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commit    7900e94fbb2d36fe798f2deda56d71071957c0e0
Author:   Fujii Masao <fujii@postgresql.org>
Date:     Wed Nov 19 05:11:48 2014 +0000
First released in: 9.5.0, 9.4.0

    Fix pg_receivexlog --slot so that it doesn't prevent the server shutdown.
    
    When pg_receivexlog --slot is connecting to the server, at the shutdown
    of the server, walsender keeps waiting for the last WAL record to be
    replicated and flushed in pg_receivexlog. But previously pg_receivexlog
    issued sync command only when WAL file was switched. So there was
    the case where the last WAL was never flushed and walsender had to
    keep waiting infinitely. This caused the server shutdown to get stuck.
    
    pg_recvlogical handles this problem by calling fsync() when it receives
    the request of immediate reply from the server. That is, at shutdown,
    walsender sends the request, pg_recvlogical receives it, flushes the last
    WAL record, and sends the flush location back to the server. Since
    walsender can see that the last WAL record is successfully flushed, it can
    exit cleanly.
    
    This commit introduces the same logic as pg_recvlogical has,
    to pg_receivexlog.
    
    Back-patch to 9.4 where pg_receivexlog was changed so that it can use
    the replication slot.
    
    Original patch by Michael Paquier, rewritten by me.
    Bug report by Furuya Osamu.


 src/bin/pg_basebackup/receivelog.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/src/bin/pg_basebackup/receivelog.c b/src/bin/pg_basebackup/receivelog.c
index 8f360ec3e46..48a34cb5546 100644
--- a/src/bin/pg_basebackup/receivelog.c
+++ b/src/bin/pg_basebackup/receivelog.c
@@ -918,6 +918,25 @@ HandleCopyStream(PGconn *conn, XLogRecPtr startpos, uint32 timeline,
 			/* If the server requested an immediate reply, send one. */
 			if (replyRequested && still_sending)
 			{
+				if (reportFlushPosition && lastFlushPosition < blockpos &&
+					walfile != 1)
+				{
+					/*
+					 * If a valid flush location needs to be reported,
+					 * flush the current WAL file so that the latest flush
+					 * location is sent back to the server. This is necessary to
+					 * see whether the last WAL data has been successfully
+					 * replicated or not, at the normal shutdown of the server.
+					 */
+					if (fsync(walfile) != 0)
+					{
+						fprintf(stderr, _("%s: could not fsync file \"%s\": %s\n"),
+								progname, current_walfile_name, strerror(errno));
+						goto error;
+					}
+					lastFlushPosition = blockpos;
+				}
+
 				now = feGetCurrentTimestamp();
 				if (!sendFeedback(conn, blockpos, now, false))
 					goto error;


[parent: e1ab2fa82369]