From eb0b03c579cfd90ebfeeaa115955a0a924c9ce0f Mon Sep 17 00:00:00 2001
From: Volker Krause <volker.krause@kdab.com>
Date: Wed, 6 Jan 2016 15:39:01 +0100
Subject: QPair<QRunnable*, int> is too large for QList to be efficient-ish.

Qt3D is making heavy use of this, causing the QList node allocations
to be among the top 10 per frame allocation sources. Switching to
QVector fixes that.

Change-Id: I3b4df329710f82bf8d6797ea1f0c79b288a08063
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>
---
 src/corelib/thread/qthreadpool.cpp | 10 +++++-----
 src/corelib/thread/qthreadpool_p.h |  2 +-
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/corelib/thread/qthreadpool.cpp b/src/corelib/thread/qthreadpool.cpp
index b6b3be8d92..e4a5368281 100644
--- a/src/corelib/thread/qthreadpool.cpp
+++ b/src/corelib/thread/qthreadpool.cpp
@@ -204,8 +204,8 @@ void QThreadPoolPrivate::enqueueTask(QRunnable *runnable, int priority)
         ++runnable->ref;
 
     // put it on the queue
-    QList<QPair<QRunnable *, int> >::const_iterator begin = queue.constBegin();
-    QList<QPair<QRunnable *, int> >::const_iterator it = queue.constEnd();
+    QVector<QPair<QRunnable *, int> >::const_iterator begin = queue.constBegin();
+    QVector<QPair<QRunnable *, int> >::const_iterator it = queue.constEnd();
     if (it != begin && priority > (*(it - 1)).second)
         it = std::upper_bound(begin, --it, priority);
     queue.insert(it - begin, qMakePair(runnable, priority));
@@ -299,7 +299,7 @@ bool QThreadPoolPrivate::waitForDone(int msecs)
 void QThreadPoolPrivate::clear()
 {
     QMutexLocker locker(&mutex);
-    for (QList<QPair<QRunnable *, int> >::const_iterator it = queue.constBegin();
+    for (QVector<QPair<QRunnable *, int> >::const_iterator it = queue.constBegin();
          it != queue.constEnd(); ++it) {
         QRunnable* r = it->first;
         if (r->autoDelete() && !--r->ref)
@@ -319,8 +319,8 @@ bool QThreadPoolPrivate::stealRunnable(QRunnable *runnable)
         return false;
     {
         QMutexLocker locker(&mutex);
-        QList<QPair<QRunnable *, int> >::iterator it = queue.begin();
-        QList<QPair<QRunnable *, int> >::iterator end = queue.end();
+        QVector<QPair<QRunnable *, int> >::iterator it = queue.begin();
+        QVector<QPair<QRunnable *, int> >::iterator end = queue.end();
 
         while (it != end) {
             if (it->first == runnable) {
diff --git a/src/corelib/thread/qthreadpool_p.h b/src/corelib/thread/qthreadpool_p.h
index 34728ed3e2..b03eefcc94 100644
--- a/src/corelib/thread/qthreadpool_p.h
+++ b/src/corelib/thread/qthreadpool_p.h
@@ -83,7 +83,7 @@ public:
     QSet<QThreadPoolThread *> allThreads;
     QQueue<QThreadPoolThread *> waitingThreads;
     QQueue<QThreadPoolThread *> expiredThreads;
-    QList<QPair<QRunnable *, int> > queue;
+    QVector<QPair<QRunnable *, int> > queue;
     QWaitCondition noActiveThreads;
 
     bool isExiting;
-- 
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