Thread-safety issue in cmake support ?

[Sandro Andrade]

On Mon, Jun 7, 2010 at 12:20 PM, Milian Wolff <mail at milianw.de> wrote:
> Sandro Andrade, 07.06.2010:
>> Hi there,
>>
>> I sent this issue some time ago regarding multiple access to KConfig
>> and I've been told to ask kde-core-devel guys
>> about KConfig thread safety. However, KConfig is neither thread-safe
>> nor even reentrant:
>>
>> http://lists.zerezo.com/kde-devel/msg12619.html
>> http://lists.kde.org/?l=kde-devel&m=118037451920733&w=2
>>
>> So I should take care of this. The problem raises from calling
>> "buildSystemManager->includeDirectories(project_item)" from multiples
>> threads. I need to obtain project's include directories but probably
>> the concurrent execution of background parser is causing such a crash
>> (see following backtrace).
>
> Either put a mutex into your plugin or directly into cmake - dunno. You should
> investigate where the function is currently used (isn't that used somewhere in
> the background parser? meaning from multiple threads?)

I'm afraid putting a mutex (actually it already exists) in plugin does not
solves the problem since it cames from somewhere out of plugin scope.

I suspect any concurrent execution of buildsystem's methods which access
KConfig (more specifically CMakeUtils methods) would produce such error
(in this case, currentInstallDir - executed from plugin - against
currentBuildDir - from some still unknown place).

Error occurs either in main thread or in plugin. When in main thread
it raises from
a slot execution which it turns call a method using introspection, making things
difficult to investigate.

IMHO, a lock in CMakeUtils would be a possible solution.

Thanks,
Sandro

>
> If so, we'd need to put it into the CMake plugin directly.
>
> anyhow: it's interesting to know that this is not threadsafe, afaik there are
> a few places in KDevelop assuming that it _is_ threadsafe ;-) Oh boy, the joy
> of multithreading :]
> --
> Milian Wolff
> mail at milianw.de
> http://milianw.de
>
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