diff options
author | Tom Lane | 2009-05-05 19:59:00 +0000 |
---|---|---|
committer | Tom Lane | 2009-05-05 19:59:00 +0000 |
commit | 969d7cd4315bfe30aed5221b69ee34e7cd132789 (patch) | |
tree | 958e2b4b6332c01c0e2adee52a79653e5c588a13 /src/include/miscadmin.h | |
parent | 8f348112f35d9dcc28fc575f8bae458883c5700a (diff) |
Install a "dead man switch" to allow the postmaster to detect cases where
a backend has done exit(0) or exit(1) without having disengaged itself
from shared memory. We are at risk for this whenever third-party code is
loaded into a backend, since such code might not know it's supposed to go
through proc_exit() instead. Also, it is reported that under Windows
there are ways to externally kill a process that cause the status code
returned to the postmaster to be indistinguishable from a voluntary exit
(thank you, Microsoft). If this does happen then the system is probably
hosed --- for instance, the dead session might still be holding locks.
So the best recovery method is to treat this like a backend crash.
The dead man switch is armed for a particular child process when it
acquires a regular PGPROC, and disarmed when the PGPROC is released;
these should be the first and last touches of shared memory resources
in a backend, or close enough anyway. This choice means there is no
coverage for auxiliary processes, but I doubt we need that, since they
shouldn't be executing any user-provided code anyway.
This patch also improves the management of the EXEC_BACKEND
ShmemBackendArray array a bit, by reducing search costs.
Although this problem is of long standing, the lack of field complaints
seems to mean it's not critical enough to risk back-patching; at least
not till we get some more testing of this mechanism.
Diffstat (limited to 'src/include/miscadmin.h')
-rw-r--r-- | src/include/miscadmin.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/src/include/miscadmin.h b/src/include/miscadmin.h index 57ee0f93dd4..51649380d51 100644 --- a/src/include/miscadmin.h +++ b/src/include/miscadmin.h @@ -13,7 +13,7 @@ * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $PostgreSQL: pgsql/src/include/miscadmin.h,v 1.209 2009/01/05 02:27:45 alvherre Exp $ + * $PostgreSQL: pgsql/src/include/miscadmin.h,v 1.210 2009/05/05 19:59:00 tgl Exp $ * * NOTES * some of the information in this file should be moved to other files. @@ -137,6 +137,7 @@ extern PGDLLIMPORT int MyProcPid; extern PGDLLIMPORT pg_time_t MyStartTime; extern PGDLLIMPORT struct Port *MyProcPort; extern long MyCancelKey; +extern int MyPMChildSlot; extern char OutputFileName[]; extern PGDLLIMPORT char my_exec_path[]; |