Issue with the thread
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@Buckwheat said in Issue with the thread:
Yes, the Qt::DirectConnection is a problem with threads.
I object to that statement! I have a 5 years old or so C++ syntax parser that is threaded and uses direct connections exclusively. I would argue that one should know what
Qt::DirectConnectionimplies, however. Same goes forQt::QueuedConnection- just mindlessly using queued calls over whatever thread the objects happen to be in means you're just as mindlessly copying data around without a reason. What one should default to is the default -Qt::AutoConnection, and use a direct or a queued connection when and only when that's what is exactly, explicitly, supposed to happen.@kshegunov said in Issue with the thread:
@kshegunov I am glad you take offense. But, the default behavior for connection seems to be queued connection when crossing thread boundaries. I have found NO exception to this in the last 7 years so obviously the Qt designers thought there might be a problem. This queuing is why you can Q_EMIT data from a thread and put it into a GUI control which can only be done from the main thread. Also, I just said "Qt::QueuedConnection is no problems with threads". I would assume he is using the defaults in his thread.
As for copying, Sending a QSharedDataPointer is 4 bytes and is reference counted. NO COPYING except a pointer. Please read carefully before making "mindlessly" making judgements.
As 99% of my posts say, it is all in your design. Know what you are doing and what protections are offered. If you need to queue packets, QSharedDataPointer is great and it manages the pointers properly.
So, in summary, feel as offended as you like. It is a free forum and we can react how we like!
