Hi, As per the bug report at https://www.postgresql.org/message-id/20170921010956.17345.61461%40wrigleys.postgresql.org it seems that the query cancellation holdoff logic in ProcessInterrupts is a bit overly aggressive in keeping other interrupts from running.
In particular I've seen an issue in the wild where
idle_in_transaction_session_timeout did not get triggered because
the HOLD_CANCEL_INTERRUPTS() in SocketBackend wraps around a pq_getbyte()
call, and so ProcessInterrupts doesn't do anything when it gets called
because the query cancel holdoff counter is positive.
Andres suggested the following re-ordering of the logic on -bugs:
> On Wed, Sep 20, 2017 at 6:29 PM, Andres Freund <and...@anarazel.de> wrote:
>>
>>
>> if (QueryCancelPending && QueryCancelHoldoffCount != 0)
>> {
>> /* rearm */
>> }
>> else if (QueryCancelPending)
>> {
>> /* handle interrupt */
>> }
>>
>
Which is implemented in the attached patch.
Unless someone wants to pick this up right away, I'll register it in the
next commitfest tomorrow.
Best,
Lukas
--
Lukas Fittl
0001-Only-skip-query-cancel-itself-when-query-cancel-hold.patch
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