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Commit8f5d65e

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Treat a WAL sender process that hasn't started streaming yet as a regular
backend, as far as the postmaster shutdown logic is concerned. That means,fast shutdown will wait for WAL sender processes to exit before signalingbgwriter to finish. This avoids race conditions between a base backup stoppingor starting, and bgwriter writing the shutdown checkpoint WAL record. We don'twant e.g the end-of-backup WAL record to be written after the shutdowncheckpoint.
1 parentfcd810c commit8f5d65e

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3 files changed

+32
-2
lines changed

3 files changed

+32
-2
lines changed

‎src/backend/replication/walsender.c

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Original file line numberDiff line numberDiff line change
@@ -315,6 +315,16 @@ StartReplication(StartReplicationCmd * cmd)
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{
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StringInfoDatabuf;
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/*
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* Let postmaster know that we're streaming. Once we've declared us as
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* a WAL sender process, postmaster will let us outlive the bgwriter and
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* kill us last in the shutdown sequence, so we get a chance to stream
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* all remaining WAL at shutdown, including the shutdown checkpoint.
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* Note that there's no going back, and we mustn't write any WAL records
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* after this.
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*/
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MarkPostmasterChildWalSender();
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/*
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* Check that we're logging enough information in the WAL for
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* log-shipping.

‎src/backend/storage/ipc/pmsignal.c

Lines changed: 21 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -49,6 +49,8 @@
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*
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* Actually there is a fourth state, WALSENDER. This is just like ACTIVE,
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* but carries the extra information that the child is a WAL sender.
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* WAL senders too start in ACTIVE state, but switch to WALSENDER once they
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* start streaming the WAL (and they never go back to ACTIVE after that).
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*/
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#definePM_CHILD_UNUSED0/* these values must fit in sig_atomic_t */
@@ -225,8 +227,25 @@ MarkPostmasterChildActive(void)
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Assert(slot>0&&slot <=PMSignalState->num_child_flags);
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slot--;
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Assert(PMSignalState->PMChildFlags[slot]==PM_CHILD_ASSIGNED);
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PMSignalState->PMChildFlags[slot]=
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(am_walsender ?PM_CHILD_WALSENDER :PM_CHILD_ACTIVE);
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PMSignalState->PMChildFlags[slot]=PM_CHILD_ACTIVE;
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}
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/*
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* MarkPostmasterChildWalSender - mark a postmaster child as a WAL sender
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* process. This is called in the child process, sometime after marking the
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* child as active.
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*/
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void
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MarkPostmasterChildWalSender(void)
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{
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intslot=MyPMChildSlot;
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Assert(am_walsender);
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Assert(slot>0&&slot <=PMSignalState->num_child_flags);
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slot--;
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Assert(PMSignalState->PMChildFlags[slot]==PM_CHILD_ACTIVE);
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PMSignalState->PMChildFlags[slot]=PM_CHILD_WALSENDER;
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}
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/*

‎src/include/storage/pmsignal.h

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Original file line numberDiff line numberDiff line change
@@ -48,6 +48,7 @@ extern bool ReleasePostmasterChildSlot(int slot);
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externboolIsPostmasterChildWalSender(intslot);
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externvoidMarkPostmasterChildActive(void);
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externvoidMarkPostmasterChildInactive(void);
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externvoidMarkPostmasterChildWalSender(void);
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externboolPostmasterIsAlive(boolamDirectChild);
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#endif/* PMSIGNAL_H */

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