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969d7cd431
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.
51 lines
1.4 KiB
C
51 lines
1.4 KiB
C
/*-------------------------------------------------------------------------
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*
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* postmaster.h
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* Exports from postmaster/postmaster.c.
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*
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* Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $PostgreSQL: pgsql/src/include/postmaster/postmaster.h,v 1.20 2009/05/05 19:59:00 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef _POSTMASTER_H
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#define _POSTMASTER_H
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/* GUC options */
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extern bool EnableSSL;
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extern bool SilentMode;
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extern int ReservedBackends;
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extern int PostPortNumber;
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extern int Unix_socket_permissions;
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extern char *Unix_socket_group;
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extern char *UnixSocketDir;
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extern char *ListenAddresses;
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extern bool ClientAuthInProgress;
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extern int PreAuthDelay;
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extern int AuthenticationTimeout;
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extern bool Log_connections;
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extern bool log_hostname;
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extern char *bonjour_name;
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#ifdef WIN32
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extern HANDLE PostmasterHandle;
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#endif
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extern const char *progname;
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extern int PostmasterMain(int argc, char *argv[]);
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extern void ClosePostmasterPorts(bool am_syslogger);
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extern int MaxLivePostmasterChildren(void);
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#ifdef EXEC_BACKEND
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extern pid_t postmaster_forkexec(int argc, char *argv[]);
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extern int SubPostmasterMain(int argc, char *argv[]);
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extern Size ShmemBackendArraySize(void);
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extern void ShmemBackendArrayAllocation(void);
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#endif
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#endif /* _POSTMASTER_H */
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