[pgpool-hackers: 1793] Re: Problem with locking in In Memory Cache

[Tatsuo Ishii]

Glad to hear that! Thank for feedback.

The patch will be included in the next releases.

Best regards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp

> Ishii-san,
> 
> Many thanks for patching.
> The patch work fine.
> 
> Best regards,
> ---
> Dang Minh Huong
> NEC Solution Innovators, Ltd.
> http://www.nec-solutioninnovators.co.jp/en/
> 
>> -----Original Message-----
>> From: Tatsuo Ishii [mailto:ishii at sraoss.co.jp]
>> Sent: Tuesday, September 06, 2016 8:06 AM
>> To: Dangminh Huong(ダンＭ フーン) <huo-dangminh at ys.jp.nec.com>;
>> Yanagisawa Hiroshi(柳澤 博) <hir-yanagisawa at ut.jp.nec.com>;
>> pgpool-hackers at pgpool.net
>> Subject: Re: [pgpool-hackers: 1789] Re: Problem with locking in In
>> Memory Cache
>> 
>> You are right. Pgpool-II should have fowarded sync message from
>> frontend to backend. Attached is a patch against 3.4 stable tree.
>> 
>> Best regards,
>> --
>> Tatsuo Ishii
>> SRA OSS, Inc. Japan
>> English: http://www.sraoss.co.jp/index_en.php
>> Japanese:http://www.sraoss.co.jp
>> 
>> > Thank you for the report. I will look into this.
>> >
>> > Best regards,
>> > --
>> > Tatsuo Ishii
>> > SRA OSS, Inc. Japan
>> > English: http://www.sraoss.co.jp/index_en.php
>> > Japanese:http://www.sraoss.co.jp
>> >
>> >> Hi,
>> >>
>> >> I have found a problem with table locking In In Memory Cache feature.
>> >> Confirmed in pgpool-II 3.4.8 in both memcached and sharedmemory
>> mode.
>> >>
>> >> When using JDBC to access to pgpool-II. In the second time of (the
>> same) query
>> >> executing, it returned result from cached, but after that
>> pg_stat_activity's state of query
>> >> was still in 'active' and not change.
>> >> So the locks made by executed query was not release too.
>> >>
>> >> Take a look at source and i found that, in extended protocol, locking
>> of table
>> >> was made when 'P'(Parse) message is sent, and release when 'S'(Sync)
>> message
>> >> is sent to backend.
>> >> But when memory_cache_enabled is true. Parse message is sent but
>> Sync message
>> >> is not sent to backend.
>> >> In pool_fetch_from_memory_cache function. It sound that when cache
>> found,
>> >> Sync message from frontend was discard but not forward to backend
>> to finish query.
>> >> I think, it is necessary to tell to backend to finish executed query
>> here, is that right?
>> >>
>> >> Best regards,
>> >> ---
>> >> Dang Minh Huong
>> >> NEC Solution Innovators, Ltd.
>> >> http://www.nec-solutioninnovators.co.jp/en/
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