Re: [HACKERS] Fix PID file location? - Mailing list pgsql-patches

I have generated the following patch that moves postmaster.pid into the
configuration directory.  pg_ctl only knows about the configuration
directory because it can't read postgresql.conf, so it seems that is the
right place to move it.

I have tested it and it seems to work. I would like to backpatch this to
8.0.X because it is currently broken without it.  This patch does
require that the postgres unix user have write permission in the
configuration directory to create the pid file on startup.

---------------------------------------------------------------------------

Josh Berkus wrote:
> Hey, folks,
>
> I've noticed a problem with alternate PGDATA locations.  Here's how to
> reproduce:
>
> On 8.0.2 on RHAS4:
>
> 1) Initdb a directory (on my system, /pgdata/pgdata)
> 2) Move the .conf files to an alternate location ( /etc/pgsql/)
> 3) Set $PGDATA to the alternate location ( /etc/pgsql )
> 4) Edit postgresql.conf to support this file arrangement
>     data_directory = '/pgdata/pgdata'
> 5) pg_ctl start PostgreSQL
> 6) pg_ctl stop PostgreSQL
> 7) Get an error:  "No PID file found".
>
> The problem seems to be that pg_ctl expects the PID file to be in $PGDATA, but
> the file actually gets written by the postmaster to the actual data
> directory.  You can work around this by setting "external_pid_file", but this
> then prevents you from using external_pid_file for another purpose.
>
> Seems like it should be a relatively easy fix, although I'm not sure whether
> the postmaster should write the PID to $PGDATA, or whether pg_ctl should be
> made to look in the right place.  Probably the latter.

---------------------------------------------------------------------------

> More about this: due to the PID file not being in the right place, pg_ctl stop
> never reports success:
>
> waiting for postmaster to shut
> down............................................................... failed
> pg_ctl: postmaster does not shut down
>
> This appears to be because the duplicate PID in the conf directory is not
> removed on shutdown.


--
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073
Index: doc/src/sgml/runtime.sgml
===================================================================
RCS file: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v
retrieving revision 1.321
diff -c -c -r1.321 runtime.sgml
*** doc/src/sgml/runtime.sgml    25 May 2005 02:56:15 -0000    1.321
--- doc/src/sgml/runtime.sgml    27 May 2005 20:46:42 -0000
***************
*** 309,318 ****
     <para>
      While the <command>postmaster</command> is running, its
      <acronym>PID</acronym> is stored in the file
!     <filename>postmaster.pid</filename> in the data directory. This is
!     used to prevent multiple <command>postmaster</command> processes
!     running in the same data directory and can also be used for
!     shutting down the <command>postmaster</command> process.
     </para>

     <sect2 id="postmaster-start-failures">
--- 309,319 ----
     <para>
      While the <command>postmaster</command> is running, its
      <acronym>PID</acronym> is stored in the file
!     <filename>postmaster.pid</filename> in the data or configuration
!     directory. This is used to prevent multiple
!     <command>postmaster</command> processes running in the same data
!     directory and can also be used for shutting down the
!     <command>postmaster</command> process.
     </para>

     <sect2 id="postmaster-start-failures">
***************
*** 4933,4940 ****
     Alternatively, you can send the signal directly using <command>kill</>.
     The <acronym>PID</> of the <command>postmaster</command> process can be
     found using the <command>ps</command> program, or from the file
!    <filename>postmaster.pid</filename> in the data directory. For
!    example, to do a fast shutdown:
  <screen>
  $ <userinput>kill -INT `head -1 /usr/local/pgsql/data/postmaster.pid`</userinput>
  </screen>
--- 4934,4941 ----
     Alternatively, you can send the signal directly using <command>kill</>.
     The <acronym>PID</> of the <command>postmaster</command> process can be
     found using the <command>ps</command> program, or from the file
!    <filename>postmaster.pid</filename> in the data or configuration directory.
!    For example, to do a fast shutdown:
  <screen>
  $ <userinput>kill -INT `head -1 /usr/local/pgsql/data/postmaster.pid`</userinput>
  </screen>
Index: src/backend/bootstrap/bootstrap.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/bootstrap/bootstrap.c,v
retrieving revision 1.204
diff -c -c -r1.204 bootstrap.c
*** src/backend/bootstrap/bootstrap.c    6 May 2005 17:24:52 -0000    1.204
--- src/backend/bootstrap/bootstrap.c    27 May 2005 20:46:43 -0000
***************
*** 367,373 ****

      /* If standalone, create lockfile for data directory */
      if (!IsUnderPostmaster)
!         CreateDataDirLockFile(DataDir, false);

      SetProcessingMode(BootstrapProcessing);
      IgnoreSystemIndexes(true);
--- 367,373 ----

      /* If standalone, create lockfile for data directory */
      if (!IsUnderPostmaster)
!         CreateDataDirLockFile(userDoption, false);

      SetProcessingMode(BootstrapProcessing);
      IgnoreSystemIndexes(true);
Index: src/backend/postmaster/postmaster.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v
retrieving revision 1.451
diff -c -c -r1.451 postmaster.c
*** src/backend/postmaster/postmaster.c    15 May 2005 00:26:18 -0000    1.451
--- src/backend/postmaster/postmaster.c    27 May 2005 20:46:45 -0000
***************
*** 689,695 ****
       * :-(). For the same reason, it's best to grab the TCP socket(s)
       * before the Unix socket.
       */
!     CreateDataDirLockFile(DataDir, true);

      /*
       * Remove old temporary files.    At this point there can be no other
--- 689,695 ----
       * :-(). For the same reason, it's best to grab the TCP socket(s)
       * before the Unix socket.
       */
!     CreateDataDirLockFile(userDoption, true);

      /*
       * Remove old temporary files.    At this point there can be no other
Index: src/backend/tcop/postgres.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/tcop/postgres.c,v
retrieving revision 1.444
diff -c -c -r1.444 postgres.c
*** src/backend/tcop/postgres.c    24 May 2005 04:18:04 -0000    1.444
--- src/backend/tcop/postgres.c    27 May 2005 20:46:47 -0000
***************
*** 2795,2801 ****
          /*
           * Create lockfile for data directory.
           */
!         CreateDataDirLockFile(DataDir, false);

          XLOGPathInit();
          BaseInit();
--- 2795,2801 ----
          /*
           * Create lockfile for data directory.
           */
!         CreateDataDirLockFile(userDoption, false);

          XLOGPathInit();
          BaseInit();
Index: src/backend/utils/init/miscinit.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/utils/init/miscinit.c,v
retrieving revision 1.139
diff -c -c -r1.139 miscinit.c
*** src/backend/utils/init/miscinit.c    14 Apr 2005 20:03:26 -0000    1.139
--- src/backend/utils/init/miscinit.c    27 May 2005 20:46:47 -0000
***************
*** 706,719 ****
  }

  void
! CreateDataDirLockFile(const char *datadir, bool amPostmaster)
  {
      char        lockfile[MAXPGPATH];

!     snprintf(lockfile, sizeof(lockfile), "%s/postmaster.pid", datadir);
!     CreateLockFile(lockfile, amPostmaster, true, datadir);
      /* Save name of lockfile for RecordSharedMemoryInLockFile */
      strcpy(directoryLockFile, lockfile);
  }

  void
--- 706,733 ----
  }

  void
! CreateDataDirLockFile(const char *userDoption, bool amPostmaster)
  {
      char        lockfile[MAXPGPATH];

!     char       *configdir;
!
!     /*    configdir is -D option, or $PGDATA if no -D.
!      *    The pid file has to be created in the -D/PGDATA
!      *    location because that is the only location pg_ctl
!      *    knows about.
!      */
!     if (userDoption)
!         configdir = make_absolute_path(userDoption);
!     else
!         configdir = make_absolute_path(getenv("PGDATA"));
!
!     snprintf(lockfile, sizeof(lockfile), "%s/postmaster.pid", configdir);
!     CreateLockFile(lockfile, amPostmaster, true, configdir);
      /* Save name of lockfile for RecordSharedMemoryInLockFile */
      strcpy(directoryLockFile, lockfile);
+
+     free(configdir);
  }

  void
Index: src/include/miscadmin.h
===================================================================
RCS file: /cvsroot/pgsql/src/include/miscadmin.h,v
retrieving revision 1.175
diff -c -c -r1.175 miscadmin.h
*** src/include/miscadmin.h    26 Feb 2005 18:43:34 -0000    1.175
--- src/include/miscadmin.h    27 May 2005 20:46:49 -0000
***************
*** 309,315 ****
  extern void ResetReindexProcessing(void);
  extern bool ReindexIsProcessingHeap(Oid heapOid);
  extern bool ReindexIsProcessingIndex(Oid indexOid);
! extern void CreateDataDirLockFile(const char *datadir, bool amPostmaster);
  extern void CreateSocketLockFile(const char *socketfile, bool amPostmaster);
  extern void TouchSocketLockFile(void);
  extern void RecordSharedMemoryInLockFile(unsigned long id1,
--- 309,315 ----
  extern void ResetReindexProcessing(void);
  extern bool ReindexIsProcessingHeap(Oid heapOid);
  extern bool ReindexIsProcessingIndex(Oid indexOid);
! extern void CreateDataDirLockFile(const char *userDoption, bool amPostmaster);
  extern void CreateSocketLockFile(const char *socketfile, bool amPostmaster);
  extern void TouchSocketLockFile(void);
  extern void RecordSharedMemoryInLockFile(unsigned long id1,