[Interest] Difficulty running Timer from QThread
Israel Brewster
ijbrewster at alaska.edu
Mon Jul 19 05:29:02 CEST 2021
Yes, this is a FAQ, but I can’t seem to figure out what I am doing wrong. I am using the worker pattern of QThread, (as opposed to subclassing), running Qt 5.15.2. In my controller’s constructor, I have the following code to initialize a worker:
worker=new VLCWorker();
worker->moveToThread(&vlcWorkerThread);
worker->initVLC(videoWin);
vlcWorkerThread.start();
The initVLC function, among other things, creates a timer and connects it to a slot in the worker:
rtspStartTimer=new QTimer;
rtspStartTimer->setSingleShot(true);
connect(rtspStartTimer, &QTimer::timeout,
this, &VLCWorker::rtspStarting);
Later, at some point during program execution, I try to start this timer from a function in the worker (which itself was triggered by a signal from the main thread):
qDebug()<<"*****Trying to start timer which lives in thread"<<(long)rtspStartTimer->thread()<<" from thread "<<(long)this->thread();
rtspStartTimer->start(250);
qDebug()<<"*****Timer attempt complete";
Unfortunately, this doesn’t work, giving me the following output:
Debug: 2021-07-18T19:26:12.009 - *****Trying to start timer which lives in thread 140235980165688 from thread 140235980165688 (../DoorBellCamC/vlccontroller.cpp:121, void VLCWorker::rtspStarting())
Warning: 2021-07-18T19:26:12.009 - QObject::startTimer: Timers cannot be started from another thread (:0, )
Debug: 2021-07-18T19:26:12.009 - *****Timer attempt complete (../DoorBellCamC/vlccontroller.cpp:123, void VLCWorker::rtspStarting())
So even though the output of the debug confirms that the timer lives in the same thread I am trying to call start from, I still get the error about “timers cannot be started from another thread”. What am I doing wrong?
---
Israel Brewster
Software Engineer
Alaska Volcano Observatory
Geophysical Institute - UAF
2156 Koyukuk Drive
Fairbanks AK 99775-7320
Work: 907-474-5172
cell: 907-328-9145
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