Adjust comment about timeout when waiting for WAL at recovery

A timeout of 5s is used when waiting for WAL to become available at
recovery so as the startup process is able to react promptly if a
trigger file shows up.  However this missed the fact that the startup
process also relies on the timeout to check periodically the status of
any active WAL receiver.

Discussion: https://postgr.es/m/20190131070956.GE13429@paquier.xyz

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 2ab7d804f032a60f1f23bdcdb1ad991aecd5b3a7..a9f3272849550ebe9854d20a9a72281e965f63a4 100644 (file)
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -12104,7 +12104,8 @@ WaitForWALToBecomeAvailable(XLogRecPtr RecPtr, bool randAccess,
 
                    /*
                     * Wait for more WAL to arrive. Time out after 5 seconds
-                    * to react to a trigger file promptly.
+                    * to react to a trigger file promptly and to check if the
+                    * WAL receiver is still active.
                     */
                    (void) WaitLatch(&XLogCtl->recoveryWakeupLatch,
                                     WL_LATCH_SET | WL_TIMEOUT |