[Lldb-commits] [PATCH] D117601: [lldb] Make Python initialization atomic

[Jonas Devlieghere via Phabricator via lldb-commits]

JDevlieghere created this revision.
JDevlieghere added reviewers: labath, mib.
JDevlieghere requested review of this revision.

We got a few crash reports that showed LLDB initializing Python on two separate 
threads. Make `g_initialized` atomic to prevent that from happening.


https://reviews.llvm.org/D117601

Files:
  lldb/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp


Index: lldb/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp
===================================================================
--- lldb/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp
+++ lldb/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp
@@ -85,7 +85,7 @@
   return static_cast<ScriptInterpreterPythonImpl *>(script_interpreter);
 }
 
-static bool g_initialized = false;
+static std::atomic<bool> g_initialized(false);
 
 namespace {
 
@@ -3194,11 +3194,12 @@
 #endif
 
 void ScriptInterpreterPythonImpl::InitializePrivate() {
-  if (g_initialized)
+  bool initialized = false;
+  const bool exchanged =
+      g_initialized.compare_exchange_strong(initialized, true);
+  if (!exchanged)
     return;
 
-  g_initialized = true;
-
   LLDB_SCOPED_TIMER();
 
   // RAII-based initialization which correctly handles multiple-initialization,



Index: lldb/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp
===================================================================
--- lldb/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp
+++ lldb/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp
@@ -85,7 +85,7 @@
   return static_cast<ScriptInterpreterPythonImpl *>(script_interpreter);
 }
 
-static bool g_initialized = false;
+static std::atomic<bool> g_initialized(false);
 
 namespace {
 
@@ -3194,11 +3194,12 @@
 #endif
 
 void ScriptInterpreterPythonImpl::InitializePrivate() {
-  if (g_initialized)
+  bool initialized = false;
+  const bool exchanged =
+      g_initialized.compare_exchange_strong(initialized, true);
+  if (!exchanged)
     return;
 
-  g_initialized = true;
-
   LLDB_SCOPED_TIMER();
 
   // RAII-based initialization which correctly handles multiple-initialization,

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