v30-0002-Add-inactive_timeout-based-replication-slot-inva.patch

From 64bb4f8396595dae62ee07726dfacadb6e87f119 Mon Sep 17 00:00:00 2001
From: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Date: Sun, 31 Mar 2024 04:40:42 +0000
Subject: [PATCH v30 2/2] Add inactive_timeout based replication slot
 invalidation.

Till now, postgres has the ability to invalidate inactive
replication slots based on the amount of WAL (set via
max_slot_wal_keep_size GUC) that will be needed for the slots in
case they become active. However, choosing a default value for
max_slot_wal_keep_size is tricky. Because the amount of WAL a
customer generates, and their allocated storage will vary greatly
in production, making it difficult to pin down a one-size-fits-all
value. It is often easy for developers to set a timeout of say 1
or 2 or 3 days at slot level, after which the inactive slots get
dropped.

To achieve the above, postgres introduces a GUC allowing users
set inactive timeout and then a slot stays inactive for this much
amount of time it invalidates the slot. The invalidation check
happens at various locations to help being as latest as possible,
these locations include the following:
- Whenever the slot is acquired and the slot acquisition errors
out if invalidated.
- During checkpoint
Note that this new invalidation mechanism won't kick-in for the
slots that are currently being synced from the primary to the
standby.

Author: Bharath Rupireddy
Reviewed-by: Bertrand Drouvot, Amit Kapila, Shveta Malik
Discussion: https://www.postgresql.org/message-id/CALj2ACW4aUe-_uFQOjdWCEN-xXoLGhmvRFnL8SNw_TZ5nJe+aw@mail.gmail.com
---
 doc/src/sgml/config.sgml                      |  25 ++
 doc/src/sgml/system-views.sgml                |   7 +
 .../replication/logical/logicalfuncs.c        |   2 +-
 src/backend/replication/logical/slotsync.c    |   4 +-
 src/backend/replication/slot.c                | 196 +++++++++++-
 src/backend/replication/slotfuncs.c           |   2 +-
 src/backend/replication/walsender.c           |   4 +-
 src/backend/utils/adt/pg_upgrade_support.c    |   2 +-
 src/backend/utils/misc/guc_tables.c           |  12 +
 src/backend/utils/misc/postgresql.conf.sample |   1 +
 src/include/replication/slot.h                |   8 +-
 src/test/recovery/meson.build                 |   1 +
 src/test/recovery/t/050_invalidate_slots.pl   | 278 ++++++++++++++++++
 13 files changed, 518 insertions(+), 24 deletions(-)
 create mode 100644 src/test/recovery/t/050_invalidate_slots.pl

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index f65c17e5ae..126b461bb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4545,6 +4545,31 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"'  # Windows
       </listitem>
      </varlistentry>
 
+     <varlistentry id="guc-replication-slot-inactive-timeout" xreflabel="replication_slot_inactive_timeout">
+      <term><varname>replication_slot_inactive_timeout</varname> (<type>integer</type>)
+      <indexterm>
+       <primary><varname>replication_slot_inactive_timeout</varname> configuration parameter</primary>
+      </indexterm>
+      </term>
+      <listitem>
+       <para>
+        Invalidates replication slots that are inactive for longer the
+        specified amount of time. If this value is specified without units,
+        it is taken as seconds. A value of zero (which is default) disables
+        the timeout mechanism. This parameter can only be set in the
+        <filename>postgresql.conf</filename> file or on the server
+        command line.
+       </para>
+
+       <para>
+        The timeout is measured from the time since the slot has become
+        inactive (known from its
+        <structfield>inactive_since</structfield> value) until it gets
+        used (i.e., its <structfield>active</structfield> is set to true).
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry id="guc-track-commit-timestamp" xreflabel="track_commit_timestamp">
       <term><varname>track_commit_timestamp</varname> (<type>boolean</type>)
       <indexterm>
diff --git a/doc/src/sgml/system-views.sgml b/doc/src/sgml/system-views.sgml
index c8d97ab375..5c05fd1c07 100644
--- a/doc/src/sgml/system-views.sgml
+++ b/doc/src/sgml/system-views.sgml
@@ -2582,6 +2582,13 @@ SELECT * FROM pg_locks pl LEFT JOIN pg_prepared_xacts ppx
           perform logical decoding.  It is set only for logical slots.
          </para>
         </listitem>
+        <listitem>
+         <para>
+          <literal>inactive_timeout</literal> means that the slot has been
+          inactive for the duration specified by
+          <xref linkend="guc-replication-slot-inactive-timeout"/> parameter.
+         </para>
+        </listitem>
        </itemizedlist>
       </para></entry>
      </row>
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index b4dd5cce75..56fc1a45a9 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -197,7 +197,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
 	else
 		end_of_wal = GetXLogReplayRecPtr(NULL);
 
-	ReplicationSlotAcquire(NameStr(*name), true);
+	ReplicationSlotAcquire(NameStr(*name), true, true);
 
 	PG_TRY();
 	{
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 9c95a4b062..71b6a254cf 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -321,7 +321,7 @@ drop_local_obsolete_slots(List *remote_slot_list)
 
 			if (synced_slot)
 			{
-				ReplicationSlotAcquire(NameStr(local_slot->data.name), true);
+				ReplicationSlotAcquire(NameStr(local_slot->data.name), true, false);
 				ReplicationSlotDropAcquired();
 			}
 
@@ -531,7 +531,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid)
 		 * InvalidatePossiblyObsoleteSlot() where it invalidates slot directly
 		 * if the slot is not acquired by other processes.
 		 */
-		ReplicationSlotAcquire(remote_slot->name, true);
+		ReplicationSlotAcquire(remote_slot->name, true, false);
 
 		Assert(slot == MyReplicationSlot);
 
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 7dbb44b7b0..7182d89b58 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -108,10 +108,11 @@ const char *const SlotInvalidationCauses[] = {
 	[RS_INVAL_WAL_REMOVED] = "wal_removed",
 	[RS_INVAL_HORIZON] = "rows_removed",
 	[RS_INVAL_WAL_LEVEL] = "wal_level_insufficient",
+	[RS_INVAL_INACTIVE_TIMEOUT] = "inactive_timeout",
 };
 
 /* Maximum number of invalidation causes */
-#define	RS_INVAL_MAX_CAUSES RS_INVAL_WAL_LEVEL
+#define	RS_INVAL_MAX_CAUSES RS_INVAL_INACTIVE_TIMEOUT
 
 StaticAssertDecl(lengthof(SlotInvalidationCauses) == (RS_INVAL_MAX_CAUSES + 1),
 				 "array length mismatch");
@@ -141,6 +142,7 @@ ReplicationSlot *MyReplicationSlot = NULL;
 /* GUC variables */
 int			max_replication_slots = 10; /* the maximum number of replication
 										 * slots */
+int			replication_slot_inactive_timeout = 0;
 
 /*
  * This GUC lists streaming replication standby server slot names that
@@ -159,6 +161,7 @@ static XLogRecPtr ss_oldest_flush_lsn = InvalidXLogRecPtr;
 
 static void ReplicationSlotShmemExit(int code, Datum arg);
 static void ReplicationSlotDropPtr(ReplicationSlot *slot);
+static bool InvalidateSlotForInactiveTimeout(ReplicationSlot *slot);
 
 /* internal persistency functions */
 static void RestoreSlotFromDisk(const char *name);
@@ -536,9 +539,14 @@ ReplicationSlotName(int index, Name name)
  *
  * An error is raised if nowait is true and the slot is currently in use. If
  * nowait is false, we sleep until the slot is released by the owning process.
+ *
+ * If check_for_timeout_invalidation is true, the slot is checked for
+ * invalidation based on replication_slot_inactive_timeout GUC, and an error is
+ * raised after making the slot ours.
  */
 void
-ReplicationSlotAcquire(const char *name, bool nowait)
+ReplicationSlotAcquire(const char *name, bool nowait,
+					   bool check_for_timeout_invalidation)
 {
 	ReplicationSlot *s;
 	int			active_pid;
@@ -616,6 +624,34 @@ retry:
 	/* We made this slot active, so it's ours now. */
 	MyReplicationSlot = s;
 
+	/*
+	 * Check if the given slot can be invalidated based on its inactive
+	 * timeout. If yes, persist the invalidated state to disk and then error
+	 * out. We do this only after making the slot ours to avoid anyone else
+	 * acquiring it while we check for its invalidation.
+	 */
+	if (check_for_timeout_invalidation)
+	{
+		/* The slot is ours by now */
+		Assert(s->active_pid == MyProcPid);
+
+		if (InvalidateReplicationSlotForInactiveTimeout(s, true))
+		{
+			/*
+			 * If the slot has been invalidated, recalculate the resource
+			 * limits.
+			 */
+			ReplicationSlotsComputeRequiredXmin(false);
+			ReplicationSlotsComputeRequiredLSN();
+
+			ereport(ERROR,
+					(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+					 errmsg("can no longer get changes from replication slot \"%s\"",
+							NameStr(MyReplicationSlot->data.name)),
+					 errdetail("This slot has been invalidated because it was inactive for more than the time specified by replication_slot_inactive_timeout parameter.")));
+		}
+	}
+
 	/*
 	 * The call to pgstat_acquire_replslot() protects against stats for a
 	 * different slot, from before a restart or such, being present during
@@ -790,7 +826,7 @@ ReplicationSlotDrop(const char *name, bool nowait)
 {
 	Assert(MyReplicationSlot == NULL);
 
-	ReplicationSlotAcquire(name, nowait);
+	ReplicationSlotAcquire(name, nowait, false);
 
 	/*
 	 * Do not allow users to drop the slots which are currently being synced
@@ -813,7 +849,7 @@ ReplicationSlotAlter(const char *name, bool failover)
 {
 	Assert(MyReplicationSlot == NULL);
 
-	ReplicationSlotAcquire(name, false);
+	ReplicationSlotAcquire(name, false, true);
 
 	if (SlotIsPhysical(MyReplicationSlot))
 		ereport(ERROR,
@@ -989,6 +1025,20 @@ ReplicationSlotDropPtr(ReplicationSlot *slot)
 	LWLockRelease(ReplicationSlotAllocationLock);
 }
 
+/*
+ * Helper for ReplicationSlotSave
+ */
+static inline void
+SaveGivenReplicationSlot(ReplicationSlot *slot, int elevel)
+{
+	char		path[MAXPGPATH];
+
+	Assert(slot != NULL);
+
+	sprintf(path, "pg_replslot/%s", NameStr(slot->data.name));
+	SaveSlotToPath(slot, path, elevel);
+}
+
 /*
  * Serialize the currently acquired slot's state from memory to disk, thereby
  * guaranteeing the current state will survive a crash.
@@ -996,12 +1046,21 @@ ReplicationSlotDropPtr(ReplicationSlot *slot)
 void
 ReplicationSlotSave(void)
 {
-	char		path[MAXPGPATH];
+	SaveGivenReplicationSlot(MyReplicationSlot, ERROR);
+}
 
-	Assert(MyReplicationSlot != NULL);
+/*
+ * Helper for ReplicationSlotMarkDirty
+ */
+static inline void
+MarkGivenReplicationSlotDirty(ReplicationSlot *slot)
+{
+	Assert(slot != NULL);
 
-	sprintf(path, "pg_replslot/%s", NameStr(MyReplicationSlot->data.name));
-	SaveSlotToPath(MyReplicationSlot, path, ERROR);
+	SpinLockAcquire(&slot->mutex);
+	slot->just_dirtied = true;
+	slot->dirty = true;
+	SpinLockRelease(&slot->mutex);
 }
 
 /*
@@ -1014,14 +1073,7 @@ ReplicationSlotSave(void)
 void
 ReplicationSlotMarkDirty(void)
 {
-	ReplicationSlot *slot = MyReplicationSlot;
-
-	Assert(MyReplicationSlot != NULL);
-
-	SpinLockAcquire(&slot->mutex);
-	MyReplicationSlot->just_dirtied = true;
-	MyReplicationSlot->dirty = true;
-	SpinLockRelease(&slot->mutex);
+	MarkGivenReplicationSlotDirty(MyReplicationSlot);
 }
 
 /*
@@ -1515,6 +1567,9 @@ ReportSlotInvalidation(ReplicationSlotInvalidationCause cause,
 		case RS_INVAL_WAL_LEVEL:
 			appendStringInfoString(&err_detail, _("Logical decoding on standby requires wal_level >= logical on the primary server."));
 			break;
+		case RS_INVAL_INACTIVE_TIMEOUT:
+			appendStringInfoString(&err_detail, _("The slot has been inactive for more than the time specified by replication_slot_inactive_timeout parameter."));
+			break;
 		case RS_INVAL_NONE:
 			pg_unreachable();
 	}
@@ -1559,6 +1614,13 @@ InvalidatePossiblyObsoleteSlot(ReplicationSlotInvalidationCause cause,
 	XLogRecPtr	initial_restart_lsn = InvalidXLogRecPtr;
 	ReplicationSlotInvalidationCause invalidation_cause_prev PG_USED_FOR_ASSERTS_ONLY = RS_INVAL_NONE;
 
+	/*
+	 * This function isn't expected to be called for inactive timeout based
+	 * invalidation. A separate function
+	 * InvalidateReplicationSlotForInactiveTimeout is to be used for that.
+	 */
+	Assert(cause != RS_INVAL_INACTIVE_TIMEOUT);
+
 	for (;;)
 	{
 		XLogRecPtr	restart_lsn;
@@ -1628,6 +1690,10 @@ InvalidatePossiblyObsoleteSlot(ReplicationSlotInvalidationCause cause,
 					if (SlotIsLogical(s))
 						invalidation_cause = cause;
 					break;
+				case RS_INVAL_INACTIVE_TIMEOUT:
+					/* not reachable */
+					Assert(false);
+					break;
 				case RS_INVAL_NONE:
 					pg_unreachable();
 			}
@@ -1781,6 +1847,7 @@ InvalidatePossiblyObsoleteSlot(ReplicationSlotInvalidationCause cause,
  * - RS_INVAL_HORIZON: requires a snapshot <= the given horizon in the given
  *   db; dboid may be InvalidOid for shared relations
  * - RS_INVAL_WAL_LEVEL: is logical
+ * - RS_INVAL_INACTIVE_TIMEOUT: inactive slot timeout occurs
  *
  * NB - this runs as part of checkpoint, so avoid raising errors if possible.
  */
@@ -1796,6 +1863,13 @@ InvalidateObsoleteReplicationSlots(ReplicationSlotInvalidationCause cause,
 	Assert(cause != RS_INVAL_WAL_REMOVED || oldestSegno > 0);
 	Assert(cause != RS_INVAL_NONE);
 
+	/*
+	 * This function isn't expected to be called for inactive timeout based
+	 * invalidation. A separate function
+	 * InvalidateReplicationSlotForInactiveTimeout is to be used for that.
+	 */
+	Assert(cause != RS_INVAL_INACTIVE_TIMEOUT);
+
 	if (max_replication_slots == 0)
 		return invalidated;
 
@@ -1832,6 +1906,81 @@ restart:
 	return invalidated;
 }
 
+/*
+ * Invalidate given slot based on replication_slot_inactive_timeout GUC.
+ *
+ * Returns true if the slot has got invalidated.
+ *
+ * NB - this function also runs as part of checkpoint, so avoid raising errors
+ * if possible.
+ */
+bool
+InvalidateReplicationSlotForInactiveTimeout(ReplicationSlot *slot,
+											bool persist_state)
+{
+	if (!InvalidateSlotForInactiveTimeout(slot))
+		return false;
+
+	/* Make sure the invalidated state persists across server restart */
+	MarkGivenReplicationSlotDirty(slot);
+
+	if (persist_state)
+		SaveGivenReplicationSlot(slot, ERROR);
+
+	ReportSlotInvalidation(RS_INVAL_INACTIVE_TIMEOUT, false, 0,
+						   slot->data.name, InvalidXLogRecPtr,
+						   InvalidXLogRecPtr, InvalidTransactionId);
+
+	return true;
+}
+
+/*
+ * Helper for InvalidateReplicationSlotForInactiveTimeout
+ */
+static bool
+InvalidateSlotForInactiveTimeout(ReplicationSlot *slot)
+{
+	ReplicationSlotInvalidationCause inavidation_cause = RS_INVAL_NONE;
+
+	if (replication_slot_inactive_timeout == 0)
+		return false;
+	else if (slot->inactive_since > 0)
+	{
+		TimestampTz now;
+
+		/*
+		 * Do not invalidate the slots which are currently being synced from
+		 * the primary to the standby.
+		 */
+		if (RecoveryInProgress() && slot->data.synced)
+			return false;
+
+		LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
+		SpinLockAcquire(&slot->mutex);
+
+		/*
+		 * Check if the slot needs to be invalidated due to
+		 * replication_slot_inactive_timeout GUC. We do this with the spinlock
+		 * held to avoid race conditions -- for example the inactive_since
+		 * could change, or the slot could be dropped.
+		 */
+		now = GetCurrentTimestamp();
+		if (TimestampDifferenceExceeds(slot->inactive_since, now,
+									   replication_slot_inactive_timeout * 1000))
+		{
+			inavidation_cause = RS_INVAL_INACTIVE_TIMEOUT;
+			slot->data.invalidated = RS_INVAL_INACTIVE_TIMEOUT;
+		}
+
+		SpinLockRelease(&slot->mutex);
+		LWLockRelease(ReplicationSlotControlLock);
+
+		return (inavidation_cause == RS_INVAL_INACTIVE_TIMEOUT);
+	}
+
+	return false;
+}
+
 /*
  * Flush all replication slots to disk.
  *
@@ -1844,6 +1993,7 @@ void
 CheckPointReplicationSlots(bool is_shutdown)
 {
 	int			i;
+	bool		invalidated = false;
 
 	elog(DEBUG1, "performing replication slot checkpoint");
 
@@ -1867,6 +2017,13 @@ CheckPointReplicationSlots(bool is_shutdown)
 		/* save the slot to disk, locking is handled in SaveSlotToPath() */
 		sprintf(path, "pg_replslot/%s", NameStr(s->data.name));
 
+		/*
+		 * Here's an opportunity to invalidate inactive replication slots
+		 * based on timeout, so let's do it.
+		 */
+		if (InvalidateReplicationSlotForInactiveTimeout(s, false))
+			invalidated = true;
+
 		/*
 		 * Slot's data is not flushed each time the confirmed_flush LSN is
 		 * updated as that could lead to frequent writes.  However, we decide
@@ -1893,6 +2050,13 @@ CheckPointReplicationSlots(bool is_shutdown)
 		SaveSlotToPath(s, path, LOG);
 	}
 	LWLockRelease(ReplicationSlotAllocationLock);
+
+	/* If the slot has been invalidated, recalculate the resource limits */
+	if (invalidated)
+	{
+		ReplicationSlotsComputeRequiredXmin(false);
+		ReplicationSlotsComputeRequiredLSN();
+	}
 }
 
 /*
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index da57177c25..677c0bf0a2 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -651,7 +651,7 @@ pg_replication_slot_advance(PG_FUNCTION_ARGS)
 		moveto = Min(moveto, GetXLogReplayRecPtr(NULL));
 
 	/* Acquire the slot so we "own" it */
-	ReplicationSlotAcquire(NameStr(*slotname), true);
+	ReplicationSlotAcquire(NameStr(*slotname), true, true);
 
 	/* A slot whose restart_lsn has never been reserved cannot be advanced */
 	if (XLogRecPtrIsInvalid(MyReplicationSlot->data.restart_lsn))
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index bc40c454de..96eeb8b7d2 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -846,7 +846,7 @@ StartReplication(StartReplicationCmd *cmd)
 
 	if (cmd->slotname)
 	{
-		ReplicationSlotAcquire(cmd->slotname, true);
+		ReplicationSlotAcquire(cmd->slotname, true, true);
 		if (SlotIsLogical(MyReplicationSlot))
 			ereport(ERROR,
 					(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
@@ -1459,7 +1459,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
 
 	Assert(!MyReplicationSlot);
 
-	ReplicationSlotAcquire(cmd->slotname, true);
+	ReplicationSlotAcquire(cmd->slotname, true, true);
 
 	/*
 	 * Force a disconnect, so that the decoding code doesn't need to care
diff --git a/src/backend/utils/adt/pg_upgrade_support.c b/src/backend/utils/adt/pg_upgrade_support.c
index c54b08fe18..82956d58d3 100644
--- a/src/backend/utils/adt/pg_upgrade_support.c
+++ b/src/backend/utils/adt/pg_upgrade_support.c
@@ -299,7 +299,7 @@ binary_upgrade_logical_slot_has_caught_up(PG_FUNCTION_ARGS)
 	slot_name = PG_GETARG_NAME(0);
 
 	/* Acquire the given slot */
-	ReplicationSlotAcquire(NameStr(*slot_name), true);
+	ReplicationSlotAcquire(NameStr(*slot_name), true, false);
 
 	Assert(SlotIsLogical(MyReplicationSlot));
 
diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c
index 92fcd5fa4d..c63f76505f 100644
--- a/src/backend/utils/misc/guc_tables.c
+++ b/src/backend/utils/misc/guc_tables.c
@@ -2971,6 +2971,18 @@ struct config_int ConfigureNamesInt[] =
 		NULL, NULL, NULL
 	},
 
+	{
+		{"replication_slot_inactive_timeout", PGC_SIGHUP, REPLICATION_SENDING,
+			gettext_noop("Sets the amount of time to wait before invalidating an "
+						 "inactive replication slot."),
+			NULL,
+			GUC_UNIT_S
+		},
+		&replication_slot_inactive_timeout,
+		0, 0, INT_MAX,
+		NULL, NULL, NULL
+	},
+
 	{
 		{"commit_delay", PGC_SUSET, WAL_SETTINGS,
 			gettext_noop("Sets the delay in microseconds between transaction commit and "
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index adcc0257f9..18dd57e589 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -334,6 +334,7 @@
 #wal_sender_timeout = 60s	# in milliseconds; 0 disables
 #track_commit_timestamp = off	# collect timestamp of transaction commit
 				# (change requires restart)
+#replication_slot_inactive_timeout = 0	# in seconds; 0 disables
 
 # - Primary Server -
 
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 7b937d1a0c..8f5e602745 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -53,6 +53,8 @@ typedef enum ReplicationSlotInvalidationCause
 	RS_INVAL_HORIZON,
 	/* wal_level insufficient for slot */
 	RS_INVAL_WAL_LEVEL,
+	/* inactive slot timeout has occurred */
+	RS_INVAL_INACTIVE_TIMEOUT,
 } ReplicationSlotInvalidationCause;
 
 extern PGDLLIMPORT const char *const SlotInvalidationCauses[];
@@ -230,6 +232,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
 /* GUCs */
 extern PGDLLIMPORT int max_replication_slots;
 extern PGDLLIMPORT char *standby_slot_names;
+extern PGDLLIMPORT int replication_slot_inactive_timeout;
 
 /* shmem initialization functions */
 extern Size ReplicationSlotsShmemSize(void);
@@ -245,7 +248,8 @@ extern void ReplicationSlotDrop(const char *name, bool nowait);
 extern void ReplicationSlotDropAcquired(void);
 extern void ReplicationSlotAlter(const char *name, bool failover);
 
-extern void ReplicationSlotAcquire(const char *name, bool nowait);
+extern void ReplicationSlotAcquire(const char *name, bool nowait,
+								   bool check_for_timeout_invalidation);
 extern void ReplicationSlotRelease(void);
 extern void ReplicationSlotCleanup(void);
 extern void ReplicationSlotSave(void);
@@ -264,6 +268,8 @@ extern bool InvalidateObsoleteReplicationSlots(ReplicationSlotInvalidationCause
 											   XLogSegNo oldestSegno,
 											   Oid dboid,
 											   TransactionId snapshotConflictHorizon);
+extern bool InvalidateReplicationSlotForInactiveTimeout(ReplicationSlot *slot,
+														bool persist_state);
 extern ReplicationSlot *SearchNamedReplicationSlot(const char *name, bool need_lock);
 extern int	ReplicationSlotIndex(ReplicationSlot *slot);
 extern bool ReplicationSlotName(int index, Name name);
diff --git a/src/test/recovery/meson.build b/src/test/recovery/meson.build
index b1eb77b1ec..708a2a3798 100644
--- a/src/test/recovery/meson.build
+++ b/src/test/recovery/meson.build
@@ -51,6 +51,7 @@ tests += {
       't/040_standby_failover_slots_sync.pl',
       't/041_checkpoint_at_promote.pl',
       't/042_low_level_backup.pl',
+      't/050_invalidate_slots.pl',
     ],
   },
 }
diff --git a/src/test/recovery/t/050_invalidate_slots.pl b/src/test/recovery/t/050_invalidate_slots.pl
new file mode 100644
index 0000000000..8e919915f1
--- /dev/null
+++ b/src/test/recovery/t/050_invalidate_slots.pl
@@ -0,0 +1,278 @@
+# Copyright (c) 2024, PostgreSQL Global Development Group
+
+# Test for replication slots invalidation
+use strict;
+use warnings FATAL => 'all';
+
+use PostgreSQL::Test::Utils;
+use PostgreSQL::Test::Cluster;
+use Test::More;
+use Time::HiRes qw(usleep);
+
+# =============================================================================
+# Testcase start: Invalidate streaming standby's slot as well as logical
+# failover slot on primary due to inactive timeout GUC. Also, check the logical
+# failover slot synced on to the standby doesn't invalidate the slot on its own,
+# but gets the invalidated state from the remote slot on the primary.
+
+# Initialize primary node
+my $primary = PostgreSQL::Test::Cluster->new('primary');
+$primary->init(allows_streaming => 'logical');
+
+# Avoid checkpoint during the test, otherwise, the test can get unpredictable
+$primary->append_conf(
+	'postgresql.conf', q{
+checkpoint_timeout = 1h
+autovacuum = off
+});
+$primary->start;
+
+# Take backup
+my $backup_name = 'my_backup';
+$primary->backup($backup_name);
+
+# Create a standby linking to the primary using the replication slot
+my $standby1 = PostgreSQL::Test::Cluster->new('standby1');
+$standby1->init_from_backup($primary, $backup_name, has_streaming => 1);
+
+my $connstr_1 = $primary->connstr;
+$standby1->append_conf(
+	'postgresql.conf', qq(
+hot_standby_feedback = on
+primary_slot_name = 'sb1_slot'
+primary_conninfo = '$connstr_1 dbname=postgres'
+));
+
+# Create sync slot on the primary
+$primary->psql('postgres',
+	q{SELECT pg_create_logical_replication_slot('lsub1_sync_slot', 'test_decoding', false, false, true);}
+);
+
+$primary->safe_psql(
+	'postgres', qq[
+    SELECT pg_create_physical_replication_slot(slot_name := 'sb1_slot');
+]);
+
+$standby1->start;
+
+my $standby1_logstart = -s $standby1->logfile;
+
+# Wait until standby has replayed enough data
+$primary->wait_for_catchup($standby1);
+
+# Synchronize the primary server slots to the standby.
+$standby1->safe_psql('postgres', "SELECT pg_sync_replication_slots();");
+
+# Confirm that the logical failover slot is created on the standby and is
+# flagged as 'synced'.
+is( $standby1->safe_psql(
+		'postgres',
+		q{SELECT count(*) = 1 FROM pg_replication_slots
+		  WHERE slot_name = 'lsub1_sync_slot' AND synced AND NOT temporary;}
+	),
+	"t",
+	'logical slot has synced as true on standby');
+
+my $logstart = -s $primary->logfile;
+
+# Set timeout so that the next checkpoint will invalidate the inactive
+# replication slot.
+$primary->safe_psql(
+	'postgres', qq[
+    ALTER SYSTEM SET replication_slot_inactive_timeout TO '2s';
+]);
+$primary->reload;
+
+# Wait for the logical failover slot to become inactive on the primary. Note
+# that nobody has acquired that slot yet, so due to inactive timeout setting
+# above it must get invalidated.
+wait_for_slot_invalidation($primary, 'lsub1_sync_slot', $logstart);
+
+# Set timeout on the standby also to check the synced slots don't get
+# invalidated due to timeout on the standby.
+$standby1->safe_psql(
+	'postgres', qq[
+    ALTER SYSTEM SET replication_slot_inactive_timeout TO '2s';
+]);
+$standby1->reload;
+
+# Now, sync the logical failover slot from the remote slot on the primary.
+# Note that the remote slot has already been invalidated due to inactive
+# timeout. Now, the standby must also see it as invalidated.
+$standby1->safe_psql('postgres', "SELECT pg_sync_replication_slots();");
+
+# Wait for the inactive replication slot to be invalidated.
+$standby1->poll_query_until(
+	'postgres', qq[
+	SELECT COUNT(slot_name) = 1 FROM pg_replication_slots
+		WHERE slot_name = 'lsub1_sync_slot' AND
+		invalidation_reason = 'inactive_timeout';
+])
+  or die
+  "Timed out while waiting for replication slot lsub1_sync_slot invalidation to be synced on standby";
+
+# Synced slot mustn't get invalidated on the standby, it must sync invalidation
+# from the primary. So, we must not see the slot's invalidation message in server
+# log.
+ok( !$standby1->log_contains(
+		"invalidating obsolete replication slot \"lsub1_sync_slot\"",
+		$standby1_logstart),
+	'check that syned slot has not been invalidated on the standby');
+
+# Stop standby to make the standby's replication slot on the primary inactive
+$standby1->stop;
+
+# Wait for the standby's replication slot to become inactive
+wait_for_slot_invalidation($primary, 'sb1_slot', $logstart);
+
+# Testcase end: Invalidate streaming standby's slot as well as logical failover
+# slot on primary due to inactive timeout GUC. Also, check the logical failover
+# slot synced on to the standby doesn't invalidate the slot on its own, but
+# gets the invalidated state from the remote slot on the primary.
+# =============================================================================
+
+# =============================================================================
+# Testcase start: Invalidate logical subscriber's slot due to inactive timeout
+# GUC.
+
+my $publisher = $primary;
+
+# Prepare for the next test
+$publisher->safe_psql(
+	'postgres', qq[
+    ALTER SYSTEM SET replication_slot_inactive_timeout TO '0';
+]);
+$publisher->reload;
+
+# Create subscriber node
+my $subscriber = PostgreSQL::Test::Cluster->new('sub');
+$subscriber->init;
+$subscriber->start;
+
+# Create tables
+$publisher->safe_psql('postgres', "CREATE TABLE test_tbl (id int)");
+$subscriber->safe_psql('postgres', "CREATE TABLE test_tbl (id int)");
+
+# Insert some data
+$subscriber->safe_psql('postgres',
+	"INSERT INTO test_tbl VALUES (generate_series(1, 5));");
+
+# Setup logical replication
+my $publisher_connstr = $publisher->connstr . ' dbname=postgres';
+$publisher->safe_psql('postgres', "CREATE PUBLICATION pub FOR ALL TABLES");
+$publisher->safe_psql(
+	'postgres', qq[
+    SELECT pg_create_logical_replication_slot(slot_name := 'lsub1_slot', plugin := 'pgoutput');
+]);
+
+$subscriber->safe_psql('postgres',
+	"CREATE SUBSCRIPTION sub CONNECTION '$publisher_connstr' PUBLICATION pub WITH (slot_name = 'lsub1_slot', create_slot = false)"
+);
+
+$subscriber->wait_for_subscription_sync($publisher, 'sub');
+
+my $result =
+  $subscriber->safe_psql('postgres', "SELECT count(*) FROM test_tbl");
+
+is($result, qq(5), "check initial copy was done");
+
+# Prepare for the next test
+$publisher->safe_psql(
+	'postgres', qq[
+    ALTER SYSTEM SET replication_slot_inactive_timeout TO '2s';
+]);
+$publisher->reload;
+
+$logstart = -s $publisher->logfile;
+
+# Stop subscriber to make the replication slot on publisher inactive
+$subscriber->stop;
+
+# Wait for the replication slot to become inactive and then invalidated due to
+# timeout.
+wait_for_slot_invalidation($publisher, 'lsub1_slot', $logstart);
+
+# Testcase end: Invalidate logical subscriber's slot due to inactive timeout
+# GUC.
+# =============================================================================
+
+# =============================================================================
+# Start: Helper functions used for this test file
+
+sub wait_for_slot_invalidation
+{
+	my ($node, $slot_name, $offset) = @_;
+	my $name = $node->name;
+
+	# Wait for the replication slot to become inactive
+	$node->poll_query_until(
+		'postgres', qq[
+		SELECT COUNT(slot_name) = 1 FROM pg_replication_slots
+			WHERE slot_name = '$slot_name' AND active = 'f';
+	])
+	  or die
+	  "Timed out while waiting for replication slot to become inactive";
+
+	# Wait for the replication slot info to be updated
+	$node->poll_query_until(
+		'postgres', qq[
+		SELECT COUNT(slot_name) = 1 FROM pg_replication_slots
+			WHERE inactive_since IS NOT NULL
+				AND slot_name = '$slot_name' AND active = 'f';
+	])
+	  or die
+	  "Timed out while waiting for info of replication slot $slot_name to be updated on node $name";
+
+	check_for_slot_invalidation_in_server_log($node, $slot_name, $offset);
+
+	# Wait for the inactive replication slot to be invalidated.
+	$node->poll_query_until(
+		'postgres', qq[
+		SELECT COUNT(slot_name) = 1 FROM pg_replication_slots
+			WHERE slot_name = '$slot_name' AND
+			invalidation_reason = 'inactive_timeout';
+	])
+	  or die
+	  "Timed out while waiting for inactive replication slot $slot_name to be invalidated on node $name";
+
+	# Check that the invalidated slot cannot be acquired
+	my ($result, $stdout, $stderr);
+
+	($result, $stdout, $stderr) = $primary->psql(
+		'postgres', qq[
+			SELECT pg_replication_slot_advance('$slot_name', '0/1');
+	]);
+
+	ok( $stderr =~ /can no longer get changes from replication slot "$slot_name"/,
+		"detected error upon trying to acquire invalidated slot $slot_name on node $name"
+	  )
+	  or die
+	  "could not detect error upon trying to acquire invalidated slot $slot_name";
+}
+
+# Check for invalidation of slot in server log.
+sub check_for_slot_invalidation_in_server_log
+{
+	my ($node, $slot_name, $offset) = @_;
+	my $invalidated = 0;
+
+	for (my $i = 0; $i < 10 * $PostgreSQL::Test::Utils::timeout_default; $i++)
+	{
+		$node->safe_psql('postgres', "CHECKPOINT");
+		if ($node->log_contains(
+				"invalidating obsolete replication slot \"$slot_name\"",
+				$offset))
+		{
+			$invalidated = 1;
+			last;
+		}
+		usleep(100_000);
+	}
+	ok($invalidated,
+		"check that slot $slot_name invalidation has been logged");
+}
+
+# =============================================================================
+# End: Helper functions used for this test file
+
+done_testing();
-- 
2.34.1