Hi Simon, Hi all,
if (!logged && (wait_s > 0 || wait_us > 500000))
{
const char *oldactivitymsg;
int len;
oldactivitymsg = get_ps_display(&len);
snprintf(waitactivitymsg, sizeof(waitactivitymsg),
"waiting for max_standby_delay (%u s)",
MaxStandbyDelay);
set_ps_display(waitactivitymsg, false);
if (len > 100)
len = 100;
memcpy(waitactivitymsg, oldactivitymsg, len);
pgstat_report_waiting(true);
logged = true;
}
..
if (logged)
{
set_ps_display(waitactivitymsg, false);
pgstat_report_waiting(false);
}
That doesnt work because get_ps_display returns the internal buffer. This
leads to the situation that after conflict resolution the
"waiting for max_standby_delay ..."
message is displayed until the next segment starts where its replaced
again by the
"... recovering ..." line.
Additionally the old code may print unintialized memory if get_ps_display
returns a string without a \0 terminator.
The attached patch fixes that.
Andres
From a0198eab28552b9af9a70298f49a17348077c6fd Mon Sep 17 00:00:00 2001
From: Andres Freund <[email protected]>
Date: Sun, 7 Feb 2010 19:52:07 +0100
Subject: [PATCH] The stat reporting in ResolveRecoveryConflictWithVirtualXIDs had a
small bug - it tried to use the buffer returned by get_ps_display() as
temp. storage - which does not work.
---
src/backend/storage/ipc/standby.c | 17 +++++++++++------
1 files changed, 11 insertions(+), 6 deletions(-)
diff --git a/src/backend/storage/ipc/standby.c b/src/backend/storage/ipc/standby.c
index 63a9c68..995a2dc 100644
*** a/src/backend/storage/ipc/standby.c
--- b/src/backend/storage/ipc/standby.c
*************** ResolveRecoveryConflictWithVirtualXIDs(V
*** 161,166 ****
--- 161,167 ----
ProcSignalReason reason)
{
char waitactivitymsg[100];
+ char oldactivitymsg[101];
while (VirtualTransactionIdIsValid(*waitlist))
{
*************** ResolveRecoveryConflictWithVirtualXIDs(V
*** 183,199 ****
TimestampDifference(waitStart, now, &wait_s, &wait_us);
if (!logged && (wait_s > 0 || wait_us > 500000))
{
! const char *oldactivitymsg;
int len;
! oldactivitymsg = get_ps_display(&len);
snprintf(waitactivitymsg, sizeof(waitactivitymsg),
"waiting for max_standby_delay (%u s)",
MaxStandbyDelay);
set_ps_display(waitactivitymsg, false);
- if (len > 100)
- len = 100;
- memcpy(waitactivitymsg, oldactivitymsg, len);
pgstat_report_waiting(true);
--- 184,204 ----
TimestampDifference(waitStart, now, &wait_s, &wait_us);
if (!logged && (wait_s > 0 || wait_us > 500000))
{
! const char *oldactivitymsgp;
int len;
! oldactivitymsgp = get_ps_display(&len);
!
! if (len > 100)
! len = 100;
!
! memcpy(oldactivitymsg, oldactivitymsgp, len);
! oldactivitymsg[len] = 0;
!
snprintf(waitactivitymsg, sizeof(waitactivitymsg),
"waiting for max_standby_delay (%u s)",
MaxStandbyDelay);
set_ps_display(waitactivitymsg, false);
pgstat_report_waiting(true);
*************** ResolveRecoveryConflictWithVirtualXIDs(V
*** 223,229 ****
/* Reset ps display */
if (logged)
{
! set_ps_display(waitactivitymsg, false);
pgstat_report_waiting(false);
}
--- 228,234 ----
/* Reset ps display */
if (logged)
{
! set_ps_display(oldactivitymsg, false);
pgstat_report_waiting(false);
}
--
1.6.5.12.gd65df24
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