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https://github.com/postgres/postgres.git
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Keep track of the last active slot in the shared ProcState array, so
that search loops only have to scan that far and not through all maxBackends entries. This eliminates a performance penalty for setting maxBackends much higher than the average number of active backends. Also, eliminate no-longer-used 'backend tag' concept. Remove setting of environment variables at backend start (except for CYR_RECODE), since none of them are being examined by the backend any longer.
This commit is contained in:
Tom Lane
@@ -11,7 +11,7 @@
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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 1.181 2000/11/09 11:25:59 vadim Exp $
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* $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.182 2000/11/12 20:51:51 tgl Exp $
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*
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* NOTES
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*
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@@ -107,55 +107,45 @@ typedef struct bkend
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Port *MyBackendPort = NULL;
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/* list of active backends. For garbage collection only now. */
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static Dllist *BackendList;
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/* list of ports associated with still open, but incomplete connections */
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static Dllist *PortList;
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/* The socket number we are listening for connections on */
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int PostPortName;
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/*
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* This is a boolean indicating that there is at least one backend that
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* is accessing the current shared memory and semaphores. Between the
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* time that we start up, or throw away shared memory segments and start
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* over, and the time we generate the next backend (because we received a
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* connection request), it is false. Other times, it is true.
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*/
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/*
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* This is a sequence number that indicates how many times we've had to
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* throw away the shared memory and start over because we doubted its
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* integrity. It starts off at zero and is incremented every time we
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* start over. We use this to ensure that we use a new IPC shared memory
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* key for the new shared memory segment in case the old segment isn't
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* entirely gone yet.
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*
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* The sequence actually cycles back to 0 after 9, so pathologically there
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* could be an IPC failure if 10 sets of backends are all stuck and won't
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* release IPC resources.
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*/
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static short shmem_seq = 0;
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/*
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* This is a sequence number that indicates how many times we've had to
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* throw away the shared memory and start over because we doubted its
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* integrity. It starts off at zero and is incremented every time we
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* start over. We use this to ensure that we use a new IPC shared memory
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* key for the new shared memory segment in case the old segment isn't
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* entirely gone yet.
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*
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* The sequence actually cycles back to 0 after 9, so pathologically there
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* could be an IPC failure if 10 sets of backends are all stuck and won't
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* release IPC resources.
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*/
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/*
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* This is the base IPC shared memory key. Other keys are generated by
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* adding to this.
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*/
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static IpcMemoryKey ipc_key;
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/*
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* This is the base IPC shared memory key. Other keys are generated by
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* adding to this.
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*/
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/*
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* MaxBackends is the actual limit on the number of backends we will
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* start. The default is established by configure, but it can be
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* readjusted from 1..MAXBACKENDS with the postmaster -N switch. Note
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* that a larger MaxBackends value will increase the size of the shared
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* memory area as well as cause the postmaster to grab more kernel
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* semaphores, even if you never actually use that many backends.
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*/
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int MaxBackends = DEF_MAXBACKENDS;
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/*
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* MaxBackends is the actual limit on the number of backends we will
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* start. The default is established by configure, but it can be
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* readjusted from 1..MAXBACKENDS with the postmaster -N switch. Note
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* that a larger MaxBackends value will increase the size of the shared
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* memory area as well as cause the postmaster to grab more kernel
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* semaphores, even if you never actually use that many backends.
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*/
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static int NextBackendTag = INT_MAX; /* 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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@@ -587,6 +577,22 @@ PostmasterMain(int argc, char *argv[])
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exit(1);
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}
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if (DebugLvl > 2)
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{
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extern char **environ;
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char **p;
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fprintf(stderr, "%s: PostmasterMain: initial environ dump:\n",
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progname);
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fprintf(stderr, "-----------------------------------------\n");
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for (p = environ; *p; ++p)
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fprintf(stderr, "\t%s\n", *p);
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fprintf(stderr, "-----------------------------------------\n");
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}
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/*
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* Establish input sockets.
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*/
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#ifdef USE_SSL
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if (EnableSSL && !NetServer)
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{
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@@ -600,7 +606,8 @@ PostmasterMain(int argc, char *argv[])
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if (NetServer)
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{
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status = StreamServerPort(AF_INET, (unsigned short)PostPortName, &ServerSock_INET);
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status = StreamServerPort(AF_INET, (unsigned short) PostPortName,
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&ServerSock_INET);
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if (status != STATUS_OK)
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{
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fprintf(stderr, "%s: cannot create INET stream port\n",
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@@ -610,7 +617,8 @@ PostmasterMain(int argc, char *argv[])
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}
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#ifdef HAVE_UNIX_SOCKETS
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status = StreamServerPort(AF_UNIX, (unsigned short)PostPortName, &ServerSock_UNIX);
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status = StreamServerPort(AF_UNIX, (unsigned short) PostPortName,
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&ServerSock_UNIX);
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if (status != STATUS_OK)
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{
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fprintf(stderr, "%s: cannot create UNIX stream port\n",
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@@ -618,10 +626,11 @@ PostmasterMain(int argc, char *argv[])
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ExitPostmaster(1);
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}
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#endif
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/* set up shared memory and semaphores */
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reset_shared(PostPortName);
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/* Init XLOG pathes */
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/* Init XLOG paths */
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snprintf(XLogDir, MAXPGPATH, "%s/pg_xlog", DataDir);
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snprintf(ControlFilePath, MAXPGPATH, "%s/global/pg_control", DataDir);
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@@ -1706,43 +1715,7 @@ static int
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BackendStartup(Port *port)
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{
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Backend *bn; /* for backend cleanup */
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int pid,
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i;
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#ifdef CYR_RECODE
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#define NR_ENVIRONMENT_VBL 5
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char ChTable[80];
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#else
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#define NR_ENVIRONMENT_VBL 4
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#endif
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static char envEntry[NR_ENVIRONMENT_VBL][2 * ARGV_SIZE];
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for (i = 0; i < NR_ENVIRONMENT_VBL; ++i)
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MemSet(envEntry[i], 0, 2 * ARGV_SIZE);
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/*
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* Set up the necessary environment variables for the backend This
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* should really be some sort of message....
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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", NextBackendTag);
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putenv(envEntry[1]);
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sprintf(envEntry[2], "PGDATA=%s", DataDir);
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putenv(envEntry[2]);
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sprintf(envEntry[3], "IPC_KEY=%d", ipc_key);
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putenv(envEntry[3]);
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#ifdef CYR_RECODE
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GetCharSetByHost(ChTable, port->raddr.in.sin_addr.s_addr, DataDir);
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if (*ChTable != '\0')
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{
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sprintf(envEntry[4], "PG_RECODETABLE=%s", ChTable);
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putenv(envEntry[4]);
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}
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#endif
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int pid;
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/*
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* Compute the cancel key that will be assigned to this backend. The
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@@ -1751,19 +1724,6 @@ BackendStartup(Port *port)
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*/
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MyCancelKey = PostmasterRandom();
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if (DebugLvl > 2)
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{
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char **p;
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extern char **environ;
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fprintf(stderr, "%s: BackendStartup: environ dump:\n",
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progname);
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fprintf(stderr, "-----------------------------------------\n");
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for (p = environ; *p; ++p)
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fprintf(stderr, "\t%s\n", *p);
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fprintf(stderr, "-----------------------------------------\n");
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}
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/*
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* Flush stdio channels just before fork, to avoid double-output
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* problems. Ideally we'd use fflush(NULL) here, but there are still a
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@@ -1779,12 +1739,30 @@ BackendStartup(Port *port)
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/* Specific beos actions before backend startup */
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beos_before_backend_startup();
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#endif
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if ((pid = fork()) == 0)
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{ /* child */
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#ifdef __BEOS__
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/* Specific beos backend stratup actions */
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/* Specific beos backend startup actions */
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beos_backend_startup();
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#endif
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#ifdef CYR_RECODE
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{
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/* Save charset for this host while we still have client addr */
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char ChTable[80];
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static char cyrEnvironment[100];
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GetCharSetByHost(ChTable, port->raddr.in.sin_addr.s_addr, DataDir);
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if (*ChTable != '\0')
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{
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snprintf(cyrEnvironment, sizeof(cyrEnvironment),
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"PG_RECODETABLE=%s", ChTable);
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putenv(cyrEnvironment);
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}
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}
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#endif
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if (DoBackend(port))
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{
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fprintf(stderr, "%s child[%d]: BackendStartup: backend startup failed\n",
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@@ -1799,7 +1777,7 @@ BackendStartup(Port *port)
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if (pid < 0)
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{
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#ifdef __BEOS__
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/* Specific beos backend stratup actions */
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/* Specific beos backend startup actions */
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beos_backend_startup_failed();
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#endif
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fprintf(stderr, "%s: BackendStartup: fork failed: %s\n",
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@@ -1812,14 +1790,6 @@ BackendStartup(Port *port)
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progname, pid, port->user, port->database,
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port->sock);
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/* Generate a new backend tag for every backend we start */
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/*
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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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* list of backends.
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@@ -2179,21 +2149,7 @@ static pid_t
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SSDataBase(int xlop)
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{
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pid_t pid;
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int i;
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Backend *bn;
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static char ssEntry[4][2 * ARGV_SIZE];
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for (i = 0; i < 4; ++i)
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MemSet(ssEntry[i], 0, 2 * ARGV_SIZE);
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sprintf(ssEntry[0], "POSTPORT=%d", PostPortName);
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putenv(ssEntry[0]);
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sprintf(ssEntry[1], "POSTID=%d", NextBackendTag);
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putenv(ssEntry[1]);
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sprintf(ssEntry[2], "PGDATA=%s", DataDir);
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putenv(ssEntry[2]);
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sprintf(ssEntry[3], "IPC_KEY=%d", ipc_key);
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putenv(ssEntry[3]);
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fflush(stdout);
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fflush(stderr);
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@@ -2258,8 +2214,6 @@ SSDataBase(int xlop)
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ExitPostmaster(1);
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}
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NextBackendTag -= 1;
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if (xlop != BS_XLOG_CHECKPOINT)
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return(pid);
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