mysterious hang in pthread_create

Daniel Eischen deischen at freebsd.org
Fri Aug 29 16:47:06 UTC 2008


On Fri, 29 Aug 2008, Kostik Belousov wrote:

> On Fri, Aug 29, 2008 at 05:18:18PM +0300, Andriy Gapon wrote:
>>
>> Kostik, thanks!
>>
>> on 29/08/2008 17:10 Kostik Belousov said the following:
>>> I am wondering why did you not fixed it youself with all this information.
>>
>> I am wondering that myself now :-)
>> I got bogged in rtld details and simply didn't think about the solution
>> of doing setthreaded earlier.
>>
>> I will try your patch a couple of hours later.
>> BTW, a forward question - should this patch help in the case of an
>> exception thrown (and caught) before main(), i.e. in constructors of
>> static/global objects?
> If the objects are from the executable, then yes. I do not know about
> present situation, but some time ago g++ and several other compilers
> called ctr for global objects from the main() function. Regardeless
> of this, init for main executable shall be called after init for
> dependencies is finished. See initlist_add_objects().
>
> On the other hand, ctr calls from linked dso may get fixed in regard
> of exception throwing, or may not, depending on the relative order of
> the dso loading against libthr.
>
>>
>>> Anyway, patch below seems to work for me. David may have an opinion on
>>> the change.
>>>
>>> diff --git a/lib/libthr/thread/thr_init.c b/lib/libthr/thread/thr_init.c
>>> index f96bba9..785d610 100644
>>> --- a/lib/libthr/thread/thr_init.c
>>> +++ b/lib/libthr/thread/thr_init.c
>>> @@ -355,6 +355,9 @@ _libpthread_init(struct pthread *curthread)
>>>  		if (_thread_event_mask & TD_CREATE)
>>>  			_thr_report_creation(curthread, curthread);
>>>  	}
>>> +
>>> +	if (_thr_isthreaded() == 0)
>>> +		_thr_setthreaded(1);
>>>  }
>>>
>>>  /*

I think the intent of __isthreaded (and _thr_setthreaded()) was
to be set if there were more than 1 thread, not to indicate that
the thread library has been initialized.

-- 
DE


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