arangodb · jsteemann · Mar 13, 2020 · Mar 13, 2020 · Mar 13, 2020 · Mar 13, 2020
diff --git a/CHANGELOG b/CHANGELOG
@@ -1,7 +1,9 @@
 devel
 -----
 
-
+* Allow to override the detected total amount of memory via an environment
+  variable ARANGODB_OVERRIDE_DETECTED_TOTAL_MEMORY.
+
 * `splice-subqueries` optimization is not limited by any type of operation within the
   subquery any more. It can now be applied on every subquery and will be by default.
   However they may be a performance impact on some queries where splice-subqueries

diff --git a/lib/ApplicationFeatures/EnvironmentFeature.cpp b/lib/ApplicationFeatures/EnvironmentFeature.cpp
@@ -246,6 +246,15 @@ void EnvironmentFeature::prepare() {
     // file not found or value not convertible into integer
   }
 
+  // Report memory found:
+  uint64_t ram = PhysicalMemory::getValue();
+  std::string overriddenmsg;
+  if (PhysicalMemory::overridden()) {
+    overriddenmsg = " (overridden by environment variable)";
+  }
+  LOG_TOPIC("25362", INFO, Logger::MEMORY)
+  << "Available physical memory: " << ram << overriddenmsg;
+
   // test local ipv6 support
   try {
     if (!basics::FileUtils::exists("/proc/net/if_inet6")) {

diff --git a/lib/Basics/PhysicalMemory.cpp b/lib/Basics/PhysicalMemory.cpp
@@ -23,6 +23,8 @@
 #include "Basics/operating-system.h"
 
 #include "Basics/PhysicalMemory.h"
+#include "Basics/StringUtils.h"
+#include "Basics/files.h"
 
 #ifdef TRI_HAVE_UNISTD_H
 #include <unistd.h>
@@ -90,10 +92,32 @@ uint64_t physicalMemoryImpl() {
 #endif
 #endif
 
-
 struct PhysicalMemoryCache {
-  PhysicalMemoryCache() : cachedValue(physicalMemoryImpl()) {}
-  uint64_t const cachedValue;
+  PhysicalMemoryCache() : cachedValue(physicalMemoryImpl()), overridden(false) {
+    std::string value;
+    if (TRI_GETENV("ARANGODB_OVERRIDE_DETECTED_TOTAL_MEMORY", value)) {
+      if (!value.empty()) {
+        uint64_t multiplier = 1;
+        if (value.back() == 'G' || value.back() == 'g') {
+          multiplier = 1024*1024*1024;
+          value.pop_back();
+        } else if (value.back() == 'M' || value.back() == 'm') {
+          multiplier = 1024 * 1024;
+          value.pop_back();
+        } else if (value.back() == 'K' || value.back() == 'k') {
+          multiplier = 1024;
+          value.pop_back();
+        }
+        uint64_t v = arangodb::basics::StringUtils::uint64(value) * multiplier;
+        if (v != 0) {
+          cachedValue = v;
+          overridden = true;
+        }
+      }
+    }
+  }
+  uint64_t cachedValue;
+  bool overridden;
 };
 
 PhysicalMemoryCache const cache;
@@ -104,3 +128,8 @@ PhysicalMemoryCache const cache;
 uint64_t arangodb::PhysicalMemory::getValue() {
   return ::cache.cachedValue;
 }
+
+/// @brief return if physical memory size was overridden
+bool arangodb::PhysicalMemory::overridden() {
+  return ::cache.overridden;
+}
diff --git a/lib/Basics/PhysicalMemory.h b/lib/Basics/PhysicalMemory.h
@@ -30,6 +30,7 @@ namespace PhysicalMemory {
 
 /// @brief return system's physical memory
 uint64_t getValue();
+bool overridden();
 
 } 
 }  // namespace arangodb

diff --git a/lib/Logger/LogTopic.cpp b/lib/Logger/LogTopic.cpp
@@ -132,7 +132,7 @@ LogTopic Logger::GRAPHS("graphs", LogLevel::INFO);
 LogTopic Logger::HEARTBEAT("heartbeat", LogLevel::INFO);
 LogTopic Logger::HTTPCLIENT("httpclient", LogLevel::WARN);
 LogTopic Logger::MAINTENANCE("maintenance", LogLevel::WARN);
-LogTopic Logger::MEMORY("memory", LogLevel::WARN);
+LogTopic Logger::MEMORY("memory", LogLevel::INFO);
 LogTopic Logger::MMAP("mmap");
 LogTopic Logger::PERFORMANCE("performance", LogLevel::WARN);
 LogTopic Logger::PREGEL("pregel", LogLevel::INFO);