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	Tue, 17 Mar 2026 07:37:36 -0700 (PDT)
Message-ID:	<163ebe7e-2acb-429e-a793-f7879b62c024@gmail.com>
Date:	Tue, 17 Mar 2026 16:37:32 +0200
MIME-Version:	1.0
User-Agent:	Mozilla Thunderbird
Subject:	Re: std::mutex bug: Windows handle growth
To:	Frank Eskesen <feskesen AT hvc DOT rr DOT com>,
	Cygin Mailing List <cygwin AT cygwin DOT com>
References:	<2d48a740-ce2b-4259-8947-f5c875dd1672 AT hvc DOT rr DOT com>
	<406b3882-15be-4d24-945c-42f1e2715e87 AT gmail DOT com>
	<ablgU3yUW0YI_QDf AT calimero DOT vinschen DOT de>
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From:	Noel Grandin via Cygwin <cygwin AT cygwin DOT com>
Reply-To:	Noel Grandin <noelgrandin AT gmail DOT com>
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On 3/17/2026 4:08 PM, Corinna Vinschen via Cygwin wrote:
> On Mar 17 09:06, Noel Grandin via Cygwin wrote:
> No, checking trylock() is correct.  pthread_mutex_destroy() must not
> destroy a busy mutex.  trylock() returns != 0 if the lock is busy.
> 

Aha! I misread that code.

> Given the implementation of std::mutex is based on pthread_mutex,
> Frank's code is wrong, or at least somewhat borderline.  The mutex
> should first be unlocked before leaving do_something().
> 

std::lock_guard will unlock in its destructor, so it should unlock before leaving do_something().

Regards, Noel Grandin.

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