database/mariadb
1
0
Fork 0
mirror of https://github.com/MariaDB/server.git synced 2025-08-07 00:04:31 +03:00
Code Activity

Backport of:

Browse Source 
-------------------------------------------------------------
revno: 2877
committer: Davi Arnaut <Davi.Arnaut@Sun.COM>
branch nick: 35164-6.0
timestamp: Wed 2008-10-15 19:53:18 -0300
message:
Bug#35164: Large number of invalid pthread_attr_setschedparam calls
Bug#37536: Thread scheduling causes performance degradation at low thread count
Bug#12702: Long queries take 100% of CPU and freeze other applications under Windows

The problem is that although having threads with different priorities
yields marginal improvements [1] in some platforms [2], relying on some
statically defined priorities (QUERY_PRIOR and WAIT_PRIOR) to play well
(or to work at all) with different scheduling practices and disciplines
is, at best, a shot in the dark as the meaning of priority values may
change depending on the scheduling policy set for the process.

Another problem is that increasing priorities can hurt other concurrent
(running on the same hardware) applications (such as AMP) by causing
starvation problems as MySQL threads will successively preempt lower
priority processes. This can be evidenced by Bug#12702.

The solution is to not change the threads priorities and rely on the
system scheduler to perform its job. This also enables a system admin
to increase or decrease the scheduling priority of the MySQL process,
if intended.

Furthermore, the internal wrappers and code for changing the priority
of threads is being removed as they are now unused and ancient.

1. Due to unintentional side effects. On Solaris this could artificially
help benchmarks as calling the priority changing syscall millions of
times is more beneficial than the actual setting of the priority.

2. Where it actually works. It has never worked on Linux as the default
scheduling policy SCHED_OTHER only accepts the static priority 0.


configure.in:
  Remove checks for functions that are not used anymore.
include/config-netware.h:
  Remove unused define.
include/my_pthread.h:
  Remove thread priority changing wrappers.
mysys/my_pthread.c:
  Remove thread priority changing wrappers. They do not work properly
  and their implementations were incorrectly protected by a check for
  HAVE_PTHREAD_SETSCHEDPARAM.
mysys/thr_alarm.c:
  Remove meaningless (100) increase of a thread priority.
sql/mysql_priv.h:
  Remove meaningless thread priority values.
sql/mysqld.cc:
  Don't change thread priorities.
sql/slave.cc:
  Don't change thread priorities.
sql/slave.h:
  Update function prototype.
sql/sql_parse.cc:
  Don't change thread priorities.
sql/sql_prepare.cc:
  Don't change thread priorities.
sql/unireg.h:
  Mark flag as obsolete.
storage/innobase/handler/ha_innodb.cc:
  Remove use of obsolete flag and associated behavior.
storage/innobase/include/srv0srv.h:
  Remove use of obsolete flag and associated variables.
storage/innobase/os/os0thread.c:
  Remove use of obsolete flag and associated behavior.
storage/innobase/srv/srv0srv.c:
  Remove use of obsolete flag and associated variables.
This commit is contained in:
Konstantin Osipov
2009-11-23 19:57:31 +03:00
parent 9f49582531
commit bae0e81310
16 changed files with 20 additions and 172 deletions
Download Patch File Download Diff File Expand all files Collapse all files

35
include/my_pthread.h
View File

@@ -35,7 +35,6 @@ typedef DWORD pthread_t;
typedef struct thread_attr {
DWORD dwStackSize ;
DWORD dwCreatingFlag ;
int priority ;
} pthread_attr_t ;
typedef struct { int dummy; } pthread_condattr_t;
@@ -110,7 +109,6 @@ int pthread_cond_broadcast(pthread_cond_t *cond);
int pthread_cond_destroy(pthread_cond_t *cond);
int pthread_attr_init(pthread_attr_t *connect_att);
int pthread_attr_setstacksize(pthread_attr_t *connect_att,DWORD stack);
int pthread_attr_setprio(pthread_attr_t *connect_att,int priority);
int pthread_attr_destroy(pthread_attr_t *connect_att);
struct tm *localtime_r(const time_t *timep,struct tm *tmp);
struct tm *gmtime_r(const time_t *timep,struct tm *tmp);
@@ -141,19 +139,18 @@ int pthread_join(pthread_t thread, void **value_ptr);
#define pthread_mutex_trylock(A) win_pthread_mutex_trylock((A))
#define pthread_mutex_unlock(A) LeaveCriticalSection(A)
#define pthread_mutex_destroy(A) DeleteCriticalSection(A)
#define my_pthread_setprio(A,B) SetThreadPriority(GetCurrentThread(), (B))
#define pthread_kill(A,B) pthread_dummy((A) ? 0 : ESRCH)
/* Dummy defines for easier code */
#define pthread_attr_setdetachstate(A,B) pthread_dummy(0)
#define my_pthread_attr_setprio(A,B) pthread_attr_setprio(A,B)
#define pthread_attr_setscope(A,B)
#define pthread_detach_this_thread()
#define pthread_condattr_init(A)
#define pthread_condattr_destroy(A)
#define my_pthread_getprio(thread_id) pthread_dummy(0)
/* per the platform's documentation */
#define pthread_yield() Sleep(0)
#else /* Normal threads */
@@ -181,8 +178,6 @@ void my_pthread_exit(void *status);
#define pthread_exit(A) my_pthread_exit(A)
#endif
extern int my_pthread_getprio(pthread_t thread_id);
#define pthread_key(T,V) pthread_key_t V
#define my_pthread_getspecific_ptr(T,V) my_pthread_getspecific(T,(V))
#define my_pthread_setspecific_ptr(T,V) pthread_setspecific(T,(void*) (V))
@@ -254,32 +249,6 @@ int sigwait(sigset_t *setp, int *sigp); /* Use our implemention */
#define my_sigset(A,B) signal((A),(B))
#endif
#ifndef my_pthread_setprio
#if defined(HAVE_PTHREAD_SETPRIO_NP) /* FSU threads */
#define my_pthread_setprio(A,B) pthread_setprio_np((A),(B))
#elif defined(HAVE_PTHREAD_SETPRIO)
#define my_pthread_setprio(A,B) pthread_setprio((A),(B))
#elif defined(HAVE_PTHREAD_SETSCHEDPRIO) && !defined (__GNUC__)
/*
Workaround for bug on Solaris where pthread.h have bug in GNU
version of pthread.h => configure says yes, header files says
no. So not used with gcc and issue is Solaris only, so will
be used on Solaris using SunStudio.
*/
#define my_pthread_setprio(A,B) pthread_setschedprio((A),(B))
#else
extern void my_pthread_setprio(pthread_t thread_id,int prior);
#endif
#endif
#ifndef my_pthread_attr_setprio
#ifdef HAVE_PTHREAD_ATTR_SETPRIO
#define my_pthread_attr_setprio(A,B) pthread_attr_setprio((A),(B))
#else
extern void my_pthread_attr_setprio(pthread_attr_t *attr, int priority);
#endif
#endif
#if !defined(HAVE_PTHREAD_ATTR_SETSCOPE) || defined(HAVE_DEC_3_2_THREADS)
#define pthread_attr_setscope(A,B)
#undef HAVE_GETHOSTBYADDR_R /* No definition */