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Subject: Re: problem with mmap and fork()
To: cygwin AT cygwin DOT com
References: <CAAoGPJzdYcCDB=J4ZdfDq1xwLYvZBmT1rC937xHjMd8vseZ-=A AT mail DOT gmail DOT com>
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Date: Sat, 23 Feb 2019 10:30:10 +0100
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To: cygwin AT cygwin DOT com
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Subject: Re: problem with mmap and fork()
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On 23. 02. 19 1:02, Glyn Gowing wrote:
> Hello everyone,
>=20
> I have a program (attached) that works correctly on my mac but does
> not work with Cygwin on Windows 10. I'm running the latest version of
> Cygwin (downloaded the updates two days ago) and using gcc as the c
> compiler.
>=20
> What happens in the buggy execution is that the child obtains a lock
> before the parent releases it. I'm using mmap and a pthread_mutex_t
> object along with fork(). Again, this exact code works correctly on my
> Mac running Mojave.
>=20
> I've looked at the archives and online and I can't find any hints as
> to what I may be doing incorrectly here
>=20

You cannot fork() and keep using threading primitives in the child. The
child has only one thread and the mutexes are usually in a state that
can be inconsistent. Basically, the only safe thing to do in
multithreaded process after fork is to exec() and reinitialize your
application.

--=20
VH


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