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Allow maximum number of backends to be set at configure time

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(--with-maxbackends).  Add a postmaster switch (-N backends) that allows
the limit to be reduced at postmaster start time.  (You can't increase it,
sorry to say, because there are still some fixed-size arrays.)
Grab the number of semaphores indicated by min(MAXBACKENDS, -N) at
postmaster startup, so that this particular form of bogus configuration
is exposed immediately rather than under heavy load.
This commit is contained in:
Tom Lane
1999-02-19 06:06:39 +00:00
parent 612b8434e4
commit e77b630cf0
14 changed files with 502 additions and 392 deletions
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44
src/backend/postmaster/postmaster.c
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@@ -10,7 +10,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.101 1999/02/13 23:17:40 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.102 1999/02/19 06:06:00 tgl Exp $
*
* NOTES
*
@@ -162,8 +162,17 @@ static IpcMemoryKey ipc_key;
* adding to this.
*/
static int MaxBackends = MAXBACKENDS;
static int NextBackendId = MAXINT; /* XXX why? */
/*
* MaxBackends is the actual soft limit on the number of backends
* we will start. It defaults to the hard limit established at compilation
* time, but can be readjusted with postmaster's xxx switch.
* One reason to reduce MaxBackends is to allow startup under a kernel
* that won't let us get MAXBACKENDS semaphores!
*/
static int NextBackendTag = MAXINT; /* XXX why count down not up? */
static char *progname = (char *) NULL;
static char **real_argv;
static int real_argc;
@@ -388,7 +397,7 @@ PostmasterMain(int argc, char *argv[])
DataDir = getenv("PGDATA"); /* default value */
opterr = 0;
while ((opt = getopt(nonblank_argc, argv, "A:a:B:b:D:dim:Mno:p:Ss")) != EOF)
while ((opt = getopt(nonblank_argc, argv, "A:a:B:b:D:dim:MN:no:p:Ss")) != EOF)
{
switch (opt)
{
@@ -463,6 +472,17 @@ PostmasterMain(int argc, char *argv[])
* 'postmaster'
*/
break;
case 'N':
/*
* The max number of backends to start.
* Can't set to less than 1 or more than compiled-in limit.
*/
MaxBackends = atoi(optarg);
if (MaxBackends < 1)
MaxBackends = 1;
if (MaxBackends > MAXBACKENDS)
MaxBackends = MAXBACKENDS;
break;
case 'n':
/* Don't reinit shared mem after abnormal exit */
Reinit = false;
@@ -621,6 +641,8 @@ usage(const char *progname)
fprintf(stderr, "\t-b backend\tuse a specific backend server executable\n");
fprintf(stderr, "\t-d [1|2|3]\tset debugging level\n");
fprintf(stderr, "\t-i \t\tlisten on TCP/IP sockets as well as Unix domain socket\n");
fprintf(stderr, "\t-N nprocs\tset max number of backend servers (1..%d)\n",
MAXBACKENDS);
fprintf(stderr, "\t-n \t\tdon't reinitialize shared memory after abnormal exit\n");
fprintf(stderr, "\t-o option\tpass 'option' to each backend servers\n");
fprintf(stderr, "\t-p port\tspecify port for postmaster to listen on\n");
@@ -765,7 +787,7 @@ ServerLoop(void)
if (status == STATUS_OK && port->pktInfo.state == Idle)
{
/* Can't start backend if max backend count is exceeded. */
if (CountChildren() >= MaxBackendId)
if (CountChildren() >= MaxBackends)
PacketSendError(&port->pktInfo,
"Sorry, too many clients already");
else
@@ -1009,7 +1031,7 @@ static void
reset_shared(short port)
{
ipc_key = port * 1000 + shmem_seq * 100;
CreateSharedMemoryAndSemaphores(ipc_key);
CreateSharedMemoryAndSemaphores(ipc_key, MaxBackends);
ActiveBackends = FALSE;
shmem_seq += 1;
if (shmem_seq >= 10)
@@ -1272,7 +1294,7 @@ BackendStartup(Port *port)
*/
sprintf(envEntry[0], "POSTPORT=%d", PostPortName);
putenv(envEntry[0]);
sprintf(envEntry[1], "POSTID=%d", NextBackendId);
sprintf(envEntry[1], "POSTID=%d", NextBackendTag);
putenv(envEntry[1]);
sprintf(envEntry[2], "PG_USER=%s", port->user);
putenv(envEntry[2]);
@@ -1348,9 +1370,11 @@ BackendStartup(Port *port)
progname, pid, port->user, port->database,
port->sock);
/* adjust backend counter */
/* XXX Don't know why this is done, but for now backend needs it */
NextBackendId -= 1;
/* Generate a new backend tag for every backend we start */
/* XXX theoretically this could wrap around, if you have the patience
* to start 2^31 backends ...
*/
NextBackendTag -= 1;
/*
* Everything's been successful, it's safe to add this backend to our
@@ -1459,7 +1483,7 @@ DoBackend(Port *port)
/* OK, let's unblock our signals, all together now... */
sigprocmask(SIG_SETMASK, &oldsigmask, 0);
/* Close the postmater sockets */
/* Close the postmaster sockets */
if (NetServer)
StreamClose(ServerSock_INET);
#ifndef __CYGWIN32__