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Re: [BUGS] BUG #14821: idle_in_transaction_session_timeout sometimesgets ignored when statement timeout is pending - Mailing list pgsql-bugs

From Lukas Fittl
Subject Re: [BUGS] BUG #14821: idle_in_transaction_session_timeout sometimesgets ignored when statement timeout is pending
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Msg-id CAP53PkxQnv3OWJpyNPGJYT62uY=n1=2CF_Lpc6gVOFnc0-gazw@mail.gmail.com
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Responses Re: [HACKERS] Re: [BUGS] BUG #14821:idle_in_transaction_session_timeout sometimes gets ignored when statementtimeout is pending
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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 <andres@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
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