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Add GUC to control the time to wait before retrieving WAL after failed attempt.

author Fujii Masao <fujii@postgresql.org>

2015年2月23日 11:55:17 +0000 (20:55 +0900)

committer Fujii Masao <fujii@postgresql.org>

2015年2月23日 11:55:17 +0000 (20:55 +0900)

Previously when the standby server failed to retrieve WAL files from any sources
(i.e., streaming replication, local pg_xlog directory or WAL archive), it always
waited for five seconds (hard-coded) before the next attempt. For example,
this is problematic in warm-standby because restore_command can fail
every five seconds even while new WAL file is expected to be unavailable for
a long time and flood the log files with its error messages.

This commit adds new parameter, wal_retrieve_retry_interval, to control that
wait time.

Alexey Vasiliev and Michael Paquier, reviewed by Andres Freund and me.

doc/src/sgml/config.sgml patch | blob | blame | history

src/backend/access/transam/xlog.c patch | blob | blame | history

src/backend/utils/misc/guc.c patch | blob | blame | history

src/backend/utils/misc/postgresql.conf.sample patch | blob | blame | history

src/include/access/xlog.h patch | blob | blame | history

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml

index 6bcb106518e4eefe33c9b69129d737f93a1646be..a3917aac7855bc3c71f7e6bb6b3c78078d981314 100644 (file)

--- a/doc/src/sgml/config.sgml

+++ b/doc/src/sgml/config.sgml

@@ -2985,6 +2985,24 @@ include_dir 'conf.d'

</listitem>

</varlistentry>

+ <varlistentry id="guc-wal-retrieve-retry-interval" xreflabel="wal_retrieve_retry_interval">

+ <term><varname>wal_retrieve_retry_interval</varname> (<type>integer</type>)

+ <indexterm>

+ <primary><varname>wal_retrieve_retry_interval</> configuration parameter</primary>

+ </indexterm>

+ </term>

+ <listitem>

+ <para>

+ Specify how long the standby server should wait when WAL data is not

+ available from any sources (streaming replication,

+ local <filename>pg_xlog</> or WAL archive) before retrying to

+ retrieve WAL data. This parameter can only be set in the

+ <filename>postgresql.conf</> file or on the server command line.

+ The default value is 5 seconds. Units are milliseconds if not specified.

+ </para>

+ </listitem>

+ </varlistentry>

</variablelist>

</sect2>

</sect1>

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c

index 629a457965ff2e6987bd6ccd5ee0cabb26fe212c..f68f82b255c0608d7a7f958865a2abe3d179911c 100644 (file)

--- a/src/backend/access/transam/xlog.c

+++ b/src/backend/access/transam/xlog.c

@@ -93,6 +93,7 @@ int sync_method = DEFAULT_SYNC_METHOD;

int wal_level = WAL_LEVEL_MINIMAL;

int CommitDelay = 0; /* precommit delay in microseconds */

int CommitSiblings = 5; /* # concurrent xacts needed to sleep */

+int wal_retrieve_retry_interval = 5000;

#ifdef WAL_DEBUG

bool XLOG_DEBUG = false;

@@ -10340,8 +10341,8 @@ static bool

WaitForWALToBecomeAvailable(XLogRecPtr RecPtr, bool randAccess,

bool fetching_ckpt, XLogRecPtr tliRecPtr)

{

- static pg_time_t last_fail_time = 0;

- pg_time_t now;

+ static TimestampTz last_fail_time = 0;

+ TimestampTz now;

/*-------

* Standby mode is implemented by a state machine:

@@ -10351,7 +10352,7 @@ WaitForWALToBecomeAvailable(XLogRecPtr RecPtr, bool randAccess,

* 2. Check trigger file

* 3. Read from primary server via walreceiver (XLOG_FROM_STREAM)

* 4. Rescan timelines

- * 5. Sleep 5 seconds, and loop back to 1.

+ * 5. Sleep wal_retrieve_retry_interval milliseconds, and loop back to 1.

* Failure to read from the current source advances the state machine to

* the next state.

@@ -10490,14 +10491,25 @@ 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 wal_retrieve_retry_interval

+ * milliseconds to avoid busy-waiting.

- now = (pg_time_t) time(NULL);

- if ((now - last_fail_time) < 5)

+ now = GetCurrentTimestamp();

+ if (!TimestampDifferenceExceeds(last_fail_time, now,

+ wal_retrieve_retry_interval))

{

- pg_usleep(1000000L * (5 - (now - last_fail_time)));

- now = (pg_time_t) time(NULL);

+ long secs, wait_time;

+ int usecs;

+ TimestampDifference(last_fail_time, now, &secs, &usecs);

+ wait_time = wal_retrieve_retry_interval -

+ (secs * 1000 + usecs / 1000);

+ WaitLatch(&XLogCtl->recoveryWakeupLatch,

+ WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH,

+ wait_time);

+ ResetLatch(&XLogCtl->recoveryWakeupLatch);

+ now = GetCurrentTimestamp();

}

last_fail_time = now;

currentSource = XLOG_FROM_ARCHIVE;

@@ -10653,12 +10665,11 @@ WaitForWALToBecomeAvailable(XLogRecPtr RecPtr, bool randAccess,

}

- * Wait for more WAL to arrive. Time out after 5 seconds,

- * like when polling the archive, to react to a trigger

- * file promptly.

+ * Wait for more WAL to arrive. Time out after 5 seconds

+ * to react to a trigger file promptly.

WaitLatch(&XLogCtl->recoveryWakeupLatch,

- WL_LATCH_SET | WL_TIMEOUT,

+ WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH,

5000L);

ResetLatch(&XLogCtl->recoveryWakeupLatch);

break;

diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c

index 95727776d3851a2d1a55ca3d3fa824a7cf492bbc..cf401d3cf03ecbb30987151ae0e8784e14033a12 100644 (file)

--- a/src/backend/utils/misc/guc.c

+++ b/src/backend/utils/misc/guc.c

@@ -2363,6 +2363,18 @@ static struct config_int ConfigureNamesInt[] =

NULL, NULL, NULL

+ {

+ {"wal_retrieve_retry_interval", PGC_SIGHUP, REPLICATION_STANDBY,

+ gettext_noop("Sets the time to wait before retrying to retrieve WAL"

+ "after a failed attempt."),

+ NULL,

+ GUC_UNIT_MS

+ },

+ &wal_retrieve_retry_interval,

+ 5000, 1, INT_MAX,

+ NULL, NULL, NULL

+ },

{

{"wal_segment_size", PGC_INTERNAL, PRESET_OPTIONS,

gettext_noop("Shows the number of pages per write ahead log segment."),

diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample

index b053659f88e85a2aff7b2ddcbb12b0ca4b2897d0..29d8485964d696cccc0d45e63c1644485973b1f1 100644 (file)

--- a/src/backend/utils/misc/postgresql.conf.sample

+++ b/src/backend/utils/misc/postgresql.conf.sample

@@ -260,6 +260,8 @@

#wal_receiver_timeout = 60s # time that receiver waits for

# communication from master

# in milliseconds; 0 disables

+#wal_retrieve_retry_interval = 5s # time to wait before retrying to

+ # retrieve WAL after a failed attempt

#------------------------------------------------------------------------------

diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h

index 138deaf7c8fa393507c59eec49e3b2cbee67d5a3..be27a85648665ba7aaa9f4d61c516feaf7dcb675 100644 (file)

--- a/src/include/access/xlog.h

+++ b/src/include/access/xlog.h

@@ -93,6 +93,7 @@ extern int CheckPointSegments;

extern int wal_keep_segments;

extern int XLOGbuffers;

extern int XLogArchiveTimeout;

+extern int wal_retrieve_retry_interval;

extern bool XLogArchiveMode;

extern char *XLogArchiveCommand;

extern bool EnableHotStandby;

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