Always treat a standby returning an an invalid flush location as async

This ensures that a standby such as pg_receivexlog will not be selected
as sync standby - which would cause the master to block waiting for
a location that could never happen.

Fujii Masao

diff --git a/src/backend/replication/syncrep.c b/src/backend/replication/syncrep.c
index a3319642c628e99aef7c5cf55b40d2ddb907bbe5..088f7b67f91309cb9c37856c0fbe14ae3b486397 100644 (file)
--- a/src/backend/replication/syncrep.c
+++ b/src/backend/replication/syncrep.c
@@ -377,10 +377,12 @@ SyncRepReleaseWaiters(void)
        /*
         * If this WALSender is serving a standby that is not on the list of
         * potential standbys then we have nothing to do. If we are still starting
-        * up or still running base backup, then leave quickly also.
+        * up, still running base backup or the current flush position is still
+        * invalid, then leave quickly also.
         */
        if (MyWalSnd->sync_standby_priority == 0 ||
-               MyWalSnd->state < WALSNDSTATE_STREAMING)
+               MyWalSnd->state < WALSNDSTATE_STREAMING ||
+               XLogRecPtrIsInvalid(MyWalSnd->flush))
                return;
 
        /*
@@ -400,7 +402,8 @@ SyncRepReleaseWaiters(void)
                        walsnd->state == WALSNDSTATE_STREAMING &&
                        walsnd->sync_standby_priority > 0 &&
                        (priority == 0 ||
-                        priority > walsnd->sync_standby_priority))
+                        priority > walsnd->sync_standby_priority) &&
+                       !XLogRecPtrIsInvalid(walsnd->flush))
                {
                        priority = walsnd->sync_standby_priority;
                        syncWalSnd = walsnd;

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index 650b74fff7d5ca5b6201abfce8efffd332f04d64..0996d6d59484f6b474c0277c7e87dc80776cd42b 100644 (file)
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -280,6 +280,11 @@ WalReceiverMain(void)
        walrcv_connect(conninfo, startpoint);
        DisableWalRcvImmediateExit();
 
+       /* Initialize LogstreamResult, reply_message and feedback_message */
+       LogstreamResult.Write = LogstreamResult.Flush = GetXLogReplayRecPtr(NULL);
+       MemSet(&reply_message, 0, sizeof(reply_message));
+       MemSet(&feedback_message, 0, sizeof(feedback_message));
+
        /* Loop until end-of-streaming or error */
        for (;;)
        {

diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 45a3b2ef2941063d9901d1f060a73c2e3897c751..16c2a7681ec0948ef12051624f5dc27b69cfebb2 100644 (file)
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1530,12 +1530,19 @@ pg_stat_get_wal_senders(PG_FUNCTION_ARGS)
 
                if (walsnd->pid != 0)
                {
-                       sync_priority[i] = walsnd->sync_standby_priority;
+                       /*
+                        * Treat a standby such as a pg_basebackup background process
+                        * which always returns an invalid flush location, as an
+                        * asynchronous standby.
+                        */
+                       sync_priority[i] = XLogRecPtrIsInvalid(walsnd->flush) ?
+                               0 : walsnd->sync_standby_priority;
 
                        if (walsnd->state == WALSNDSTATE_STREAMING &&
                                walsnd->sync_standby_priority > 0 &&
                                (priority == 0 ||
-                                priority > walsnd->sync_standby_priority))
+                                priority > walsnd->sync_standby_priority) &&
+                               !XLogRecPtrIsInvalid(walsnd->flush))
                        {
                                priority = walsnd->sync_standby_priority;
                                sync_standby = i;