multi-threading task under SolarMutex -> deadlock

[Stephan Bergmann]

On 05/18/2016 08:22 PM, Norbert Thiebaud wrote:
> If we want to use multi-threading. we will have, at least, to solve
> the signal handler situation, since as it stand it makes the 'promise
> that this worker thread won't try to hold the solarmutex' impossible
> to uphold.

The crash handling code called from within the signal handler is just a 
big mess of illegal activity (that apparently happens to work some of 
the time, but is also known to fail spectacularly sometimes).  Locking 
the SolarMutex is just one of many illegal aspects.  I wouldn't worry 
trying to take care of it independently of cleaning up the big mess 
completely.

> Maybe a way around that may be to make sure that all worker thread use
> a pthread_sigmask to essentially prevent any of them to be interrupted
> for signal handling, by blocking all signal in these thread.
> in the same vein we could have a dedicated signal handler thread
> looping on a sigwait... then we can do the crazy thing we do in a
> handler without as many limitation

You cannot block SIGBUS, SIGSEGV etc. synchronously generated by the OS.