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-rw-r--r--src/corelib/concurrent/qthreadpool.cpp10
1 files changed, 8 insertions, 2 deletions
diff --git a/src/corelib/concurrent/qthreadpool.cpp b/src/corelib/concurrent/qthreadpool.cpp
index 83374da..9c53b7e 100644
--- a/src/corelib/concurrent/qthreadpool.cpp
+++ b/src/corelib/concurrent/qthreadpool.cpp
@@ -222,6 +222,8 @@ void QThreadPoolPrivate::enqueueTask(QRunnable *runnable, int priority)
int QThreadPoolPrivate::activeThreadCount() const
{
+ // To improve scalability this function is called without holding
+ // the mutex lock -- keep it thread-safe.
return (allThreads.count()
- expiredThreads.count()
- waitingThreads
@@ -481,6 +483,12 @@ bool QThreadPool::tryStart(QRunnable *runnable)
return false;
Q_D(QThreadPool);
+
+ // To improve scalability perform a check on the thread count
+ // before locking the mutex.
+ if (d->allThreads.isEmpty() == false && d->activeThreadCount() >= d->maxThreadCount)
+ return false;
+
QMutexLocker locker(&d->mutex);
return d->tryStart(runnable);
}
@@ -527,7 +535,6 @@ void QThreadPool::setExpiryTimeout(int expiryTimeout)
int QThreadPool::maxThreadCount() const
{
Q_D(const QThreadPool);
- QMutexLocker locker(&d->mutex);
return d->maxThreadCount;
}
@@ -556,7 +563,6 @@ void QThreadPool::setMaxThreadCount(int maxThreadCount)
int QThreadPool::activeThreadCount() const
{
Q_D(const QThreadPool);
- QMutexLocker locker(&d->mutex);
return d->activeThreadCount();
}