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Allow maximum number of backends to be set at configure time
(--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
@@ -10,7 +10,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.101 1999/02/13 23:17:40 momjian Exp $
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* $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.102 1999/02/19 06:06:00 tgl Exp $
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*
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* NOTES
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*
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@@ -162,8 +162,17 @@ static IpcMemoryKey ipc_key;
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* adding to this.
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*/
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static int MaxBackends = MAXBACKENDS;
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static int NextBackendId = MAXINT; /* XXX why? */
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/*
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* MaxBackends is the actual soft limit on the number of backends
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* we will start. It defaults to the hard limit established at compilation
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* time, but can be readjusted with postmaster's xxx switch.
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* One reason to reduce MaxBackends is to allow startup under a kernel
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* that won't let us get MAXBACKENDS semaphores!
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*/
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static int NextBackendTag = MAXINT; /* XXX why count down not up? */
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static char *progname = (char *) NULL;
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static char **real_argv;
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static int real_argc;
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@@ -388,7 +397,7 @@ PostmasterMain(int argc, char *argv[])
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DataDir = getenv("PGDATA"); /* default value */
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opterr = 0;
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while ((opt = getopt(nonblank_argc, argv, "A:a:B:b:D:dim:Mno:p:Ss")) != EOF)
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while ((opt = getopt(nonblank_argc, argv, "A:a:B:b:D:dim:MN:no:p:Ss")) != EOF)
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{
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switch (opt)
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{
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@@ -463,6 +472,17 @@ PostmasterMain(int argc, char *argv[])
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* 'postmaster'
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*/
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break;
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case 'N':
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/*
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* The max number of backends to start.
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* Can't set to less than 1 or more than compiled-in limit.
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*/
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MaxBackends = atoi(optarg);
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if (MaxBackends < 1)
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MaxBackends = 1;
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if (MaxBackends > MAXBACKENDS)
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MaxBackends = MAXBACKENDS;
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break;
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case 'n':
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/* Don't reinit shared mem after abnormal exit */
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Reinit = false;
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@@ -621,6 +641,8 @@ usage(const char *progname)
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fprintf(stderr, "\t-b backend\tuse a specific backend server executable\n");
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fprintf(stderr, "\t-d [1|2|3]\tset debugging level\n");
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fprintf(stderr, "\t-i \t\tlisten on TCP/IP sockets as well as Unix domain socket\n");
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fprintf(stderr, "\t-N nprocs\tset max number of backend servers (1..%d)\n",
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MAXBACKENDS);
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fprintf(stderr, "\t-n \t\tdon't reinitialize shared memory after abnormal exit\n");
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fprintf(stderr, "\t-o option\tpass 'option' to each backend servers\n");
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fprintf(stderr, "\t-p port\tspecify port for postmaster to listen on\n");
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@@ -765,7 +787,7 @@ ServerLoop(void)
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if (status == STATUS_OK && port->pktInfo.state == Idle)
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{
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/* Can't start backend if max backend count is exceeded. */
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if (CountChildren() >= MaxBackendId)
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if (CountChildren() >= MaxBackends)
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PacketSendError(&port->pktInfo,
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"Sorry, too many clients already");
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else
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@@ -1009,7 +1031,7 @@ static void
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reset_shared(short port)
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{
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ipc_key = port * 1000 + shmem_seq * 100;
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CreateSharedMemoryAndSemaphores(ipc_key);
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CreateSharedMemoryAndSemaphores(ipc_key, MaxBackends);
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ActiveBackends = FALSE;
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shmem_seq += 1;
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if (shmem_seq >= 10)
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@@ -1272,7 +1294,7 @@ BackendStartup(Port *port)
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*/
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sprintf(envEntry[0], "POSTPORT=%d", PostPortName);
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putenv(envEntry[0]);
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sprintf(envEntry[1], "POSTID=%d", NextBackendId);
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sprintf(envEntry[1], "POSTID=%d", NextBackendTag);
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putenv(envEntry[1]);
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sprintf(envEntry[2], "PG_USER=%s", port->user);
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putenv(envEntry[2]);
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@@ -1348,9 +1370,11 @@ BackendStartup(Port *port)
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progname, pid, port->user, port->database,
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port->sock);
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/* adjust backend counter */
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/* XXX Don't know why this is done, but for now backend needs it */
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NextBackendId -= 1;
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/* Generate a new backend tag for every backend we start */
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/* XXX theoretically this could wrap around, if you have the patience
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* to start 2^31 backends ...
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*/
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NextBackendTag -= 1;
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/*
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* Everything's been successful, it's safe to add this backend to our
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@@ -1459,7 +1483,7 @@ DoBackend(Port *port)
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/* OK, let's unblock our signals, all together now... */
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sigprocmask(SIG_SETMASK, &oldsigmask, 0);
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/* Close the postmater sockets */
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/* Close the postmaster sockets */
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if (NetServer)
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StreamClose(ServerSock_INET);
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#ifndef __CYGWIN32__
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@@ -7,7 +7,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/storage/ipc/ipci.c,v 1.18 1999/02/13 23:18:11 momjian Exp $
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* $Header: /cvsroot/pgsql/src/backend/storage/ipc/ipci.c,v 1.19 1999/02/19 06:06:04 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@@ -44,17 +44,19 @@ SystemPortAddressCreateIPCKey(SystemPortAddress address)
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CreateSharedMemoryAndSemaphores
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is called exactly *ONCE* by the postmaster.
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It is *NEVER* called by the postgres backend
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It is *NEVER* called by the postgres backend,
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except in the case of a standalone backend.
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0) destroy any existing semaphores for both buffer
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and lock managers.
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1) create the appropriate *SHARED* memory segments
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for the two resource managers.
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2) create shared semaphores as needed.
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**************************************************/
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void
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CreateSharedMemoryAndSemaphores(IPCKey key)
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CreateSharedMemoryAndSemaphores(IPCKey key, int maxBackends)
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{
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int size;
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@@ -98,7 +100,7 @@ CreateSharedMemoryAndSemaphores(IPCKey key)
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* do process table stuff
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* ----------------
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*/
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InitProcGlobal(key);
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InitProcGlobal(key, maxBackends);
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on_shmem_exit(ProcFreeAllSemaphores, NULL);
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CreateSharedInvalidationState(key);
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@@ -120,7 +122,7 @@ AttachSharedMemoryAndSemaphores(IPCKey key)
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*/
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if (key == PrivateIPCKey)
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{
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CreateSharedMemoryAndSemaphores(key);
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CreateSharedMemoryAndSemaphores(key, 1);
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return;
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}
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@@ -7,7 +7,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinvaladt.c,v 1.16 1999/02/13 23:18:16 momjian Exp $
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* $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinvaladt.c,v 1.17 1999/02/19 06:06:03 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@@ -119,7 +119,7 @@ SIAssignBackendId(SISeg *segInOutP, BackendTag backendTag)
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stateP = NULL;
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for (index = 0; index < MaxBackendId; index += 1)
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for (index = 0; index < MAXBACKENDS; index++)
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{
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if (segInOutP->procState[index].tag == InvalidBackendTag ||
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segInOutP->procState[index].tag == backendTag)
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@@ -141,7 +141,7 @@ SIAssignBackendId(SISeg *segInOutP, BackendTag backendTag)
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/* verify that all "procState" entries checked for matching tags */
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for (index += 1; index < MaxBackendId; index += 1)
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for (index++; index < MAXBACKENDS; index++)
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{
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if (segInOutP->procState[index].tag == backendTag)
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{
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@@ -565,7 +565,7 @@ SIDecProcLimit(SISeg *segP, int num)
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{
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int i;
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for (i = 0; i < MaxBackendId; i++)
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for (i = 0; i < MAXBACKENDS; i++)
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{
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/* decrement only, if there is a limit > 0 */
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if (segP->procState[i].limit > 0)
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@@ -622,7 +622,7 @@ SISetProcStateInvalid(SISeg *segP)
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{
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int i;
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for (i = 0; i < MaxBackendId; i++)
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for (i = 0; i < MAXBACKENDS; i++)
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{
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if (segP->procState[i].limit == 0)
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{
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@@ -696,7 +696,7 @@ SIDelExpiredDataEntries(SISeg *segP)
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h;
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min = 9999999;
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for (i = 0; i < MaxBackendId; i++)
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for (i = 0; i < MAXBACKENDS; i++)
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{
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h = SIGetProcStateLimit(segP, i);
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if (h >= 0)
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@@ -740,7 +740,7 @@ SISegInit(SISeg *segP)
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SISetEndEntryChain(segP, InvalidOffset);
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SISetNumEntries(segP, 0);
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SISetMaxNumEntries(segP, MAXNUMMESSAGES);
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for (i = 0; i < MaxBackendId; i++)
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for (i = 0; i < MAXBACKENDS; i++)
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{
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segP->procState[i].limit = -1; /* no backend active !! */
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segP->procState[i].resetState = false;
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@@ -7,7 +7,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/lock.c,v 1.41 1999/02/13 23:18:25 momjian Exp $
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* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/lock.c,v 1.42 1999/02/19 06:06:06 tgl Exp $
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*
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* NOTES
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* Outside modules can create a lock table and acquire/release
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@@ -1492,8 +1492,8 @@ LockShmemSize()
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nXidBuckets = 1 << (int) my_log2((NLOCKS_PER_XACT - 1) / DEF_FFACTOR + 1);
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nXidSegs = 1 << (int) my_log2((nLockBuckets - 1) / DEF_SEGSIZE + 1);
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size += MAXALIGN(NBACKENDS * sizeof(PROC)); /* each MyProc */
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size += MAXALIGN(NBACKENDS * sizeof(LOCKMETHODCTL)); /* each
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size += MAXALIGN(MAXBACKENDS * sizeof(PROC)); /* each MyProc */
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size += MAXALIGN(MAXBACKENDS * sizeof(LOCKMETHODCTL)); /* each
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* lockMethodTable->ctl */
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size += MAXALIGN(sizeof(PROC_HDR)); /* ProcGlobal */
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@@ -1504,10 +1504,10 @@ LockShmemSize()
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(MAXALIGN(sizeof(BUCKET_INDEX)) +
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MAXALIGN(sizeof(LOCK))); /* contains hash key */
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size += MAXALIGN(my_log2(NBACKENDS) * sizeof(void *));
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size += MAXALIGN(my_log2(MAXBACKENDS) * sizeof(void *));
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size += MAXALIGN(sizeof(HHDR));
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size += nXidSegs * MAXALIGN(DEF_SEGSIZE * sizeof(SEGMENT));
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size += NBACKENDS * /* XXX not multiple of BUCKET_ALLOC_INCR? */
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size += MAXBACKENDS * /* XXX not multiple of BUCKET_ALLOC_INCR? */
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(MAXALIGN(sizeof(BUCKET_INDEX)) +
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MAXALIGN(sizeof(XIDLookupEnt))); /* contains hash key */
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@@ -1552,7 +1552,7 @@ DeadLockCheck(SHM_QUEUE *lockQueue, LOCK *findlock, bool skip_check)
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HTAB *xidTable;
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bool found;
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static PROC *checked_procs[MaxBackendId];
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static PROC *checked_procs[MAXBACKENDS];
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static int nprocs;
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static bool MyNHolding;
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@@ -1674,7 +1674,7 @@ DeadLockCheck(SHM_QUEUE *lockQueue, LOCK *findlock, bool skip_check)
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if (j >= nprocs && lock != findlock)
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{
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checked_procs[nprocs++] = proc;
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Assert(nprocs <= MaxBackendId);
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Assert(nprocs <= MAXBACKENDS);
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/*
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* For non-MyProc entries, we are looking only
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@@ -7,7 +7,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.48 1999/02/13 23:18:28 momjian Exp $
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* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.49 1999/02/19 06:06:08 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@@ -46,7 +46,7 @@
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* This is so that we can support more backends. (system-wide semaphore
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* sets run out pretty fast.) -ay 4/95
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*
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* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.48 1999/02/13 23:18:28 momjian Exp $
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* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.49 1999/02/19 06:06:08 tgl Exp $
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*/
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#include <sys/time.h>
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#include <unistd.h>
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@@ -108,13 +108,24 @@ static void ProcFreeSem(IpcSemaphoreKey semKey, int semNum);
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/*
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* InitProcGlobal -
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* initializes the global process table. We put it here so that
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* the postmaster can do this initialization. (ProcFreeAllSem needs
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* the postmaster can do this initialization. (ProcFreeAllSemaphores needs
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* to read this table on exiting the postmaster. If we have the first
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* backend do this, starting up and killing the postmaster without
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* starting any backends will be a problem.)
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*
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* We also allocate all the per-process semaphores we will need to support
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* the requested number of backends. We used to allocate semaphores
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* only when backends were actually started up, but that is bad because
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* it lets Postgres fail under load --- a lot of Unix systems are
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* (mis)configured with small limits on the number of semaphores, and
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* running out when trying to start another backend is a common failure.
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* So, now we grab enough semaphores to support the desired max number
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* of backends immediately at initialization --- if the sysadmin has set
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* MaxBackends higher than his kernel will support, he'll find out sooner
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* rather than later.
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*/
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void
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InitProcGlobal(IPCKey key)
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InitProcGlobal(IPCKey key, int maxBackends)
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{
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bool found = false;
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@@ -134,6 +145,24 @@ InitProcGlobal(IPCKey key)
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ProcGlobal->currKey = IPCGetProcessSemaphoreInitKey(key);
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for (i = 0; i < MAX_PROC_SEMS / PROC_NSEMS_PER_SET; i++)
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ProcGlobal->freeSemMap[i] = 0;
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/* Pre-create the semaphores for the first maxBackends processes */
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for (i = 0;
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i < (maxBackends+PROC_NSEMS_PER_SET-1) / PROC_NSEMS_PER_SET;
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i++)
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{
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IPCKey semKey = ProcGlobal->currKey + i;
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int semId;
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int semstat;
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semId = IpcSemaphoreCreate(semKey,
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PROC_NSEMS_PER_SET,
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IPCProtection,
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IpcSemaphoreDefaultStartValue,
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0,
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&semstat);
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/* mark this sema set allocated */
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ProcGlobal->freeSemMap[i] = (1 << PROC_NSEMS_PER_SET);
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}
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}
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}
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@@ -222,6 +251,11 @@ InitProcess(IPCKey key)
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ProcGetNewSemKeyAndNum(&semKey, &semNum);
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/* Note: because of the pre-allocation done in InitProcGlobal,
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* this call should always attach to an existing semaphore.
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* It will (try to) create a new group of semaphores only if
|
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* the postmaster tries to start more backends than it said it would.
|
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*/
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semId = IpcSemaphoreCreate(semKey,
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PROC_NSEMS_PER_SET,
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IPCProtection,
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@@ -823,20 +857,20 @@ ProcGetNewSemKeyAndNum(IPCKey *key, int *semNum)
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{
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int i;
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||||
int32 *freeSemMap = ProcGlobal->freeSemMap;
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unsigned int fullmask;
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int32 fullmask = (1 << (PROC_NSEMS_PER_SET+1)) - 1;
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/*
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* we hold ProcStructLock when entering this routine. We scan through
|
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* the bitmap to look for a free semaphore.
|
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*/
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fullmask = ~0 >> (32 - PROC_NSEMS_PER_SET);
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|
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for (i = 0; i < MAX_PROC_SEMS / PROC_NSEMS_PER_SET; i++)
|
||||
{
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int mask = 1;
|
||||
int j;
|
||||
|
||||
if (freeSemMap[i] == fullmask)
|
||||
continue; /* none free for this set */
|
||||
continue; /* this set is fully allocated */
|
||||
|
||||
for (j = 0; j < PROC_NSEMS_PER_SET; j++)
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{
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@@ -845,8 +879,9 @@ ProcGetNewSemKeyAndNum(IPCKey *key, int *semNum)
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/*
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* a free semaphore found. Mark it as allocated.
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* Also set the bit indicating whole set is allocated.
|
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*/
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freeSemMap[i] |= mask;
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||||
freeSemMap[i] |= mask + (1 << PROC_NSEMS_PER_SET);
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||||
|
||||
*key = ProcGlobal->currKey + i;
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*semNum = j;
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@@ -862,8 +897,7 @@ ProcGetNewSemKeyAndNum(IPCKey *key, int *semNum)
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||||
/*
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* ProcFreeSem -
|
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* free up our semaphore in the semaphore set. If we're the last one
|
||||
* in the set, also remove the semaphore set.
|
||||
* free up our semaphore in the semaphore set.
|
||||
*/
|
||||
static void
|
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ProcFreeSem(IpcSemaphoreKey semKey, int semNum)
|
||||
@@ -876,14 +910,19 @@ ProcFreeSem(IpcSemaphoreKey semKey, int semNum)
|
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mask = ~(1 << semNum);
|
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freeSemMap[i] &= mask;
|
||||
|
||||
if (freeSemMap[i] == 0)
|
||||
IpcSemaphoreKill(semKey);
|
||||
/* Formerly we'd release a semaphore set if it was now completely unused,
|
||||
* but now we keep the semaphores to ensure we won't run out when
|
||||
* starting new backends --- cf. InitProcGlobal. Note that the
|
||||
* PROC_NSEMS_PER_SET+1'st bit of the freeSemMap entry remains set to
|
||||
* indicate it is still allocated; ProcFreeAllSemaphores() needs that.
|
||||
*/
|
||||
}
|
||||
|
||||
/*
|
||||
* ProcFreeAllSemaphores -
|
||||
* on exiting the postmaster, we free up all the semaphores allocated
|
||||
* to the lmgrs of the backends.
|
||||
* called at shmem_exit time, ie when exiting the postmaster or
|
||||
* destroying shared state for a failed set of backends.
|
||||
* Free up all the semaphores allocated to the lmgrs of the backends.
|
||||
*/
|
||||
void
|
||||
ProcFreeAllSemaphores()
|
||||
|
||||
@@ -7,7 +7,7 @@
|
||||
*
|
||||
*
|
||||
* IDENTIFICATION
|
||||
* $Header: /cvsroot/pgsql/src/backend/utils/init/postinit.c,v 1.37 1999/02/13 23:20:02 momjian Exp $
|
||||
* $Header: /cvsroot/pgsql/src/backend/utils/init/postinit.c,v 1.38 1999/02/19 06:06:10 tgl Exp $
|
||||
*
|
||||
* NOTES
|
||||
* InitPostgres() is the function called from PostgresMain
|
||||
@@ -571,7 +571,7 @@ InitPostgres(char *name) /* database name */
|
||||
*/
|
||||
InitProcess(PostgresIpcKey);
|
||||
|
||||
if (MyBackendId > MaxBackendId || MyBackendId <= 0)
|
||||
if (MyBackendId > MAXBACKENDS || MyBackendId <= 0)
|
||||
{
|
||||
elog(FATAL, "cinit2: bad backend id %d (%d)",
|
||||
MyBackendTag,
|
||||
|
||||
Reference in New Issue
Block a user