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Sourcecode: postgresql-8.4 version File versions  Download package

fork_process.c

/*
 * fork_process.c
 *     A simple wrapper on top of fork(). This does not handle the
 *     EXEC_BACKEND case; it might be extended to do so, but it would be
 *     considerably more complex.
 *
 * Copyright (c) 1996-2009, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
 *      $PostgreSQL: pgsql/src/backend/postmaster/fork_process.c,v 1.9 2009/01/01 17:23:46 momjian Exp $
 */
#include "postgres.h"
#include "postmaster/fork_process.h"

#include <time.h>
#include <sys/time.h>
#include <unistd.h>

#ifndef WIN32
/*
 * Wrapper for fork(). Return values are the same as those for fork():
 * -1 if the fork failed, 0 in the child process, and the PID of the
 * child in the parent process.
 */
pid_t
fork_process(void)
{
      pid_t       result;

#ifdef LINUX_PROFILE
      struct itimerval prof_itimer;
#endif

      /*
       * Flush stdio channels just before fork, to avoid double-output problems.
       * Ideally we'd use fflush(NULL) here, but there are still a few non-ANSI
       * stdio libraries out there (like SunOS 4.1.x) that coredump if we do.
       * Presently stdout and stderr are the only stdio output channels used by
       * the postmaster, so fflush'ing them should be sufficient.
       */
      fflush(stdout);
      fflush(stderr);

#ifdef LINUX_PROFILE

      /*
       * Linux's fork() resets the profiling timer in the child process. If we
       * want to profile child processes then we need to save and restore the
       * timer setting.  This is a waste of time if not profiling, however, so
       * only do it if commanded by specific -DLINUX_PROFILE switch.
       */
      getitimer(ITIMER_PROF, &prof_itimer);
#endif

      result = fork();
      if (result == 0)
      {
            /* fork succeeded, in child */
#ifdef LINUX_PROFILE
            setitimer(ITIMER_PROF, &prof_itimer, NULL);
#endif

      }

      return result;
}

#endif   /* ! WIN32 */

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