diff options
author | David Faure <david.faure@kdab.com> | 2013-06-21 10:32:17 +0200 |
---|---|---|
committer | The Qt Project <gerrit-noreply@qt-project.org> | 2013-08-24 13:09:46 +0200 |
commit | dacf9961da86751a59da0e84bc943fe0d1c8d95b (patch) | |
tree | 88fb959024904484ec8e7442b88c4777246a42a4 /tests/auto/corelib/thread/qthreadpool | |
parent | 7c2a418857cd20e3e59852f0c1561a26f17d9825 (diff) |
QThreadPool: fix counting of waiting threads
QTBUG-21051 has a testcase where activeThreadCount() could actually
end up at -1 (converted to an autotest in this commit).
The reason was: start() calls tryStart() which returns false due to
too many active threads (reserveThread() causes this), so it calls
enqueueTask() - which actually wakes up the waiting thread, but
it didn't decrement the number of waiting threads.
Note that tryStart() is "if I can grab a waiting thread, enqueue task and wake it"
while start(), in case tryStart() fails, wants to "enqueue, and then if I can grab
a waiting thread, wake it". This is why enqueue shouldn't wake; waking must happen
only if we can grab a thread (d->waitingThreads > 0).
Task-number: QTBUG-21051
Change-Id: I3d98337103031c9bdf0bf365295f245be0c66aa7
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Diffstat (limited to 'tests/auto/corelib/thread/qthreadpool')
-rw-r--r-- | tests/auto/corelib/thread/qthreadpool/tst_qthreadpool.cpp | 56 |
1 files changed, 56 insertions, 0 deletions
diff --git a/tests/auto/corelib/thread/qthreadpool/tst_qthreadpool.cpp b/tests/auto/corelib/thread/qthreadpool/tst_qthreadpool.cpp index 10a59ac301..cdf240d757 100644 --- a/tests/auto/corelib/thread/qthreadpool/tst_qthreadpool.cpp +++ b/tests/auto/corelib/thread/qthreadpool/tst_qthreadpool.cpp @@ -90,6 +90,7 @@ private slots: void reserveThread(); void releaseThread_data(); void releaseThread(); + void reserveAndStart(); void start(); void tryStart(); void tryStartPeakThreadCount(); @@ -630,6 +631,61 @@ void tst_QThreadPool::releaseThread() threadpool->setMaxThreadCount(savedLimit); } +void tst_QThreadPool::reserveAndStart() // QTBUG-21051 +{ + class WaitingTask : public QRunnable + { + public: + QAtomicInt count; + QSemaphore waitForStarted; + + WaitingTask() { setAutoDelete(false); } + + void run() + { + count.ref(); + waitForStarted.release(); + } + }; + + // Set up + QThreadPool *threadpool = QThreadPool::globalInstance(); + int savedLimit = threadpool->maxThreadCount(); + threadpool->setMaxThreadCount(1); + QCOMPARE(threadpool->activeThreadCount(), 0); + + // reserve + threadpool->reserveThread(); + QCOMPARE(threadpool->activeThreadCount(), 1); + + // start a task, to get a running thread + WaitingTask *task = new WaitingTask; + threadpool->start(task); + QCOMPARE(threadpool->activeThreadCount(), 2); + task->waitForStarted.acquire(); + QTRY_COMPARE(task->count.load(), 1); + QTRY_COMPARE(threadpool->activeThreadCount(), 1); + + // now the thread is waiting, but tryStart() will fail since activeThreadCount() >= maxThreadCount() + QVERIFY(!threadpool->tryStart(task)); + QTRY_COMPARE(threadpool->activeThreadCount(), 1); + + // start() will therefore do a failing tryStart(), followed by enqueueTask() + // which will actually wake up the waiting thread. + threadpool->start(task); + QTRY_COMPARE(threadpool->activeThreadCount(), 2); + task->waitForStarted.acquire(); + QTRY_COMPARE(task->count.load(), 2); + QTRY_COMPARE(threadpool->activeThreadCount(), 1); + + threadpool->releaseThread(); + QTRY_COMPARE(threadpool->activeThreadCount(), 0); + + delete task; + + threadpool->setMaxThreadCount(savedLimit); +} + QAtomicInt count; class CountingRunnable : public QRunnable { |