On win32, don't use SO_REUSEADDR for TCP sockets.

Per failure on buildfarm member baiji and subsequent discussion.

diff --git a/src/backend/libpq/pqcomm.c b/src/backend/libpq/pqcomm.c
index a78f668ccb4b110bb004daf44fcdfcaa88a4a9cf..f083f6085cd774dc071bdfcd9bc7dd183efffd50 100644 (file)
--- a/src/backend/libpq/pqcomm.c
+++ b/src/backend/libpq/pqcomm.c
@@ -337,6 +337,16 @@ StreamServerPort(int family, char *hostName, unsigned short portNumber,
                        continue;
                }
 
+#ifndef WIN32
+               /*
+                * Without the SO_REUSEADDR flag, a new postmaster can't be started right away after
+                * a stop or crash, giving "address already in use" error on TCP ports.
+                *
+                * On win32, however, this behavior only happens if the SO_EXLUSIVEADDRUSE is set.
+                * With SO_REUSEADDR, win32 allows multiple servers to listen on the same address,
+                * resulting in unpredictable behavior. With no flags at all, win32 behaves as
+                * Unix with SO_REUSEADDR.
+                */
                if (!IS_AF_UNIX(addr->ai_family))
                {
                        if ((setsockopt(fd, SOL_SOCKET, SO_REUSEADDR,
@@ -349,6 +359,7 @@ StreamServerPort(int family, char *hostName, unsigned short portNumber,
                                continue;
                        }
                }
+#endif
 
 #ifdef IPV6_V6ONLY
                if (addr->ai_family == AF_INET6)