[pgpool-hackers: 2241] Re: [pgpool-committers: 3836] pgpool: Branch refs/heads/bug271 was created

[Tatsuo Ishii]

> Tatsuo,
> 
> 
> the symptoms of the "hanged" pgpool are following:
> 1) DB applications fail with 2 types of errors:
>   - failed to prepare statement (PARSE)
>   - failed to extract ResultSet - failed selects
> 
> 2) The problem is reproduced within a single JDBC connection, series of transactions are passed into it before the problem appears.
> 
> I'm deeply analysed pgpool logs from the series of failures and revealed a sample case (i.e. pgpool process). It's logs are attached.
> I'm not sure I'm right but it seems the balancing logic is broken it its sequence of messages - how the are processed. I'am triggered by the fact it was sending PARSE messages to the both backends.

Please provide a reproducable test case. I do not see any error
message in the log.

> P/S: I was trying to attach the debugger to pgpool but I'm failed to detect a piece of code which I should focus at. Also it is a little bit hard to detect a pgpool process which should be debugged.

Use ps to find a pgpool process which shows 'idle' state. Or you could
set num_init_children to 1. In this case there's only one pgpool child
process.

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

> Sergey.
> ________________________________
> From: Sergey Kim
> Sent: Wednesday, April 5, 2017 1:48 PM
> To: Tatsuo Ishii
> Cc: Boris Voskanov; pgpool-hackers at pgpool.net; Sergey Onuchin
> Subject: Re: [pgpool-hackers: 2227] Re: [pgpool-committers: 3836] pgpool: Branch refs/heads/bug271 was created
> 
> 
> ... also it happens only when balancing is enabled in pgpool.
> 
> 
> ________________________________
> From: Sergey Kim
> Sent: Wednesday, April 5, 2017 1:34:45 PM
> To: Tatsuo Ishii
> Cc: Boris Voskanov; pgpool-hackers at pgpool.net; Sergey Onuchin
> Subject: Re: [pgpool-hackers: 2227] Re: [pgpool-committers: 3836] pgpool: Branch refs/heads/bug271 was created
> 
> 
> Tatsuo,
> 
> 
> the 2nd day of tests revealed a problem in pgpool which I trying to reproduce in a standalone test.
> 
> 
> Sometimes PARSE messages hang in pgpool and DB clients hang due to this reason. I'm just wanted to notify you on the problem. I'm fighting to reproduce it artificially.
> 
> 
> Sergey.
> 
> 
> ...the primary message was cut