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15910b1c36
Previously, on standby promotion, the startup process sent SIGUSR1 to the slotsync worker (or a backend performing slot synchronization) and waited for it to exit. This worked in most cases, but if the process was blocked waiting for a response from the primary (e.g., due to a network failure), SIGUSR1 would not interrupt the wait. As a result, the process could remain stuck, causing the startup process to wait for a long time and delaying promotion. This commit fixes the issue by introducing a new procsignal reason, PROCSIG_SLOTSYNC_MESSAGE. On promotion, the startup process sends this signal, and the handler sets interrupt flags so the process exits (or errors out) promptly at CHECK_FOR_INTERRUPTS(), allowing promotion to complete without delay. Backpatch to v17, where slotsync was introduced. Author: Nisha Moond <nisha.moond412@gmail.com> Reviewed-by: shveta malik <shveta.malik@gmail.com> Reviewed-by: Amit Kapila <amit.kapila16@gmail.com> Reviewed-by: Zhijie Hou <houzj.fnst@fujitsu.com> Reviewed-by: Fujii Masao <masao.fujii@gmail.com> Discussion: https://postgr.es/m/CAHGQGwFzNYroAxSoyJhqTU-pH=t4Ej6RyvhVmBZ91Exj_TPMMQ@mail.gmail.com Backpatch-through: 17
76 lines
2.6 KiB
C
76 lines
2.6 KiB
C
/*-------------------------------------------------------------------------
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*
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* procsignal.h
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* Routines for interprocess signaling
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*
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*
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* Portions Copyright (c) 1996-2024, 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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* src/include/storage/procsignal.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef PROCSIGNAL_H
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#define PROCSIGNAL_H
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#include "storage/procnumber.h"
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/*
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* Reasons for signaling a Postgres child process (a backend or an auxiliary
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* process, like checkpointer). We can cope with concurrent signals for different
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* reasons. However, if the same reason is signaled multiple times in quick
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* succession, the process is likely to observe only one notification of it.
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* This is okay for the present uses.
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*
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* Also, because of race conditions, it's important that all the signals be
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* defined so that no harm is done if a process mistakenly receives one.
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*/
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typedef enum
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{
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PROCSIG_CATCHUP_INTERRUPT, /* sinval catchup interrupt */
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PROCSIG_NOTIFY_INTERRUPT, /* listen/notify interrupt */
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PROCSIG_PARALLEL_MESSAGE, /* message from cooperating parallel backend */
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PROCSIG_WALSND_INIT_STOPPING, /* ask walsenders to prepare for shutdown */
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PROCSIG_BARRIER, /* global barrier interrupt */
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PROCSIG_LOG_MEMORY_CONTEXT, /* ask backend to log the memory contexts */
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PROCSIG_PARALLEL_APPLY_MESSAGE, /* Message from parallel apply workers */
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PROCSIG_SLOTSYNC_MESSAGE, /* ask slot synchronization to stop */
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/* Recovery conflict reasons */
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PROCSIG_RECOVERY_CONFLICT_FIRST,
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PROCSIG_RECOVERY_CONFLICT_DATABASE = PROCSIG_RECOVERY_CONFLICT_FIRST,
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PROCSIG_RECOVERY_CONFLICT_TABLESPACE,
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PROCSIG_RECOVERY_CONFLICT_LOCK,
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PROCSIG_RECOVERY_CONFLICT_SNAPSHOT,
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PROCSIG_RECOVERY_CONFLICT_LOGICALSLOT,
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PROCSIG_RECOVERY_CONFLICT_BUFFERPIN,
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PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK,
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PROCSIG_RECOVERY_CONFLICT_LAST = PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK,
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NUM_PROCSIGNALS /* Must be last! */
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} ProcSignalReason;
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typedef enum
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{
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PROCSIGNAL_BARRIER_SMGRRELEASE, /* ask smgr to close files */
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} ProcSignalBarrierType;
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/*
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* prototypes for functions in procsignal.c
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*/
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extern Size ProcSignalShmemSize(void);
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extern void ProcSignalShmemInit(void);
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extern void ProcSignalInit(void);
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extern int SendProcSignal(pid_t pid, ProcSignalReason reason,
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ProcNumber procNumber);
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extern uint64 EmitProcSignalBarrier(ProcSignalBarrierType type);
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extern void WaitForProcSignalBarrier(uint64 generation);
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extern void ProcessProcSignalBarrier(void);
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extern void procsignal_sigusr1_handler(SIGNAL_ARGS);
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#endif /* PROCSIGNAL_H */
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