8000 PublishStartupProcessInformation() to avoid rare hang in recovery. · jaylevitt/postgres@7c24bac · GitHub
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simonat2ndQuadrantsimonat2ndQuadrant
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PublishStartupProcessInformation() to avoid rare hang in recovery.
Bgwriter could cause hang in recovery during page concurrent cleaning. Bug report and testing by Bernd Helmle, fix by me
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3 files changed

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3 files changed

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lines changed

‎src/backend/access/transam/xlog.c

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@@ -44,6 +44,7 @@
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#include "storage/fd.h"
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#include "storage/ipc.h"
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#include "storage/pmsignal.h"
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#include "storage/proc.h"
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#include "storage/procarray.h"
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#include "storage/smgr.h"
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#include "storage/spin.h"
@@ -5569,6 +5570,7 @@ StartupXLOG(void)
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*/
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if (InArchiveRecovery && IsUnderPostmaster)
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{
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PublishStartupProcessInformation();
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SetForwardFsyncRequests();
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SendPostmasterSignal(PMSIGNAL_RECOVERY_STARTED);
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bgwriterLaunched = true;

‎src/backend/storage/lmgr/proc.c

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@@ -1287,12 +1287,53 @@ ProcWaitForSignal(void)
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void
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ProcSendSignal(int pid)
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{
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PGPROC *proc = BackendPidGetProc(pid);
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PGPROC *proc = NULL;
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proc = BackendPidGetProc(pid);
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if (proc == NULL)
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{
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/* use volatile pointer to prevent code rearrangement */
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volatile PROC_HDR *procglobal = ProcGlobal;
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SpinLockAcquire(ProcStructLock);
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/*
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* Check to see whether it is the Startup process we wish to signal.
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* This call is made by the buffer manager when it wishes to wake up a
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* process that has been waiting for a pin in so it can obtain a
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* cleanup lock using LockBufferForCleanup(). Startup is not a normal
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* backend, so BackendPidGetProc() will not return any pid at all. So
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* we remember the information for this special case.
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*/
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if (pid == procglobal->startupProcPid)
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proc = procglobal->startupProc;
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SpinLockRelease(ProcStructLock);
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}
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if (proc != NULL)
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PGSemaphoreUnlock(&proc->sem);
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}
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/*
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* Record the PID and PGPROC structures for the Startup process, for use in
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* ProcSendSignal(). See comments there for further explanation.
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*/
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void
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PublishStartupProcessInformation(void)
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{
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/* use volatile pointer to prevent code rearrangement */
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volatile PROC_HDR *procglobal = ProcGlobal;
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SpinLockAcquire(ProcStructLock);
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procglobal->startupProc = MyProc;
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procglobal->startupProcPid = MyProcPid;
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SpinLockRelease(ProcStructLock);
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}
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/*****************************************************************************
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* SIGALRM interrupt support

‎src/include/storage/proc.h

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@@ -133,6 +133,11 @@ typedef struct PROC_HDR
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PGPROC *autovacFreeProcs;
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/* Current shared estimate of appropriate spins_per_delay value */
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int spins_per_delay;
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/* PGPROC of Startup process */
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PGPROC *startupProc;
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/* Pid of Startup process */
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int startupProcPid;
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} PROC_HDR;
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/*
@@ -175,6 +180,7 @@ extern void LockWaitCancel(void);
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extern void ProcWaitForSignal(void);
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extern void ProcSendSignal(int pid);
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extern void PublishStartupProcessInformation(void);
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extern bool enable_sig_alarm(int delayms, bool is_statement_timeout);
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extern bool disable_sig_alarm(bool is_statement_timeout);

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