From: | Fujii Masao <masao(dot)fujii(at)oss(dot)nttdata(dot)com> |
---|---|
To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
Cc: | Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>, 蔡梦娟(玊于) <mengjuan(dot)cmj(at)alibaba-inc(dot)com>, pgsql-hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Andres Freund <andres(at)anarazel(dot)de> |
Subject: | Re: Queries that should be canceled will get stuck on secure_write function |
Date: | 2021-08-25 01:58:52 |
Message-ID: | 968dc403-6d5d-30ef-b2ec-0227786b7191@oss.nttdata.com |
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Lists: | pgsql-hackers |
On 2021/08/25 2:30, Robert Haas wrote:
> Hmm, maybe you're right. What about pg_cancel_backend()?
I was thinking that it's valid even if secure_write() doesn't react to
pg_cancel_backend() because it's basically called outside transaction block,
i.e., there is no longer transaction to cancel in that case. But there can be
some cases where secure_write() is called inside transaction block,
for example, when the query generates NOTICE message. In these cases,
secure_write() might need to react to the cancel request.
BTW, when an error happens, I found that a backend calls EmitErrorReport()
to report an error to a client, and then calls AbortCurrentTransaction()
to abort the transaction. If secure_write() called by EmitErrorReport()
gets stuck, a backend gets stuck inside transaction block and the locks
keep being held unnecessarily. Isn't this problematic? Can we change
the order of them?
Regards,
--
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION
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