Create and use wait events for read, write, and fsync operations.

Previous commits, notably 53be0b1add7064ca5db3cd884302dfc3268d884e and
6f3bd98ebfc008cbd676da777bb0b2376c4c4bfa, made it possible to see from
pg_stat_activity when a backend was stuck waiting for another backend,
but it's also fairly common for a backend to be stuck waiting for an
I/O.  Add wait events for those operations, too.

Rushabh Lathia, with further hacking by me.  Reviewed and tested by
Michael Paquier, Amit Kapila, Rajkumar Raghuwanshi, and Rahila Syed.

Discussion: http://postgr.es/m/CAGPqQf0LsYHXREPAZqYGVkDqHSyjf=KsD=k0GTVPAuzyThh-VQ@mail.gmail.com

1 files changed, 17 insertions, 0 deletions

diff --git a/src/backend/utils/init/miscinit.c b/src/backend/utils/init/miscinit.c
index e0298ee35ff..8d149bf2728 100644
--- a/src/backend/utils/init/miscinit.c
+++ b/src/backend/utils/init/miscinit.c
@@ -35,6 +35,7 @@
 #include "libpq/libpq.h"
 #include "mb/pg_wchar.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "postmaster/postmaster.h"
 #include "storage/fd.h"
@@ -856,11 +857,13 @@ CreateLockFile(const char *filename, bool amPostmaster,
 					 errmsg("could not open lock file \"%s\": %m",
 							filename)));
 		}
+		pgstat_report_wait_start(WAIT_EVENT_LOCK_FILE_CREATE_READ);
 		if ((len = read(fd, buffer, sizeof(buffer) - 1)) < 0)
 			ereport(FATAL,
 					(errcode_for_file_access(),
 					 errmsg("could not read lock file \"%s\": %m",
 							filename)));
+		pgstat_report_wait_end();
 		close(fd);
 
 		if (len == 0)
@@ -1009,6 +1012,7 @@ CreateLockFile(const char *filename, bool amPostmaster,
 		strlcat(buffer, "\n", sizeof(buffer));
 
 	errno = 0;
+	pgstat_report_wait_start(WAIT_EVENT_LOCK_FILE_CREATE_WRITE);
 	if (write(fd, buffer, strlen(buffer)) != strlen(buffer))
 	{
 		int			save_errno = errno;
@@ -1021,6 +1025,9 @@ CreateLockFile(const char *filename, bool amPostmaster,
 				(errcode_for_file_access(),
 				 errmsg("could not write lock file \"%s\": %m", filename)));
 	}
+	pgstat_report_wait_end();
+
+	pgstat_report_wait_start(WAIT_EVENT_LOCK_FILE_CREATE_SYNC);
 	if (pg_fsync(fd) != 0)
 	{
 		int			save_errno = errno;
@@ -1032,6 +1039,7 @@ CreateLockFile(const char *filename, bool amPostmaster,
 				(errcode_for_file_access(),
 				 errmsg("could not write lock file \"%s\": %m", filename)));
 	}
+	pgstat_report_wait_end();
 	if (close(fd) != 0)
 	{
 		int			save_errno = errno;
@@ -1164,7 +1172,9 @@ AddToDataDirLockFile(int target_line, const char *str)
 						DIRECTORY_LOCK_FILE)));
 		return;
 	}
+	pgstat_report_wait_start(WAIT_EVENT_LOCK_FILE_ADDTODATADIR_READ);
 	len = read(fd, srcbuffer, sizeof(srcbuffer) - 1);
+	pgstat_report_wait_end();
 	if (len < 0)
 	{
 		ereport(LOG,
@@ -1217,9 +1227,11 @@ AddToDataDirLockFile(int target_line, const char *str)
 	 */
 	len = strlen(destbuffer);
 	errno = 0;
+	pgstat_report_wait_start(WAIT_EVENT_LOCK_FILE_ADDTODATADIR_WRITE);
 	if (lseek(fd, (off_t) 0, SEEK_SET) != 0 ||
 		(int) write(fd, destbuffer, len) != len)
 	{
+		pgstat_report_wait_end();
 		/* if write didn't set errno, assume problem is no disk space */
 		if (errno == 0)
 			errno = ENOSPC;
@@ -1230,6 +1242,8 @@ AddToDataDirLockFile(int target_line, const char *str)
 		close(fd);
 		return;
 	}
+	pgstat_report_wait_end();
+	pgstat_report_wait_start(WAIT_EVENT_LOCK_FILE_ADDTODATADIR_SYNC);
 	if (pg_fsync(fd) != 0)
 	{
 		ereport(LOG,
@@ -1237,6 +1251,7 @@ AddToDataDirLockFile(int target_line, const char *str)
 				 errmsg("could not write to file \"%s\": %m",
 						DIRECTORY_LOCK_FILE)));
 	}
+	pgstat_report_wait_end();
 	if (close(fd) != 0)
 	{
 		ereport(LOG,
@@ -1293,7 +1308,9 @@ RecheckDataDirLockFile(void)
 				return true;
 		}
 	}
+	pgstat_report_wait_start(WAIT_EVENT_LOCK_FILE_RECHECKDATADIR_READ);
 	len = read(fd, buffer, sizeof(buffer) - 1);
+	pgstat_report_wait_end();
 	if (len < 0)
 	{
 		ereport(LOG,