From 63d18a6057d4ae95f0e7afe07ec97c75e0da55b8 Mon Sep 17 00:00:00 2001
From: "gkodinov/kgeorge@magare.gmz" <>
Date: Fri, 24 Aug 2007 18:06:44 +0300
Subject: Bug #28284: Test "mysqlslap" reports "out of memory"

When locking a "fast" mutex a static variable cpu_count
was used as a flag to initialize itself on the first usage
by calling sysconf() and setting non-zero value.
This is not thread and optimization safe on some
platforms. That's why the global initialization needs
to be done once in a designated function.
This will also speed up the usage (by a small bit)
because it won't have to check if it's initialized on
every call.

Fixed by moving the fast mutexes initialization out of
my_pthread_fastmutex_lock() to fastmutex_global_init()
and call it from my_init()
---
 mysys/thr_mutex.c | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

(limited to 'mysys/thr_mutex.c')

diff --git a/mysys/thr_mutex.c b/mysys/thr_mutex.c
index 007bae2accf..e7a927e562a 100644
--- a/mysys/thr_mutex.c
+++ b/mysys/thr_mutex.c
@@ -394,15 +394,11 @@ ulong mutex_delay(ulong delayloops)
 #define MY_PTHREAD_FASTMUTEX_SPINS 8
 #define MY_PTHREAD_FASTMUTEX_DELAY 4
 
+static int cpu_count= 0;
+
 int my_pthread_fastmutex_init(my_pthread_fastmutex_t *mp,
                               const pthread_mutexattr_t *attr)
 {
-  static int cpu_count= 0;
-#ifdef _SC_NPROCESSORS_CONF
-  if (!cpu_count && (attr == MY_MUTEX_INIT_FAST))
-    cpu_count= sysconf(_SC_NPROCESSORS_CONF);
-#endif
-  
   if ((cpu_count > 1) && (attr == MY_MUTEX_INIT_FAST))
     mp->spins= MY_PTHREAD_FASTMUTEX_SPINS; 
   else
@@ -432,4 +428,13 @@ int my_pthread_fastmutex_lock(my_pthread_fastmutex_t *mp)
   }
   return pthread_mutex_lock(&mp->mutex);
 }
+
+
+void fastmutex_global_init(void)
+{
+#ifdef _SC_NPROCESSORS_CONF
+  cpu_count= sysconf(_SC_NPROCESSORS_CONF);
+#endif
+}
+  
 #endif /* defined(THREAD) && defined(MY_PTHREAD_FASTMUTEX) && !defined(SAFE_MUTEX) */ 
-- 
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