In pgstat.c, use a timeout in WaitLatchOrSocket only on Windows.

We have no need for a timeout here really, but some broken products from
Redmond seem to lose FD_READ events occasionally, and waking up and
retrying the recv() is the only known way to work around that.  Perhaps
somebody will be motivated to figure out a better answer here; but not I.

diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index bb7c61b058bd55e7a2e973e4fc6870a1fca9b8d1..424cfcaf4f71672307f0eb6208ed0ee42f2cb8b2 100644 (file)
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -3113,7 +3113,8 @@ PgstatCollectorMain(int argc, char *argv[])
             * Try to receive and process a message.  This will not block,
             * since the socket is set to non-blocking mode.
             *
-            * XXX On Windows, we have to force pgwin32_recv to cooperate.
+            * XXX On Windows, we have to force pgwin32_recv to cooperate,
+            * despite the previous use of pg_set_noblock() on the socket.
             * This is extremely broken and should be fixed someday.
             */
 #ifdef WIN32
@@ -3231,11 +3232,27 @@ PgstatCollectorMain(int argc, char *argv[])
        }                       /* end of inner message-processing loop */
 
        /* Sleep until there's something to do */
-       /* XXX should not need a timeout here */
+#ifndef WIN32
+       wr = WaitLatchOrSocket(&pgStatLatch,
+                              WL_LATCH_SET | WL_POSTMASTER_DEATH | WL_SOCKET_READABLE,
+                              pgStatSock,
+                              -1L);
+#else
+       /*
+        * Windows, at least in its Windows Server 2003 R2 incarnation,
+        * sometimes loses FD_READ events.  Waking up and retrying the recv()
+        * fixes that, so don't sleep indefinitely.  This is a crock of the
+        * first water, but until somebody wants to debug exactly what's
+        * happening there, this is the best we can do.  The two-second
+        * timeout matches our pre-9.2 behavior, and needs to be short enough
+        * to not provoke "pgstat wait timeout" complaints from
+        * backend_read_statsfile.
+        */
        wr = WaitLatchOrSocket(&pgStatLatch,
                               WL_LATCH_SET | WL_POSTMASTER_DEATH | WL_SOCKET_READABLE | WL_TIMEOUT,
                               pgStatSock,
-                              2000L);
+                              2 * 1000L /* msec */);
+#endif
 
        /*
         * Emergency bailout if postmaster has died.  This is to avoid the