1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
|
/*
* 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) 1996-2008, PostgreSQL Global Development Group
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/postmaster/fork_process.c,v 1.8 2008/01/01 19:45:51 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 */
|
