Re: GCC 4.6.2 C++ thread cancellation issue

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Mike Dalpee <mikedalpee@xxxxxxxxxxxx> writes:

> The system is RHEL 6.1 X86_64,  using glibc 2.12 that comes with the system.  I was going to give GCC 4.7 a try, but unfortunately, they closed a very arcance template dependent name resolution loophole that my 3rd-party legacy code was exploiting and it will be a bear to try to fix it. 
>
> Threads are being cancelled using libpthread pthread_cancel, synrchonously I believe - will have to verify that.
>
> So perhaps going to a later version of glibc might be worth a try?  I see 2.15 is the latest.  If so, do you know what special build options I must chose to make the exception handling work correctly?

glibc 2.12 is sufficiently recent that I would not expect upgrading to
the latest glibc to help.

Do you have a small single file test case?

Ian

> ________________________________________
> From: Ian Lance Taylor [iant@xxxxxxxxxx]
> Sent: Monday, May 07, 2012 6:40 PM
> To: Mike Dalpee
> Cc: gcc-help@xxxxxxxxxxx
> Subject: Re: GCC 4.6.2 C++ thread cancellation issue
>
> Mike Dalpee <mikedalpee@xxxxxxxxxxxx> writes:
>
>> I am trying to port some legacy code to properly work in the face of
>> thread cancellation.
>
> What thread library are you using?  E.g., are you using glibc on a
> GNU/Linux system, or something else?
>
> How are you cancelling the thread?  Via pthread_cancel or something
> else?
>
> Are you using an ARM system or something else?
>
>
>> Based on information I have gleaned from searching the net, it appears
>> that any catch(...) handlers that try to finalize the exception must
>> be augmented to first catch abi::_forced_unwind and simply rethrow the
>> exception for cancellation to work properly.
>
> That seems plausible, assuming you use a simple "throw;" to rethrow the
> exception.
>
>
>> I am running into a problem where the rethrow of abi::_forced_unwind
>> is being treated as an unhandled exception by the runtime, thereby
>> causing an abort to occur.  So, my questions are:
>>
>> 1) Should what I am doing work?
>
> Ideally, yes.
>
>> 2) Is there a particular way GCC must be built for the rethrow to work?
>
> No.
>
>> 3) Is there a particular combination of GCC/GLIBC versions required
>> for the rethrow to work?
>
> The GCC version shouldn't matter.  The way that GLIBC was built does
> matter.
>
> Ian


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