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Skip largely pointless master reconnection attempt.

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Experimental - see notes in code.
This commit is contained in:
Ian Barwick
2016-08-16 13:25:39 +09:00
parent 9831cabd4d
commit 6bd1c6a36d
1 changed files with 37 additions and 14 deletions
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51
repmgrd.c
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@@ -799,14 +799,13 @@ standby_monitor(void)
/*
* Check that the upstream node is still available
* If not, initiate failover process
*/
check_connection(&upstream_conn, upstream_node_type, upstream_conninfo);
/*
*
* This takes up to local_options.reconnect_attempts *
* local_options.reconnect_interval seconds
*/
check_connection(&upstream_conn, upstream_node_type, upstream_conninfo);
if (PQstatus(upstream_conn) != CONNECTION_OK)
{
int previous_master_node_id = master_options.node;
@@ -1330,21 +1329,43 @@ do_master_failover(void)
nodes[i].is_visible = false;
nodes[i].is_ready = false;
/* Copy details of the failed master node */
/* XXX only node_id is actually used later */
if (nodes[i].type == MASTER)
{
failed_master.node_id = nodes[i].node_id;
failed_master.xlog_location = nodes[i].xlog_location;
failed_master.is_ready = nodes[i].is_ready;
}
log_debug(_("node=%i conninfo=\"%s\" type=%s\n"),
nodes[i].node_id,
nodes[i].conninfo_str,
node_type);
/* XXX do we need to try and connect to the master here? */
/* Copy details of the failed master node */
if (nodes[i].type == MASTER)
{
/* XXX only node_id is currently used */
failed_master.node_id = nodes[i].node_id;
/*
* XXX experimental
*
* Currently an attempt is made to connect to the master,
* which is very likely to be a waste of time at this point, as we'll
* have spent the last however many seconds trying to do just that
* in check_connection() before deciding it's gone away.
*
* If the master did come back at this point, the voting algorithm should decide
* it's the "best candidate" anyway and no standby will promote itself or
* attempt to follow* another server.
*
* If we don't try and connect to the master here (and the code generally
* assumes it's failed anyway) but it does come back any time from here
* onwards, promotion will fail and the promotion candidate will
* notice the reappearance.
*
* TLDR version: by skipping the master connection attempt (and the chances
* the master would reappear between the last attempt in check_connection()
* and now are minimal) we can remove useless cycles during the failover process;
* if the master does reappear it will be caught before later anyway.
*/
continue;
}
node_conn = establish_db_connection(nodes[i].conninfo_str, false);
/* if we can't see the node just skip it */
@@ -1706,6 +1727,8 @@ do_master_failover(void)
{
log_notice(_("Original master reappeared before this standby was promoted - no action taken\n"));
/* XXX log an event here? */
PQfinish(master_conn);
master_conn = NULL;