From: Junio C Hamano Date: Tue, 16 Feb 2010 02:32:12 GMT Subject: Re: [PATCH] fix threaded grep for machines with only one cpu Message-ID: <7vocjpnc5v.fsf@alter.siamese.dyndns.org> In-Reply-To: <7vwryet2cw.fsf@alter.siamese.dyndns.org> Junio C Hamano writes: > So at least for grep_mutex your patch shouldn't matter. Please explain > use of which mutex is broken and how your patch fixes it. Is this the answer to my question? With your patch, your single-threaded program will end up locking and unlocking this mutex needlessly, and the mutex is left undestroyed after you are done, I think. builtin-grep.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) 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) /* Signalled when a new work_item is added to todo. */ static pthread_cond_t cond_add;