Hi Amit and Andres,
Here's updated patch
On Mon, Aug 9, 2021 at 11:14 AM Ashutosh Bapat <
ashutosh.ba...@enterprisedb.com> wrote:
>
>
> On Sat, Aug 7, 2021 at 11:40 AM Andres Freund <and...@anarazel.de> wrote:
>
>> Hi,
>>
>> On 2021-07-12 17:28:15 +0530, Ashutosh Bapat wrote:
>> > On Mon, Jul 12, 2021 at 8:39 AM Amit Kapila <amit.kapil...@gmail.com>
>> wrote:
>> >
>> > > On Mon, Jul 5, 2021 at 12:54 PM Masahiko Sawada <
>> sawada.m...@gmail.com>
>> > > Today, again looking at this patch, I don't think doing elog inside
>> > > spinlock is a good idea. We can either release spinlock before it or
>> > > use some variable to remember that we need to write such an elog and
>> > > do it after releasing the lock. What do you think?
>> >
>> >
>> > The elog will be effective only under DEBUG1, otherwise it will be
>> almost a
>> > NOOP. I am wondering whether it's worth adding a bool assignment and
>> move
>> > the elog out only for DEBUG1. Anyway, will defer it to you.
>>
>> It's *definitely* not ok to do an elog() while holding a spinlock.
>> Consider
>> what happens if the elog tries to format the message and runs out of
>> memory. Or if elog detects the stack depth is too deep. An ERROR would be
>> thrown, and we'd loose track of the held spinlock.
>>
>
> Thanks for the clarification.
>
> Amit,
> I will provide the patch changed accordingly.
>
> --
> Best Wishes,
> Ashutosh
>
--
--
Best Wishes,
Ashutosh
From 0a2f2c1f530d72219d9db7bd1ff77c1ae8c4ffe4 Mon Sep 17 00:00:00 2001
From: Ashutosh Bapat <ashutosh.ba...@2ndquadrant.com>
Date: Thu, 13 May 2021 13:40:33 +0530
Subject: [PATCH] Report new catalog_xmin candidate in
LogicalIncreaseXminForSlot()
Similar to LogicalIncreaseRestartDecodingForSlot() add a debug message
to LogicalIncreaseXminForSlot() reporting a new catalog_xmin candidate.
---
src/backend/replication/logical/logical.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 64b8280c13..6c8c387e73 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -1565,6 +1565,7 @@ LogicalIncreaseXminForSlot(XLogRecPtr current_lsn, TransactionId xmin)
{
bool updated_xmin = false;
ReplicationSlot *slot;
+ bool got_new_xmin = false;
slot = MyReplicationSlot;
@@ -1602,12 +1603,22 @@ LogicalIncreaseXminForSlot(XLogRecPtr current_lsn, TransactionId xmin)
{
slot->candidate_catalog_xmin = xmin;
slot->candidate_xmin_lsn = current_lsn;
+
+ /*
+ * Add a line about new xmin in server logs at an appropriate log level
+ * after releasing the spinlock.
+ */
+ got_new_xmin = true;
}
SpinLockRelease(&slot->mutex);
/* candidate already valid with the current flush position, apply */
if (updated_xmin)
LogicalConfirmReceivedLocation(slot->data.confirmed_flush);
+
+ if (got_new_xmin)
+ elog(DEBUG1, "got new catalog_xmin %u at %X/%X", xmin,
+ LSN_FORMAT_ARGS(current_lsn));
}
/*
--
2.25.1
