File 0001-Do-not-multithread-if-already-in-a-global-threadpool.patch of Package libqt5-qtbase
From 5801eb483cce1a9c459b3e86d57dc6fe6f643480 Mon Sep 17 00:00:00 2001
From: Allan Sandfeld Jensen <allan.jensen@qt.io>
Date: Tue, 2 Jun 2020 10:59:21 +0200
Subject: [PATCH] Do not multithread if already in a global threadpool thread
This can lead to a deadlock if we block all the worker threads, waiting
for the worker threads to finish.
Fixes: QTBUG-84619
Change-Id: I92b7f96007897d86ece0c34223bab0df4ccbed9a
Reviewed-by: Sona Kurazyan <sona.kurazyan@qt.io>
(cherry picked from commit 87d32424de2f471a520c1f3ba0c3035fbff7ee06)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
---
src/corelib/thread/qthreadpool.cpp | 24 ++++++++++++++++++++++++
src/corelib/thread/qthreadpool.h | 2 ++
src/gui/image/qimage.cpp | 7 ++++---
src/gui/image/qimage_conversions.cpp | 15 +++++++++------
src/gui/painting/qimagescale.cpp | 5 +++--
src/gui/painting/qimagescale_neon.cpp | 5 +++--
src/gui/painting/qimagescale_sse4.cpp | 5 +++--
7 files changed, 48 insertions(+), 15 deletions(-)
diff --git a/src/corelib/thread/qthreadpool.cpp b/src/corelib/thread/qthreadpool.cpp
index 44cdf071df..a583298f01 100644
--- a/src/corelib/thread/qthreadpool.cpp
+++ b/src/corelib/thread/qthreadpool.cpp
@@ -52,6 +52,7 @@ Q_GLOBAL_STATIC(QThreadPool, theInstance)
*/
class QThreadPoolThread : public QThread
{
+ Q_OBJECT
public:
QThreadPoolThread(QThreadPoolPrivate *manager);
void run() override;
@@ -745,6 +746,28 @@ void QThreadPool::clear()
d->clear();
}
+#if QT_VERSION < QT_VERSION_CHECK(6,0,0)
+/*!
+ \internal
+
+ Returns \c true if \a thread is a thread managed by this thread pool.
+*/
+#else
+/*!
+ \since 6.0
+
+ Returns \c true if \a thread is a thread managed by this thread pool.
+*/
+#endif
+bool QThreadPool::contains(const QThread *thread) const
+{
+ Q_D(const QThreadPool);
+ const QThreadPoolThread *poolThread = qobject_cast<const QThreadPoolThread *>(thread);
+ if (!poolThread)
+ return false;
+ return d->allThreads.contains(const_cast<QThreadPoolThread *>(poolThread));
+}
+
#if QT_DEPRECATED_SINCE(5, 9)
/*!
\since 5.5
@@ -766,3 +789,4 @@ void QThreadPool::cancel(QRunnable *runnable)
QT_END_NAMESPACE
#include "moc_qthreadpool.cpp"
+#include "qthreadpool.moc"
diff --git a/src/corelib/thread/qthreadpool.h b/src/corelib/thread/qthreadpool.h
index e3691ab010..004f76a240 100644
--- a/src/corelib/thread/qthreadpool.h
+++ b/src/corelib/thread/qthreadpool.h
@@ -93,6 +93,8 @@ public:
void clear();
+ bool contains(const QThread *thread) const;
+
#if QT_DEPRECATED_SINCE(5, 9)
QT_DEPRECATED_X("use tryTake(), but note the different deletion rules")
void cancel(QRunnable *runnable);
diff --git a/src/gui/image/qimage.cpp b/src/gui/image/qimage.cpp
index 2646d298e9..17c31cd8ae 100644
--- a/src/gui/image/qimage.cpp
+++ b/src/gui/image/qimage.cpp
@@ -5047,15 +5047,16 @@ void QImage::applyColorTransform(const QColorTransform &transform)
};
}
-#if QT_CONFIG(thread)
+#if QT_CONFIG(thread) && !defined(Q_OS_WASM)
int segments = sizeInBytes() / (1<<16);
segments = std::min(segments, height());
- if (segments > 1) {
+ QThreadPool *threadPool = QThreadPool::globalInstance();
+ if (segments > 1 && !threadPool->contains(QThread::currentThread())) {
QSemaphore semaphore;
int y = 0;
for (int i = 0; i < segments; ++i) {
int yn = (height() - y) / (segments - i);
- QThreadPool::globalInstance()->start([&, y, yn]() {
+ threadPool->start([&, y, yn]() {
transformSegment(y, y + yn);
semaphore.release(1);
});
diff --git a/src/gui/image/qimage_conversions.cpp b/src/gui/image/qimage_conversions.cpp
index 506ebc797f..cbfdbdeadb 100644
--- a/src/gui/image/qimage_conversions.cpp
+++ b/src/gui/image/qimage_conversions.cpp
@@ -236,14 +236,15 @@ void convert_generic(QImageData *dest, const QImageData *src, Qt::ImageConversio
int segments = src->nbytes / (1<<16);
segments = std::min(segments, src->height);
- if (segments <= 1)
+ QThreadPool *threadPool = QThreadPool::globalInstance();
+ if (segments <= 1 || threadPool->contains(QThread::currentThread()))
return convertSegment(0, src->height);
QSemaphore semaphore;
int y = 0;
for (int i = 0; i < segments; ++i) {
int yn = (src->height - y) / (segments - i);
- QThreadPool::globalInstance()->start([&, y, yn]() {
+ threadPool->start([&, y, yn]() {
convertSegment(y, y + yn);
semaphore.release(1);
});
@@ -290,14 +291,15 @@ void convert_generic_to_rgb64(QImageData *dest, const QImageData *src, Qt::Image
int segments = src->nbytes / (1<<16);
segments = std::min(segments, src->height);
- if (segments <= 1)
+ QThreadPool *threadPool = QThreadPool::globalInstance();
+ if (segments <= 1 || threadPool->contains(QThread::currentThread()))
return convertSegment(0, src->height);
QSemaphore semaphore;
int y = 0;
for (int i = 0; i < segments; ++i) {
int yn = (src->height - y) / (segments - i);
- QThreadPool::globalInstance()->start([&, y, yn]() {
+ threadPool->start([&, y, yn]() {
convertSegment(y, y + yn);
semaphore.release(1);
});
@@ -396,12 +398,13 @@ bool convert_generic_inplace(QImageData *data, QImage::Format dst_format, Qt::Im
#ifdef QT_USE_THREAD_PARALLEL_IMAGE_CONVERSIONS
int segments = data->nbytes / (1<<16);
segments = std::min(segments, data->height);
- if (segments > 1) {
+ QThreadPool *threadPool = QThreadPool::globalInstance();
+ if (segments > 1 && !threadPool->contains(QThread::currentThread())) {
QSemaphore semaphore;
int y = 0;
for (int i = 0; i < segments; ++i) {
int yn = (data->height - y) / (segments - i);
- QThreadPool::globalInstance()->start([&, y, yn]() {
+ threadPool->start([&, y, yn]() {
convertSegment(y, y + yn);
semaphore.release(1);
});
diff --git a/src/gui/painting/qimagescale.cpp b/src/gui/painting/qimagescale.cpp
index 2395c891ce..aac1e20f7b 100644
--- a/src/gui/painting/qimagescale.cpp
+++ b/src/gui/painting/qimagescale.cpp
@@ -307,12 +307,13 @@ static inline void multithread_pixels_function(QImageScaleInfo *isi, int dh, con
#if QT_CONFIG(thread) && !defined(Q_OS_WASM)
int segments = (qsizetype(isi->sh) * isi->sw) / (1<<16);
segments = std::min(segments, dh);
- if (segments > 1) {
+ QThreadPool *threadPool = QThreadPool::globalInstance();
+ if (segments > 1 && !threadPool->contains(QThread::currentThread())) {
QSemaphore semaphore;
int y = 0;
for (int i = 0; i < segments; ++i) {
int yn = (dh - y) / (segments - i);
- QThreadPool::globalInstance()->start([&, y, yn]() {
+ threadPool->start([&, y, yn]() {
scaleSection(y, y + yn);
semaphore.release(1);
});
diff --git a/src/gui/painting/qimagescale_neon.cpp b/src/gui/painting/qimagescale_neon.cpp
index 65fe3fac3c..046e56b419 100644
--- a/src/gui/painting/qimagescale_neon.cpp
+++ b/src/gui/painting/qimagescale_neon.cpp
@@ -58,12 +58,13 @@ static inline void multithread_pixels_function(QImageScaleInfo *isi, int dh, con
#if QT_CONFIG(thread) && !defined(Q_OS_WASM)
int segments = (qsizetype(isi->sh) * isi->sw) / (1<<16);
segments = std::min(segments, dh);
- if (segments > 1) {
+ QThreadPool *threadPool = QThreadPool::globalInstance();
+ if (segments > 1 && !threadPool->contains(QThread::currentThread())) {
QSemaphore semaphore;
int y = 0;
for (int i = 0; i < segments; ++i) {
int yn = (dh - y) / (segments - i);
- QThreadPool::globalInstance()->start([&, y, yn]() {
+ threadPool->start([&, y, yn]() {
scaleSection(y, y + yn);
semaphore.release(1);
});
diff --git a/src/gui/painting/qimagescale_sse4.cpp b/src/gui/painting/qimagescale_sse4.cpp
index 1760e72f65..70cfa08d95 100644
--- a/src/gui/painting/qimagescale_sse4.cpp
+++ b/src/gui/painting/qimagescale_sse4.cpp
@@ -59,12 +59,13 @@ static inline void multithread_pixels_function(QImageScaleInfo *isi, int dh, con
#if QT_CONFIG(thread) && !defined(Q_OS_WASM)
int segments = (qsizetype(isi->sh) * isi->sw) / (1<<16);
segments = std::min(segments, dh);
- if (segments > 1) {
+ QThreadPool *threadPool = QThreadPool::globalInstance();
+ if (segments > 1 && !threadPool->contains(QThread::currentThread())) {
QSemaphore semaphore;
int y = 0;
for (int i = 0; i < segments; ++i) {
int yn = (dh - y) / (segments - i);
- QThreadPool::globalInstance()->start([&, y, yn]() {
+ threadPool->start([&, y, yn]() {
scaleSection(y, y + yn);
semaphore.release(1);
});
--
2.25.1
