Hi Gary,
Gary V. Vaughan wrote:
> Thanks for merging my last patch series into the new release. git 1.7.3.2
> now compiles correctly on all of our hosts, save Solaris 2.6 (SunOS 5.6)
> which has no recursive mutex support in its pthreads.
Nice.
> --- a/builtin/pack-objects.c
> +++ b/builtin/pack-objects.c
> @@ -1561,7 +1561,11 @@ static pthread_cond_t progress_cond;
> */
> static void init_threaded_search(void)
> {
> +#ifndef NO_RECURSIVE_MUTEX
> init_recursive_mutex(&read_mutex);
> +#else
> + pthread_mutex_init(&read_mutex, NULL);
> +#endif
Wouldn't that defeat the purpose of using a recursive mutex in the first
place? Let's see...
$ git log -m --first-parent -S'init_recursive_mutex' -- builtin/pack-objects.c
commit ea5f75a64ae52590b06713d45d84de03ca109ccc
Merge: af65543 9374919
Author: Junio C Hamano <gitster@xxxxxxxxx>
Date: Fri May 21 04:02:16 2010 -0700
Merge branch 'np/malloc-threading'
* np/malloc-threading:
Thread-safe xmalloc and xrealloc needs a recursive mutex
Make xmalloc and xrealloc thread-safe
$ git log -S'init_recursive_mutex' af65543..9374919
commit 937491944292fa3303b565b9bd8914c6b644ab13
Author: Johannes Sixt <j6t@xxxxxxxx>
Date: Thu Apr 8 09:15:39 2010 +0200
Thread-safe xmalloc and xrealloc needs a recursive mutex
The mutex used to protect object access (read_mutex) may need to be
acquired recursively. Introduce init_recursive_mutex() helper function
in thread-utils.c that constructs a mutex with the PHREAD_MUTEX_RECURSIVE
attribute.
pthread_mutex_init() emulation on Win32 is already recursive as it is
implemented on top of the CRITICAL_SECTION type, which is recursive.
http://msdn.microsoft.com/en-us/library/ms682530%28VS.85%29.aspx
Add do-nothing compatibility wrappers for pthread_mutexattr* functions.
Initial-version-by: Fredrik Kuivinen <frekui@xxxxxxxxx>
Signed-off-by: Johannes Sixt <j6t@xxxxxxxx>
Signed-off-by: Junio C Hamano <gitster@xxxxxxxxx>
Presumably the problem scenarios are something like this:
ll_find_deltas():
init_threaded_search() [sets try_to_free_routine]
threaded_find_deltas() ->
find_deltas() ->
try_delta() [acquires read_lock] ->
read_sha1_file() ->
read_object() ->
xmemdupz() ->
xmallocz() ->
xmalloc() ->
try_to_free_from_threads() ->
read_lock() --- deadlock.
Hope that helps,
Jonathan
--
To unsubscribe from this list: send the line "unsubscribe git" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html