diff options
Diffstat (limited to 'src/backend/postmaster/postmaster.c')
| -rw-r--r-- | src/backend/postmaster/postmaster.c | 159 |
1 files changed, 94 insertions, 65 deletions
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c index e807d3d0696..6a0d1198652 100644 --- a/src/backend/postmaster/postmaster.c +++ b/src/backend/postmaster/postmaster.c @@ -6,12 +6,29 @@ * to the Postmaster and the postmaster uses the info in the * message to setup a backend process. * + * The postmaster also manages system-wide operations such as + * startup, shutdown, and periodic checkpoints. The postmaster + * itself doesn't do those operations, mind you --- it just forks + * off a subprocess to do them at the right times. It also takes + * care of resetting the system if a backend crashes. + * + * The postmaster process creates the shared memory and semaphore + * pools during startup, but as a rule does not touch them itself. + * In particular, it is not a member of the PROC array of backends + * and so it cannot participate in lock-manager operations. Keeping + * the postmaster away from shared memory operations makes it simpler + * and more reliable. The postmaster is almost always able to recover + * from crashes of individual backends by resetting shared memory; + * if it did much with shared memory then it would be prone to crashing + * along with the backends. + * + * * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.208 2001/02/20 01:34:40 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.209 2001/03/13 01:17:05 tgl Exp $ * * NOTES * @@ -21,16 +38,15 @@ * lock manager. * * Synchronization: - * The Postmaster shares memory with the backends and will have to lock - * the shared memory it accesses. The Postmaster should never block - * on messages from clients. + * The Postmaster shares memory with the backends but should avoid + * touching shared memory, so as not to become stuck if a crashing + * backend screws up locks or shared memory. Likewise, the Postmaster + * should never block on messages from frontend clients. * * Garbage Collection: * The Postmaster cleans up after backends if they have an emergency * exit and/or core dump. * - * Communication: - * *------------------------------------------------------------------------- */ @@ -194,8 +210,6 @@ extern char *optarg; extern int optind, opterr; -extern void GetRedoRecPtr(void); - /* * postmaster.c - function prototypes */ @@ -207,6 +221,7 @@ static void reset_shared(unsigned short port); static void SIGHUP_handler(SIGNAL_ARGS); static void pmdie(SIGNAL_ARGS); static void reaper(SIGNAL_ARGS); +static void schedule_checkpoint(SIGNAL_ARGS); static void dumpstatus(SIGNAL_ARGS); static void CleanupProc(int pid, int exitstatus); static int DoBackend(Port *port); @@ -491,7 +506,7 @@ PostmasterMain(int argc, char *argv[]) /* * In the event that some backend dumps core, send - * SIGSTOP, rather than SIGUSR1, to all its peers. This + * SIGSTOP, rather than SIGQUIT, to all its peers. This * lets the wily post_hacker collect core dumps from * everyone. */ @@ -643,11 +658,11 @@ PostmasterMain(int argc, char *argv[]) pqsignal(SIGHUP, SIGHUP_handler); /* reread config file and have children do same */ pqsignal(SIGINT, pmdie); /* send SIGTERM and ShutdownDataBase */ - pqsignal(SIGQUIT, pmdie); /* send SIGUSR1 and die */ + pqsignal(SIGQUIT, pmdie); /* send SIGQUIT and die */ pqsignal(SIGTERM, pmdie); /* wait for children and ShutdownDataBase */ pqsignal(SIGALRM, SIG_IGN); /* ignored */ pqsignal(SIGPIPE, SIG_IGN); /* ignored */ - pqsignal(SIGUSR1, pmdie); /* currently ignored, but see note in pmdie */ + pqsignal(SIGUSR1, schedule_checkpoint); /* start a background checkpoint */ pqsignal(SIGUSR2, pmdie); /* send SIGUSR2, don't die */ pqsignal(SIGCHLD, reaper); /* handle child termination */ pqsignal(SIGTTIN, SIG_IGN); /* ignored */ @@ -773,25 +788,22 @@ ServerLoop(void) struct timeval *timeout = NULL; struct timeval timeout_tv; - if (CheckPointPID == 0 && checkpointed && !FatalError) + if (CheckPointPID == 0 && checkpointed && + Shutdown == NoShutdown && !FatalError) { time_t now = time(NULL); if (CheckPointTimeout + checkpointed > now) { + /* Not time for checkpoint yet, so set a timeout for select */ timeout_tv.tv_sec = CheckPointTimeout + checkpointed - now; timeout_tv.tv_usec = 0; timeout = &timeout_tv; } else { + /* Time to make the checkpoint... */ CheckPointPID = CheckPointDataBase(); - /* - * Since this code is executed periodically, it's a fine - * place to do other actions that should happen every now - * and then on no particular schedule. Such as... - */ - TouchSocketLockFile(); } } @@ -1256,7 +1268,7 @@ ConnCreate(int serverFd) { fprintf(stderr, "%s: ConnCreate: malloc failed\n", progname); - SignalChildren(SIGUSR1); + SignalChildren(SIGQUIT); ExitPostmaster(1); } @@ -1374,7 +1386,7 @@ SIGHUP_handler(SIGNAL_ARGS) /* - * pmdie -- signal handler for cleaning up after a kill signal. + * pmdie -- signal handler for processing various postmaster signals. */ static void pmdie(SIGNAL_ARGS) @@ -1388,18 +1400,6 @@ pmdie(SIGNAL_ARGS) switch (postgres_signal_arg) { - case SIGUSR1: - /* - * Currently the postmaster ignores SIGUSR1 (maybe it should - * do something useful instead?) But we must have some handler - * installed for SIGUSR1, not just set it to SIG_IGN. Else, a - * freshly spawned backend would likewise have it set to SIG_IGN, - * which would mean the backend would ignore any attempt to kill - * it before it had gotten as far as setting up its own handler. - */ - errno = save_errno; - return; - case SIGUSR2: /* @@ -1419,7 +1419,7 @@ pmdie(SIGNAL_ARGS) /* * Smart Shutdown: * - * let children to end their work and ShutdownDataBase. + * Wait for children to end their work and ShutdownDataBase. */ if (Shutdown >= SmartShutdown) { @@ -1458,7 +1458,7 @@ pmdie(SIGNAL_ARGS) * Fast Shutdown: * * abort all children with SIGTERM (rollback active transactions - * and exit) and ShutdownDataBase. + * and exit) and ShutdownDataBase when they are gone. */ if (Shutdown >= FastShutdown) { @@ -1509,7 +1509,7 @@ pmdie(SIGNAL_ARGS) /* * Immediate Shutdown: * - * abort all children with SIGUSR1 and exit without attempt to + * abort all children with SIGQUIT and exit without attempt to * properly shutdown data base system. */ tnow = time(NULL); @@ -1517,10 +1517,10 @@ pmdie(SIGNAL_ARGS) fflush(stderr); if (ShutdownPID > 0) kill(ShutdownPID, SIGQUIT); - else if (StartupPID > 0) + if (StartupPID > 0) kill(StartupPID, SIGQUIT); - else if (DLGetHead(BackendList)) - SignalChildren(SIGUSR1); + if (DLGetHead(BackendList)) + SignalChildren(SIGQUIT); break; } @@ -1593,11 +1593,13 @@ reaper(SIGNAL_ARGS) } /* - * Startup succeeded - remember its ID - * and RedoRecPtr + * Startup succeeded - remember its ID and RedoRecPtr */ SetThisStartUpID(); + /* + * Arrange for first checkpoint to occur after standard delay. + */ CheckPointPID = 0; checkpointed = time(NULL); @@ -1697,6 +1699,7 @@ CleanupProc(int pid, if (!FatalError) { checkpointed = time(NULL); + /* Update RedoRecPtr for future child backends */ GetRedoRecPtr(); } } @@ -1731,7 +1734,7 @@ CleanupProc(int pid, * This backend is still alive. Unless we did so already, * tell it to commit hara-kiri. * - * SIGUSR1 is the special signal that says exit without proc_exit + * SIGQUIT is the special signal that says exit without proc_exit * and let the user know what's going on. But if SendStop is set * (-s on command line), then we send SIGSTOP instead, so that we * can get core dumps from all backends by hand. @@ -1741,9 +1744,9 @@ CleanupProc(int pid, if (DebugLvl) fprintf(stderr, "%s: CleanupProc: sending %s to process %d\n", progname, - (SendStop ? "SIGSTOP" : "SIGUSR1"), + (SendStop ? "SIGSTOP" : "SIGQUIT"), bp->pid); - kill(bp->pid, (SendStop ? SIGSTOP : SIGUSR1)); + kill(bp->pid, (SendStop ? SIGSTOP : SIGQUIT)); } } else @@ -1772,7 +1775,7 @@ CleanupProc(int pid, } /* - * Send a signal to all chidren processes. + * Send a signal to all backend children. */ static void SignalChildren(int signal) @@ -2108,6 +2111,24 @@ ExitPostmaster(int status) proc_exit(status); } +/* Request to schedule a checkpoint (no-op if one is currently running) */ +static void +schedule_checkpoint(SIGNAL_ARGS) +{ + int save_errno = errno; + + PG_SETMASK(&BlockSig); + + /* Ignore request if checkpointing is currently disabled */ + if (CheckPointPID == 0 && checkpointed && + Shutdown == NoShutdown && !FatalError) + { + CheckPointPID = CheckPointDataBase(); + } + + errno = save_errno; +} + static void dumpstatus(SIGNAL_ARGS) { @@ -2116,12 +2137,13 @@ dumpstatus(SIGNAL_ARGS) PG_SETMASK(&BlockSig); + fprintf(stderr, "%s: dumpstatus:\n", progname); + curr = DLGetHead(PortList); while (curr) { Port *port = DLE_VAL(curr); - fprintf(stderr, "%s: dumpstatus:\n", progname); fprintf(stderr, "\tsock %d\n", port->sock); curr = DLGetSucc(curr); } @@ -2240,6 +2262,9 @@ InitSSL(void) #endif +/* + * Fire off a subprocess for startup/shutdown/checkpoint. + */ static pid_t SSDataBase(int xlop) { @@ -2273,7 +2298,7 @@ SSDataBase(int xlop) /* Close the postmaster's sockets */ ClosePostmasterPorts(NULL); - + /* Set up command-line arguments for subprocess */ av[ac++] = "postgres"; av[ac++] = "-d"; @@ -2293,14 +2318,6 @@ SSDataBase(int xlop) optind = 1; - pqsignal(SIGQUIT, SIG_DFL); -#ifdef HAVE_SIGPROCMASK - sigdelset(&BlockSig, SIGQUIT); -#else - BlockSig &= ~(sigmask(SIGQUIT)); -#endif - PG_SETMASK(&BlockSig); - BootstrapMain(ac, av); ExitPostmaster(0); } @@ -2320,19 +2337,31 @@ SSDataBase(int xlop) ExitPostmaster(1); } - if (xlop != BS_XLOG_CHECKPOINT) - return(pid); - - if (!(bn = (Backend *) calloc(1, sizeof(Backend)))) + /* + * The startup and shutdown processes are not considered normal backends, + * but the checkpoint process is. Checkpoint must be added to the list + * of backends. + */ + if (xlop == BS_XLOG_CHECKPOINT) { - fprintf(stderr, "%s: CheckPointDataBase: malloc failed\n", - progname); - ExitPostmaster(1); - } + if (!(bn = (Backend *) calloc(1, sizeof(Backend)))) + { + fprintf(stderr, "%s: CheckPointDataBase: malloc failed\n", + progname); + ExitPostmaster(1); + } - bn->pid = pid; - bn->cancel_key = 0; - DLAddHead(BackendList, DLNewElem(bn)); + bn->pid = pid; + bn->cancel_key = PostmasterRandom(); + DLAddHead(BackendList, DLNewElem(bn)); + + /* + * Since this code is executed periodically, it's a fine + * place to do other actions that should happen every now + * and then on no particular schedule. Such as... + */ + TouchSocketLockFile(); + } return (pid); } |