Callback deadlock

[Stephan Bergmann]

On 06/29/2015 09:25 AM, Stephan Bergmann wrote:
> On 06/29/2015 07:58 AM, Matthew J. Francis wrote:
>> I'm intermittently experiencing the attached deadlock in some Python
>> code.
>>
>> As far as I can tell, the deadlock appears to be between a call to an
>> XTopWindowListener in thread 1 (the listener, also in Python code,
>> doesn't yet do anything more than print "I am here" on a callback) and
>> the main thread which is attempting to enumerate the paragraphs of a
>> text document in thread 2.
>>
>> Could anyone with more experience in UNO and locking matters help me to
>> understand what's going on here? If what I'm trying to do is essentially
>> not going to work, there is the alternative of busy-waiting for windows
>> to appear, but I'd like to avoid that if possible.
>
> In <http://pastebin.com/52FkaF2w>, the main thread 1 issued an URP
> request of css.awt.XTopWindowListener.windowActivated (and blocks
> waiting on the reply), while thread 2 serves an incoming URP request on
> SwXText::getPropertySetInfo (which happens to block waiting on the
> SolarMutex).
>
> No other thread 3--9 looks like it has the SolarMutex locked, so it must
> be thread 1 that has it locked while making the windowActivated call,
> which would be a programming error somewhere in the call chain leading
> up to there.

(But the remote Python end is presumably also doing things wrong.  It 
smells like processing of the incoming windowActivated request is 
blocked by the outgoing getPropertySetInfo request waiting for its reply.)