Fix bug so logical rep launcher saves correctly time of last startup of worker.

Previously the logical replication launcher stored the last timestamp
when it started the worker, in the local variable "last_start_time",
in order to check whether wal_retrive_retry_interval elapsed since
the last startup of worker. If it has elapsed, the launcher sees
pg_subscription and starts new worker if necessary. This is for
limitting the startup of worker to once a wal_retrieve_retry_interval.

The bug was that the variable "last_start_time" was defined and
always initialized with 0 at the beginning of the launcher's main loop.
So even if it's set to the last timestamp in later phase of the loop,
it's always reset to 0. Therefore the launcher could not check
correctly whether wal_retrieve_retry_interval elapsed since
the last startup.

This patch moves the variable "last_start_time" outside the main loop
so that it will not be reset.

Reviewed-by: Petr Jelinek
Discussion: http://postgr.es/m/CAHGQGwGJrPO++XM4mFENAwpy1eGXKsGdguYv43GUgLgU-x8nTQ@mail.gmail.com

diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 549b612e9aeb1128704501c68b2e622ed02814b4..cf0cb37acc6e20d35554e9a1787b3b755324fccc 100644 (file)
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -781,6 +781,8 @@ ApplyLauncherWakeup(void)
 void
 ApplyLauncherMain(Datum main_arg)
 {
+       TimestampTz             last_start_time = 0;
+
        ereport(DEBUG1,
                        (errmsg("logical replication launcher started")));
 
@@ -812,7 +814,6 @@ ApplyLauncherMain(Datum main_arg)
                MemoryContext   subctx;
                MemoryContext   oldctx;
                TimestampTz             now;
-               TimestampTz             last_start_time = 0;
                long                    wait_time = DEFAULT_NAPTIME_PER_CYCLE;
 
                now = GetCurrentTimestamp();