Re: Enhancing Memory Context Statistics Reporting

From: Daniel Gustafsson <daniel(at)yesql(dot)se>
To: Rahila Syed <rahilasyed90(at)gmail(dot)com>
Cc: torikoshia <torikoshia(at)oss(dot)nttdata(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Enhancing Memory Context Statistics Reporting
Date: 2026-01-12 13:31:38
Message-ID: 43D5E807-AC37-4136-85FD-15B6F1BEF840@yesql.se
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> On 9 Jan 2026, at 12:22, Rahila Syed <rahilasyed90(at)gmail(dot)com> wrote:

> After further discussion and reviewing Robert's email[1] on this topic, a safer solution
> is to avoid running ProcessGetMemoryContextInterrupt during an aborted transaction.
> This should help prevent additional errors when the transaction is already in error handling
> state. Also, reporting memory context statistics from an aborting transaction won't
> be very useful as some of that memory usage won't be valid after abort completes.

+1, I think was the right call to make.

> Attached is the updated patch that addresses this.

A few small comments on v47:

+static const char *ContextTypeToString(NodeTag type);
I think context_type_to_string() would be a better name on this internal
function to model it closer to the existing int_list_to_array(). Personally I
would also place it before its first use to avoid the prototype, but that's
personal preference.

+static void
+memstats_dsa_cleanup(char *key)
This function warrants a documentation comment describing when it should be
used safely.

+ memstats_dsa_cleanup(key);
+ memstats_client_key_reset(procNumber);
+ ConditionVariableCancelSleep();
+ PG_RETURN_NULL();
I think we should notify the user in these two timeout cases, why not adding an
ereport(NOTICE, "request for memory context statistics timed out")); or
something with a better wording than that.

+ Size sz = 0;
+ Size TotalProcs = 0;
+
+ TotalProcs = add_size(TotalProcs, NUM_AUXILIARY_PROCS);
+ TotalProcs = add_size(TotalProcs, MaxBackends);
+ sz = add_size(sz, mul_size(TotalProcs, sizeof(int)));
+
+ return sz
As we discussed off-list, the call to add_size() call can be omitted as it
won't affect the calculation.

+# Copyright (c) 2025, PostgreSQL Global Development Group
Here, and possibly elsewhere, it should say 2026 instead I think.

--
Daniel Gustafsson

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