QWebSocket SIGPIPE on QWebSocketPrivate::close due to Timeout

Context

I am developping a multithreaded server that serves mass requests from mass clients.

My WebSocketServer is in an exclusive thread that only unstacks and parses the requests (deserialization) before adding them to a shared structure, then sends a response (within the same thread).

All the operations are sheduled through signal / slot direct connections, except for the shared structure that is directly used (protected by a QMutex).

Another thread checks that shared structure and handles the requests.

Problem

In the internal event notification from WebSocketServer, QAbstractSocketPrivate::flush() leads to a SIGPIPE during to the qt_safe_write_nosignal call.

The root cause is I try to write to an apparently closed socket while handling the resquests.

The problem is my server is not notified in time.

If my client crashes, I must not stop my server process too as I am serving lots of requests from other clients.

Questions

So, several questions here:

• is it due to SIGPIPE that is ignored once only (qt_ignore_sigpipe()) ?
• how can be several SIGPIPEs then ?
• is there any mean to work around it ?

Debug infos

Here you can find the stack trace:

{{1 write 0x7f5ee270e85d }}
{{2 qt_safe_write qcore_unix_p.h 280 0x7f5ee4c7fb41 }}
{{3 qt_safe_write_nosignal qcore_unix_p.h 289 0x7f5ee4c7fb41 }}
{{4 QNativeSocketEnginePrivate::nativeWrite qnativesocketengine_unix.cpp 1280 0x7f5ee4c7fb41 }}
{{5 QNativeSocketEngine::write qnativesocketengine.cpp 918 0x7f5ee4c7bb38 }}
{{6 QAbstractSocketPrivate::writeToSocket qabstractsocket.cpp 849 0x7f5ee4c68609 }}
{{7 QAbstractSocketPrivate::flush qabstractsocket.cpp 892 0x7f5ee4c66844 }}
{{8 QAbstractSocket::flush qabstractsocket.cpp 2460 0x7f5ee4c68788 }}
{{9 QWebSocketPrivate::close qwebsocket_p.cpp 352 0x7f5ee4b51d6b }}
{{10 QWebSocketPrivate::processClose qwebsocket_p.cpp 1197 0x7f5ee4b51ee6 }}
{{11 call qobjectdefs_impl.h 136 0x7f5ee4b58c2c }}
{{12 call<QtPrivate::List<QWebSocketProtocol::CloseCode, QString const&>, void> qobjectdefs_impl.h 169 0x7f5ee4b58c2c }}
{{13 QtPrivate::QPrivateSlotObject<void (QWebSocketPrivate:: *)(QWebSocketProtocol::CloseCode, QString), QtPrivate::List<QWebSocketProtocol::CloseCode, QString const&>, void>::impl qobject_p.h 311 0x7f5ee4b58c2c }}
{{14 call qobject_impl.h 101 0x7f5ee47dd48f }}
{{15 QMetaObject::activate qobject.cpp 3750 0x7f5ee47dd48f }}
{{16 QMetaObject::activate qobject.cpp 3629 0x7f5ee47dd92b }}
{{17 QWebSocketDataProcessor::closeReceived moc_qwebsocketdataprocessor_p.cpp 248 0x7f5ee4b68e2e }}
{{18 QWebSocketDataProcessor::processControlFrame qwebsocketdataprocessor.cpp 274 0x7f5ee4b656fe }}
{{19 QWebSocketDataProcessor::process qwebsocketdataprocessor.cpp 131 0x7f5ee4b65920 }}
{{20 QWebSocketPrivate::processData qwebsocket_p.cpp 1159 0x7f5ee4b5801d }}
{{21 call qobjectdefs_impl.h 136 0x7f5ee4b58883 }}
{{22 call<QtPrivate::List<>, void> qobjectdefs_impl.h 169 0x7f5ee4b58883 }}
{{23 QtPrivate::QPrivateSlotObject<void (QWebSocketPrivate:: *)(), QtPrivate::List<>, void>::impl(int, QtPrivate::QSlotObjectBase *, QObject *, void * *, bool *) qobject_p.h 311 0x7f5ee4b58883 }}
{{24 call qobject_impl.h 101 0x7f5ee47d9015 }}
{{25 QMetaCallEvent::placeMetaCall qobject.cpp 502 0x7f5ee47d9015 }}
{{26 QObject::event qobject.cpp 1247 0x7f5ee47dddb2 }}
{{27 QCoreApplicationPrivate::notify_helper qcoreapplication.cpp 1158 0x7f5ee47ad55b }}
{{28 doNotify qcoreapplication.cpp 1099 0x7f5ee47ad5e0 }}
{{29 QCoreApplication::notify qcoreapplication.cpp 1085 0x7f5ee47ad6d1 }}
{{30 QCoreApplication::notifyInternal2 qcoreapplication.cpp 1024 0x7f5ee47ad67e }}
{{31 sendEvent qcoreapplication.h 233 0x7f5ee47b28c6 }}
{{32 QCoreApplicationPrivate::sendPostedEvents qcoreapplication.cpp 1699 0x7f5ee47b28c6 }}
{{33 QEventDispatcherUNIX::processEvents qeventdispatcher_unix.cpp 466 0x7f5ee4803b0a }}
{{34 QEventLoop::processEvents qeventloop.cpp 134 0x7f5ee47ab521 }}
{{35 QEventLoop::exec qeventloop.cpp 212 0x7f5ee47ab979 }}
{{36 QThread::exec qthread.cpp 515 0x7f5ee45e0af6 }}
{{37 QThread::run qthread.cpp 582 0x7f5ee45e0b87 }}
{{38 QThreadPrivate::start qthread_unix.cpp 368 0x7f5ee45e6e79 }}
{{39 start_thread 0x7f5ee2410e25 }}
40 clone

The close reason is the following:

QWebSocketProtocol::CloseCodeGoingAway (0x03e9)
"Timeout when reading data from socket."