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