On Tue, Nov 22, 2022 at 03:03:52AM +0000, Hayato Kuroda (Fujitsu) wrote:
> Just One comment: IIUC the statement "ALTER SUBSCRIPTION" can be executed
> inside the transaction. So if two subscriptions are altered in the same
> transaction, only one of them will awake. Is it expected behavior?
>
> I think we can hold a suboid list and record oids when the subscription are
> altered, and then the backend process can consume all of list cells at the
> end of
> the transaction.
I think you are correct. I did it this way in v2. I've also moved the
bulk of the logic to logical/worker.c.
--
Nathan Bossart
Amazon Web Services: https://aws.amazon.com
>From 57bbd9e8d9da72c50d9a41704f3f42b37aba33ab Mon Sep 17 00:00:00 2001
From: Nathan Bossart <nathandboss...@gmail.com>
Date: Mon, 21 Nov 2022 16:01:01 -0800
Subject: [PATCH v2 1/1] wake up logical workers after ALTER SUBSCRIPTION
---
src/backend/access/transam/xact.c | 3 ++
src/backend/commands/subscriptioncmds.c | 3 ++
src/backend/replication/logical/worker.c | 46 ++++++++++++++++++++++++
src/include/replication/logicalworker.h | 3 ++
4 files changed, 55 insertions(+)
diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 8086b857b9..dc00e66cfb 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -47,6 +47,7 @@
#include "pgstat.h"
#include "replication/logical.h"
#include "replication/logicallauncher.h"
+#include "replication/logicalworker.h"
#include "replication/origin.h"
#include "replication/snapbuild.h"
#include "replication/syncrep.h"
@@ -2360,6 +2361,7 @@ CommitTransaction(void)
AtEOXact_PgStat(true, is_parallel_worker);
AtEOXact_Snapshot(true, false);
AtEOXact_ApplyLauncher(true);
+ AtEOXact_LogicalRepWorkers(true);
pgstat_report_xact_timestamp(0);
CurrentResourceOwner = NULL;
@@ -2860,6 +2862,7 @@ AbortTransaction(void)
AtEOXact_HashTables(false);
AtEOXact_PgStat(false, is_parallel_worker);
AtEOXact_ApplyLauncher(false);
+ AtEOXact_LogicalRepWorkers(false);
pgstat_report_xact_timestamp(0);
}
diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index d673557ea4..9f225008c4 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -34,6 +34,7 @@
#include "nodes/makefuncs.h"
#include "pgstat.h"
#include "replication/logicallauncher.h"
+#include "replication/logicalworker.h"
#include "replication/origin.h"
#include "replication/slot.h"
#include "replication/walreceiver.h"
@@ -1031,6 +1032,8 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
form = (Form_pg_subscription) GETSTRUCT(tup);
subid = form->oid;
+ LogicalRepWorkersWakeupAtCommit(subid);
+
/* must be owner */
if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
diff --git a/src/backend/replication/logical/worker.c b/src/backend/replication/logical/worker.c
index e48a3f589a..f61cce7abf 100644
--- a/src/backend/replication/logical/worker.c
+++ b/src/backend/replication/logical/worker.c
@@ -253,6 +253,8 @@ WalReceiverConn *LogRepWorkerWalRcvConn = NULL;
Subscription *MySubscription = NULL;
static bool MySubscriptionValid = false;
+static List *on_commit_wakeup_workers_subids = NIL;
+
bool in_remote_transaction = false;
static XLogRecPtr remote_final_lsn = InvalidXLogRecPtr;
@@ -4092,3 +4094,47 @@ reset_apply_error_context_info(void)
apply_error_callback_arg.remote_attnum = -1;
set_apply_error_context_xact(InvalidTransactionId, InvalidXLogRecPtr);
}
+
+/*
+ * Wakeup the stored subscriptions' workers on commit if requested.
+ */
+void
+AtEOXact_LogicalRepWorkers(bool isCommit)
+{
+ if (isCommit && on_commit_wakeup_workers_subids != NIL)
+ {
+ ListCell *subid;
+
+ LWLockAcquire(LogicalRepWorkerLock, LW_SHARED);
+ foreach(subid, on_commit_wakeup_workers_subids)
+ {
+ List *workers;
+ ListCell *worker;
+
+ workers = logicalrep_workers_find(lfirst_oid(subid), true);
+ foreach(worker, workers)
+ logicalrep_worker_wakeup_ptr((LogicalRepWorker *) lfirst(worker));
+ }
+ LWLockRelease(LogicalRepWorkerLock);
+ }
+
+ on_commit_wakeup_workers_subids = NIL;
+}
+
+/*
+ * Request wakeup of the workers for the given subscription ID on commit of the
+ * transaction.
+ *
+ * This is used to ensure that the workers reread the subscription info as soon
+ * as possible.
+ */
+void
+LogicalRepWorkersWakeupAtCommit(Oid subid)
+{
+ MemoryContext oldcxt;
+
+ oldcxt = MemoryContextSwitchTo(TopTransactionContext);
+ on_commit_wakeup_workers_subids = lappend_oid(on_commit_wakeup_workers_subids,
+ subid);
+ MemoryContextSwitchTo(oldcxt);
+}
diff --git a/src/include/replication/logicalworker.h b/src/include/replication/logicalworker.h
index cd1b6e8afc..2c2340d758 100644
--- a/src/include/replication/logicalworker.h
+++ b/src/include/replication/logicalworker.h
@@ -16,4 +16,7 @@ extern void ApplyWorkerMain(Datum main_arg);
extern bool IsLogicalWorker(void);
+extern void LogicalRepWorkersWakeupAtCommit(Oid subid);
+extern void AtEOXact_LogicalRepWorkers(bool isCommit);
+
#endif /* LOGICALWORKER_H */
--
2.25.1
