[pgpool-general: 953] Re: Query Memory Cache goes OOM

[Sebastian Kornehl]

Hi,

I attached the log file.

Thanks for your Help!

Sebastian

On 09/05/2012 04:23 AM, Tatsuo Ishii wrote:
> 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
>>
>> _______________________________________________
>> pgpool-general mailing list
>> pgpool-general at pgpool.net
>> http://www.pgpool.net/mailman/listinfo/pgpool-general

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