external_pid_file not removed on postmaster exit
It seems strange that the external_pid_file is never removed. There is
even a C comment about it:
/* Should we remove the pid file on postmaster exit? */
I think it should be removed with proc_exit hook just like the main
postmaster.pid file.
Does anyone remember why this was not done originally or have any
concerns?
From: pgsql-hackers-owner@postgresql.org [pgsql-hackers-owner@postgresql.org] on behalf of Peter Eisentraut [peter_e@gmx.net]
Sent: Friday, July 27, 2012 10:39 AM
It seems strange that the external_pid_file is never removed. There is
even a C comment about it:
/* Should we remove the pid file on postmaster exit? */
I think it should be removed with proc_exit hook just like the main
postmaster.pid file.
external_pid_file is created first time when it is enabled in postgresql.conf
I think it should be removed once the parameter external_pid_file is unset;
Making handling of both postmaster.pid and external_pid_file same in terms of creation and removal may not be best choice
as both have different purpose.
With Regards,
Amit Kapila.
Amit kapila <amit.kapila@huawei.com> writes:
I think it should be removed with proc_exit hook just like the main
postmaster.pid file.
external_pid_file is created first time when it is enabled in postgresql.conf
I think it should be removed once the parameter external_pid_file is unset;
Unset? If that parameter is not PGC_POSTMASTER, it certainly ought to
be. In any case, that has little to do with what Peter is complaining
about ...
regards, tom lane
From: Tom Lane [tgl@sss.pgh.pa.us]
Sent: Saturday, July 28, 2012 9:46 PM
Amit kapila <amit.kapila@huawei.com> writes:
I think it should be removed with proc_exit hook just like the main
postmaster.pid file.
external_pid_file is created first time when it is enabled in postgresql.conf
I think it should be removed once the parameter external_pid_file is unset;
Unset?
By Unset, I mean to say when the configuration parameter 'external_pid_file' is disabled (#external_pid_file).
But if the path/filename is changed to different name across restart of server, it will not be able to delete the previous file.
So it will not workout the way I was trying to think.
However if it is deleted at proc_exit as suggested by Peter, there will be no problem.
The reason why I have thought the file not to get deleted at every proc_exit, is
a. Initially I thought it might be un-necessary to delete and re-create the file at server shutdown and start.
b. I was not sure if this file has usage only till server is running.
With Regards,
Amit Kapila.
On Fri, 2012-07-27 at 08:09 +0300, Peter Eisentraut wrote:
It seems strange that the external_pid_file is never removed. There is
even a C comment about it:/* Should we remove the pid file on postmaster exit? */
I think it should be removed with proc_exit hook just like the main
postmaster.pid file.Does anyone remember why this was not done originally or have any
concerns?
Since that was not the case, I propose the attached patch to unlink the
external pid file.
Attachments:
pg-unlink-external-pid-file.patchtext/x-patch; charset=UTF-8; name=pg-unlink-external-pid-file.patchDownload
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index a4fb2a4..73520a6 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -329,6 +329,7 @@
/*
* postmaster.c - function prototypes
*/
+static void unlink_external_pid_file(int status, Datum arg);
static void getInstallationPaths(const char *argv0);
static void checkDataDir(void);
static Port *ConnCreate(int serverFd);
@@ -1071,7 +1072,6 @@ static bool save_backend_variables(BackendParameters *param, Port *port,
{
fprintf(fpidfile, "%d\n", MyProcPid);
fclose(fpidfile);
- /* Should we remove the pid file on postmaster exit? */
/* Make PID file world readable */
if (chmod(external_pid_file, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH) != 0)
@@ -1081,6 +1081,8 @@ static bool save_backend_variables(BackendParameters *param, Port *port,
else
write_stderr("%s: could not write external PID file \"%s\": %s\n",
progname, external_pid_file, strerror(errno));
+
+ on_proc_exit(unlink_external_pid_file, 0);
}
/*
@@ -1183,6 +1185,17 @@ static bool save_backend_variables(BackendParameters *param, Port *port,
/*
+ * on_proc_exit callback to delete external_pid_file
+ */
+static void
+unlink_external_pid_file(int status, Datum arg)
+{
+ if (external_pid_file)
+ unlink(external_pid_file);
+}
+
+
+/*
* Compute and check the directory paths to files that are part of the
* installation (as deduced from the postgres executable's own location)
*/