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Do not multithread if already in a global threadpool thread

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This can lead to a deadlock if we block all the worker threads, waiting
for the worker threads to finish.

Pick-to: 5.15
Fixes: QTBUG-84619
Change-Id: I92b7f96007897d86ece0c34223bab0df4ccbed9a
Reviewed-by: Sona Kurazyan <sona.kurazyan@qt.io>
This commit is contained in:
Allan Sandfeld Jensen 2020-06-02 10:59:21 +02:00
parent 6a31a7b024
commit 87d32424de
7 changed files with 48 additions and 15 deletions
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24
src/corelib/thread/qthreadpool.cpp
View File

@ -52,6 +52,7 @@ Q_GLOBAL_STATIC(QThreadPool, theInstance)
*/
class QThreadPoolThread : public QThread
{
Q_OBJECT
public:
QThreadPoolThread(QThreadPoolPrivate *manager);
void run() override;
@ -763,6 +764,28 @@ 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
@ -784,3 +807,4 @@ void QThreadPool::cancel(QRunnable *runnable)
QT_END_NAMESPACE
#include "moc_qthreadpool.cpp"
#include "qthreadpool.moc"

2
src/corelib/thread/qthreadpool.h
View File

@ -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);

7
src/gui/image/qimage.cpp
View File

@ -4786,15 +4786,16 @@ 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);
});

15
src/gui/image/qimage_conversions.cpp
View File

@ -237,14 +237,15 @@ 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);
});
@ -291,14 +292,15 @@ 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);
});
@ -397,12 +399,13 @@ 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);
});

5
src/gui/painting/qimagescale.cpp
View File

@ -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);
});

5
src/gui/painting/qimagescale_neon.cpp
View File

@ -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);
});

5
src/gui/painting/qimagescale_sse4.cpp
View File

@ -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);
});