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Add some optional code (conditionally compiled under #ifdef LWLOCK_STATS)

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to track the number of LWLock acquisitions and the number of times we
block waiting for an LWLock, on a per-process basis.  After having needed
this twice in the past few months, seems like it should go into CVS.
This commit is contained in:
Tom Lane 2006-04-21 16:45:12 +00:00
parent efe222268f
commit b5498a26de
1 changed files with 58 additions and 1 deletions
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59
src/backend/storage/lmgr/lwlock.c
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@ -15,7 +15,7 @@
* Portions Copyright (c) 1994, Regents of the University of California * Portions Copyright (c) 1994, Regents of the University of California
* *
* IDENTIFICATION * IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/storage/lmgr/lwlock.c,v 1.38 2006/03/05 15:58:39 momjian Exp $ * $PostgreSQL: pgsql/src/backend/storage/lmgr/lwlock.c,v 1.39 2006/04/21 16:45:12 tgl Exp $
* *
*------------------------------------------------------------------------- *-------------------------------------------------------------------------
*/ */
@ -25,6 +25,7 @@
#include "access/multixact.h" #include "access/multixact.h"
#include "access/subtrans.h" #include "access/subtrans.h"
#include "miscadmin.h" #include "miscadmin.h"
#include "storage/ipc.h"
#include "storage/lwlock.h" #include "storage/lwlock.h"
#include "storage/proc.h" #include "storage/proc.h"
#include "storage/spin.h" #include "storage/spin.h"
@ -84,6 +85,13 @@ NON_EXEC_STATIC LWLockPadded *LWLockArray = NULL;
static int num_held_lwlocks = 0; static int num_held_lwlocks = 0;
static LWLockId held_lwlocks[MAX_SIMUL_LWLOCKS]; static LWLockId held_lwlocks[MAX_SIMUL_LWLOCKS];
#ifdef LWLOCK_STATS
static int counts_for_pid = 0;
static int *sh_acquire_counts;
static int *ex_acquire_counts;
static int *block_counts;
#endif
#ifdef LOCK_DEBUG #ifdef LOCK_DEBUG
bool Trace_lwlocks = false; bool Trace_lwlocks = false;
@ -109,6 +117,31 @@ LOG_LWDEBUG(const char *where, LWLockId lockid, const char *msg)
#define LOG_LWDEBUG(a,b,c) #define LOG_LWDEBUG(a,b,c)
#endif /* LOCK_DEBUG */ #endif /* LOCK_DEBUG */
#ifdef LWLOCK_STATS
static void
print_lwlock_stats(int code, Datum arg)
{
int i;
int *LWLockCounter = (int *) ((char *) LWLockArray - 2 * sizeof(int));
int numLocks = LWLockCounter[1];
/* Grab an LWLock to keep different backends from mixing reports */
LWLockAcquire(0, LW_EXCLUSIVE);
for (i = 0; i < numLocks; i++)
{
if (sh_acquire_counts[i] || ex_acquire_counts[i] || block_counts[i])
fprintf(stderr, "PID %d lwlock %d: shacq %u exacq %u blk %u\n",
MyProcPid, i, sh_acquire_counts[i], ex_acquire_counts[i],
block_counts[i]);
}
LWLockRelease(0);
}
#endif /* LWLOCK_STATS */
/* /*
* Compute number of LWLocks to allocate. * Compute number of LWLocks to allocate.
@ -263,6 +296,26 @@ LWLockAcquire(LWLockId lockid, LWLockMode mode)
PRINT_LWDEBUG("LWLockAcquire", lockid, lock); PRINT_LWDEBUG("LWLockAcquire", lockid, lock);
#ifdef LWLOCK_STATS
/* Set up local count state first time through in a given process */
if (counts_for_pid != MyProcPid)
{
int *LWLockCounter = (int *) ((char *) LWLockArray - 2 * sizeof(int));
int numLocks = LWLockCounter[1];
sh_acquire_counts = calloc(numLocks, sizeof(int));
ex_acquire_counts = calloc(numLocks, sizeof(int));
block_counts = calloc(numLocks, sizeof(int));
counts_for_pid = MyProcPid;
on_shmem_exit(print_lwlock_stats, 0);
}
/* Count lock acquisition attempts */
if (mode == LW_EXCLUSIVE)
ex_acquire_counts[lockid]++;
else
sh_acquire_counts[lockid]++;
#endif /* LWLOCK_STATS */
/* /*
* We can't wait if we haven't got a PGPROC. This should only occur * We can't wait if we haven't got a PGPROC. This should only occur
* during bootstrap or shared memory initialization. Put an Assert here * during bootstrap or shared memory initialization. Put an Assert here
@ -369,6 +422,10 @@ LWLockAcquire(LWLockId lockid, LWLockMode mode)
*/ */
LOG_LWDEBUG("LWLockAcquire", lockid, "waiting"); LOG_LWDEBUG("LWLockAcquire", lockid, "waiting");
#ifdef LWLOCK_STATS
block_counts[lockid]++;
#endif
for (;;) for (;;)
{ {
/* "false" means cannot accept cancel/die interrupt here. */ /* "false" means cannot accept cancel/die interrupt here. */