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Provide much better wait information in pg_stat_activity.

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When a process is waiting for a heavyweight lock, we will now indicate
the type of heavyweight lock for which it is waiting.  Also, you can
now see when a process is waiting for a lightweight lock - in which
case we will indicate the individual lock name or the tranche, as
appropriate - or for a buffer pin.

Amit Kapila, Ildus Kurbangaliev, reviewed by me.  Lots of helpful
discussion and suggestions by many others, including Alexander
Korotkov, Vladimir Borodin, and many others.
This commit is contained in:
Robert Haas
2016-03-10 12:44:09 -05:00
parent a3a8309d45
commit 53be0b1add
24 changed files with 796 additions and 104 deletions
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116
src/backend/postmaster/pgstat.c
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@@ -48,12 +48,12 @@
#include "postmaster/autovacuum.h"
#include "postmaster/fork_process.h"
#include "postmaster/postmaster.h"
#include "storage/proc.h"
#include "storage/backendid.h"
#include "storage/dsm.h"
#include "storage/fd.h"
#include "storage/ipc.h"
#include "storage/latch.h"
#include "storage/lmgr.h"
#include "storage/pg_shmem.h"
#include "storage/procsignal.h"
#include "storage/sinvaladt.h"
@@ -2723,7 +2723,6 @@ pgstat_bestart(void)
#else
beentry->st_ssl = false;
#endif
beentry->st_waiting = false;
beentry->st_state = STATE_UNDEFINED;
beentry->st_appname[0] = '\0';
beentry->st_activity[0] = '\0';
@@ -2810,6 +2809,8 @@ pgstat_report_activity(BackendState state, const char *cmd_str)
{
if (beentry->st_state != STATE_DISABLED)
{
volatile PGPROC *proc = MyProc;
/*
* track_activities is disabled, but we last reported a
* non-disabled state. As our final update, change the state and
@@ -2820,9 +2821,9 @@ pgstat_report_activity(BackendState state, const char *cmd_str)
beentry->st_state_start_timestamp = 0;
beentry->st_activity[0] = '\0';
beentry->st_activity_start_timestamp = 0;
/* st_xact_start_timestamp and st_waiting are also disabled */
/* st_xact_start_timestamp and wait_event_info are also disabled */
beentry->st_xact_start_timestamp = 0;
beentry->st_waiting = false;
proc->wait_event_info = 0;
pgstat_increment_changecount_after(beentry);
}
return;
@@ -2978,32 +2979,6 @@ pgstat_report_xact_timestamp(TimestampTz tstamp)
pgstat_increment_changecount_after(beentry);
}
/* ----------
* pgstat_report_waiting() -
*
* Called from lock manager to report beginning or end of a lock wait.
*
* NB: this *must* be able to survive being called before MyBEEntry has been
* initialized.
* ----------
*/
void
pgstat_report_waiting(bool waiting)
{
volatile PgBackendStatus *beentry = MyBEEntry;
if (!pgstat_track_activities || !beentry)
return;
/*
* Since this is a single-byte field in a struct that only this process
* may modify, there seems no need to bother with the st_changecount
* protocol. The update must appear atomic in any case.
*/
beentry->st_waiting = waiting;
}
/* ----------
* pgstat_read_current_status() -
*
@@ -3119,6 +3094,87 @@ pgstat_read_current_status(void)
localBackendStatusTable = localtable;
}
/* ----------
* pgstat_get_wait_event_type() -
*
* Return a string representing the current wait event type, backend is
* waiting on.
*/
const char *
pgstat_get_wait_event_type(uint32 wait_event_info)
{
uint8 classId;
const char *event_type;
/* report process as not waiting. */
if (wait_event_info == 0)
return NULL;
wait_event_info = wait_event_info >> 24;
classId = wait_event_info & 0XFF;
switch (classId)
{
case WAIT_LWLOCK_NAMED:
event_type = "LWLockNamed";
break;
case WAIT_LWLOCK_TRANCHE:
event_type = "LWLockTranche";
break;
case WAIT_LOCK:
event_type = "Lock";
break;
case WAIT_BUFFER_PIN:
event_type = "BufferPin";
break;
default:
event_type = "???";
break;
}
return event_type;
}
/* ----------
* pgstat_get_wait_event() -
*
* Return a string representing the current wait event, backend is
* waiting on.
*/
const char *
pgstat_get_wait_event(uint32 wait_event_info)
{
uint8 classId;
uint16 eventId;
const char *event_name;
/* report process as not waiting. */
if (wait_event_info == 0)
return NULL;
eventId = wait_event_info & ((1 << 24) - 1);
wait_event_info = wait_event_info >> 24;
classId = wait_event_info & 0XFF;
switch (classId)
{
case WAIT_LWLOCK_NAMED:
case WAIT_LWLOCK_TRANCHE:
event_name = GetLWLockIdentifier(classId, eventId);
break;
case WAIT_LOCK:
event_name = GetLockNameFromTagType(eventId);
break;
case WAIT_BUFFER_PIN:
event_name = "BufferPin";
break;
default:
event_name = "unknown wait event";
break;
}
return event_name;
}
/* ----------
* pgstat_get_backend_current_activity() -