PostgreSQL pg_ctl start超时分析

do_start->
  pm_pid = start_postmaster();
  if (do_wait){
    print_msg(_("waiting for server to start..."));
    switch (wait_for_postmaster(pm_pid, false)){
      case POSTMASTER_READY:
        print_msg(_(" done\n"));
        print_msg(_("server started\n"));
        break;
      case POSTMASTER_STILL_STARTING:
        print_msg(_(" stopped waiting\n"));
        write_stderr(_("%s: server did not start in time\n"), progname);
        exit(1);
        break;
      case POSTMASTER_FAILED:
        print_msg(_(" stopped waiting\n"));
        write_stderr(_("%s: could not start server\n" "Examine the log output.\n"), progname);
        exit(1);
        break;
    }
  }else
    print_msg(_("server starting\n"));
wait_for_postmaster->
  for (i = 0; i < wait_seconds * WAITS_PER_SEC; i++){
    if ((optlines = readfile(pid_file, &numlines)) != NULL && numlines >= LOCK_FILE_LINE_PM_STATUS){
      pmpid = atol(optlines[LOCK_FILE_LINE_PID - 1]);
      pmstart = atol(optlines[LOCK_FILE_LINE_START_TIME - 1]);
      if (pmstart >= start_time - 2 && pmpid == pm_pid){
        char     *pmstatus = optlines[LOCK_FILE_LINE_PM_STATUS - 1];
        if (strcmp(pmstatus, PM_STATUS_READY) == 0 || strcmp(pmstatus, PM_STATUS_STANDBY) == 0){
          /* postmaster is done starting up */
          free_readfile(optlines);
          return POSTMASTER_READY;
        }
      }
    }
    free_readfile(optlines);
    if (waitpid((pid_t) pm_pid, &exitstatus, WNOHANG) == (pid_t) pm_pid)
      return POSTMASTER_FAILED;
    pg_usleep(USEC_PER_SEC / WAITS_PER_SEC);
  }
  /* out of patience; report that postmaster is still starting up */
  return POSTMASTER_STILL_STARTING;

PostmasterMain->
  pqsignal_no_restart(SIGUSR1, sigusr1_handler);  /* message from child process */
  pqsignal_no_restart(SIGCHLD, reaper); /* handle child termination */
  ...
  StartupXLOG();
  ...
  proc_exit(0);//exit函数向主进程发送SIGCHLD信号
reaper->//进程终止或者停止的信号
  AddToDataDirLockFile(LOCK_FILE_LINE_PM_STATUS, PM_STATUS_READY);
postmaster进程接收子进程信号：
sigusr1_handler->
  if (CheckPostmasterSignal(PMSIGNAL_RECOVERY_STARTED) &&
    pmState == PM_STARTUP && Shutdown == NoShutdown){
    CheckpointerPID = StartCheckpointer();
    BgWriterPID = StartBackgroundWriter();
    if (XLogArchivingAlways())
      PgArchPID = pgarch_start();
    //hot_standby在postgresql.conf文件中配置TRUE
    //表示在恢复的时候允许连接
    if (!EnableHotStandby){
      //将standby写入postmaster.pid文件，表示up但不允许连接
      AddToDataDirLockFile(LOCK_FILE_LINE_PM_STATUS, PM_STATUS_STANDBY);
    }
    pmState = PM_RECOVERY;
  }
  if (CheckPostmasterSignal(PMSIGNAL_BEGIN_HOT_STANDBY) &&
    pmState == PM_RECOVERY && Shutdown == NoShutdown){
    PgStatPID = pgstat_start();
    //将ready写入postmaster.pid文件，允许连接
    AddToDataDirLockFile(LOCK_FILE_LINE_PM_STATUS, PM_STATUS_READY);
    pmState = PM_HOT_STANDBY;
  }
  ...

StartupXLOG->
  ReadCheckpointRecord
  if (ArchiveRecoveryRequested && IsUnderPostmaster){//有recovery.conf文件则ArchiveRecoveryRequested为TRUE
    //有recovery.conf文件则ArchiveRecoveryRequested为TRUE
    PublishStartupProcessInformation();
    SetForwardFsyncRequests();
    //向master进程发送PMSIGNAL_RECOVERY_STARTED信号
    SendPostmasterSignal(PMSIGNAL_RECOVERY_STARTED);
    bgwriterLaunched = true;
  }
  CheckRecoveryConsistency();-->...
  |-- if (standbyState == STANDBY_SNAPSHOT_READY && !LocalHotStandbyActive &&
  |   reachedConsistency && IsUnderPostmaster){
  |   SpinLockAcquire(&XLogCtl->info_lck);
  |   XLogCtl->SharedHotStandbyActive = true;
  |   SpinLockRelease(&XLogCtl->info_lck);
  |   LocalHotStandbyActive = true;
  |   SendPostmasterSignal(PMSIGNAL_BEGIN_HOT_STANDBY);
  |-- }
  ...