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From: Heiko Voigt <hvoigt@hvoigt•net>
To: Junio C Hamano <gitster@pobox•com>
Cc: Fredrik Kuivinen <frekui@gmail•com>,
	git@vger•kernel.org,
	Johannes Schindelin <Johannes.Schindelin@gmx•de>
Subject: Re: Re: [PATCH] fix threaded grep for machines with only one cpu
Date: Tue, 16 Feb 2010 19:02:09 +0100	[thread overview]
Message-ID: <20100216180209.GA1532@book.hvoigt.net> (raw)
In-Reply-To: <7vljetlx8r.fsf@alter.siamese.dyndns.org>

On Mon, Feb 15, 2010 at 06:39:48PM -0800, Junio C Hamano wrote:
> Junio C Hamano <gitster@pobox•com> writes:
> 
> > Is this the answer to my question?

Sorry I forgot to add a reference to the thread from which the patch
originated: http://groups.google.com/group/msysgit/msg/5da53cf1ccf417cf

> IOW, please try this patch.  I am planning to queue it to 'maint' as part
> of 1.7.0.1 if this is the right solution (which I obviously think it is).

Yes your patch does it correctly I just verified that the segfaults are
gone as well. I think your solution is even nicer than mine. Thanks.

> -- >8 --
> From: Junio C Hamano <gitster@pobox•com>
> Date: Mon, 15 Feb 2010 18:34:28 -0800
> Subject: [PATCH] Fix use of mutex in threaded grep
[...]
> diff --git a/builtin-grep.c b/builtin-grep.c
> index 26d4deb..5c1545e 100644
> --- a/builtin-grep.c
> +++ b/builtin-grep.c
> @@ -81,8 +81,8 @@ static pthread_mutex_t read_sha1_mutex;
>  
>  #define grep_lock() pthread_mutex_lock(&grep_mutex)
>  #define grep_unlock() pthread_mutex_unlock(&grep_mutex)
> -#define read_sha1_lock() pthread_mutex_lock(&read_sha1_mutex)
> -#define read_sha1_unlock() pthread_mutex_unlock(&read_sha1_mutex)
> +#define read_sha1_lock() do { if (use_threads) pthread_mutex_lock(&read_sha1_mutex); } while (0)
> +#define read_sha1_unlock() do { if (use_threads) pthread_mutex_unlock(&read_sha1_mutex); } while (0)

One minor thing: Would it not be even nicer having the while loop inside
the if clause? E.g like this

#define read_sha1_lock() if (use_threads) do { pthread_mutex_lock(&read_sha1_mutex); } while (0)
#define read_sha1_unlock() if (use_threads) do { pthread_mutex_unlock(&read_sha1_mutex); } while (0)

If the purpose was to force a thread switch it is not necessary when not
using threads.

cheers Heiko

  parent reply	other threads:[~2010-02-16 18:02 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-02-15 22:50 [PATCH] fix threaded grep for machines with only one cpu Heiko Voigt
2010-02-15 23:09 ` Johannes Schindelin
2010-02-16  1:07 ` Junio C Hamano
2010-02-16  1:12   ` Junio C Hamano
2010-02-16  2:32   ` Junio C Hamano
2010-02-16  2:39     ` Junio C Hamano
2010-02-16  7:54       ` Fredrik Kuivinen
2010-02-16  8:15       ` Johannes Schindelin
2010-02-16 23:59         ` Junio C Hamano
2010-02-17  1:01           ` Johannes Schindelin
2010-02-17  1:26             ` Junio C Hamano
2010-02-17  2:41               ` Nicolas Pitre
2010-02-17 22:43           ` Heiko Voigt
2010-02-18  9:10             ` Johannes Schindelin
2010-02-16 18:02       ` Heiko Voigt [this message]
2010-02-16 18:59         ` Nicolas Pitre
2010-02-16 19:20         ` Junio C Hamano
2010-02-16 19:26           ` Sverre Rabbelier
2010-02-16 20:00           ` Nicolas Pitre
2010-02-16 20:19             ` Johannes Schindelin
2010-02-16 20:37               ` Nicolas Pitre
2010-02-16 20:57             ` Heiko Voigt
2010-02-16 21:20               ` Nicolas Pitre
2010-02-16 22:54                 ` Junio C Hamano
2010-02-17 17:56                   ` Heiko Voigt
2010-02-17 15:29             ` Paolo Bonzini

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