Re: [HACKERS] Re: [BUGS] BUG #14821: idle_in_transaction_session_timeout sometimes gets ignored when statement timeout is pending

[Lukas Fittl]

On Wed, Oct 11, 2017 at 2:11 PM Andres Freund  wrote:

> I've pushed this. Thanks for the report & fix!
>

Excellent, thanks!

Best,
Lukas
-- 
Lukas Fittl

Re: [HACKERS] Re: [BUGS] BUG #14821: idle_in_transaction_session_timeout sometimes gets ignored when statement timeout is pending

[Andres Freund]

Hi,

On 2017-09-20 20:27:05 -0700, Lukas Fittl wrote:
> 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:

I've pushed this. Thanks for the report & fix!

Greetings,

Andres Freund


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[HACKERS] Re: [BUGS] BUG #14821: idle_in_transaction_session_timeout sometimes gets ignored when statement timeout is pending

[Lukas Fittl]

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  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
Description: Binary data

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