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, 14 insertions, 0 deletions

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index e129a6b8e40..3f242a8ed70 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -115,6 +115,8 @@
 #include "access/transam.h"
 #include "access/xact.h"
 
+#include "pgstat.h"
+
 #include "replication/logical.h"
 #include "replication/reorderbuffer.h"
 #include "replication/snapbuild.h"
@@ -1580,6 +1582,7 @@ SnapBuildSerialize(SnapBuild *builder, XLogRecPtr lsn)
 		ereport(ERROR,
 				(errmsg("could not open file \"%s\": %m", path)));
 
+	pgstat_report_wait_start(WAIT_EVENT_SNAPBUILD_WRITE);
 	if ((write(fd, ondisk, needed_length)) != needed_length)
 	{
 		CloseTransientFile(fd);
@@ -1587,6 +1590,7 @@ SnapBuildSerialize(SnapBuild *builder, XLogRecPtr lsn)
 				(errcode_for_file_access(),
 				 errmsg("could not write to file \"%s\": %m", tmppath)));
 	}
+	pgstat_report_wait_end();
 
 	/*
 	 * fsync the file before renaming so that even if we crash after this we
@@ -1596,6 +1600,7 @@ SnapBuildSerialize(SnapBuild *builder, XLogRecPtr lsn)
 	 * some noticeable overhead since it's performed synchronously during
 	 * decoding?
 	 */
+	pgstat_report_wait_start(WAIT_EVENT_SNAPBUILD_SYNC);
 	if (pg_fsync(fd) != 0)
 	{
 		CloseTransientFile(fd);
@@ -1603,6 +1608,7 @@ SnapBuildSerialize(SnapBuild *builder, XLogRecPtr lsn)
 				(errcode_for_file_access(),
 				 errmsg("could not fsync file \"%s\": %m", tmppath)));
 	}
+	pgstat_report_wait_end();
 	CloseTransientFile(fd);
 
 	fsync_fname("pg_logical/snapshots", true);
@@ -1677,7 +1683,9 @@ SnapBuildRestore(SnapBuild *builder, XLogRecPtr lsn)
 
 
 	/* read statically sized portion of snapshot */
+	pgstat_report_wait_start(WAIT_EVENT_SNAPBUILD_READ);
 	readBytes = read(fd, &ondisk, SnapBuildOnDiskConstantSize);
+	pgstat_report_wait_end();
 	if (readBytes != SnapBuildOnDiskConstantSize)
 	{
 		CloseTransientFile(fd);
@@ -1703,7 +1711,9 @@ SnapBuildRestore(SnapBuild *builder, XLogRecPtr lsn)
 			SnapBuildOnDiskConstantSize - SnapBuildOnDiskNotChecksummedSize);
 
 	/* read SnapBuild */
+	pgstat_report_wait_start(WAIT_EVENT_SNAPBUILD_READ);
 	readBytes = read(fd, &ondisk.builder, sizeof(SnapBuild));
+	pgstat_report_wait_end();
 	if (readBytes != sizeof(SnapBuild))
 	{
 		CloseTransientFile(fd);
@@ -1717,7 +1727,9 @@ SnapBuildRestore(SnapBuild *builder, XLogRecPtr lsn)
 	/* restore running xacts information */
 	sz = sizeof(TransactionId) * ondisk.builder.running.xcnt_space;
 	ondisk.builder.running.xip = MemoryContextAllocZero(builder->context, sz);
+	pgstat_report_wait_start(WAIT_EVENT_SNAPBUILD_READ);
 	readBytes = read(fd, ondisk.builder.running.xip, sz);
+	pgstat_report_wait_end();
 	if (readBytes != sz)
 	{
 		CloseTransientFile(fd);
@@ -1731,7 +1743,9 @@ SnapBuildRestore(SnapBuild *builder, XLogRecPtr lsn)
 	/* restore committed xacts information */
 	sz = sizeof(TransactionId) * ondisk.builder.committed.xcnt;
 	ondisk.builder.committed.xip = MemoryContextAllocZero(builder->context, sz);
+	pgstat_report_wait_start(WAIT_EVENT_SNAPBUILD_READ);
 	readBytes = read(fd, ondisk.builder.committed.xip, sz);
+	pgstat_report_wait_end();
 	if (readBytes != sz)
 	{
 		CloseTransientFile(fd);