UITest_writerperfect_epubexport hang (only sometimes)

[Stephan Bergmann]

On 23.01.2018 09:18, Miklos Vajna wrote:
> I've added UITest_writerperfect_epubexport a while ago, and while I did
> not see it hanging in the recent past, both Noel and Stephan run into
> a hang of it from time to time.
> 
> The code is here:
> 
> writerperfect/qa/uitest/epubexport/epubexport.py
> 
> The backtrace always looks like this:
> self.ui_test.execute_blocking_action() gets an UNO method where invoking
> it opens a dialog and the python method also gets a callback. When the
> hang happens, then it seems the problem is that the Python thread waits
> for the dialog to be closed, but in fact it's already closed, so it
> waits forever joining the python thread.
> 
> I don't think there is anything really special in this test, rather I
> guess the problem happens here more frequently (than elsewhere) because
> normally these dialogs are invoked via UNO commands, where we just
> execute the UNO command, wait for the dialog to appear then work with
> it. (I did not look at the implementation, perhaps in this case there is
> no Python thread involved?)
> 
> So I wonder -- do you think it would be possible or would make sense to
> have a way similar to self.xUITest.executeCommand (execute a blocking
> command async), but for UNO methods that open a dialog? I.e. also
> similar to self.ui_test.execute_blocking_action, but without an actual
> callback.
> 
> Perhaps that would be a fix for these strange hangs.

Is anything blocking this? 
<https://ci.libreoffice.org/job/lo_gerrit/26790/Config=linux_clang_dbgutil_64/console> 
is yet another hung Gerrit/Jenkins build that might or might not be 
caused by this issue.