On Wed, Dec 31, 2014 at 12:22 AM, Alexey Vasiliev <leopard...@inbox.ru> wrote:
> Tue, 30 Dec 2014 21:39:33 +0900 от Michael Paquier
> <michael.paqu...@gmail.com>:
> As I understand now = (pg_time_t) time(NULL); return time in seconds, what is
> why I multiply value to 1000 to compare with restore_command_retry_interval
> in milliseconds.
This way of doing is incorrect, you would get a wait time of 1s even
for retries lower than 1s. In order to get the feature working
correctly and to get a comparison granularity sufficient, you need to
use TimetampTz for the tracking of the current and last failure time
and to use the APIs from TimestampTz for difference calculations.
> I am not sure about small retry interval of time, in my cases I need interval
> bigger 5 seconds (20-40 seconds). Right now I limiting this value be bigger
> 100 milliseconds.
Other people may disagree here, but I don't see any reason to put
restrictions to this interval of time.
Attached is a patch fixing the feature to use TimestampTz, updating as
well the docs and recovery.conf.sample which was incorrect, on top of
other things I noticed here and there.
Alexey, does this new patch look fine for you?
--
Michael
From 9bb71e39b218885466a53c005a87361d4ae889fa Mon Sep 17 00:00:00 2001
From: Michael Paquier <mich...@otacoo.com>
Date: Mon, 5 Jan 2015 17:10:13 +0900
Subject: [PATCH] Add restore_command_retry_interval to control retries of
restore_command
restore_command_retry_interval can be specified in recovery.conf to control
the interval of time between retries of restore_command when failures occur.
---
doc/src/sgml/recovery-config.sgml | 21 +++++++++++++
src/backend/access/transam/recovery.conf.sample | 9 ++++++
src/backend/access/transam/xlog.c | 42 ++++++++++++++++++++-----
3 files changed, 64 insertions(+), 8 deletions(-)
diff --git a/doc/src/sgml/recovery-config.sgml b/doc/src/sgml/recovery-config.sgml
index 0c64ff2..0488ae3 100644
--- a/doc/src/sgml/recovery-config.sgml
+++ b/doc/src/sgml/recovery-config.sgml
@@ -145,6 +145,27 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="restore-command-retry-interval" xreflabel="restore_command_retry_interval">
+ <term><varname>restore_command_retry_interval</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>restore_command_retry_interval</> recovery parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ If <varname>restore_command</> returns nonzero exit status code, retry
+ command after the interval of time specified by this parameter,
+ measured in milliseconds if no unit is specified. Default value is
+ <literal>5s</>.
+ </para>
+ <para>
+ This command is particularly useful for warm standby configurations
+ to leverage the amount of retries done to restore a WAL segment file
+ depending on the activity of a master node.
+ </para>
+ </listitem>
+ </varlistentry>
+
</variablelist>
</sect1>
diff --git a/src/backend/access/transam/recovery.conf.sample b/src/backend/access/transam/recovery.conf.sample
index b777400..8699a33 100644
--- a/src/backend/access/transam/recovery.conf.sample
+++ b/src/backend/access/transam/recovery.conf.sample
@@ -58,6 +58,15 @@
#
#recovery_end_command = ''
#
+#
+# restore_command_retry_interval
+#
+# specifies an optional retry interval for restore_command command, if
+# previous command returned nonzero exit status code. This can be useful
+# to increase or decrease the number of calls of restore_command.
+#
+#restore_command_retry_interval = '5s'
+#
#---------------------------------------------------------------------------
# RECOVERY TARGET PARAMETERS
#---------------------------------------------------------------------------
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 5cc7e47..1944e6f 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -235,6 +235,7 @@ static TimestampTz recoveryTargetTime;
static char *recoveryTargetName;
static int recovery_min_apply_delay = 0;
static TimestampTz recoveryDelayUntilTime;
+static int restore_command_retry_interval = 5000;
/* options taken from recovery.conf for XLOG streaming */
static bool StandbyModeRequested = false;
@@ -4881,6 +4882,26 @@ readRecoveryCommandFile(void)
(errmsg_internal("trigger_file = '%s'",
TriggerFile)));
}
+ else if (strcmp(item->name, "restore_command_retry_interval") == 0)
+ {
+ const char *hintmsg;
+
+ if (!parse_int(item->value, &restore_command_retry_interval, GUC_UNIT_MS,
+ &hintmsg))
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+ errmsg("parameter \"%s\" requires a temporal value",
+ "restore_command_retry_interval"),
+ hintmsg ? errhint("%s", _(hintmsg)) : 0));
+ ereport(DEBUG2,
+ (errmsg_internal("restore_command_retry_interval = '%s'", item->value)));
+
+ if (restore_command_retry_interval <= 0)
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+ errmsg("\"%s\" must have a value strictly positive",
+ "restore_command_retry_interval")));
+ }
else if (strcmp(item->name, "recovery_min_apply_delay") == 0)
{
const char *hintmsg;
@@ -10345,8 +10366,8 @@ static bool
WaitForWALToBecomeAvailable(XLogRecPtr RecPtr, bool randAccess,
bool fetching_ckpt, XLogRecPtr tliRecPtr)
{
- static pg_time_t last_fail_time = 0;
- pg_time_t now;
+ TimestampTz now = GetCurrentTimestamp();
+ TimestampTz last_fail_time = now;
/*-------
* Standby mode is implemented by a state machine:
@@ -10495,14 +10516,19 @@ WaitForWALToBecomeAvailable(XLogRecPtr RecPtr, bool randAccess,
* machine, so we've exhausted all the options for
* obtaining the requested WAL. We're going to loop back
* and retry from the archive, but if it hasn't been long
- * since last attempt, sleep 5 seconds to avoid
- * busy-waiting.
+ * since last attempt, sleep the amount of time specified
+ * by restore_command_retry_interval to avoid busy-waiting.
*/
- now = (pg_time_t) time(NULL);
- if ((now - last_fail_time) < 5)
+ now = GetCurrentTimestamp();
+ if (!TimestampDifferenceExceeds(last_fail_time, now,
+ restore_command_retry_interval))
{
- pg_usleep(1000000L * (5 - (now - last_fail_time)));
- now = (pg_time_t) time(NULL);
+ long secs;
+ int microsecs;
+
+ TimestampDifference(last_fail_time, now, &secs, µsecs);
+ pg_usleep(restore_command_retry_interval * 1000L - (1000000L * secs + 1L * microsecs));
+ now = GetCurrentTimestamp();
}
last_fail_time = now;
currentSource = XLOG_FROM_ARCHIVE;
--
2.2.1
--
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