On Thu, Jan 2, 2025 at 8:16 AM Peter Smith <smithpb2...@gmail.com> wrote:
>
> Hi Nisha,
>
> Here are some minor review comments for patch v58-0002.
>
Thank you for your feedback! Please find the v59 patch set addressing
all the comments.
Note: There are no new changes in patch-0001.
--
Thanks,
Nisha
From 8154e2baee6fcf348524899c1f8b643a1e3564fc Mon Sep 17 00:00:00 2001
From: Nisha Moond <nisha.moond412@gmail.com>
Date: Mon, 18 Nov 2024 16:13:26 +0530
Subject: [PATCH v59 1/2] Enhance replication slot error handling, slot
invalidation, and inactive_since setting logic
In ReplicationSlotAcquire(), raise an error for invalid slots if the
caller specifies error_if_invalid=true.
Add check if the slot is already acquired, then mark it invalidated directly.
Ensure same inactive_since time for all slots in update_synced_slots_inactive_since()
and RestoreSlotFromDisk().
---
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 13 ++--
src/backend/replication/slot.c | 69 ++++++++++++++++---
src/backend/replication/slotfuncs.c | 2 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/adt/pg_upgrade_support.c | 2 +-
src/include/replication/slot.h | 3 +-
src/test/recovery/t/019_replslot_limit.pl | 2 +-
8 files changed, 75 insertions(+), 22 deletions(-)
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 0148ec3678..ca53caac2f 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 f6945af1d4..692527b984 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -446,7 +446,7 @@ 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();
}
@@ -665,7 +665,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid)
* pre-check to ensure that at least one of the slot properties is
* changed before acquiring the slot.
*/
- ReplicationSlotAcquire(remote_slot->name, true);
+ ReplicationSlotAcquire(remote_slot->name, true, false);
Assert(slot == MyReplicationSlot);
@@ -1508,7 +1508,7 @@ ReplSlotSyncWorkerMain(char *startup_data, size_t startup_data_len)
static void
update_synced_slots_inactive_since(void)
{
- TimestampTz now = 0;
+ TimestampTz now;
/*
* We need to update inactive_since only when we are promoting standby to
@@ -1523,6 +1523,9 @@ update_synced_slots_inactive_since(void)
/* The slot sync worker or SQL function mustn't be running by now */
Assert((SlotSyncCtx->pid == InvalidPid) && !SlotSyncCtx->syncing);
+ /* Use same inactive_since time for all slots */
+ now = GetCurrentTimestamp();
+
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
for (int i = 0; i < max_replication_slots; i++)
@@ -1537,10 +1540,6 @@ update_synced_slots_inactive_since(void)
/* The slot must not be acquired by any process */
Assert(s->active_pid == 0);
- /* Use the same inactive_since time for all the slots. */
- if (now == 0)
- now = GetCurrentTimestamp();
-
SpinLockAcquire(&s->mutex);
s->inactive_since = now;
SpinLockRelease(&s->mutex);
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index b30e0473e1..47e474a548 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -163,6 +163,7 @@ static void ReplicationSlotDropPtr(ReplicationSlot *slot);
static void RestoreSlotFromDisk(const char *name);
static void CreateSlotOnDisk(ReplicationSlot *slot);
static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
+static void RaiseSlotInvalidationError(ReplicationSlot *slot);
/*
* Report shared-memory space needed by ReplicationSlotsShmemInit.
@@ -535,9 +536,12 @@ 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.
+ *
+ * An error is raised if error_if_invalid is true and the slot is found to
+ * be invalid.
*/
void
-ReplicationSlotAcquire(const char *name, bool nowait)
+ReplicationSlotAcquire(const char *name, bool nowait, bool error_if_invalid)
{
ReplicationSlot *s;
int active_pid;
@@ -615,6 +619,13 @@ retry:
/* We made this slot active, so it's ours now. */
MyReplicationSlot = s;
+ /*
+ * An error is raised if error_if_invalid is true and the slot is found to
+ * be invalid.
+ */
+ if (error_if_invalid && s->data.invalidated != RS_INVAL_NONE)
+ RaiseSlotInvalidationError(s);
+
/*
* The call to pgstat_acquire_replslot() protects against stats for a
* different slot, from before a restart or such, being present during
@@ -785,7 +796,7 @@ 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
@@ -812,7 +823,7 @@ ReplicationSlotAlter(const char *name, const bool *failover,
Assert(MyReplicationSlot == NULL);
Assert(failover || two_phase);
- ReplicationSlotAcquire(name, false);
+ ReplicationSlotAcquire(name, false, false);
if (SlotIsPhysical(MyReplicationSlot))
ereport(ERROR,
@@ -1676,11 +1687,12 @@ InvalidatePossiblyObsoleteSlot(ReplicationSlotInvalidationCause cause,
active_pid = s->active_pid;
/*
- * If the slot can be acquired, do so and mark it invalidated
- * immediately. Otherwise we'll signal the owning process, below, and
- * retry.
+ * If the slot can be acquired, do so and mark it as invalidated. If
+ * the slot is already ours, mark it as invalidated. Otherwise, we'll
+ * signal the owning process below and retry.
*/
- if (active_pid == 0)
+ if (active_pid == 0 ||
+ (MyReplicationSlot == s && active_pid == MyProcPid))
{
MyReplicationSlot = s;
s->active_pid = MyProcPid;
@@ -2208,6 +2220,7 @@ RestoreSlotFromDisk(const char *name)
bool restored = false;
int readBytes;
pg_crc32c checksum;
+ TimestampTz now;
/* no need to lock here, no concurrent access allowed yet */
@@ -2368,6 +2381,9 @@ RestoreSlotFromDisk(const char *name)
NameStr(cp.slotdata.name)),
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
+ /* Use same inactive_since time for all slots */
+ now = GetCurrentTimestamp();
+
/* nothing can be active yet, don't lock anything */
for (i = 0; i < max_replication_slots; i++)
{
@@ -2400,7 +2416,7 @@ RestoreSlotFromDisk(const char *name)
* slot from the disk into memory. Whoever acquires the slot i.e.
* makes the slot active will reset it.
*/
- slot->inactive_since = GetCurrentTimestamp();
+ slot->inactive_since = now;
restored = true;
break;
@@ -2793,3 +2809,40 @@ WaitForStandbyConfirmation(XLogRecPtr wait_for_lsn)
ConditionVariableCancelSleep();
}
+
+/*
+ * Raise an error based on the slot's invalidation cause.
+ */
+static void
+RaiseSlotInvalidationError(ReplicationSlot *slot)
+{
+ StringInfo err_detail = makeStringInfo();
+
+ Assert(slot->data.invalidated != RS_INVAL_NONE);
+
+ switch (slot->data.invalidated)
+ {
+ case RS_INVAL_WAL_REMOVED:
+ appendStringInfoString(err_detail, _("This slot has been invalidated because the required WAL has been removed."));
+ break;
+
+ case RS_INVAL_HORIZON:
+ appendStringInfoString(err_detail, _("This slot has been invalidated because the required rows have been removed."));
+ break;
+
+ case RS_INVAL_WAL_LEVEL:
+ /* translator: %s is a GUC variable name */
+ appendStringInfo(err_detail, _("This slot has been invalidated because \"%s\" is insufficient for slot."),
+ "wal_level");
+ break;
+
+ case RS_INVAL_NONE:
+ pg_unreachable();
+ }
+
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("can no longer get changes from replication slot \"%s\"",
+ NameStr(slot->data.name)),
+ errdetail_internal("%s", err_detail->data));
+}
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 977146789f..8be4b8c65b 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -536,7 +536,7 @@ 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 a0782b1bbf..3df5bd7b2a 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -816,7 +816,7 @@ 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),
@@ -1434,7 +1434,7 @@ 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 9a10907d05..d44f8c262b 100644
--- a/src/backend/utils/adt/pg_upgrade_support.c
+++ b/src/backend/utils/adt/pg_upgrade_support.c
@@ -298,7 +298,7 @@ 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, true);
Assert(SlotIsLogical(MyReplicationSlot));
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index bf62b36ad0..47ebdaecb6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -253,7 +253,8 @@ extern void ReplicationSlotDropAcquired(void);
extern void ReplicationSlotAlter(const char *name, const bool *failover,
const bool *two_phase);
-extern void ReplicationSlotAcquire(const char *name, bool nowait);
+extern void ReplicationSlotAcquire(const char *name, bool nowait,
+ bool error_if_invalid);
extern void ReplicationSlotRelease(void);
extern void ReplicationSlotCleanup(bool synced_only);
extern void ReplicationSlotSave(void);
diff --git a/src/test/recovery/t/019_replslot_limit.pl b/src/test/recovery/t/019_replslot_limit.pl
index ae2ad5c933..66ac7c40f1 100644
--- a/src/test/recovery/t/019_replslot_limit.pl
+++ b/src/test/recovery/t/019_replslot_limit.pl
@@ -234,7 +234,7 @@ my $failed = 0;
for (my $i = 0; $i < 10 * $PostgreSQL::Test::Utils::timeout_default; $i++)
{
if ($node_standby->log_contains(
- "requested WAL segment [0-9A-F]+ has already been removed",
+ "This slot has been invalidated because the required WAL has been removed",
$logstart))
{
$failed = 1;
--
2.34.1
From a027fa8ac26973cc3adecb91a662002e0fe12765 Mon Sep 17 00:00:00 2001
From: Nisha Moond <nisha.moond412@gmail.com>
Date: Mon, 30 Dec 2024 14:57:24 +0530
Subject: [PATCH v59 2/2] Introduce 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
this GUC is a bit tricky. Because the amount of WAL a database
generates, and the allocated storage per instance will vary
greatly in production, making it difficult to pin down a
one-size-fits-all value.
It is often easy for users to set a timeout of say 1 or 2 or n
days, after which all the inactive slots get invalidated. This
commit introduces a GUC named idle_replication_slot_timeout.
When set, postgres invalidates slots (during non-shutdown
checkpoints) that are idle for longer than this amount of
time.
Note that the idle timeout invalidation mechanism is not
applicable for slots on the standby server that are being synced
from the primary server (i.e., standby slots having 'synced' field
'true'). Synced slots are always considered to be inactive because
they don't perform logical decoding to produce changes.
---
doc/src/sgml/config.sgml | 39 ++++
doc/src/sgml/logical-replication.sgml | 5 +
doc/src/sgml/regress.sgml | 10 +
doc/src/sgml/system-views.sgml | 10 +-
src/backend/replication/logical/slotsync.c | 4 +-
src/backend/replication/slot.c | 158 +++++++++++++--
src/backend/utils/adt/timestamp.c | 18 ++
src/backend/utils/misc/guc_tables.c | 14 ++
src/backend/utils/misc/postgresql.conf.sample | 1 +
src/bin/pg_basebackup/pg_createsubscriber.c | 4 +
src/bin/pg_upgrade/server.c | 7 +
src/include/replication/slot.h | 22 ++
src/include/utils/guc_hooks.h | 2 +
src/include/utils/timestamp.h | 3 +
src/test/recovery/README | 5 +
src/test/recovery/meson.build | 1 +
.../t/043_invalidate_inactive_slots.pl | 190 ++++++++++++++++++
17 files changed, 477 insertions(+), 16 deletions(-)
create mode 100644 src/test/recovery/t/043_invalidate_inactive_slots.pl
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fbdd6ce574..8953c8fd4b 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4593,6 +4593,45 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-idle-replication-slot-timeout" xreflabel="idle_replication_slot_timeout">
+ <term><varname>idle_replication_slot_timeout</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>idle_replication_slot_timeout</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Invalidate replication slots that have remained idle longer than this
+ duration. If this value is specified without units, it is taken as
+ minutes. A value of zero disables the idle timeout invalidation mechanism.
+ The default is 24 hours. This parameter can only be set in the
+ <filename>postgresql.conf</filename> file or on the server command line.
+ </para>
+
+ <para>
+ Slot invalidation due to idle timeout occurs during checkpoint.
+ Because checkpoints happen at <varname>checkpoint_timeout</varname>
+ intervals, there can be some lag between when the
+ <varname>idle_replication_slot_timeout</varname> was exceeded and when
+ the slot invalidation is triggered at the next checkpoint.
+ To avoid such lags, users can force a checkpoint to promptly invalidate
+ inactive slots. The duration of slot inactivity is calculated using the slot's
+ <link linkend="view-pg-replication-slots">pg_replication_slots</link>.<structfield>inactive_since</structfield>
+ value.
+ </para>
+
+ <para>
+ Note that the idle timeout invalidation mechanism is not
+ applicable for slots on the standby server that are being synced
+ from the primary server (i.e., standby slots having
+ <link linkend="view-pg-replication-slots">pg_replication_slots</link>.<structfield>synced</structfield>
+ value <literal>true</literal>).
+ Synced slots are always considered to be inactive because they don't
+ perform logical decoding to produce changes.
+ </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/logical-replication.sgml b/doc/src/sgml/logical-replication.sgml
index 8290cd1a08..158ec18211 100644
--- a/doc/src/sgml/logical-replication.sgml
+++ b/doc/src/sgml/logical-replication.sgml
@@ -2163,6 +2163,11 @@ CONTEXT: processing remote data for replication origin "pg_16395" during "INSER
plus some reserve for table synchronization.
</para>
+ <para>
+ Logical replication slots are also affected by
+ <link linkend="guc-idle-replication-slot-timeout"><varname>idle_replication_slot_timeout</varname></link>.
+ </para>
+
<para>
<link linkend="guc-max-wal-senders"><varname>max_wal_senders</varname></link>
should be set to at least the same as
diff --git a/doc/src/sgml/regress.sgml b/doc/src/sgml/regress.sgml
index f4cef9e80f..f2387de6b5 100644
--- a/doc/src/sgml/regress.sgml
+++ b/doc/src/sgml/regress.sgml
@@ -336,6 +336,16 @@ make check-world PG_TEST_EXTRA='kerberos ldap ssl load_balance libpq_encryption'
</para>
</listitem>
</varlistentry>
+
+ <varlistentry>
+ <term><literal>idle_replication_slot_timeout</literal></term>
+ <listitem>
+ <para>
+ Runs the test <filename>src/test/recovery/t/043_invalidate_inactive_slots.pl</filename>.
+ Not enabled by default because it is time consuming.
+ </para>
+ </listitem>
+ </varlistentry>
</variablelist>
Tests for features that are not supported by the current build
diff --git a/doc/src/sgml/system-views.sgml b/doc/src/sgml/system-views.sgml
index a586156614..199d7248ee 100644
--- a/doc/src/sgml/system-views.sgml
+++ b/doc/src/sgml/system-views.sgml
@@ -2566,7 +2566,8 @@ SELECT * FROM pg_locks pl LEFT JOIN pg_prepared_xacts ppx
</para>
<para>
The time when the slot became inactive. <literal>NULL</literal> if the
- slot is currently being streamed.
+ slot is currently being streamed. If the slot becomes invalidated,
+ this value will remain unchanged until server shutdown.
Note that for slots on the standby that are being synced from a
primary server (whose <structfield>synced</structfield> field is
<literal>true</literal>), the <structfield>inactive_since</structfield>
@@ -2620,6 +2621,13 @@ 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>idle_timeout</literal> means that the slot has remained
+ idle longer than the configured
+ <xref linkend="guc-idle-replication-slot-timeout"/> duration.
+ </para>
+ </listitem>
</itemizedlist>
</para></entry>
</row>
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 692527b984..7df6892824 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -1540,9 +1540,7 @@ update_synced_slots_inactive_since(void)
/* The slot must not be acquired by any process */
Assert(s->active_pid == 0);
- SpinLockAcquire(&s->mutex);
- s->inactive_since = now;
- SpinLockRelease(&s->mutex);
+ ReplicationSlotSetInactiveSince(s, now, true);
}
}
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 47e474a548..2eec51478f 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -107,10 +107,11 @@ const char *const SlotInvalidationCauses[] = {
[RS_INVAL_WAL_REMOVED] = "wal_removed",
[RS_INVAL_HORIZON] = "rows_removed",
[RS_INVAL_WAL_LEVEL] = "wal_level_insufficient",
+ [RS_INVAL_IDLE_TIMEOUT] = "idle_timeout",
};
/* Maximum number of invalidation causes */
-#define RS_INVAL_MAX_CAUSES RS_INVAL_WAL_LEVEL
+#define RS_INVAL_MAX_CAUSES RS_INVAL_IDLE_TIMEOUT
StaticAssertDecl(lengthof(SlotInvalidationCauses) == (RS_INVAL_MAX_CAUSES + 1),
"array length mismatch");
@@ -141,6 +142,12 @@ ReplicationSlot *MyReplicationSlot = NULL;
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+/*
+ * Invalidate replication slots that have remained idle longer than this
+ * duration; '0' disables it.
+ */
+int idle_replication_slot_timeout_mins = HOURS_PER_DAY * MINS_PER_HOUR;
+
/*
* This GUC lists streaming replication standby server slot names that
* logical WAL sender processes will wait for.
@@ -714,16 +721,12 @@ ReplicationSlotRelease(void)
*/
SpinLockAcquire(&slot->mutex);
slot->active_pid = 0;
- slot->inactive_since = now;
+ ReplicationSlotSetInactiveSince(slot, now, false);
SpinLockRelease(&slot->mutex);
ConditionVariableBroadcast(&slot->active_cv);
}
else
- {
- SpinLockAcquire(&slot->mutex);
- slot->inactive_since = now;
- SpinLockRelease(&slot->mutex);
- }
+ ReplicationSlotSetInactiveSince(slot, now, true);
MyReplicationSlot = NULL;
@@ -1519,7 +1522,8 @@ ReportSlotInvalidation(ReplicationSlotInvalidationCause cause,
NameData slotname,
XLogRecPtr restart_lsn,
XLogRecPtr oldestLSN,
- TransactionId snapshotConflictHorizon)
+ TransactionId snapshotConflictHorizon,
+ TimestampTz inactive_since)
{
StringInfoData err_detail;
bool hint = false;
@@ -1549,6 +1553,16 @@ 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_IDLE_TIMEOUT:
+ Assert(inactive_since > 0);
+ /* translator: second %s is a GUC variable name */
+ appendStringInfo(&err_detail,
+ _("The slot has remained idle since %s, which is longer than the configured \"%s\" duration."),
+ timestamptz_to_str(inactive_since),
+ "idle_replication_slot_timeout");
+ break;
+
case RS_INVAL_NONE:
pg_unreachable();
}
@@ -1565,6 +1579,30 @@ ReportSlotInvalidation(ReplicationSlotInvalidationCause cause,
pfree(err_detail.data);
}
+/*
+ * Can we invalidate an idle replication slot?
+ *
+ * Idle timeout invalidation is allowed only when:
+ *
+ * 1. Idle timeout is set
+ * 2. Slot is inactive
+ * 3. The slot is not being synced from the primary while the server
+ * is in recovery
+ *
+ * Note that the idle timeout invalidation mechanism is not
+ * applicable for slots on the standby server that are being synced
+ * from the primary server (i.e., standby slots having 'synced' field 'true').
+ * Synced slots are always considered to be inactive because they don't
+ * perform logical decoding to produce changes.
+ */
+static inline bool
+CanInvalidateIdleSlot(ReplicationSlot *s)
+{
+ return (idle_replication_slot_timeout_mins > 0 &&
+ s->inactive_since > 0 &&
+ !(RecoveryInProgress() && s->data.synced));
+}
+
/*
* Helper for InvalidateObsoleteReplicationSlots
*
@@ -1592,6 +1630,7 @@ InvalidatePossiblyObsoleteSlot(ReplicationSlotInvalidationCause cause,
TransactionId initial_catalog_effective_xmin = InvalidTransactionId;
XLogRecPtr initial_restart_lsn = InvalidXLogRecPtr;
ReplicationSlotInvalidationCause invalidation_cause_prev PG_USED_FOR_ASSERTS_ONLY = RS_INVAL_NONE;
+ TimestampTz inactive_since = 0;
for (;;)
{
@@ -1599,6 +1638,7 @@ InvalidatePossiblyObsoleteSlot(ReplicationSlotInvalidationCause cause,
NameData slotname;
int active_pid = 0;
ReplicationSlotInvalidationCause invalidation_cause = RS_INVAL_NONE;
+ TimestampTz now = 0;
Assert(LWLockHeldByMeInMode(ReplicationSlotControlLock, LW_SHARED));
@@ -1609,6 +1649,15 @@ InvalidatePossiblyObsoleteSlot(ReplicationSlotInvalidationCause cause,
break;
}
+ if (cause == RS_INVAL_IDLE_TIMEOUT)
+ {
+ /*
+ * We get the current time beforehand to avoid system call while
+ * holding the spinlock.
+ */
+ now = GetCurrentTimestamp();
+ }
+
/*
* Check if the slot needs to be invalidated. If it needs to be
* invalidated, and is not currently acquired, acquire it and mark it
@@ -1662,6 +1711,21 @@ InvalidatePossiblyObsoleteSlot(ReplicationSlotInvalidationCause cause,
if (SlotIsLogical(s))
invalidation_cause = cause;
break;
+ case RS_INVAL_IDLE_TIMEOUT:
+ Assert(now > 0);
+
+ /*
+ * Check if the slot needs to be invalidated due to
+ * idle_replication_slot_timeout GUC.
+ */
+ if (CanInvalidateIdleSlot(s) &&
+ TimestampDifferenceExceedsSeconds(s->inactive_since, now,
+ idle_replication_slot_timeout_mins * SECS_PER_MINUTE))
+ {
+ invalidation_cause = cause;
+ inactive_since = s->inactive_since;
+ }
+ break;
case RS_INVAL_NONE:
pg_unreachable();
}
@@ -1747,7 +1811,8 @@ InvalidatePossiblyObsoleteSlot(ReplicationSlotInvalidationCause cause,
{
ReportSlotInvalidation(invalidation_cause, true, active_pid,
slotname, restart_lsn,
- oldestLSN, snapshotConflictHorizon);
+ oldestLSN, snapshotConflictHorizon,
+ inactive_since);
if (MyBackendType == B_STARTUP)
(void) SendProcSignal(active_pid,
@@ -1793,7 +1858,8 @@ InvalidatePossiblyObsoleteSlot(ReplicationSlotInvalidationCause cause,
ReportSlotInvalidation(invalidation_cause, false, active_pid,
slotname, restart_lsn,
- oldestLSN, snapshotConflictHorizon);
+ oldestLSN, snapshotConflictHorizon,
+ inactive_since);
/* done with this slot for now */
break;
@@ -1816,6 +1882,7 @@ 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_IDLE_TIMEOUT: idle slot timeout has occurred
*
* NB - this runs as part of checkpoint, so avoid raising errors if possible.
*/
@@ -1868,7 +1935,8 @@ restart:
}
/*
- * Flush all replication slots to disk.
+ * Flush all replication slots to disk. Also, invalidate obsolete slots during
+ * non-shutdown checkpoint.
*
* It is convenient to flush dirty replication slots at the time of checkpoint.
* Additionally, in case of a shutdown checkpoint, we also identify the slots
@@ -1926,6 +1994,45 @@ CheckPointReplicationSlots(bool is_shutdown)
SaveSlotToPath(s, path, LOG);
}
LWLockRelease(ReplicationSlotAllocationLock);
+
+ if (!is_shutdown)
+ {
+ elog(DEBUG1, "performing replication slot invalidation checks");
+
+ /*
+ * NB: We will make another pass over replication slots for
+ * invalidation checks to keep the code simple. Testing shows that
+ * there is no noticeable overhead (when compared with wal_removed
+ * invalidation) even if we were to do idle_timeout invalidation of
+ * thousands of replication slots here. If it is ever proven that this
+ * assumption is wrong, we will have to perform the invalidation
+ * checks in the above for loop with the following changes:
+ *
+ * - Acquire ControlLock lock once before the loop.
+ *
+ * - Call InvalidatePossiblyObsoleteSlot for each slot.
+ *
+ * - Handle the cases in which ControlLock gets released just like
+ * InvalidateObsoleteReplicationSlots does.
+ *
+ * - Avoid saving slot info to disk two times for each invalidated
+ * slot.
+ *
+ * XXX: Should we move idle_timeout invalidation check closer to
+ * wal_removed in CreateCheckPoint and CreateRestartPoint?
+ *
+ * XXX: Slot invalidation due to 'idle_timeout' applies only to
+ * released slots, and is based on the 'idle_replication_slot_timeout'
+ * GUC. Active slots currently in use for replication are excluded to
+ * prevent accidental invalidation. Slots where communication between
+ * the publisher and subscriber is down are also excluded, as they are
+ * managed by the 'wal_sender_timeout'.
+ */
+ InvalidateObsoleteReplicationSlots(RS_INVAL_IDLE_TIMEOUT,
+ 0,
+ InvalidOid,
+ InvalidTransactionId);
+ }
}
/*
@@ -2414,7 +2521,9 @@ RestoreSlotFromDisk(const char *name)
/*
* Set the time since the slot has become inactive after loading the
* slot from the disk into memory. Whoever acquires the slot i.e.
- * makes the slot active will reset it.
+ * makes the slot active will reset it. Avoid calling
+ * ReplicationSlotSetInactiveSince() here, as it will not set the time
+ * for invalid slots.
*/
slot->inactive_since = now;
@@ -2836,6 +2945,12 @@ RaiseSlotInvalidationError(ReplicationSlot *slot)
"wal_level");
break;
+ case RS_INVAL_IDLE_TIMEOUT:
+ /* translator: %s is a GUC variable name */
+ appendStringInfo(err_detail, _("This slot has been invalidated because it has remained idle longer than the configured \"%s\" duration."),
+ "idle_replication_slot_timeout");
+ break;
+
case RS_INVAL_NONE:
pg_unreachable();
}
@@ -2846,3 +2961,22 @@ RaiseSlotInvalidationError(ReplicationSlot *slot)
NameStr(slot->data.name)),
errdetail_internal("%s", err_detail->data));
}
+
+/*
+ * GUC check_hook for idle_replication_slot_timeout
+ *
+ * The value of idle_replication_slot_timeout must be set to 0 during
+ * a binary upgrade. See start_postmaster() in pg_upgrade for more details.
+ */
+bool
+check_idle_replication_slot_timeout(int *newval, void **extra, GucSource source)
+{
+ if (IsBinaryUpgrade && *newval != 0)
+ {
+ GUC_check_errdetail("The value of \"%s\" must be set to 0 during binary upgrade mode.",
+ "idle_replication_slot_timeout");
+ return false;
+ }
+
+ return true;
+}
diff --git a/src/backend/utils/adt/timestamp.c b/src/backend/utils/adt/timestamp.c
index ba9bae0506..9682f9dbdc 100644
--- a/src/backend/utils/adt/timestamp.c
+++ b/src/backend/utils/adt/timestamp.c
@@ -1786,6 +1786,24 @@ TimestampDifferenceExceeds(TimestampTz start_time,
return (diff >= msec * INT64CONST(1000));
}
+/*
+ * Check if the difference between two timestamps is >= a given
+ * threshold (expressed in seconds).
+ */
+bool
+TimestampDifferenceExceedsSeconds(TimestampTz start_time,
+ TimestampTz stop_time,
+ int threshold_sec)
+{
+ long secs;
+ int usecs;
+
+ /* Calculate the difference in seconds */
+ TimestampDifference(start_time, stop_time, &secs, &usecs);
+
+ return (secs >= threshold_sec);
+}
+
/*
* Convert a time_t to TimestampTz.
*
diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c
index 22f16a3b46..ef8a0b5fce 100644
--- a/src/backend/utils/misc/guc_tables.c
+++ b/src/backend/utils/misc/guc_tables.c
@@ -3047,6 +3047,20 @@ struct config_int ConfigureNamesInt[] =
NULL, NULL, NULL
},
+ {
+ {"idle_replication_slot_timeout", PGC_SIGHUP, REPLICATION_SENDING,
+ gettext_noop("Sets the duration a replication slot can remain idle before "
+ "it is invalidated."),
+ NULL,
+ GUC_UNIT_MIN
+ },
+ &idle_replication_slot_timeout_mins,
+ HOURS_PER_DAY * MINS_PER_HOUR, /* 24 hours */
+ 0,
+ INT_MAX / SECS_PER_MINUTE,
+ check_idle_replication_slot_timeout, 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 a2ac7575ca..7284edfbc1 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -337,6 +337,7 @@
#wal_sender_timeout = 60s # in milliseconds; 0 disables
#track_commit_timestamp = off # collect timestamp of transaction commit
# (change requires restart)
+#idle_replication_slot_timeout = 24h # in minutes; 0 disables
# - Primary Server -
diff --git a/src/bin/pg_basebackup/pg_createsubscriber.c b/src/bin/pg_basebackup/pg_createsubscriber.c
index faf18ccf13..f2ef8d5ccc 100644
--- a/src/bin/pg_basebackup/pg_createsubscriber.c
+++ b/src/bin/pg_basebackup/pg_createsubscriber.c
@@ -1438,6 +1438,10 @@ start_standby_server(const struct CreateSubscriberOptions *opt, bool restricted_
appendPQExpBuffer(pg_ctl_cmd, "\"%s\" start -D ", pg_ctl_path);
appendShellString(pg_ctl_cmd, subscriber_dir);
appendPQExpBuffer(pg_ctl_cmd, " -s -o \"-c sync_replication_slots=off\"");
+
+ /* Prevent unintended slot invalidation */
+ appendPQExpBuffer(pg_ctl_cmd, " -o \"-c idle_replication_slot_timeout=0\"");
+
if (restricted_access)
{
appendPQExpBuffer(pg_ctl_cmd, " -o \"-p %s\"", opt->sub_port);
diff --git a/src/bin/pg_upgrade/server.c b/src/bin/pg_upgrade/server.c
index de6971cde6..873e5b5117 100644
--- a/src/bin/pg_upgrade/server.c
+++ b/src/bin/pg_upgrade/server.c
@@ -252,6 +252,13 @@ start_postmaster(ClusterInfo *cluster, bool report_and_exit_on_error)
if (GET_MAJOR_VERSION(cluster->major_version) >= 1700)
appendPQExpBufferStr(&pgoptions, " -c max_slot_wal_keep_size=-1");
+ /*
+ * Use idle_replication_slot_timeout=0 to prevent slot invalidation due to
+ * idle_timeout by checkpointer process during upgrade.
+ */
+ if (GET_MAJOR_VERSION(cluster->major_version) >= 1800)
+ appendPQExpBufferStr(&pgoptions, " -c idle_replication_slot_timeout=0");
+
/*
* Use -b to disable autovacuum and logical replication launcher
* (effective in PG17 or later for the latter).
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 47ebdaecb6..f3994ab000 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -56,6 +56,8 @@ typedef enum ReplicationSlotInvalidationCause
RS_INVAL_HORIZON,
/* wal_level insufficient for slot */
RS_INVAL_WAL_LEVEL,
+ /* idle slot timeout has occurred */
+ RS_INVAL_IDLE_TIMEOUT,
} ReplicationSlotInvalidationCause;
extern PGDLLIMPORT const char *const SlotInvalidationCauses[];
@@ -228,6 +230,25 @@ typedef struct ReplicationSlotCtlData
ReplicationSlot replication_slots[1];
} ReplicationSlotCtlData;
+/*
+ * Set slot's inactive_since property unless it was previously invalidated.
+ */
+static inline void
+ReplicationSlotSetInactiveSince(ReplicationSlot *s, TimestampTz now,
+ bool acquire_lock)
+{
+ if (s->data.invalidated != RS_INVAL_NONE)
+ return;
+
+ if (acquire_lock)
+ SpinLockAcquire(&s->mutex);
+
+ s->inactive_since = now;
+
+ if (acquire_lock)
+ SpinLockRelease(&s->mutex);
+}
+
/*
* Pointers to shared memory
*/
@@ -237,6 +258,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
+extern PGDLLIMPORT int idle_replication_slot_timeout_mins;
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
diff --git a/src/include/utils/guc_hooks.h b/src/include/utils/guc_hooks.h
index 87999218d6..951451a976 100644
--- a/src/include/utils/guc_hooks.h
+++ b/src/include/utils/guc_hooks.h
@@ -174,5 +174,7 @@ extern void assign_wal_sync_method(int new_wal_sync_method, void *extra);
extern bool check_synchronized_standby_slots(char **newval, void **extra,
GucSource source);
extern void assign_synchronized_standby_slots(const char *newval, void *extra);
+extern bool check_idle_replication_slot_timeout(int *newval, void **extra,
+ GucSource source);
#endif /* GUC_HOOKS_H */
diff --git a/src/include/utils/timestamp.h b/src/include/utils/timestamp.h
index d26f023fb8..e1d05d6779 100644
--- a/src/include/utils/timestamp.h
+++ b/src/include/utils/timestamp.h
@@ -143,5 +143,8 @@ extern int date2isoyear(int year, int mon, int mday);
extern int date2isoyearday(int year, int mon, int mday);
extern bool TimestampTimestampTzRequiresRewrite(void);
+extern bool TimestampDifferenceExceedsSeconds(TimestampTz start_time,
+ TimestampTz stop_time,
+ int threshold_sec);
#endif /* TIMESTAMP_H */
diff --git a/src/test/recovery/README b/src/test/recovery/README
index 896df0ad05..2941776780 100644
--- a/src/test/recovery/README
+++ b/src/test/recovery/README
@@ -30,4 +30,9 @@ PG_TEST_EXTRA=wal_consistency_checking
to the "make" command. This is resource-intensive, so it's not done
by default.
+If you want to test idle_replication_slot_timeout, add
+PG_TEST_EXTRA=idle_replication_slot_timeout
+to the "make" command. This test takes over 2 minutes, so it's not done
+by default.
+
See src/test/perl/README for more info about running these tests.
diff --git a/src/test/recovery/meson.build b/src/test/recovery/meson.build
index 56c464abb7..415d45d58a 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/043_invalidate_inactive_slots.pl',
],
},
}
diff --git a/src/test/recovery/t/043_invalidate_inactive_slots.pl b/src/test/recovery/t/043_invalidate_inactive_slots.pl
new file mode 100644
index 0000000000..efd2b050f0
--- /dev/null
+++ b/src/test/recovery/t/043_invalidate_inactive_slots.pl
@@ -0,0 +1,190 @@
+# Copyright (c) 2025, 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;
+
+# The test takes over two minutes to complete. Run it only if
+# idle_replication_slot_timeout is specified in PG_TEST_EXTRA.
+if ( !$ENV{PG_TEST_EXTRA}
+ || $ENV{PG_TEST_EXTRA} !~ /\bidle_replication_slot_timeout\b/)
+{
+ plan skip_all =>
+ 'test idle_replication_slot_timeout not enabled in PG_TEST_EXTRA';
+}
+
+# =============================================================================
+# Testcase start
+#
+# Test invalidation of streaming standby slot and logical failover slot on the
+# primary due to idle timeout. Also, test logical failover slot synced to
+# the standby from the primary doesn't get invalidated on its own, but gets the
+# invalidated state from the primary.
+
+# Initialize primary
+my $primary = PostgreSQL::Test::Cluster->new('primary');
+$primary->init(allows_streaming => 'logical');
+
+# Avoid unpredictability
+$primary->append_conf(
+ 'postgresql.conf', qq{
+checkpoint_timeout = 1h
+});
+$primary->start;
+
+# Take backup
+my $backup_name = 'my_backup';
+$primary->backup($backup_name);
+
+# Create sync slot on the primary
+$primary->psql('postgres',
+ q{SELECT pg_create_logical_replication_slot('sync_slot1', 'test_decoding', false, false, true);}
+);
+
+# Create standby slot on the primary
+$primary->safe_psql(
+ 'postgres', qq[
+ SELECT pg_create_physical_replication_slot(slot_name := 'sb_slot1', immediately_reserve := true);
+]);
+
+# Create standby
+my $standby1 = PostgreSQL::Test::Cluster->new('standby1');
+$standby1->init_from_backup($primary, $backup_name, has_streaming => 1);
+
+my $connstr = $primary->connstr;
+$standby1->append_conf(
+ 'postgresql.conf', qq(
+hot_standby_feedback = on
+primary_slot_name = 'sb_slot1'
+idle_replication_slot_timeout = 1
+primary_conninfo = '$connstr dbname=postgres'
+));
+$standby1->start;
+
+# Wait until the standby has replayed enough data
+$primary->wait_for_catchup($standby1);
+
+# Set timeout GUC on the standby to verify that the next checkpoint will not
+# invalidate synced slots.
+my $idle_timeout_1min = 1;
+
+# Sync the primary slots to the standby
+$standby1->safe_psql('postgres', "SELECT pg_sync_replication_slots();");
+
+# Confirm that the logical failover slot is created on the standby
+is( $standby1->safe_psql(
+ 'postgres',
+ q{SELECT count(*) = 1 FROM pg_replication_slots
+ WHERE slot_name = 'sync_slot1' AND synced
+ AND NOT temporary
+ AND invalidation_reason IS NULL;}
+ ),
+ 't',
+ 'logical slot sync_slot1 is synced to standby');
+
+# Give enough time for inactive_since to exceed the timeout
+sleep($idle_timeout_1min * 60 + 10);
+
+# On standby, synced slots are not invalidated by the idle timeout
+# until the invalidation state is propagated from the primary.
+$standby1->safe_psql('postgres', "CHECKPOINT");
+is( $standby1->safe_psql(
+ 'postgres',
+ q{SELECT count(*) = 1 FROM pg_replication_slots
+ WHERE slot_name = 'sync_slot1'
+ AND invalidation_reason IS NULL;}
+ ),
+ 't',
+ 'check that synced slot sync_slot1 has not been invalidated on standby');
+
+my $logstart = -s $primary->logfile;
+
+# Set timeout GUC so that the next checkpoint will invalidate inactive slots
+$primary->safe_psql(
+ 'postgres', qq[
+ ALTER SYSTEM SET idle_replication_slot_timeout TO '${idle_timeout_1min}min';
+]);
+$primary->reload;
+
+# Wait for logical failover slot to become inactive on the primary. Note that
+# nobody has acquired the slot yet, so it must get invalidated due to
+# idle timeout.
+wait_for_slot_invalidation($primary, 'sync_slot1', $logstart,
+ $idle_timeout_1min);
+
+# Re-sync the primary slots to the standby. Note that the primary slot was
+# already invalidated (above) due to idle timeout. The standby must just
+# sync the invalidated state.
+$standby1->safe_psql('postgres', "SELECT pg_sync_replication_slots();");
+
+is( $standby1->safe_psql(
+ 'postgres',
+ q{SELECT count(*) = 1 FROM pg_replication_slots
+ WHERE slot_name = 'sync_slot1'
+ AND invalidation_reason = 'idle_timeout';}
+ ),
+ "t",
+ 'check that invalidation of synced slot sync_slot1 is synced on standby');
+
+# Make the standby slot on the primary inactive and check for invalidation
+$standby1->stop;
+wait_for_slot_invalidation($primary, 'sb_slot1', $logstart,
+ $idle_timeout_1min);
+
+# Testcase end
+# =============================================================================
+
+# Wait for slot to first become idle and then get invalidated
+sub wait_for_slot_invalidation
+{
+ my ($node, $slot, $offset, $idle_timeout_mins) = @_;
+ my $node_name = $node->name;
+
+ trigger_slot_invalidation($node, $slot, $offset, $idle_timeout_mins);
+
+ # Check that an invalidated slot cannot be acquired
+ my ($result, $stdout, $stderr);
+ ($result, $stdout, $stderr) = $node->psql(
+ 'postgres', qq[
+ SELECT pg_replication_slot_advance('$slot', '0/1');
+ ]);
+ ok( $stderr =~ /can no longer get changes from replication slot "$slot"/,
+ "detected error upon trying to acquire invalidated slot $slot on node $node_name"
+ )
+ or die
+ "could not detect error upon trying to acquire invalidated slot $slot on node $node_name";
+}
+
+# Trigger slot invalidation and confirm it in the server log
+sub trigger_slot_invalidation
+{
+ my ($node, $slot, $offset, $idle_timeout_mins) = @_;
+ my $node_name = $node->name;
+ my $invalidated = 0;
+
+ # Give enough time for inactive_since to exceed the timeout
+ sleep($idle_timeout_mins * 60 + 10);
+
+ # Run a checkpoint
+ $node->safe_psql('postgres', "CHECKPOINT");
+
+ # The slot's invalidation should be logged
+ $node->wait_for_log(qr/invalidating obsolete replication slot \"$slot\"/,
+ $offset);
+
+ # Check that the invalidation reason is 'idle_timeout'
+ $node->poll_query_until(
+ 'postgres', qq[
+ SELECT COUNT(slot_name) = 1 FROM pg_replication_slots
+ WHERE slot_name = '$slot' AND
+ invalidation_reason = 'idle_timeout';
+ ])
+ or die
+ "Timed out while waiting for invalidation reason of slot $slot to be set on node $node_name";
+}
+
+done_testing();
--
2.34.1
