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/*-------------------------------------------------------------------------
* auxprocess.c
* functions related to auxiliary processes.
*
*
* Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* src/backend/postmaster/auxprocess.c
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <unistd.h>
#include <signal.h>
#include "miscadmin.h"
#include "pgstat.h"
#include "postmaster/auxprocess.h"
#include "storage/condition_variable.h"
#include "storage/ipc.h"
#include "storage/proc.h"
#include "storage/procsignal.h"
#include "utils/memutils.h"
#include "utils/ps_status.h"
static void ShutdownAuxiliaryProcess(int code, Datum arg);
/*
* AuxiliaryProcessMainCommon
*
* Common initialization code for auxiliary processes, such as the bgwriter,
* walwriter, walreceiver, and the startup process.
*/
void
AuxiliaryProcessMainCommon(void)
{
Assert(IsUnderPostmaster);
/* Release postmaster's working memory context */
if (PostmasterContext)
{
MemoryContextDelete(PostmasterContext);
PostmasterContext = NULL;
}
init_ps_display(NULL);
Assert(GetProcessingMode() == InitProcessing);
IgnoreSystemIndexes = true;
/*
* As an auxiliary process, we aren't going to do the full InitPostgres
* pushups, but there are a couple of things that need to get lit up even
* in an auxiliary process.
*/
/*
* Create a PGPROC so we can use LWLocks and access shared memory.
*/
InitAuxiliaryProcess();
BaseInit();
ProcSignalInit(false, 0);
/*
* Auxiliary processes don't run transactions, but they may need a
* resource owner anyway to manage buffer pins acquired outside
* transactions (and, perhaps, other things in future).
*/
CreateAuxProcessResourceOwner();
/* Initialize backend status information */
pgstat_beinit();
pgstat_bestart();
/* register a before-shutdown callback for LWLock cleanup */
before_shmem_exit(ShutdownAuxiliaryProcess, 0);
SetProcessingMode(NormalProcessing);
}
/*
* Begin shutdown of an auxiliary process. This is approximately the equivalent
* of ShutdownPostgres() in postinit.c. We can't run transactions in an
* auxiliary process, so most of the work of AbortTransaction() is not needed,
* but we do need to make sure we've released any LWLocks we are holding.
* (This is only critical during an error exit.)
*/
static void
ShutdownAuxiliaryProcess(int code, Datum arg)
{
LWLockReleaseAll();
ConditionVariableCancelSleep();
pgstat_report_wait_end();
}
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