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From: Daniele Varrazzo <[email protected]>
To: Akshay Joshi <[email protected]>
Cc: [email protected]
Subject: Re: psycopg2 conn.poll() hangs when used with sshtunnel
Date: Tue, 30 Oct 2018 14:26:38 +0000
Message-ID: <CA+mi_8Yy5OswpaBH_PTegjs5WS_=nr4VJNGenk7tBJW+wA_Qxg@mail.gmail.com> (raw)
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On Tue, Oct 30, 2018 at 1:55 PM Akshay Joshi <[email protected]>
wrote:

> Hi
>
> On Tue, 30 Oct 2018, 19:17 Daniele Varrazzo <[email protected]
> wrote:
>
>> It seems to me that the problem is in pqpath.c pq_get_last_result()
>> function. The loop assumes PQgetResult won't block, which seems always the
>> case with the direct connection, but PQisBusy() actually returns 1
>> connecting through the tunnel.
>>
>> So at a first read, the simplification given by pq_get_last_result() is
>> broken: the results should be returned one by one in the normal loop going
>> through PQisBusy(), PQconsumeInput(), and the polling machinery. It seems a
>> chunky refactoring but as it is now I don't like pq_get_last_result()
>> anymore :(
>>
>
>     What changes should I made to fix this? Or it should be fixed in
> psycopg2 itself.
>

It is a problem in psycopg. I have a quick fix I can release with the next
bugfix if it shows no regression (
https://github.com/psycopg/psycopg2/issues/801). A better fix requires a
non trivial rewrite of the async and green paths (
https://github.com/psycopg/psycopg2/issues/802): I'd like to do it but it
may happen later if the band aid holds.

I was just about to prepare the 2.7.6 release, so if the quick fix is easy
and doesn't cause regressions it will be released soon.

-- Daniele


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