vcl::Window::dispose deadlock

[Stephan Bergmann]

On 06/09/2015 10:02 AM, Noel Grandin wrote:
> On 2015-06-09 09:58 AM, Stephan Bergmann wrote:
>> On Windows, with master as of last night, "make check" happened to run
>> into a deadlock in soffice.bin as below.  The
>> main thread is trying to re-acquire the SolarMutex (after a
>> SolarMutexReleaser) from within the event loop, while an
>> incoming URP thread (apparently holding the SolarMutex) does
>> vcl::Window::dispose which, on Windows, blocks on sending a
>> message into the event loop.
>
> Shouldn't something that blocks on sending a message into the event loop
> drop the SolarMutex while it waits for the reply, and then reacquire it
> afterwards?

I'm not sure how this happened to work before introduction of 
Window::dispose (which got introduced as part of the VclPtr work, IIUC). 
  But doing release/re-acquire of the SolarMutex deep down the call 
stack has its own perils (and probably creates just as many data races 
as it helps work around deadlocks).