repmgrd: improve reconnection handling

Previously, if the server being monitored was not available, repmgrd
would always close the existing connection handle and open a new one.

However, in some cases, e.g. a brief network outage, the existing
connection handle is still good and does not need to be reopened.

This could be particularly problematic if monitoring_history is on,
as this risks leaving orphan sessions on the primary which (given
a sufficiently unstable network) could lead to all available backends
being occupied.

Instead, during an outage we now use a new connection to verify
the server is accessible; if the old connection is still available
(e.g. following a short network interruption) we continue using that;
if  not (e.g. the server was restarted), we use the new one.
This commit is contained in:
Ian Barwick
2018-08-30 10:24:06 +09:00
parent 216326f316
commit 0468e47ef3
8 changed files with 59 additions and 25 deletions

View File

@@ -475,7 +475,7 @@ int wait_connection_availability(PGconn *conn, long long timeout);
/* node availability functions */
bool is_server_available(const char *conninfo);
bool is_server_available_params(t_conninfo_param_list *param_list);
void connection_ping(PGconn *conn);
ExecStatusType connection_ping(PGconn *conn);
/* monitoring functions */
void