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Old 04-16-2007, 02:51 AM   #1
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Question GETTING "Xlib: unexpected async reply (sequence 0x9541): ERROR MESSAGE

hi all,
I just started to work on one project in linux. It is already running in windows and now i m porting it to the Linux machine. In my module (which is in QT), i m getting the XML string (via QUdpSocket) from windows system (client) to my Linux system (server). Depending upon the XML i have to perform the keyboard and mouse events programmatically (via X11/XLib XTestFakeButtonEvent and XSendEvent functions). Every thing is running fine. i m getting XML from windows system and (sometimes) could be able to perform the appropriate actions.
But, the problem arrise after 3-4 seconds of launching application, when my application continuously gets XML string, It stops to get any XML and stops emulating mouse events with error:

Xlib: unexpected async reply (sequence 0x3092)

Also sometimes this error message comes on console just after launching the application.

Deepak Chanalia
Old 04-23-2007, 06:54 AM   #2
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Lightbulb Solution to Xlib: unexpected async reply

Dear all,
After mugging so much in above problem i had having in my multi threaded application, eventually i come to the solution. The problem was in QDialog::connect() function; initially i was using QObject::connect (sender, Signalmethod,receiver,Slotmethod) form of connect; in this form my sender and receiver objects were in different threads and Qt was unable to synchronize these two objects in multi threading environment.

Then i used QObject::connect (sender, Signalmethod,receiver,Slotmethod, Qt::ConnectionType) form of connect function, with Qt:irectConnection as last argument. In the first form connect was using Default value for last argument which is Qt::AutoConnection, in which the signal is queued until the event loop is able to deliver it to the slot. In the Later form (using Qt:irectConnection), if the signal is emitted from the thread in which the receiving object is not lives, the slot is invoked directly. i.e. the signal is immediately delivered to the slot.

Deepak Chanalia


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