tor-browser

commit 6ced9e58b4ecfd128e421d207e8fa85715de5a9e
parent b0cc2184b03315b546d1621072341ac2c23a6f36
Author: Jens Stutte <jstutte@mozilla.com>
Date:   Wed,  3 Dec 2025 08:03:56 +0000

Bug 2003538 - Correct mIsAPoolThreadFree calculation to include idle threads. r=xpcom-reviewers,nika

Differential Revision: https://phabricator.services.mozilla.com/D274761

Diffstat:
M
xpcom/threads/nsThread.cpp
 | 
8
++++----
M
xpcom/threads/nsThread.h
 | 
6
+++---
M
xpcom/threads/nsThreadPool.cpp
 | 
10
++++++----

3 files changed, 13 insertions(+), 11 deletions(-)
diff --git a/xpcom/threads/nsThread.cpp b/xpcom/threads/nsThread.cpp
@@ -553,7 +553,7 @@ nsThread::nsThread(NotNull<SynchronizedEventQueue*> aQueue,
       mIsMainThread(aMainThread == MAIN_THREAD),
       mUseHangMonitor(aMainThread == MAIN_THREAD),
       mIsUiThread(aOptions.isUiThread),
-      mIsAPoolThreadFree(nullptr),
+      mIsAPoolThreadFreePtr(nullptr),
       mCanInvokeJS(false),
       mPerformanceCounterState(mNestedEventLoopDepth, mIsMainThread,
                                aOptions.longTaskLength) {
@@ -721,9 +721,9 @@ nsThread::UnregisterShutdownTask(nsITargetShutdownTask* aTask) {
 
 NS_IMETHODIMP
 nsThread::GetRunningEventDelay(TimeDuration* aDelay, TimeStamp* aStart) {
-  if (mIsAPoolThreadFree && *mIsAPoolThreadFree) {
-    // if there are unstarted threads in the pool, a new event to the
-    // pool would not be delayed at all (beyond thread start time)
+  if (mIsAPoolThreadFreePtr && *mIsAPoolThreadFreePtr) {
+    // If there are idle or unstarted threads in the pool, a new event to the
+    // pool would not be delayed at all (beyond thread wake / start time).
     *aDelay = TimeDuration();
     *aStart = TimeStamp();
   } else {
diff --git a/xpcom/threads/nsThread.h b/xpcom/threads/nsThread.h
@@ -202,9 +202,9 @@ class nsThread : public nsIThreadInternal,
   bool ShutdownRequired() { return mShutdownRequired; }
 
   // Lets GetRunningEventDelay() determine if the pool this is part
-  // of has an unstarted thread
+  // of has an idle or unstarted thread.
   void SetPoolThreadFreePtr(mozilla::Atomic<bool, mozilla::Relaxed>* aPtr) {
-    mIsAPoolThreadFree = aPtr;
+    mIsAPoolThreadFreePtr = aPtr;
   }
 
   void SetScriptObserver(mozilla::CycleCollectedJSContext* aScriptObserver);
@@ -292,7 +292,7 @@ class nsThread : public nsIThreadInternal,
   const bool mIsMainThread;
   bool mUseHangMonitor;
   const bool mIsUiThread;
-  mozilla::Atomic<bool, mozilla::Relaxed>* mIsAPoolThreadFree;
+  mozilla::Atomic<bool, mozilla::Relaxed>* mIsAPoolThreadFreePtr;
 
   // Set to true if this thread creates a JSRuntime.
   bool mCanInvokeJS;
diff --git a/xpcom/threads/nsThreadPool.cpp b/xpcom/threads/nsThreadPool.cpp
@@ -220,6 +220,7 @@ nsresult nsThreadPool::PutEvent(already_AddRefed<nsIRunnable> aEvent,
 
   mThreads.AppendObject(thread);
   if (mThreads.Count() >= (int32_t)mThreadLimit) {
+    MOZ_ASSERT(mMRUIdleThreads.isEmpty());
     mIsAPoolThreadFree = false;
   }
 
@@ -389,10 +390,11 @@ nsThreadPool::Run() {
           DebugOnly<bool> found = mThreads.RemoveObject(current);
           MOZ_ASSERT(found || (mShutdown && mThreads.IsEmpty()));
 
-          // Keep track if there are threads available to start. If we are
-          // shutting down, no new threads can start.
+          // Keep track if there are threads available. If we are shutting
+          // down, no new threads can start.
           mIsAPoolThreadFree =
-              !mShutdown && (mThreads.Count() < (int32_t)mThreadLimit);
+              !mMRUIdleThreads.isEmpty() ||
+              (!mShutdown && mThreads.Count() < (int32_t)mThreadLimit);
         } else {
           current->SetRunningEventDelay(TimeDuration(), TimeStamp());
 
@@ -560,7 +562,7 @@ nsThreadPool::ShutdownWithTimeout(int32_t aTimeoutMs) {
     // join each thread.
     name = mName;
     mShutdown = true;
-    mIsAPoolThreadFree = false;
+    mIsAPoolThreadFree = !mMRUIdleThreads.isEmpty();
     NotifyChangeToAllIdleThreads();
 
     // From now on we do not allow the creation of new threads, and threads