Dear Fujii Masao
I've prepared patches of v6 for other majors. I hope, it will help.
I will also think of a better approach for tap-test patch as well.
With best regards,
Vitaly
From aee002a40ecffb5fcc31ec6392a3bcfc41cfa57b Mon Sep 17 00:00:00 2001
From: Vitaly Davydov <[email protected]>
Date: Wed, 10 Jun 2026 12:12:54 +0900
Subject: [PATCH v6-REL_14_STABLE] Fix deadlock detector activation in a
recovery conflict
When the startup process in a deadlock with a backend, it sends the
signal to the backend to trigger the deadlock detector when
the deadlock timeout is elapsed (deadlock_timeout guc). Due to some
optimization in timeout.c, when spontaneous SIGALRM signals are
possible, which doesn't relate to any enabled timeout, the function
ResolveRecoveryConflictWithBufferPin can never send the signal to the
conflicting backend, becase the deadlock timeout will never be
triggered.
The patch fixes ResolveRecoveryConflictWithBufferPin by ignoring
spontaneous SIGALRM signals, that are possible in the current
implementation of timeout.c functionality.
---
src/backend/storage/buffer/bufmgr.c | 81 +++++++++++++++++++++++++++--
src/backend/storage/ipc/standby.c | 71 ++++++++++++++++---------
src/include/storage/bufmgr.h | 1 +
3 files changed, 123 insertions(+), 30 deletions(-)
diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index f563742ad44..a29b6f970bb 100644
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -1839,6 +1839,32 @@ PinBuffer_Locked(BufferDesc *buf)
ResourceOwnerRememberBuffer(CurrentResourceOwner, b);
}
+/*
+ * Register the current process as the pincount waiter for a shared buffer.
+ *
+ * The caller must hold the buffer header lock, pass the current buffer state
+ * returned by LockBufHdr(), and ensure that no other backend is already
+ * registered as the waiter.
+ */
+static void
+RegisterPinCountWaiter(BufferDesc *bufHdr, uint64 buf_state)
+{
+ Assert((buf_state & BM_PIN_COUNT_WAITER) == 0 ||
+ bufHdr->wait_backend_pid == MyProcPid);
+
+ if ((buf_state & BM_PIN_COUNT_WAITER) != 0 &&
+ bufHdr->wait_backend_pid != MyProcPid)
+ {
+ UnlockBufHdr(bufHdr, buf_state);
+ elog(ERROR, "multiple processes attempting to wait for pincount 1");
+ }
+
+ bufHdr->wait_backend_pid = MyProcPid;
+ PinCountWaitBuf = bufHdr;
+ buf_state |= BM_PIN_COUNT_WAITER;
+ UnlockBufHdr(bufHdr, buf_state);
+}
+
/*
* UnpinBuffer -- make buffer available for replacement.
*
@@ -3119,6 +3145,56 @@ BufferGetLSNAtomic(Buffer buffer)
return lsn;
}
+/*
+ * BufferIsReadyForCleanup
+ * Recheck whether the startup process can retry cleanup lock acquisition.
+ *
+ * This is only for the hot-standby path in LockBufferForCleanup(), via
+ * ResolveRecoveryConflictWithBufferPin(), after ProcWaitForSignal() returns.
+ * The caller must already be registered as the shared buffer's
+ * BM_PIN_COUNT_WAITER.
+ *
+ * Returns true when the caller itself is the only remaining pin holder, so it
+ * can retry taking the cleanup lock. Returns false if other backends still
+ * pin the shared buffer. In that case, this function guarantees that the
+ * current backend remains registered as the pincount waiter to be woken when
+ * the buffer refcount drops to 1.
+ */
+bool
+BufferIsReadyForCleanup(Buffer buffer)
+{
+ BufferDesc *bufHdr;
+ uint64 buf_state;
+ uint32 buf_refcount;
+
+ Assert(BufferIsValid(buffer));
+ Assert(!BufferIsLocal(buffer));
+
+ bufHdr = GetBufferDescriptor(buffer - 1);
+ Assert(PinCountWaitBuf == bufHdr);
+
+ buf_state = LockBufHdr(bufHdr);
+ buf_refcount = BUF_STATE_GET_REFCOUNT(buf_state);
+ Assert(buf_refcount > 0);
+ Assert((buf_state & BM_PIN_COUNT_WAITER) == 0 ||
+ bufHdr->wait_backend_pid == MyProcPid);
+
+ if (buf_refcount == 1)
+ {
+ buf_state &= ~BM_PIN_COUNT_WAITER;
+ UnlockBufHdr(bufHdr, buf_state);
+ return true;
+ }
+
+ /*
+ * If other processes still pin the buffer, register this process again as
+ * the pincount waiter to wait again.
+ */
+ RegisterPinCountWaiter(bufHdr, buf_state);
+
+ return false;
+}
+
/* ---------------------------------------------------------------------
* DropRelFileNodeBuffers
*
@@ -4219,10 +4295,7 @@ LockBufferForCleanup(Buffer buffer)
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
elog(ERROR, "multiple backends attempting to wait for pincount 1");
}
- bufHdr->wait_backend_pid = MyProcPid;
- PinCountWaitBuf = bufHdr;
- buf_state |= BM_PIN_COUNT_WAITER;
- UnlockBufHdr(bufHdr, buf_state);
+ RegisterPinCountWaiter(bufHdr, buf_state);
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
/* Wait to be signaled by UnpinBuffer() */
diff --git a/src/backend/storage/ipc/standby.c b/src/backend/storage/ipc/standby.c
index 49cccad9bf6..cb87f0b1fe1 100644
--- a/src/backend/storage/ipc/standby.c
+++ b/src/backend/storage/ipc/standby.c
@@ -749,14 +749,21 @@ cleanup:
* Deadlocks are extremely rare, and relatively expensive to check for,
* so we don't do a deadlock check right away ... only if we have had to wait
* at least deadlock_timeout.
+ *
+ * The current process should be the waiter process and should have
+ * published the waited buffer via SetStartupBufferPinWaitBufId().
*/
void
ResolveRecoveryConflictWithBufferPin(void)
{
TimestampTz ltime;
+ int bufid;
Assert(InHotStandby);
+ bufid = GetStartupBufferPinWaitBufId();
+ Assert(bufid >= 0);
+
ltime = GetStandbyLimitTime();
if (GetCurrentTimestamp() >= ltime && ltime != 0)
@@ -792,36 +799,48 @@ ResolveRecoveryConflictWithBufferPin(void)
enable_timeouts(timeouts, cnt);
}
- /*
- * Wait to be signaled by UnpinBuffer() or for the wait to be interrupted
- * by one of the timeouts established above.
- *
- * We assume that only UnpinBuffer() and the timeout requests established
- * above can wake us up here. WakeupRecovery() called by walreceiver or
- * SIGHUP signal handler, etc cannot do that because it uses the different
- * latch from that ProcWaitForSignal() waits on.
- */
- ProcWaitForSignal(PG_WAIT_BUFFER_PIN);
-
- if (got_standby_delay_timeout)
- SendRecoveryConflictWithBufferPin(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN);
- else if (got_standby_deadlock_timeout)
+ for (;;)
{
/*
- * Send out a request for hot-standby backends to check themselves for
- * deadlocks.
+ * Wait to be signaled by UnpinBuffer() or for the wait to be
+ * interrupted by one of the timeouts established above.
*
- * XXX The subsequent ResolveRecoveryConflictWithBufferPin() will wait
- * to be signaled by UnpinBuffer() again and send a request for
- * deadlocks check if deadlock_timeout happens. This causes the
- * request to continue to be sent every deadlock_timeout until the
- * buffer is unpinned or ltime is reached. This would increase the
- * workload in the startup process and backends. In practice it may
- * not be so harmful because the period that the buffer is kept pinned
- * is basically no so long. But we should fix this?
+ * ProcWaitForSignal() can also wake up for unrelated reasons, so
+ * recheck later whether cleanup can proceed.
+ */
+ ProcWaitForSignal(PG_WAIT_BUFFER_PIN);
+
+ /*
+ * Once the reference count is 1, the waiter process itself is the
+ * only backend pinning the buffer at the moment. There is a chance to
+ * lock the buffer exclusively.
*/
- SendRecoveryConflictWithBufferPin(
- PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK);
+ if (BufferIsReadyForCleanup(bufid + 1))
+ break;
+
+ if (got_standby_delay_timeout)
+ {
+ SendRecoveryConflictWithBufferPin(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN);
+ break;
+ }
+ else if (got_standby_deadlock_timeout)
+ {
+ /*
+ * Send out a request for hot-standby backends to check themselves
+ * for deadlocks.
+ *
+ * XXX The subsequent ResolveRecoveryConflictWithBufferPin() will
+ * wait to be signaled by UnpinBuffer() again and send a request
+ * for deadlocks check if deadlock_timeout happens. This causes
+ * the request to continue to be sent every deadlock_timeout until
+ * the buffer is unpinned or ltime is reached. This would increase
+ * the workload in the startup process and backends. In practice
+ * it may not be so harmful because the period that the buffer is
+ * kept pinned is basically no so long. But we should fix this?
+ */
+ SendRecoveryConflictWithBufferPin(PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK);
+ break;
+ }
}
/*
diff --git a/src/include/storage/bufmgr.h b/src/include/storage/bufmgr.h
index 85caac3253d..3ef5dc7e349 100644
--- a/src/include/storage/bufmgr.h
+++ b/src/include/storage/bufmgr.h
@@ -223,6 +223,7 @@ extern XLogRecPtr BufferGetLSNAtomic(Buffer buffer);
extern void PrintPinnedBufs(void);
#endif
extern Size BufferShmemSize(void);
+extern bool BufferIsReadyForCleanup(Buffer buffer);
extern void BufferGetTag(Buffer buffer, RelFileNode *rnode,
ForkNumber *forknum, BlockNumber *blknum);
--
2.43.0
From 4777798b041f6543b4e568d5c00d74d139b7f738 Mon Sep 17 00:00:00 2001
From: Vitaly Davydov <[email protected]>
Date: Wed, 10 Jun 2026 12:12:54 +0900
Subject: [PATCH v6-REL_15_STABLE] Fix deadlock detector activation in a
recovery conflict
When the startup process in a deadlock with a backend, it sends the
signal to the backend to trigger the deadlock detector when
the deadlock timeout is elapsed (deadlock_timeout guc). Due to some
optimization in timeout.c, when spontaneous SIGALRM signals are
possible, which doesn't relate to any enabled timeout, the function
ResolveRecoveryConflictWithBufferPin can never send the signal to the
conflicting backend, becase the deadlock timeout will never be
triggered.
The patch fixes ResolveRecoveryConflictWithBufferPin by ignoring
spontaneous SIGALRM signals, that are possible in the current
implementation of timeout.c functionality.
---
src/backend/storage/buffer/bufmgr.c | 81 +++++++++++++++++++++++++++--
src/backend/storage/ipc/standby.c | 70 ++++++++++++++++---------
src/include/storage/bufmgr.h | 1 +
3 files changed, 123 insertions(+), 29 deletions(-)
diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index a02814a8f51..224cb677626 100644
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -1847,6 +1847,32 @@ PinBuffer_Locked(BufferDesc *buf)
ResourceOwnerRememberBuffer(CurrentResourceOwner, b);
}
+/*
+ * Register the current process as the pincount waiter for a shared buffer.
+ *
+ * The caller must hold the buffer header lock, pass the current buffer state
+ * returned by LockBufHdr(), and ensure that no other backend is already
+ * registered as the waiter.
+ */
+static void
+RegisterPinCountWaiter(BufferDesc *bufHdr, uint64 buf_state)
+{
+ Assert((buf_state & BM_PIN_COUNT_WAITER) == 0 ||
+ bufHdr->wait_backend_pgprocno == MyProc->pgprocno);
+
+ if ((buf_state & BM_PIN_COUNT_WAITER) != 0 &&
+ bufHdr->wait_backend_pgprocno != MyProc->pgprocno)
+ {
+ UnlockBufHdr(bufHdr, buf_state);
+ elog(ERROR, "multiple processes attempting to wait for pincount 1");
+ }
+
+ bufHdr->wait_backend_pgprocno = MyProc->pgprocno;
+ PinCountWaitBuf = bufHdr;
+ buf_state |= BM_PIN_COUNT_WAITER;
+ UnlockBufHdr(bufHdr, buf_state);
+}
+
/*
* UnpinBuffer -- make buffer available for replacement.
*
@@ -3102,6 +3128,56 @@ BufferGetLSNAtomic(Buffer buffer)
return lsn;
}
+/*
+ * BufferIsReadyForCleanup
+ * Recheck whether the startup process can retry cleanup lock acquisition.
+ *
+ * This is only for the hot-standby path in LockBufferForCleanup(), via
+ * ResolveRecoveryConflictWithBufferPin(), after ProcWaitForSignal() returns.
+ * The caller must already be registered as the shared buffer's
+ * BM_PIN_COUNT_WAITER.
+ *
+ * Returns true when the caller itself is the only remaining pin holder, so it
+ * can retry taking the cleanup lock. Returns false if other backends still
+ * pin the shared buffer. In that case, this function guarantees that the
+ * current backend remains registered as the pincount waiter to be woken when
+ * the buffer refcount drops to 1.
+ */
+bool
+BufferIsReadyForCleanup(Buffer buffer)
+{
+ BufferDesc *bufHdr;
+ uint64 buf_state;
+ uint32 buf_refcount;
+
+ Assert(BufferIsValid(buffer));
+ Assert(!BufferIsLocal(buffer));
+
+ bufHdr = GetBufferDescriptor(buffer - 1);
+ Assert(PinCountWaitBuf == bufHdr);
+
+ buf_state = LockBufHdr(bufHdr);
+ buf_refcount = BUF_STATE_GET_REFCOUNT(buf_state);
+ Assert(buf_refcount > 0);
+ Assert((buf_state & BM_PIN_COUNT_WAITER) == 0 ||
+ bufHdr->wait_backend_pgprocno == MyProc->pgprocno);
+
+ if (buf_refcount == 1)
+ {
+ buf_state &= ~BM_PIN_COUNT_WAITER;
+ UnlockBufHdr(bufHdr, buf_state);
+ return true;
+ }
+
+ /*
+ * If other processes still pin the buffer, register this process again as
+ * the pincount waiter to wait again.
+ */
+ RegisterPinCountWaiter(bufHdr, buf_state);
+
+ return false;
+}
+
/* ---------------------------------------------------------------------
* DropRelFileNodeBuffers
*
@@ -4356,10 +4432,7 @@ LockBufferForCleanup(Buffer buffer)
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
elog(ERROR, "multiple backends attempting to wait for pincount 1");
}
- bufHdr->wait_backend_pgprocno = MyProc->pgprocno;
- PinCountWaitBuf = bufHdr;
- buf_state |= BM_PIN_COUNT_WAITER;
- UnlockBufHdr(bufHdr, buf_state);
+ RegisterPinCountWaiter(bufHdr, buf_state);
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
/* Wait to be signaled by UnpinBuffer() */
diff --git a/src/backend/storage/ipc/standby.c b/src/backend/storage/ipc/standby.c
index a36eb80e9ae..2b029cdcf10 100644
--- a/src/backend/storage/ipc/standby.c
+++ b/src/backend/storage/ipc/standby.c
@@ -750,14 +750,21 @@ cleanup:
* Deadlocks are extremely rare, and relatively expensive to check for,
* so we don't do a deadlock check right away ... only if we have had to wait
* at least deadlock_timeout.
+ *
+ * The current process should be the waiter process and should have
+ * published the waited buffer via SetStartupBufferPinWaitBufId().
*/
void
ResolveRecoveryConflictWithBufferPin(void)
{
TimestampTz ltime;
+ int bufid;
Assert(InHotStandby);
+ bufid = GetStartupBufferPinWaitBufId();
+ Assert(bufid >= 0);
+
ltime = GetStandbyLimitTime();
if (GetCurrentTimestamp() >= ltime && ltime != 0)
@@ -793,35 +800,48 @@ ResolveRecoveryConflictWithBufferPin(void)
enable_timeouts(timeouts, cnt);
}
- /*
- * Wait to be signaled by UnpinBuffer() or for the wait to be interrupted
- * by one of the timeouts established above.
- *
- * We assume that only UnpinBuffer() and the timeout requests established
- * above can wake us up here. WakeupRecovery() called by walreceiver or
- * SIGHUP signal handler, etc cannot do that because it uses the different
- * latch from that ProcWaitForSignal() waits on.
- */
- ProcWaitForSignal(PG_WAIT_BUFFER_PIN);
-
- if (got_standby_delay_timeout)
- SendRecoveryConflictWithBufferPin(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN);
- else if (got_standby_deadlock_timeout)
+ for (;;)
{
/*
- * Send out a request for hot-standby backends to check themselves for
- * deadlocks.
+ * Wait to be signaled by UnpinBuffer() or for the wait to be
+ * interrupted by one of the timeouts established above.
*
- * XXX The subsequent ResolveRecoveryConflictWithBufferPin() will wait
- * to be signaled by UnpinBuffer() again and send a request for
- * deadlocks check if deadlock_timeout happens. This causes the
- * request to continue to be sent every deadlock_timeout until the
- * buffer is unpinned or ltime is reached. This would increase the
- * workload in the startup process and backends. In practice it may
- * not be so harmful because the period that the buffer is kept pinned
- * is basically no so long. But we should fix this?
+ * ProcWaitForSignal() can also wake up for unrelated reasons, so
+ * recheck later whether cleanup can proceed.
+ */
+ ProcWaitForSignal(PG_WAIT_BUFFER_PIN);
+
+ /*
+ * Once the reference count is 1, the waiter process itself is the
+ * only backend pinning the buffer at the moment. There is a chance to
+ * lock the buffer exclusively.
*/
- SendRecoveryConflictWithBufferPin(PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK);
+ if (BufferIsReadyForCleanup(bufid + 1))
+ break;
+
+ if (got_standby_delay_timeout)
+ {
+ SendRecoveryConflictWithBufferPin(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN);
+ break;
+ }
+ else if (got_standby_deadlock_timeout)
+ {
+ /*
+ * Send out a request for hot-standby backends to check themselves
+ * for deadlocks.
+ *
+ * XXX The subsequent ResolveRecoveryConflictWithBufferPin() will
+ * wait to be signaled by UnpinBuffer() again and send a request
+ * for deadlocks check if deadlock_timeout happens. This causes
+ * the request to continue to be sent every deadlock_timeout until
+ * the buffer is unpinned or ltime is reached. This would increase
+ * the workload in the startup process and backends. In practice
+ * it may not be so harmful because the period that the buffer is
+ * kept pinned is basically no so long. But we should fix this?
+ */
+ SendRecoveryConflictWithBufferPin(PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK);
+ break;
+ }
}
/*
diff --git a/src/include/storage/bufmgr.h b/src/include/storage/bufmgr.h
index 8e93d315a67..d0a92541ed8 100644
--- a/src/include/storage/bufmgr.h
+++ b/src/include/storage/bufmgr.h
@@ -226,6 +226,7 @@ extern XLogRecPtr BufferGetLSNAtomic(Buffer buffer);
extern void PrintPinnedBufs(void);
#endif
extern Size BufferShmemSize(void);
+extern bool BufferIsReadyForCleanup(Buffer buffer);
extern void BufferGetTag(Buffer buffer, RelFileNode *rnode,
ForkNumber *forknum, BlockNumber *blknum);
--
2.43.0
From 1a14d442072a1dc4a0063825fc7f366b755bb527 Mon Sep 17 00:00:00 2001
From: Vitaly Davydov <[email protected]>
Date: Wed, 10 Jun 2026 12:12:54 +0900
Subject: [PATCH v6-REL_16_STABLE] Fix deadlock detector activation in a
recovery conflict
When the startup process in a deadlock with a backend, it sends the
signal to the backend to trigger the deadlock detector when
the deadlock timeout is elapsed (deadlock_timeout guc). Due to some
optimization in timeout.c, when spontaneous SIGALRM signals are
possible, which doesn't relate to any enabled timeout, the function
ResolveRecoveryConflictWithBufferPin can never send the signal to the
conflicting backend, becase the deadlock timeout will never be
triggered.
The patch fixes ResolveRecoveryConflictWithBufferPin by ignoring
spontaneous SIGALRM signals, that are possible in the current
implementation of timeout.c functionality.
---
src/backend/storage/buffer/bufmgr.c | 81 +++++++++++++++++++++++++++--
src/backend/storage/ipc/standby.c | 70 ++++++++++++++++---------
src/include/storage/bufmgr.h | 1 +
3 files changed, 123 insertions(+), 29 deletions(-)
diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index ef14791e2da..515ae59cc0a 100644
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -2376,6 +2376,32 @@ PinBuffer_Locked(BufferDesc *buf)
ResourceOwnerRememberBuffer(CurrentResourceOwner, b);
}
+/*
+ * Register the current process as the pincount waiter for a shared buffer.
+ *
+ * The caller must hold the buffer header lock, pass the current buffer state
+ * returned by LockBufHdr(), and ensure that no other backend is already
+ * registered as the waiter.
+ */
+static void
+RegisterPinCountWaiter(BufferDesc *bufHdr, uint64 buf_state)
+{
+ Assert((buf_state & BM_PIN_COUNT_WAITER) == 0 ||
+ bufHdr->wait_backend_pgprocno == MyProc->pgprocno);
+
+ if ((buf_state & BM_PIN_COUNT_WAITER) != 0 &&
+ bufHdr->wait_backend_pgprocno != MyProc->pgprocno)
+ {
+ UnlockBufHdr(bufHdr, buf_state);
+ elog(ERROR, "multiple processes attempting to wait for pincount 1");
+ }
+
+ bufHdr->wait_backend_pgprocno = MyProc->pgprocno;
+ PinCountWaitBuf = bufHdr;
+ buf_state |= BM_PIN_COUNT_WAITER;
+ UnlockBufHdr(bufHdr, buf_state);
+}
+
/*
* UnpinBuffer -- make buffer available for replacement.
*
@@ -3640,6 +3666,56 @@ BufferGetLSNAtomic(Buffer buffer)
return lsn;
}
+/*
+ * BufferIsReadyForCleanup
+ * Recheck whether the startup process can retry cleanup lock acquisition.
+ *
+ * This is only for the hot-standby path in LockBufferForCleanup(), via
+ * ResolveRecoveryConflictWithBufferPin(), after ProcWaitForSignal() returns.
+ * The caller must already be registered as the shared buffer's
+ * BM_PIN_COUNT_WAITER.
+ *
+ * Returns true when the caller itself is the only remaining pin holder, so it
+ * can retry taking the cleanup lock. Returns false if other backends still
+ * pin the shared buffer. In that case, this function guarantees that the
+ * current backend remains registered as the pincount waiter to be woken when
+ * the buffer refcount drops to 1.
+ */
+bool
+BufferIsReadyForCleanup(Buffer buffer)
+{
+ BufferDesc *bufHdr;
+ uint64 buf_state;
+ uint32 buf_refcount;
+
+ Assert(BufferIsValid(buffer));
+ Assert(!BufferIsLocal(buffer));
+
+ bufHdr = GetBufferDescriptor(buffer - 1);
+ Assert(PinCountWaitBuf == bufHdr);
+
+ buf_state = LockBufHdr(bufHdr);
+ buf_refcount = BUF_STATE_GET_REFCOUNT(buf_state);
+ Assert(buf_refcount > 0);
+ Assert((buf_state & BM_PIN_COUNT_WAITER) == 0 ||
+ bufHdr->wait_backend_pgprocno == MyProc->pgprocno);
+
+ if (buf_refcount == 1)
+ {
+ buf_state &= ~BM_PIN_COUNT_WAITER;
+ UnlockBufHdr(bufHdr, buf_state);
+ return true;
+ }
+
+ /*
+ * If other processes still pin the buffer, register this process again as
+ * the pincount waiter to wait again.
+ */
+ RegisterPinCountWaiter(bufHdr, buf_state);
+
+ return false;
+}
+
/* ---------------------------------------------------------------------
* DropRelationBuffers
*
@@ -4917,10 +4993,7 @@ LockBufferForCleanup(Buffer buffer)
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
elog(ERROR, "multiple backends attempting to wait for pincount 1");
}
- bufHdr->wait_backend_pgprocno = MyProc->pgprocno;
- PinCountWaitBuf = bufHdr;
- buf_state |= BM_PIN_COUNT_WAITER;
- UnlockBufHdr(bufHdr, buf_state);
+ RegisterPinCountWaiter(bufHdr, buf_state);
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
/* Wait to be signaled by UnpinBuffer() */
diff --git a/src/backend/storage/ipc/standby.c b/src/backend/storage/ipc/standby.c
index 3bdc5f7fb6c..d71fe63d99b 100644
--- a/src/backend/storage/ipc/standby.c
+++ b/src/backend/storage/ipc/standby.c
@@ -788,14 +788,21 @@ cleanup:
* Deadlocks are extremely rare, and relatively expensive to check for,
* so we don't do a deadlock check right away ... only if we have had to wait
* at least deadlock_timeout.
+ *
+ * The current process should be the waiter process and should have
+ * published the waited buffer via SetStartupBufferPinWaitBufId().
*/
void
ResolveRecoveryConflictWithBufferPin(void)
{
TimestampTz ltime;
+ int bufid;
Assert(InHotStandby);
+ bufid = GetStartupBufferPinWaitBufId();
+ Assert(bufid >= 0);
+
ltime = GetStandbyLimitTime();
if (GetCurrentTimestamp() >= ltime && ltime != 0)
@@ -831,35 +838,48 @@ ResolveRecoveryConflictWithBufferPin(void)
enable_timeouts(timeouts, cnt);
}
- /*
- * Wait to be signaled by UnpinBuffer() or for the wait to be interrupted
- * by one of the timeouts established above.
- *
- * We assume that only UnpinBuffer() and the timeout requests established
- * above can wake us up here. WakeupRecovery() called by walreceiver or
- * SIGHUP signal handler, etc cannot do that because it uses the different
- * latch from that ProcWaitForSignal() waits on.
- */
- ProcWaitForSignal(PG_WAIT_BUFFER_PIN);
-
- if (got_standby_delay_timeout)
- SendRecoveryConflictWithBufferPin(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN);
- else if (got_standby_deadlock_timeout)
+ for (;;)
{
/*
- * Send out a request for hot-standby backends to check themselves for
- * deadlocks.
+ * Wait to be signaled by UnpinBuffer() or for the wait to be
+ * interrupted by one of the timeouts established above.
*
- * XXX The subsequent ResolveRecoveryConflictWithBufferPin() will wait
- * to be signaled by UnpinBuffer() again and send a request for
- * deadlocks check if deadlock_timeout happens. This causes the
- * request to continue to be sent every deadlock_timeout until the
- * buffer is unpinned or ltime is reached. This would increase the
- * workload in the startup process and backends. In practice it may
- * not be so harmful because the period that the buffer is kept pinned
- * is basically no so long. But we should fix this?
+ * ProcWaitForSignal() can also wake up for unrelated reasons, so
+ * recheck later whether cleanup can proceed.
+ */
+ ProcWaitForSignal(PG_WAIT_BUFFER_PIN);
+
+ /*
+ * Once the reference count is 1, the waiter process itself is the
+ * only backend pinning the buffer at the moment. There is a chance to
+ * lock the buffer exclusively.
*/
- SendRecoveryConflictWithBufferPin(PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK);
+ if (BufferIsReadyForCleanup(bufid + 1))
+ break;
+
+ if (got_standby_delay_timeout)
+ {
+ SendRecoveryConflictWithBufferPin(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN);
+ break;
+ }
+ else if (got_standby_deadlock_timeout)
+ {
+ /*
+ * Send out a request for hot-standby backends to check themselves
+ * for deadlocks.
+ *
+ * XXX The subsequent ResolveRecoveryConflictWithBufferPin() will
+ * wait to be signaled by UnpinBuffer() again and send a request
+ * for deadlocks check if deadlock_timeout happens. This causes
+ * the request to continue to be sent every deadlock_timeout until
+ * the buffer is unpinned or ltime is reached. This would increase
+ * the workload in the startup process and backends. In practice
+ * it may not be so harmful because the period that the buffer is
+ * kept pinned is basically no so long. But we should fix this?
+ */
+ SendRecoveryConflictWithBufferPin(PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK);
+ break;
+ }
}
/*
diff --git a/src/include/storage/bufmgr.h b/src/include/storage/bufmgr.h
index 166524c50e0..16e06cc9175 100644
--- a/src/include/storage/bufmgr.h
+++ b/src/include/storage/bufmgr.h
@@ -236,6 +236,7 @@ extern XLogRecPtr BufferGetLSNAtomic(Buffer buffer);
#ifdef NOT_USED
extern void PrintPinnedBufs(void);
#endif
+extern bool BufferIsReadyForCleanup(Buffer buffer);
extern void BufferGetTag(Buffer buffer, RelFileLocator *rlocator,
ForkNumber *forknum, BlockNumber *blknum);
--
2.43.0
From 90f95eef0777dafbcada78a75014e6a6b34cf555 Mon Sep 17 00:00:00 2001
From: Vitaly Davydov <[email protected]>
Date: Wed, 10 Jun 2026 12:12:54 +0900
Subject: [PATCH v6-REL_17_STABLE] Fix deadlock detector activation in a
recovery conflict
When the startup process in a deadlock with a backend, it sends the
signal to the backend to trigger the deadlock detector when
the deadlock timeout is elapsed (deadlock_timeout guc). Due to some
optimization in timeout.c, when spontaneous SIGALRM signals are
possible, which doesn't relate to any enabled timeout, the function
ResolveRecoveryConflictWithBufferPin can never send the signal to the
conflicting backend, becase the deadlock timeout will never be
triggered.
The patch fixes ResolveRecoveryConflictWithBufferPin by ignoring
spontaneous SIGALRM signals, that are possible in the current
implementation of timeout.c functionality.
---
src/backend/storage/buffer/bufmgr.c | 81 +++++++++++++++++++++++++++--
src/backend/storage/ipc/standby.c | 70 ++++++++++++++++---------
src/include/storage/bufmgr.h | 1 +
3 files changed, 123 insertions(+), 29 deletions(-)
diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index 1f2bbcf24b0..d35a8a475fe 100644
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -2801,6 +2801,32 @@ PinBuffer_Locked(BufferDesc *buf)
ResourceOwnerRememberBuffer(CurrentResourceOwner, b);
}
+/*
+ * Register the current process as the pincount waiter for a shared buffer.
+ *
+ * The caller must hold the buffer header lock, pass the current buffer state
+ * returned by LockBufHdr(), and ensure that no other backend is already
+ * registered as the waiter.
+ */
+static void
+RegisterPinCountWaiter(BufferDesc *bufHdr, uint64 buf_state)
+{
+ Assert((buf_state & BM_PIN_COUNT_WAITER) == 0 ||
+ bufHdr->wait_backend_pgprocno == MyProcNumber);
+
+ if ((buf_state & BM_PIN_COUNT_WAITER) != 0 &&
+ bufHdr->wait_backend_pgprocno != MyProcNumber)
+ {
+ UnlockBufHdr(bufHdr, buf_state);
+ elog(ERROR, "multiple processes attempting to wait for pincount 1");
+ }
+
+ bufHdr->wait_backend_pgprocno = MyProcNumber;
+ PinCountWaitBuf = bufHdr;
+ buf_state |= BM_PIN_COUNT_WAITER;
+ UnlockBufHdr(bufHdr, buf_state);
+}
+
/*
* UnpinBuffer -- make buffer available for replacement.
*
@@ -4072,6 +4098,56 @@ BufferGetLSNAtomic(Buffer buffer)
return lsn;
}
+/*
+ * BufferIsReadyForCleanup
+ * Recheck whether the startup process can retry cleanup lock acquisition.
+ *
+ * This is only for the hot-standby path in LockBufferForCleanup(), via
+ * ResolveRecoveryConflictWithBufferPin(), after ProcWaitForSignal() returns.
+ * The caller must already be registered as the shared buffer's
+ * BM_PIN_COUNT_WAITER.
+ *
+ * Returns true when the caller itself is the only remaining pin holder, so it
+ * can retry taking the cleanup lock. Returns false if other backends still
+ * pin the shared buffer. In that case, this function guarantees that the
+ * current backend remains registered as the pincount waiter to be woken when
+ * the buffer refcount drops to 1.
+ */
+bool
+BufferIsReadyForCleanup(Buffer buffer)
+{
+ BufferDesc *bufHdr;
+ uint64 buf_state;
+ uint32 buf_refcount;
+
+ Assert(BufferIsValid(buffer));
+ Assert(!BufferIsLocal(buffer));
+
+ bufHdr = GetBufferDescriptor(buffer - 1);
+ Assert(PinCountWaitBuf == bufHdr);
+
+ buf_state = LockBufHdr(bufHdr);
+ buf_refcount = BUF_STATE_GET_REFCOUNT(buf_state);
+ Assert(buf_refcount > 0);
+ Assert((buf_state & BM_PIN_COUNT_WAITER) == 0 ||
+ bufHdr->wait_backend_pgprocno == MyProcNumber);
+
+ if (buf_refcount == 1)
+ {
+ buf_state &= ~BM_PIN_COUNT_WAITER;
+ UnlockBufHdr(bufHdr, buf_state);
+ return true;
+ }
+
+ /*
+ * If other processes still pin the buffer, register this process again as
+ * the pincount waiter to wait again.
+ */
+ RegisterPinCountWaiter(bufHdr, buf_state);
+
+ return false;
+}
+
/* ---------------------------------------------------------------------
* DropRelationBuffers
*
@@ -5342,10 +5418,7 @@ LockBufferForCleanup(Buffer buffer)
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
elog(ERROR, "multiple backends attempting to wait for pincount 1");
}
- bufHdr->wait_backend_pgprocno = MyProcNumber;
- PinCountWaitBuf = bufHdr;
- buf_state |= BM_PIN_COUNT_WAITER;
- UnlockBufHdr(bufHdr, buf_state);
+ RegisterPinCountWaiter(bufHdr, buf_state);
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
/* Wait to be signaled by UnpinBuffer() */
diff --git a/src/backend/storage/ipc/standby.c b/src/backend/storage/ipc/standby.c
index 872679ca447..5bac5e8e351 100644
--- a/src/backend/storage/ipc/standby.c
+++ b/src/backend/storage/ipc/standby.c
@@ -787,14 +787,21 @@ cleanup:
* Deadlocks are extremely rare, and relatively expensive to check for,
* so we don't do a deadlock check right away ... only if we have had to wait
* at least deadlock_timeout.
+ *
+ * The current process should be the waiter process and should have
+ * published the waited buffer via SetStartupBufferPinWaitBufId().
*/
void
ResolveRecoveryConflictWithBufferPin(void)
{
TimestampTz ltime;
+ int bufid;
Assert(InHotStandby);
+ bufid = GetStartupBufferPinWaitBufId();
+ Assert(bufid >= 0);
+
ltime = GetStandbyLimitTime();
if (GetCurrentTimestamp() >= ltime && ltime != 0)
@@ -830,35 +837,48 @@ ResolveRecoveryConflictWithBufferPin(void)
enable_timeouts(timeouts, cnt);
}
- /*
- * Wait to be signaled by UnpinBuffer() or for the wait to be interrupted
- * by one of the timeouts established above.
- *
- * We assume that only UnpinBuffer() and the timeout requests established
- * above can wake us up here. WakeupRecovery() called by walreceiver or
- * SIGHUP signal handler, etc cannot do that because it uses the different
- * latch from that ProcWaitForSignal() waits on.
- */
- ProcWaitForSignal(WAIT_EVENT_BUFFER_PIN);
-
- if (got_standby_delay_timeout)
- SendRecoveryConflictWithBufferPin(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN);
- else if (got_standby_deadlock_timeout)
+ for (;;)
{
/*
- * Send out a request for hot-standby backends to check themselves for
- * deadlocks.
+ * Wait to be signaled by UnpinBuffer() or for the wait to be
+ * interrupted by one of the timeouts established above.
*
- * XXX The subsequent ResolveRecoveryConflictWithBufferPin() will wait
- * to be signaled by UnpinBuffer() again and send a request for
- * deadlocks check if deadlock_timeout happens. This causes the
- * request to continue to be sent every deadlock_timeout until the
- * buffer is unpinned or ltime is reached. This would increase the
- * workload in the startup process and backends. In practice it may
- * not be so harmful because the period that the buffer is kept pinned
- * is basically no so long. But we should fix this?
+ * ProcWaitForSignal() can also wake up for unrelated reasons, so
+ * recheck later whether cleanup can proceed.
+ */
+ ProcWaitForSignal(WAIT_EVENT_BUFFER_PIN);
+
+ /*
+ * Once the reference count is 1, the waiter process itself is the
+ * only backend pinning the buffer at the moment. There is a chance to
+ * lock the buffer exclusively.
*/
- SendRecoveryConflictWithBufferPin(PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK);
+ if (BufferIsReadyForCleanup(bufid + 1))
+ break;
+
+ if (got_standby_delay_timeout)
+ {
+ SendRecoveryConflictWithBufferPin(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN);
+ break;
+ }
+ else if (got_standby_deadlock_timeout)
+ {
+ /*
+ * Send out a request for hot-standby backends to check themselves
+ * for deadlocks.
+ *
+ * XXX The subsequent ResolveRecoveryConflictWithBufferPin() will
+ * wait to be signaled by UnpinBuffer() again and send a request
+ * for deadlocks check if deadlock_timeout happens. This causes
+ * the request to continue to be sent every deadlock_timeout until
+ * the buffer is unpinned or ltime is reached. This would increase
+ * the workload in the startup process and backends. In practice
+ * it may not be so harmful because the period that the buffer is
+ * kept pinned is basically no so long. But we should fix this?
+ */
+ SendRecoveryConflictWithBufferPin(PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK);
+ break;
+ }
}
/*
diff --git a/src/include/storage/bufmgr.h b/src/include/storage/bufmgr.h
index 09c43dd9c72..d0d26ef5f65 100644
--- a/src/include/storage/bufmgr.h
+++ b/src/include/storage/bufmgr.h
@@ -286,6 +286,7 @@ extern XLogRecPtr BufferGetLSNAtomic(Buffer buffer);
#ifdef NOT_USED
extern void PrintPinnedBufs(void);
#endif
+extern bool BufferIsReadyForCleanup(Buffer buffer);
extern void BufferGetTag(Buffer buffer, RelFileLocator *rlocator,
ForkNumber *forknum, BlockNumber *blknum);
--
2.43.0
From e5e61b582b08350360292928ef8525ca33d433d7 Mon Sep 17 00:00:00 2001
From: Vitaly Davydov <[email protected]>
Date: Wed, 10 Jun 2026 12:12:54 +0900
Subject: [PATCH v6-REL_18_STABLE] Fix deadlock detector activation in a
recovery conflict
When the startup process in a deadlock with a backend, it sends the
signal to the backend to trigger the deadlock detector when
the deadlock timeout is elapsed (deadlock_timeout guc). Due to some
optimization in timeout.c, when spontaneous SIGALRM signals are
possible, which doesn't relate to any enabled timeout, the function
ResolveRecoveryConflictWithBufferPin can never send the signal to the
conflicting backend, becase the deadlock timeout will never be
triggered.
The patch fixes ResolveRecoveryConflictWithBufferPin by ignoring
spontaneous SIGALRM signals, that are possible in the current
implementation of timeout.c functionality.
---
src/backend/storage/buffer/bufmgr.c | 81 +++++++++++++++++++++++++++--
src/backend/storage/ipc/standby.c | 70 ++++++++++++++++---------
src/include/storage/bufmgr.h | 1 +
3 files changed, 123 insertions(+), 29 deletions(-)
diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index 27fd7e9720a..9addd202f2d 100644
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -3258,6 +3258,32 @@ WakePinCountWaiter(BufferDesc *buf)
UnlockBufHdr(buf, buf_state);
}
+/*
+ * Register the current process as the pincount waiter for a shared buffer.
+ *
+ * The caller must hold the buffer header lock, pass the current buffer state
+ * returned by LockBufHdr(), and ensure that no other backend is already
+ * registered as the waiter.
+ */
+static void
+RegisterPinCountWaiter(BufferDesc *bufHdr, uint64 buf_state)
+{
+ Assert((buf_state & BM_PIN_COUNT_WAITER) == 0 ||
+ bufHdr->wait_backend_pgprocno == MyProcNumber);
+
+ if ((buf_state & BM_PIN_COUNT_WAITER) != 0 &&
+ bufHdr->wait_backend_pgprocno != MyProcNumber)
+ {
+ UnlockBufHdr(bufHdr, buf_state);
+ elog(ERROR, "multiple processes attempting to wait for pincount 1");
+ }
+
+ bufHdr->wait_backend_pgprocno = MyProcNumber;
+ PinCountWaitBuf = bufHdr;
+ buf_state |= BM_PIN_COUNT_WAITER;
+ UnlockBufHdr(bufHdr, buf_state);
+}
+
/*
* UnpinBuffer -- make buffer available for replacement.
*
@@ -4517,6 +4543,56 @@ BufferGetLSNAtomic(Buffer buffer)
return lsn;
}
+/*
+ * BufferIsReadyForCleanup
+ * Recheck whether the startup process can retry cleanup lock acquisition.
+ *
+ * This is only for the hot-standby path in LockBufferForCleanup(), via
+ * ResolveRecoveryConflictWithBufferPin(), after ProcWaitForSignal() returns.
+ * The caller must already be registered as the shared buffer's
+ * BM_PIN_COUNT_WAITER.
+ *
+ * Returns true when the caller itself is the only remaining pin holder, so it
+ * can retry taking the cleanup lock. Returns false if other backends still
+ * pin the shared buffer. In that case, this function guarantees that the
+ * current backend remains registered as the pincount waiter to be woken when
+ * the buffer refcount drops to 1.
+ */
+bool
+BufferIsReadyForCleanup(Buffer buffer)
+{
+ BufferDesc *bufHdr;
+ uint64 buf_state;
+ uint32 buf_refcount;
+
+ Assert(BufferIsValid(buffer));
+ Assert(!BufferIsLocal(buffer));
+
+ bufHdr = GetBufferDescriptor(buffer - 1);
+ Assert(PinCountWaitBuf == bufHdr);
+
+ buf_state = LockBufHdr(bufHdr);
+ buf_refcount = BUF_STATE_GET_REFCOUNT(buf_state);
+ Assert(buf_refcount > 0);
+ Assert((buf_state & BM_PIN_COUNT_WAITER) == 0 ||
+ bufHdr->wait_backend_pgprocno == MyProcNumber);
+
+ if (buf_refcount == 1)
+ {
+ buf_state &= ~BM_PIN_COUNT_WAITER;
+ UnlockBufHdr(bufHdr, buf_state);
+ return true;
+ }
+
+ /*
+ * If other processes still pin the buffer, register this process again as
+ * the pincount waiter to wait again.
+ */
+ RegisterPinCountWaiter(bufHdr, buf_state);
+
+ return false;
+}
+
/* ---------------------------------------------------------------------
* DropRelationBuffers
*
@@ -5750,10 +5826,7 @@ LockBufferForCleanup(Buffer buffer)
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
elog(ERROR, "multiple backends attempting to wait for pincount 1");
}
- bufHdr->wait_backend_pgprocno = MyProcNumber;
- PinCountWaitBuf = bufHdr;
- buf_state |= BM_PIN_COUNT_WAITER;
- UnlockBufHdr(bufHdr, buf_state);
+ RegisterPinCountWaiter(bufHdr, buf_state);
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
/* Wait to be signaled by UnpinBuffer() */
diff --git a/src/backend/storage/ipc/standby.c b/src/backend/storage/ipc/standby.c
index 7fa8d9247e0..924cfd671a1 100644
--- a/src/backend/storage/ipc/standby.c
+++ b/src/backend/storage/ipc/standby.c
@@ -788,14 +788,21 @@ cleanup:
* Deadlocks are extremely rare, and relatively expensive to check for,
* so we don't do a deadlock check right away ... only if we have had to wait
* at least deadlock_timeout.
+ *
+ * The current process should be the waiter process and should have
+ * published the waited buffer via SetStartupBufferPinWaitBufId().
*/
void
ResolveRecoveryConflictWithBufferPin(void)
{
TimestampTz ltime;
+ int bufid;
Assert(InHotStandby);
+ bufid = GetStartupBufferPinWaitBufId();
+ Assert(bufid >= 0);
+
ltime = GetStandbyLimitTime();
if (GetCurrentTimestamp() >= ltime && ltime != 0)
@@ -831,35 +838,48 @@ ResolveRecoveryConflictWithBufferPin(void)
enable_timeouts(timeouts, cnt);
}
- /*
- * Wait to be signaled by UnpinBuffer() or for the wait to be interrupted
- * by one of the timeouts established above.
- *
- * We assume that only UnpinBuffer() and the timeout requests established
- * above can wake us up here. WakeupRecovery() called by walreceiver or
- * SIGHUP signal handler, etc cannot do that because it uses the different
- * latch from that ProcWaitForSignal() waits on.
- */
- ProcWaitForSignal(WAIT_EVENT_BUFFER_PIN);
-
- if (got_standby_delay_timeout)
- SendRecoveryConflictWithBufferPin(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN);
- else if (got_standby_deadlock_timeout)
+ for (;;)
{
/*
- * Send out a request for hot-standby backends to check themselves for
- * deadlocks.
+ * Wait to be signaled by UnpinBuffer() or for the wait to be
+ * interrupted by one of the timeouts established above.
*
- * XXX The subsequent ResolveRecoveryConflictWithBufferPin() will wait
- * to be signaled by UnpinBuffer() again and send a request for
- * deadlocks check if deadlock_timeout happens. This causes the
- * request to continue to be sent every deadlock_timeout until the
- * buffer is unpinned or ltime is reached. This would increase the
- * workload in the startup process and backends. In practice it may
- * not be so harmful because the period that the buffer is kept pinned
- * is basically no so long. But we should fix this?
+ * ProcWaitForSignal() can also wake up for unrelated reasons, so
+ * recheck later whether cleanup can proceed.
+ */
+ ProcWaitForSignal(WAIT_EVENT_BUFFER_PIN);
+
+ /*
+ * Once the reference count is 1, the waiter process itself is the
+ * only backend pinning the buffer at the moment. There is a chance to
+ * lock the buffer exclusively.
*/
- SendRecoveryConflictWithBufferPin(PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK);
+ if (BufferIsReadyForCleanup(bufid + 1))
+ break;
+
+ if (got_standby_delay_timeout)
+ {
+ SendRecoveryConflictWithBufferPin(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN);
+ break;
+ }
+ else if (got_standby_deadlock_timeout)
+ {
+ /*
+ * Send out a request for hot-standby backends to check themselves
+ * for deadlocks.
+ *
+ * XXX The subsequent ResolveRecoveryConflictWithBufferPin() will
+ * wait to be signaled by UnpinBuffer() again and send a request
+ * for deadlocks check if deadlock_timeout happens. This causes
+ * the request to continue to be sent every deadlock_timeout until
+ * the buffer is unpinned or ltime is reached. This would increase
+ * the workload in the startup process and backends. In practice
+ * it may not be so harmful because the period that the buffer is
+ * kept pinned is basically no so long. But we should fix this?
+ */
+ SendRecoveryConflictWithBufferPin(PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK);
+ break;
+ }
}
/*
diff --git a/src/include/storage/bufmgr.h b/src/include/storage/bufmgr.h
index 41fdc1e7693..b30723d8129 100644
--- a/src/include/storage/bufmgr.h
+++ b/src/include/storage/bufmgr.h
@@ -285,6 +285,7 @@ extern void DropDatabaseBuffers(Oid dbid);
extern bool BufferIsPermanent(Buffer buffer);
extern XLogRecPtr BufferGetLSNAtomic(Buffer buffer);
+extern bool BufferIsReadyForCleanup(Buffer buffer);
extern void BufferGetTag(Buffer buffer, RelFileLocator *rlocator,
ForkNumber *forknum, BlockNumber *blknum);
--
2.43.0
