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Revert "Fix "pg_ctl start -w" to test child process status directly."

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This reverts commit c869a7d5b4.
As pointed out by Maksym Sobolyev in bug #14199, that approach doesn't
work if the postmaster forks itself an extra time due to silent_mode
being enabled.  We removed silent_mode in 9.2, so the pg_ctl change is
fine in 9.2 and later, but it fails when that option is enabled in 9.1.
Seeing that 9.1 is close to end-of-life, let's adopt the most conservative
fix we can, which is to revert the pg_ctl change in the 9.1 branch.

Discussion: <20160618042812.5798.85609@wrigleys.postgresql.org>
This commit is contained in:
Tom Lane
2016-06-19 13:45:03 -04:00
parent b9b925f83f
commit d56c02f1ac
1 changed files with 78 additions and 107 deletions
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185
src/bin/pg_ctl/pg_ctl.c
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@ -28,7 +28,6 @@
#include <time.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <unistd.h>
#ifdef HAVE_SYS_RESOURCE_H
@ -155,10 +154,10 @@ static int pgwin32_is_service(void);
static pgpid_t get_pgpid(void);
static char **readfile(const char *path);
static pgpid_t start_postmaster(void);
static int start_postmaster(void);
static void read_post_opts(void);
static PGPing test_postmaster_connection(pgpid_t pm_pid, bool do_checkpoint);
static PGPing test_postmaster_connection(bool);
static bool postmaster_is_alive(pid_t pid);
#if defined(HAVE_GETRLIMIT) && defined(RLIMIT_CORE)
@ -402,73 +401,36 @@ readfile(const char *path)
* start/test/stop routines
*/
/*
* Start the postmaster and return its PID.
*
* Currently, on Windows what we return is the PID of the shell process
* that launched the postmaster (and, we trust, is waiting for it to exit).
* So the PID is usable for "is the postmaster still running" checks,
* but cannot be compared directly to postmaster.pid.
*
* On Windows, we also save aside a handle to the shell process in
* "postmasterProcess", which the caller should close when done with it.
*/
static pgpid_t
static int
start_postmaster(void)
{
char cmd[MAXPGPATH];
#ifndef WIN32
pgpid_t pm_pid;
/* Flush stdio channels just before fork, to avoid double-output problems */
fflush(stdout);
fflush(stderr);
pm_pid = fork();
if (pm_pid < 0)
{
/* fork failed */
write_stderr(_("%s: could not start server: %s\n"),
progname, strerror(errno));
exit(1);
}
if (pm_pid > 0)
{
/* fork succeeded, in parent */
return pm_pid;
}
/* fork succeeded, in child */
/*
* Since there might be quotes to handle here, it is easier simply to pass
* everything to a shell to process them. Use exec so that the postmaster
* has the same PID as the current child process.
* everything to a shell to process them.
*
* XXX it would be better to fork and exec so that we would know the child
* postmaster's PID directly; then test_postmaster_connection could use
* the PID without having to rely on reading it back from the pidfile.
*/
if (log_file != NULL)
snprintf(cmd, MAXPGPATH, "exec \"%s\" %s%s < \"%s\" >> \"%s\" 2>&1",
snprintf(cmd, MAXPGPATH, SYSTEMQUOTE "\"%s\" %s%s < \"%s\" >> \"%s\" 2>&1 &" SYSTEMQUOTE,
exec_path, pgdata_opt, post_opts,
DEVNULL, log_file);
else
snprintf(cmd, MAXPGPATH, "exec \"%s\" %s%s < \"%s\" 2>&1",
snprintf(cmd, MAXPGPATH, SYSTEMQUOTE "\"%s\" %s%s < \"%s\" 2>&1 &" SYSTEMQUOTE,
exec_path, pgdata_opt, post_opts, DEVNULL);
(void) execl("/bin/sh", "/bin/sh", "-c", cmd, (char *) NULL);
/* exec failed */
write_stderr(_("%s: could not start server: %s\n"),
progname, strerror(errno));
exit(1);
return 0; /* keep dumb compilers quiet */
return system(cmd);
#else /* WIN32 */
/*
* As with the Unix case, it's easiest to use the shell (CMD.EXE) to
* handle redirection etc. Unfortunately CMD.EXE lacks any equivalent of
* "exec", so we don't get to find out the postmaster's PID immediately.
* On win32 we don't use system(). So we don't need to use & (which would
* be START /B on win32). However, we still call the shell (CMD.EXE) with
* it to handle redirection etc.
*/
PROCESS_INFORMATION pi;
@ -480,15 +442,10 @@ start_postmaster(void)
exec_path, pgdata_opt, post_opts, DEVNULL);
if (!CreateRestrictedProcess(cmd, &pi, false))
{
write_stderr(_("%s: could not start server: error code %lu\n"),
progname, (unsigned long) GetLastError());
exit(1);
}
/* Don't close command process handle here; caller must do so */
postmasterProcess = pi.hProcess;
return GetLastError();
CloseHandle(pi.hProcess);
CloseHandle(pi.hThread);
return pi.dwProcessId; /* Shell's PID, not postmaster's! */
return 0;
#endif /* WIN32 */
}
@ -497,21 +454,15 @@ start_postmaster(void)
/*
* Find the pgport and try a connection
*
* On Unix, pm_pid is the PID of the just-launched postmaster. On Windows,
* it may be the PID of an ancestor shell process, so we can't check the
* contents of postmaster.pid quite as carefully.
*
* On Windows, the static variable postmasterProcess is an implicit argument
* to this routine; it contains a handle to the postmaster process or an
* ancestor shell process thereof.
*
* Note that the checkpoint parameter enables a Windows service control
* manager checkpoint, it's got nothing to do with database checkpoints!!
*/
static PGPing
test_postmaster_connection(pgpid_t pm_pid, bool do_checkpoint)
test_postmaster_connection(bool do_checkpoint)
{
PGPing ret = PQPING_NO_RESPONSE;
bool found_stale_pidfile = false;
pgpid_t pm_pid = 0;
char connstr[MAXPGPATH * 2 + 256];
int i;
@ -566,27 +517,29 @@ test_postmaster_connection(pgpid_t pm_pid, bool do_checkpoint)
optlines[5] != NULL)
{
/* File is complete enough for us, parse it */
pgpid_t pmpid;
long pmpid;
time_t pmstart;
/*
* Make sanity checks. If it's for the wrong PID, or the
* recorded start time is before pg_ctl started, then
* either we are looking at the wrong data directory, or
* this is a pre-existing pidfile that hasn't (yet?) been
* overwritten by our child postmaster. Allow 2 seconds
* slop for possible cross-process clock skew.
* Make sanity checks. If it's for a standalone backend
* (negative PID), or the recorded start time is before
* pg_ctl started, then either we are looking at the wrong
* data directory, or this is a pre-existing pidfile that
* hasn't (yet?) been overwritten by our child postmaster.
* Allow 2 seconds slop for possible cross-process clock
* skew.
*/
pmpid = atol(optlines[LOCK_FILE_LINE_PID - 1]);
pmstart = atol(optlines[LOCK_FILE_LINE_START_TIME - 1]);
if (pmstart >= start_time - 2 &&
#ifndef WIN32
pmpid == pm_pid
#else
/* Windows can only reject standalone-backend PIDs */
pmpid > 0
#endif
)
if (pmpid <= 0 || pmstart < start_time - 2)
{
/*
* Set flag to report stale pidfile if it doesn't get
* overwritten before we give up waiting.
*/
found_stale_pidfile = true;
}
else
{
/*
* OK, seems to be a valid pidfile from our child.
@ -596,6 +549,9 @@ test_postmaster_connection(pgpid_t pm_pid, bool do_checkpoint)
char *hostaddr;
char host_str[MAXPGPATH];
found_stale_pidfile = false;
pm_pid = (pgpid_t) pmpid;
/*
* Extract port number and host string to use. Prefer
* using Unix socket if available.
@ -667,23 +623,37 @@ test_postmaster_connection(pgpid_t pm_pid, bool do_checkpoint)
}
/*
* Check whether the child postmaster process is still alive. This
* lets us exit early if the postmaster fails during startup.
*
* On Windows, we may be checking the postmaster's parent shell, but
* that's fine for this purpose.
* The postmaster should create postmaster.pid very soon after being
* started. If it's not there after we've waited 5 or more seconds,
* assume startup failed and give up waiting. (Note this covers both
* cases where the pidfile was never created, and where it was created
* and then removed during postmaster exit.) Also, if there *is* a
* file there but it appears stale, issue a suitable warning and give
* up waiting.
*/
#ifndef WIN32
if (i >= 5)
{
int exitstatus;
struct stat statbuf;
if (waitpid((pid_t) pm_pid, &exitstatus, WNOHANG) == (pid_t) pm_pid)
if (stat(pid_file, &statbuf) != 0)
return PQPING_NO_RESPONSE;
if (found_stale_pidfile)
{
write_stderr(_("\n%s: this data directory appears to be running a pre-existing postmaster\n"),
progname);
return PQPING_NO_RESPONSE;
}
#else
if (WaitForSingleObject(postmasterProcess, 0) == WAIT_OBJECT_0)
}
/*
* If we've been able to identify the child postmaster's PID, check
* the process is still alive. This covers cases where the postmaster
* successfully created the pidfile but then crashed without removing
* it.
*/
if (pm_pid > 0 && !postmaster_is_alive((pid_t) pm_pid))
return PQPING_NO_RESPONSE;
#endif
/* No response, or startup still in process; wait */
#if defined(WIN32)
@ -846,7 +816,7 @@ static void
do_start(void)
{
pgpid_t old_pid = 0;
pgpid_t pm_pid;
int exitcode;
if (ctl_command != RESTART_COMMAND)
{
@ -886,13 +856,19 @@ do_start(void)
}
#endif
pm_pid = start_postmaster();
exitcode = start_postmaster();
if (exitcode != 0)
{
write_stderr(_("%s: could not start server: exit code was %d\n"),
progname, exitcode);
exit(1);
}
if (do_wait)
{
print_msg(_("waiting for server to start..."));
switch (test_postmaster_connection(pm_pid, false))
switch (test_postmaster_connection(false))
{
case PQPING_OK:
print_msg(_(" done\n"));
@ -918,12 +894,6 @@ do_start(void)
}
else
print_msg(_("server starting\n"));
#ifdef WIN32
/* Now we don't need the handle to the shell process anymore */
CloseHandle(postmasterProcess);
postmasterProcess = INVALID_HANDLE_VALUE;
#endif
}
@ -1528,7 +1498,7 @@ pgwin32_ServiceMain(DWORD argc, LPTSTR *argv)
if (do_wait)
{
write_eventlog(EVENTLOG_INFORMATION_TYPE, _("Waiting for server startup...\n"));
if (test_postmaster_connection(postmasterPID, true) != PQPING_OK)
if (test_postmaster_connection(true) != PQPING_OK)
{
write_eventlog(EVENTLOG_ERROR_TYPE, _("Timed out waiting for server startup\n"));
pgwin32_SetServiceStatus(SERVICE_STOPPED);
@ -1555,9 +1525,10 @@ pgwin32_ServiceMain(DWORD argc, LPTSTR *argv)
{
/*
* status.dwCheckPoint can be incremented by
* test_postmaster_connection(), so it might not start from 0.
* test_postmaster_connection(true), so it might not
* start from 0.
*/
int maxShutdownCheckPoint = status.dwCheckPoint + 12;
int maxShutdownCheckPoint = status.dwCheckPoint + 12;;
kill(postmasterPID, SIGINT);