Instead of believing SOMAXCONN from the system header files (which is

a lie on many Unixen), invoke listen() with MIN(MaxBackends*2, 10000).
The clamp value 10000 is configurable in config.h.in, if that proves
to be necessary --- hopefully it won't.

diff --git a/src/backend/libpq/pqcomm.c b/src/backend/libpq/pqcomm.c
index e325086..81c57a4 100644 (file)
--- a/src/backend/libpq/pqcomm.c
+++ b/src/backend/libpq/pqcomm.c
@@ -29,7 +29,7 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- *     $Id: pqcomm.c,v 1.117 2001/03/22 03:59:30 momjian Exp $
+ *     $Id: pqcomm.c,v 1.118 2001/07/11 19:03:07 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -80,11 +80,6 @@
 #include "miscadmin.h"
 
 
-#ifndef SOMAXCONN
-#define SOMAXCONN 5                            /* from Linux listen(2) man page */
-#endif
-
-
 static void pq_close(void);
 
 
@@ -185,6 +180,7 @@ StreamServerPort(int family, char *hostName, unsigned short portNumber,
        SockAddr        saddr;
        int                     fd,
                                err;
+       int                     maxconn;
        size_t          len = 0;
        int                     one = 1;
 
@@ -350,7 +346,25 @@ StreamServerPort(int family, char *hostName, unsigned short portNumber,
        }
 #endif  /* HAVE_UNIX_SOCKETS */
 
-       listen(fd, SOMAXCONN);
+       /*
+        * Select appropriate accept-queue length limit.  PG_SOMAXCONN is
+        * only intended to provide a clamp on the request on platforms where
+        * an overly large request provokes a kernel error (are there any?).
+        */
+       maxconn = MaxBackends * 2;
+       if (maxconn > PG_SOMAXCONN)
+               maxconn = PG_SOMAXCONN;
+
+       err = listen(fd, maxconn);
+       if (err < 0)
+       {
+               snprintf(PQerrormsg, PQERRORMSG_LENGTH,
+                                "FATAL: StreamServerPort: listen() failed: %s\n",
+                                strerror(errno));
+               fputs(PQerrormsg, stderr);
+               pqdebug("%s", PQerrormsg);
+               return STATUS_ERROR;
+       }
 
        *fdP = fd;
 

diff --git a/src/include/config.h.in b/src/include/config.h.in
index fde5a13..941cfe8 100644 (file)
--- a/src/include/config.h.in
+++ b/src/include/config.h.in
@@ -8,7 +8,7 @@
  * or in config.h afterwards.  Of course, if you edit config.h, then your
  * changes will be overwritten the next time you run configure.
  *
- * $Id: config.h.in,v 1.166 2001/06/11 22:12:48 momjian Exp $
+ * $Id: config.h.in,v 1.167 2001/07/11 19:03:07 tgl Exp $
  */
 
 #ifndef CONFIG_H
@@ -233,6 +233,16 @@
 #define DEFAULT_MAX_EXPR_DEPTH 10000
 
 /*
+ * PG_SOMAXCONN: maximum accept-queue length limit passed to listen(2).
+ * You'd think we should use SOMAXCONN from <sys/socket.h>, but on many
+ * systems that symbol is much smaller than the kernel's actual limit.
+ * In any case, this symbol need be twiddled only if you have a kernel
+ * that refuses large limit values, rather than silently reducing the
+ * value to what it can handle (which is what most if not all Unixen do).
+ */
+#define PG_SOMAXCONN   10000
+
+/*
  * You can try changing this if you have a machine with bytes of another
  * size, but no guarantee...
  */