object> getLocalRootSpanTags() {
     final Map<String, String> runtimeTags = getRuntimeTags();