From: | Michael Paquier <michael(dot)paquier(at)gmail(dot)com> |
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To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp>, Fujii Masao <masao(dot)fujii(at)gmail(dot)com>, PostgreSQL mailing lists <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Cannot shutdown subscriber after DROP SUBSCRIPTION |
Date: | 2017-02-02 05:36:52 |
Message-ID: | CAB7nPqSEnBZ0vbLs9dMdXgiHMeu_=wxeuAgRzstNkHwUJSu6aw@mail.gmail.com |
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Lists: | pgsql-hackers |
On Thu, Feb 2, 2017 at 2:13 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp> writes:
>> Then, the reason for the TRY-CATCH cluase is that I found that
>> some functions called from there can throw exceptions.
>
> Yes, but all LWLocks should be released by normal error recovery.
> It should not be necessary for this code to clean that up by hand.
> If it were necessary, there would be TRY-CATCH around every single
> LWLockAcquire in the backend, and we'd have an unreadable and
> unmaintainable system. Please don't add a TRY-CATCH unless it's
> *necessary* -- and you haven't explained why this one is.
Putting hands into the code and at the problem, I can see that
dropping a subscription on a node makes it unresponsive in case of a
stop. And that's just because calls to LWLockRelease are missing as in
the patch attached. A try/catch problem should not be necessary.
--
Michael
Attachment | Content-Type | Size |
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drop-subs-locks.patch | application/octet-stream | 566 bytes |
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