oikBruce Momjian wrote:
> Bruce Momjian wrote:
> > > > When we get the termination signal, why can't we just set a global
> > > > boolean, do a query cancel, and in the setjmp() code block check the
> > > > global and exit --- at that stage we know we have released all locks and
> > > > can exit cleanly.
> > >
> > > I have implemented this idea with the attached patch.
> >
> > One problem I have with my patch is that SIGTERM is currently used by
> > the postmaster to shut down backends. Now because the postmaster knows
> > that all backend are terminating, it can accept a dirtier shutdown than
> > one where we are terminating just one backend and the rest are going to
> > keep running. The new SIGTERM coding is going to exit a backend only in
> > a place where cancel is checked.
>
> I have a idea --- to have pg_terminate_backend() set a PGPROC boolean
> and then send a query cancel signal to the backend --- the backend can
> then check the boolean and exit if required. I will work on a new
> version of this patch tomorrow/Monday.
Updated patch attached. I didn't modify SIGTERM at all but set a PRPROC
boolean and piggybacked on SIGINT. I think I got the PGPROC locking
right. I had to split apart pg_signal_backend() so I could do the
permission and pid checks independent of the signalling, because I
pg_terminate_backend() needs to check, then set the PGPROC variable,
then send the signal.
I also added an administration doc mention about when to use
pg_terminate_backend().
--
Bruce Momjian <[EMAIL PROTECTED]> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ If your life is a hard drive, Christ can be your backup. +
Index: doc/src/sgml/func.sgml
===================================================================
RCS file: /cvsroot/pgsql/doc/src/sgml/func.sgml,v
retrieving revision 1.429
diff -c -c -r1.429 func.sgml
*** doc/src/sgml/func.sgml 10 Apr 2008 13:34:33 -0000 1.429
--- doc/src/sgml/func.sgml 14 Apr 2008 17:19:10 -0000
***************
*** 11849,11854 ****
--- 11849,11857 ----
<primary>pg_cancel_backend</primary>
</indexterm>
<indexterm>
+ <primary>pg_terminate_backend</primary>
+ </indexterm>
+ <indexterm>
<primary>pg_reload_conf</primary>
</indexterm>
<indexterm>
***************
*** 11885,11890 ****
--- 11888,11900 ----
</row>
<row>
<entry>
+ <literal><function>pg_terminate_backend</function>(<parameter>pid</parameter> <type>int</>)</literal>
+ </entry>
+ <entry><type>boolean</type></entry>
+ <entry>Terminate a backend</entry>
+ </row>
+ <row>
+ <entry>
<literal><function>pg_reload_conf</function>()</literal>
</entry>
<entry><type>boolean</type></entry>
***************
*** 11907,11915 ****
</para>
<para>
! <function>pg_cancel_backend</> sends a query cancel
! (<systemitem>SIGINT</>) signal to a backend process identified by
! process ID. The process ID of an active backend can be found from
the <structfield>procpid</structfield> column in the
<structname>pg_stat_activity</structname> view, or by listing the
<command>postgres</command> processes on the server with
--- 11917,11926 ----
</para>
<para>
! <function>pg_cancel_backend</> and <function>pg_terminate_backend</>
! send a query cancel (<systemitem>SIGINT</>) signal to a backend process
! identified by process ID. The
! process ID of an active backend can be found from
the <structfield>procpid</structfield> column in the
<structname>pg_stat_activity</structname> view, or by listing the
<command>postgres</command> processes on the server with
Index: doc/src/sgml/runtime.sgml
===================================================================
RCS file: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v
retrieving revision 1.411
diff -c -c -r1.411 runtime.sgml
*** doc/src/sgml/runtime.sgml 31 Mar 2008 02:43:14 -0000 1.411
--- doc/src/sgml/runtime.sgml 14 Apr 2008 17:19:10 -0000
***************
*** 1372,1377 ****
--- 1372,1384 ----
well.
</para>
</important>
+
+ <para>
+ To terminate a session while allowing other sessions to continue, use
+ <function>pg_terminate_backend()</> (<xref
+ linkend="functions-admin-signal-table">) rather than sending a signal
+ to the child process.
+ </para>
</sect1>
<sect1 id="preventing-server-spoofing">
Index: src/backend/tcop/postgres.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/tcop/postgres.c,v
retrieving revision 1.548
diff -c -c -r1.548 postgres.c
*** src/backend/tcop/postgres.c 2 Apr 2008 18:31:50 -0000 1.548
--- src/backend/tcop/postgres.c 14 Apr 2008 17:19:10 -0000
***************
*** 2541,2547 ****
* waiting for input, however.
*/
if (ImmediateInterruptOK && InterruptHoldoffCount == 0 &&
! CritSectionCount == 0 && !DoingCommandRead)
{
/* bump holdoff count to make ProcessInterrupts() a no-op */
/* until we are done getting ready for it */
--- 2541,2548 ----
* waiting for input, however.
*/
if (ImmediateInterruptOK && InterruptHoldoffCount == 0 &&
! CritSectionCount == 0 &&
! (!DoingCommandRead || MyProc->terminate))
{
/* bump holdoff count to make ProcessInterrupts() a no-op */
/* until we are done getting ready for it */
***************
*** 2621,2626 ****
--- 2622,2631 ----
ereport(ERROR,
(errcode(ERRCODE_QUERY_CANCELED),
errmsg("canceling autovacuum task")));
+ else if (MyProc->terminate)
+ ereport(ERROR,
+ (errcode(ERRCODE_ADMIN_SHUTDOWN),
+ errmsg("terminating backend due to administrator command")));
else
ereport(ERROR,
(errcode(ERRCODE_QUERY_CANCELED),
***************
*** 3459,3464 ****
--- 3464,3472 ----
/* We don't have a transaction command open anymore */
xact_started = false;
+ if (MyProc->terminate)
+ die(SIGINT);
+
/* Now we can allow interrupts again */
RESUME_INTERRUPTS();
}
Index: src/backend/utils/adt/misc.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/utils/adt/misc.c,v
retrieving revision 1.59
diff -c -c -r1.59 misc.c
*** src/backend/utils/adt/misc.c 4 Apr 2008 16:57:21 -0000 1.59
--- src/backend/utils/adt/misc.c 14 Apr 2008 17:19:11 -0000
***************
*** 27,32 ****
--- 27,33 ----
#include "postmaster/syslogger.h"
#include "storage/fd.h"
#include "storage/pmsignal.h"
+ #include "storage/proc.h"
#include "storage/procarray.h"
#include "utils/builtins.h"
#include "tcop/tcopprot.h"
***************
*** 89,95 ****
* Functions to send signals to other backends.
*/
static bool
! pg_signal_backend(int pid, int sig)
{
if (!superuser())
ereport(ERROR,
--- 90,96 ----
* Functions to send signals to other backends.
*/
static bool
! pg_signal_check(int pid)
{
if (!superuser())
ereport(ERROR,
***************
*** 106,112 ****
--- 107,122 ----
(errmsg("PID %d is not a PostgreSQL server process", pid)));
return false;
}
+ else
+ return true;
+ }
+ /*
+ * Functions to send signals to other backends.
+ */
+ static bool
+ pg_signal_backend(int pid, int sig)
+ {
/* If we have setsid(), signal the backend's whole process group */
#ifdef HAVE_SETSID
if (kill(-pid, sig))
***************
*** 125,131 ****
Datum
pg_cancel_backend(PG_FUNCTION_ARGS)
{
! PG_RETURN_BOOL(pg_signal_backend(PG_GETARG_INT32(0), SIGINT));
}
Datum
--- 135,177 ----
Datum
pg_cancel_backend(PG_FUNCTION_ARGS)
{
! int pid = PG_GETARG_INT32(0);
!
! if (pg_signal_check(pid))
! PG_RETURN_BOOL(pg_signal_backend(pid, SIGINT));
! else
! PG_RETURN_BOOL(false);
! }
!
! /*
! * To cleanly terminate a backend, we set PGPROC(pid)->terminate
! * then send a cancel signal. We get ProcArrayLock only when
! * setting PGPROC->terminate so the function might fail in
! * several places, but that is fine because in those cases the
! * backend is already gone.
! */
! Datum
! pg_terminate_backend(PG_FUNCTION_ARGS)
! {
! int pid = PG_GETARG_INT32(0);
! volatile PGPROC *term_proc;
!
! /* Is this the super-user, and can we find the PGPROC entry for the pid? */
! if (pg_signal_check(pid) && (term_proc = BackendPidGetProc(pid)) != NULL)
! {
! LWLockAcquire(ProcArrayLock, LW_EXCLUSIVE);
! /* Recheck now that we have the ProcArray lock. */
! if (term_proc->pid == pid)
! {
! term_proc->terminate = true;
! LWLockRelease(ProcArrayLock);
! PG_RETURN_BOOL(pg_signal_backend(pid, SIGINT));
! }
! else
! LWLockRelease(ProcArrayLock);
! }
!
! PG_RETURN_BOOL(false);
}
Datum
***************
*** 169,185 ****
PG_RETURN_BOOL(true);
}
- #ifdef NOT_USED
-
- /* Disabled in 8.0 due to reliability concerns; FIXME someday */
- Datum
- pg_terminate_backend(PG_FUNCTION_ARGS)
- {
- PG_RETURN_INT32(pg_signal_backend(PG_GETARG_INT32(0), SIGTERM));
- }
- #endif
-
-
/* Function to find out which databases make use of a tablespace */
typedef struct
--- 215,220 ----
Index: src/include/catalog/pg_proc.h
===================================================================
RCS file: /cvsroot/pgsql/src/include/catalog/pg_proc.h,v
retrieving revision 1.488
diff -c -c -r1.488 pg_proc.h
*** src/include/catalog/pg_proc.h 10 Apr 2008 22:25:25 -0000 1.488
--- src/include/catalog/pg_proc.h 14 Apr 2008 17:19:11 -0000
***************
*** 3157,3162 ****
--- 3157,3164 ----
DATA(insert OID = 2171 ( pg_cancel_backend PGNSP PGUID 12 1 0 f f t f v 1 16 "23" _null_ _null_ _null_ pg_cancel_backend - _null_ _null_ ));
DESCR("cancel a server process' current query");
+ DATA(insert OID = 2096 ( pg_terminate_backend PGNSP PGUID 12 1 0 f f t f v 1 16 "23" _null_ _null_ _null_ pg_terminate_backend - _null_ _null_ ));
+ DESCR("terminate a server process");
DATA(insert OID = 2172 ( pg_start_backup PGNSP PGUID 12 1 0 f f t f v 1 25 "25" _null_ _null_ _null_ pg_start_backup - _null_ _null_ ));
DESCR("prepare for taking an online backup");
DATA(insert OID = 2173 ( pg_stop_backup PGNSP PGUID 12 1 0 f f t f v 0 25 "" _null_ _null_ _null_ pg_stop_backup - _null_ _null_ ));
Index: src/include/storage/proc.h
===================================================================
RCS file: /cvsroot/pgsql/src/include/storage/proc.h,v
retrieving revision 1.104
diff -c -c -r1.104 proc.h
*** src/include/storage/proc.h 26 Jan 2008 19:55:08 -0000 1.104
--- src/include/storage/proc.h 14 Apr 2008 17:19:11 -0000
***************
*** 91,96 ****
--- 91,98 ----
bool inCommit; /* true if within commit critical section */
+ bool terminate; /* admin requested termination */
+
uint8 vacuumFlags; /* vacuum-related flags, see above */
/* Info about LWLock the process is currently waiting for, if any. */
Index: src/include/utils/builtins.h
===================================================================
RCS file: /cvsroot/pgsql/src/include/utils/builtins.h,v
retrieving revision 1.312
diff -c -c -r1.312 builtins.h
*** src/include/utils/builtins.h 4 Apr 2008 18:45:36 -0000 1.312
--- src/include/utils/builtins.h 14 Apr 2008 17:19:11 -0000
***************
*** 416,421 ****
--- 416,422 ----
extern Datum current_database(PG_FUNCTION_ARGS);
extern Datum current_query(PG_FUNCTION_ARGS);
extern Datum pg_cancel_backend(PG_FUNCTION_ARGS);
+ extern Datum pg_terminate_backend(PG_FUNCTION_ARGS);
extern Datum pg_reload_conf(PG_FUNCTION_ARGS);
extern Datum pg_tablespace_databases(PG_FUNCTION_ARGS);
extern Datum pg_rotate_logfile(PG_FUNCTION_ARGS);
--
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