v11_v12_0001.diff

--- v11-0001-Add-statistics-related-to-write-sync-wal-records.patch	2021-03-03 14:27:02.119713795 +0900
+++ v12-0001-Add-statistics-related-to-write-sync-wal-records.patch	2021-03-03 20:22:47.258763274 +0900
@@ -1,4 +1,4 @@
-From c97fff03cd2bd51b28f6c6fde56c48792683f44e Mon Sep 17 00:00:00 2001
+From d870cfa78e501097cc56780ebb3140db6b9261e5 Mon Sep 17 00:00:00 2001
 From: Masahiro Ikeda <ikedamsh@oss.nttdata.com>
 Date: Fri, 12 Feb 2021 11:19:59 +0900
 Subject: [PATCH 1/2] Add statistics related to write/sync wal records.
@@ -30,10 +30,10 @@
  doc/src/sgml/config.sgml                      | 23 +++++++-
  doc/src/sgml/monitoring.sgml                  | 56 ++++++++++++++++++
  doc/src/sgml/wal.sgml                         | 12 +++-
- src/backend/access/transam/xlog.c             | 57 +++++++++++++++++++
+ src/backend/access/transam/xlog.c             | 59 +++++++++++++++++--
  src/backend/catalog/system_views.sql          |  4 ++
  src/backend/postmaster/pgstat.c               |  4 ++
- src/backend/postmaster/walwriter.c            | 16 ++++--
+ src/backend/postmaster/walwriter.c            | 21 +++++++
  src/backend/utils/adt/pgstatfuncs.c           | 24 +++++++-
  src/backend/utils/misc/guc.c                  |  9 +++
  src/backend/utils/misc/postgresql.conf.sample |  1 +
@@ -41,7 +41,7 @@
  src/include/catalog/pg_proc.dat               |  6 +-
  src/include/pgstat.h                          | 10 ++++
  src/test/regress/expected/rules.out           |  6 +-
- 14 files changed, 214 insertions(+), 15 deletions(-)
+ 14 files changed, 221 insertions(+), 15 deletions(-)
 
 diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
 index b5718fc136..c232f537b2 100644
@@ -182,7 +182,7 @@
     from having to do writes.  On such systems
     one should increase the number of <acronym>WAL</acronym> buffers by
 diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
-index fe56324439..98f558b4c7 100644
+index fe56324439..fafc1b7fac 100644
 --- a/src/backend/access/transam/xlog.c
 +++ b/src/backend/access/transam/xlog.c
 @@ -110,6 +110,7 @@ int			CommitDelay = 0;	/* precommit delay in microseconds */
@@ -232,51 +232,60 @@
  				if (written <= 0)
  				{
  					char		xlogfname[MAXFNAMELEN];
-@@ -10526,6 +10549,21 @@ void
+@@ -10526,6 +10549,24 @@ void
  issue_xlog_fsync(int fd, XLogSegNo segno)
  {
  	char	   *msg = NULL;
-+	bool		issue_fsync = false;
 +	instr_time	start;
 +
-+	/* Check whether the WAL file was synced to disk right now */
-+	if (enableFsync &&
-+		(sync_method == SYNC_METHOD_FSYNC ||
-+		 sync_method == SYNC_METHOD_FSYNC_WRITETHROUGH ||
-+		 sync_method == SYNC_METHOD_FDATASYNC))
-+	{
-+		/* Measure I/O timing to sync the WAL file */
-+		if (track_wal_io_timing)
-+			INSTR_TIME_SET_CURRENT(start);
-+
-+		issue_fsync = true;
-+	}
++	/*
++	 * Check whether the WAL file was synced to disk right now.
++	 *
++	 * If fsync is disabled, never issue fsync method.
++	 *
++	 * If sync_mothod is SYNC_METHOD_OPEN or SYNC_METHOD_OPEN_DSYNC, the WAL
++	 * file is already synced.
++	 */
++	if (!enableFsync ||
++		sync_method == SYNC_METHOD_OPEN ||
++		sync_method == SYNC_METHOD_OPEN_DSYNC)
++		return;
++
++	/* Measure I/O timing to sync the WAL file */
++	if (track_wal_io_timing)
++		INSTR_TIME_SET_CURRENT(start);
  
  	pgstat_report_wait_start(WAIT_EVENT_WAL_SYNC);
  	switch (sync_method)
-@@ -10570,6 +10608,25 @@ issue_xlog_fsync(int fd, XLogSegNo segno)
+@@ -10546,10 +10587,6 @@ issue_xlog_fsync(int fd, XLogSegNo segno)
+ 				msg = _("could not fdatasync file \"%s\": %m");
+ 			break;
+ #endif
+-		case SYNC_METHOD_OPEN:
+-		case SYNC_METHOD_OPEN_DSYNC:
+-			/* write synced it already */
+-			break;
+ 		default:
+ 			elog(PANIC, "unrecognized wal_sync_method: %d", sync_method);
+ 			break;
+@@ -10570,6 +10607,20 @@ issue_xlog_fsync(int fd, XLogSegNo segno)
  	}
  
  	pgstat_report_wait_end();
 +
 +	/*
 +	 * Increment the I/O timing and the number of times WAL files were synced.
-+	 *
-+	 * Check whether the WAL file was synced to disk right now because
-+	 * statistics must be incremented when syncing really occurred.
 +	 */
-+	if (issue_fsync)
++	if (track_wal_io_timing)
 +	{
-+		if (track_wal_io_timing)
-+		{
-+			instr_time	duration;
++		instr_time	duration;
 +
-+			INSTR_TIME_SET_CURRENT(duration);
-+			INSTR_TIME_SUBTRACT(duration, start);
-+			WalStats.m_wal_sync_time += INSTR_TIME_GET_MICROSEC(duration);
-+		}
-+		WalStats.m_wal_sync++;
++		INSTR_TIME_SET_CURRENT(duration);
++		INSTR_TIME_SUBTRACT(duration, start);
++		WalStats.m_wal_sync_time += INSTR_TIME_GET_MICROSEC(duration);
 +	}
++
++	WalStats.m_wal_sync++;
  }
  
  /*
@@ -311,38 +320,52 @@
  
  /* ----------
 diff --git a/src/backend/postmaster/walwriter.c b/src/backend/postmaster/walwriter.c
-index 4f1a8e356b..08fa7032c0 100644
+index 4f1a8e356b..8491e6f6d6 100644
 --- a/src/backend/postmaster/walwriter.c
 +++ b/src/backend/postmaster/walwriter.c
-@@ -223,6 +223,7 @@ WalWriterMain(void)
+@@ -78,6 +78,11 @@ int			WalWriterFlushAfter = 128;
+ #define LOOPS_UNTIL_HIBERNATE		50
+ #define HIBERNATE_FACTOR			25
+ 
++/*
++ * Minimum time between stats file updates; in milliseconds.
++ */
++#define PGSTAT_STAT_INTERVAL	500
++
+ /*
+  * Main entry point for walwriter process
+  *
+@@ -222,7 +227,12 @@ WalWriterMain(void)
+ 	 */
  	for (;;)
  	{
++		/* we assume this inits to all zeroes: */
++		static TimestampTz last_report = 0;
++
  		long		cur_timeout;
 +		int			rc;
++		TimestampTz now;
  
  		/*
  		 * Advertise whether we might hibernate in this cycle.  We do this
-@@ -263,9 +264,16 @@ WalWriterMain(void)
- 		else
- 			cur_timeout = WalWriterDelay * HIBERNATE_FACTOR;
- 
--		(void) WaitLatch(MyLatch,
--						 WL_LATCH_SET | WL_TIMEOUT | WL_EXIT_ON_PM_DEATH,
--						 cur_timeout,
--						 WAIT_EVENT_WAL_WRITER_MAIN);
-+		rc = WaitLatch(MyLatch,
-+					   WL_LATCH_SET | WL_TIMEOUT | WL_EXIT_ON_PM_DEATH,
-+					   cur_timeout,
-+					   WAIT_EVENT_WAL_WRITER_MAIN);
-+
+@@ -253,6 +263,17 @@ WalWriterMain(void)
+ 		else if (left_till_hibernate > 0)
+ 			left_till_hibernate--;
+ 
 +		/*
-+		 * Send WAL statistics only if WalWriterDelay has elapsed to minimize
-+		 * the overhead in WAL-writing.
++		 * Don't send a message unless it's been at least PGSTAT_STAT_INTERVAL
++		 * msec since we last sent one
 +		 */
-+		if (rc & WL_TIMEOUT)
++		now = GetCurrentTimestamp();
++		if (TimestampDifferenceExceeds(last_report, now, PGSTAT_STAT_INTERVAL))
++		{
 +			pgstat_send_wal();
- 	}
- }
++			last_report = now;
++		}
++
+ 		/*
+ 		 * Sleep until we are signaled or WalWriterDelay has elapsed.  If we
+ 		 * haven't done anything useful for quite some time, lengthen the
 diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
 index 62bff52638..7296ef04ff 100644
 --- a/src/backend/utils/adt/pgstatfuncs.c