[pgpool-general: 951] Re: Query Memory Cache goes OOM

[Tatsuo Ishii]

I couldn't reproduce your problem here.
Can you try to run with valgrind to detect memory leak?
Just in case how to use valgrind:

1) start pgpool by following command
   valgrind --trace-children=yes --leak-check=full pgpool [your pgpool options here...]
   Note that you need to -n option of pgpool and redirect pgpool log to somewhere.

2) stop pgpool.

3) send pgpool log.
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese: http://www.sraoss.co.jp

> Hi all,
> 
> I'm testing the new query cache (pgpool-II version 3.2.0) on CentOS 5.
> 
> System Specs:
> 4 cores
> 4 GB Ram
> 
> shmmax= 2147483648 (=2 GB)
> 
> When I start pgpool, my memory usage looks like this:
> 
> Mem: 4194304k total, 660016k used, 3534288k free, 62116k buffers
> 
> My test scenario is the following:
> 
> # Config:
> 
> memory_cache_enabled = on
> memqcache_method = 'shmem'
> memqcache_total_size =  262144000 #250MB
> memqcache_max_num_cache = 10
> memqcache_expire = 15
> memqcache_auto_cache_invalidation = off
> memqcache_maxcache = 409600 #400kb
> memqcache_cache_block_size = 1048576 #1MB
> memqcache_oiddir = '/var/log/pgpool/oiddir'
> 
> Table: data
> id integer pkey
> value character varying(255)
> [some more columns]
> 
> SELECT value FROM data WHERE id =${randomNumber};
> 
> so when I start the first
> while true; do psql -c "foobar ..." ; sleep 1; done
> 
> everything looks good. When I start 9 more loops (= 10 selects per
> second), the used memory increases fast. After ~2 minutes it looks
> like this:
> 
> Mem: 4194304k total, 2439012k used, 1755292k free, 62588k buffers
> 
> after 2 more minutes:
> 
> Mem: 4194304k total, 4053796k used, 140508k free, 62752k buffers
> 
> When I add more clients, the machine begins to swap and dies.
> 
> show pool_cache gives:
> 
>  num_cache_hits | num_selects | cache_hit_ratio | num_hash_entries |
>  used_hash_entries | num_cache_entries | used_cache_enrties_size |
>  free_cache_entries_size | fragment_cache_entries_size
> ----------------+-------------+-----------------+------------------+-------------------+-------------------+-------------------------+----------------------
> ---+-----------------------------
>  0 | 1527 | 0.00 | 16 | 15 | 15 | 1746 | 262142254 | 0
> (1 row)
> 
> So my question:
> 
> What I'm doing wrong? The plan is to connect more Frontends with 300+
> statements per second.
> When I turn memory_cache_enabled off the problem does not occur.
> 
> Thanks in advance!
> 
> Sebastian
> 
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