[pgpool-general: 297] Re: lots of errors: kind does not match between master

[Tatsuo Ishii]

>>> I'm running pgpool-II-3.1.2 on a Linux-x86_64 server, doing load
>>> balancing for a postgresql-9.04 cluster, that has 1 master, and two
>>> streaming replication slaves.  Over the past few weeks, I've noticed
>>> the following errors appearing in the pgpool log with increasing
>>> frequency.  At this point, they're appearing at a rate of nearly 1
>>> every other second:
>>> 2012-03-25 14:33:31 ERROR: pid 24101: pool_read_kind: kind does not
>>> match between master(45) slot[1] (52)
>>> 2012-03-25 14:33:31 LOG:   pid 24101: pool_read_kind: error message
>>> from master backend:sorry, too many clients already
>>
>> Do you see the same error in PostgreSQL master's log?
> 
> Yes, I do see it there as well, although all of the client connections
> are going through pgpool, nothing connects directly to the master.

You set max_connections=200 in your postgresql.conf. Unless you
customize superuser_reserved_connections, actual number of connections
pgpool can use is 200 -3 = 197 because the default of
superuser_reserved_connections is 3. You have num_init_children = 195
in pgpool.conf so the mergin is 197 - 195 = 2. If your master
PostgreSQL is busy, disconnecting from pgpool to PostgreSQL may take
some time, and actual number of connections from pgpool to PostgreSQL
might exceed temporarily 197. So I'd suggest to increase
max_connections of master a little bit if you want to avoid the error
message.
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
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