Explain postmaster's treatment of SIGURG.

Add a few words of comment to explain why SIGURG doesn't follow the
dummy_handler pattern used for SIGUSR2, since that might otherwise
appear to be a bug.

Discussion: https://postgr.es/m/4006115.1618577212%40sss.pgh.pa.us

diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index 4a3ca78c1b7063f69eb20e9d936629cd2849049f..b05db5a47350364643be34392c032e72770c9095 100644 (file)
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -660,6 +660,11 @@ PostmasterMain(int argc, char *argv[])
    pqsignal_pm(SIGCHLD, reaper);   /* handle child termination */
 
 #ifdef SIGURG
+   /*
+    * Ignore SIGURG for now.  Child processes may change this (see
+    * InitializeLatchSupport), but they will not receive any such signals
+    * until they wait on a latch.
+    */
    pqsignal_pm(SIGURG, SIG_IGN);   /* ignored */
 #endif