[Qt-interest] QMutex deadlock without using QMutex

[Gabriel M. Beddingfield]

Hi Andre,

On Tue, 27 Apr 2010, Andre Somers wrote:

> I am running into a weird problem.
> For running calculations on a large dataset, I split up the work over a
> number of threads. I use signals and slots to communicate between the
> worker threads and a coordinator thread, and also between that
> coordinator thread and the rest of the application. I do not use any
> explicit thread synchronisation methods like QMutex in that part of the
> application.

Shooting from the hip:  this sounds like a mistake.  You 
have a multi-threaded, message-passing application, but 
you're ignoring the fundamentals of multi-threaded, 
message-passing programming.

> Still, I get this error in my output:
> QMutex::lock: Deadlock detected in thread <some number>
>
> What could this mean? Are there other causes conceivable for this

Can't tell what's happening without a backtrace.  Having 
debugging symbols for Qt libs is probably also necc.

-gabriel