Re: (ITS#3950) sched_yield() considered harmful

[hyc@symas.com]

Bernardo Innocenti wrote:
> Howard Chu wrote:
>   
>> Please try the OpenLDAP 2.3 release; I don't believe any performance
>> issue exists here.
>>     
>
> Sorry, I've just upgraded to 2.3.11 and the problem is still there.
> (see the audit trail of #3950 for more information).
>
> Is there a way to build slapd without threading?

There was, but I suspect a lot of the code in 2.3 will break without it now.

>   Or using a backend
> that doesn't require sched_yield()?  This issue is killing a critical
> server of mine.
>   

Try this patch for libldap_r/thr_posix.c; recompile libldap_r and relink 
slapd...

RCS file: /repo/OpenLDAP/pkg/ldap/libraries/libldap_r/thr_posix.c,v
retrieving revision 1.40
diff -u -r1.40 thr_posix.c
--- thr_posix.c 17 Sep 2005 21:28:08 -0000      1.40
+++ thr_posix.c 25 Nov 2005 20:07:23 -0000
@@ -20,6 +20,11 @@

 #include <ac/errno.h>

+#if defined( HAVE_YIELDING_SELECT )
+#include <ac/socket.h>
+#include <ac/time.h>
+#endif
+
 #include "ldap_pvt_thread.h" /* Get the thread interface */
 #define LDAP_THREAD_IMPLEMENTATION
 #define LDAP_THREAD_RDWR_IMPLEMENTATION
@@ -207,7 +212,11 @@
 int
 ldap_pvt_thread_yield( void )
 {
-#if HAVE_THR_YIELD
+#if HAVE_YIELDING_SELECT
+       struct timeval tv = {0,0};
+       select( 0, NULL, NULL, NULL, &tv );
+       return 0;
+#elif HAVE_THR_YIELD
        return thr_yield();

 #elif HAVE_PTHREADS == 10




-- 
  -- Howard Chu
  Chief Architect, Symas Corp.  http://www.symas.com
  Director, Highland Sun        http://highlandsun.com/hyc
  OpenLDAP Core Team            http://www.openldap.org/project/