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From "Herman Chan" <herman...@gmail.com>
Subject Re: max_dbs_open and idle db
Date Wed, 25 Jun 2014 18:01:51 GMT
A follow up question.

We have around 90K+ databases on our server.  We used to set 
max_dbs_open to 100K, our server was reaching a pretty high memory usage 
(~90%) of 68GB.  So we decided to half the max_dbs_open to 50K thinking 
that not all database is open/access all the time.  Doing that did take 
our memory usage down but now that we see there is a lot of opening and 
closing index in our log file.  Does that happen when couch is trying to 
close some db?

If that's the case, it is surprising for us since when we are listening 
to the change feed, only ~2000 dbs is being changed at all time.  Does 
couch reference to a database even there is no client attached to it?

Thanks,
Herman

On 24 Jun 2014, at 11:12, Alexander Shorin wrote:

> Database considered idle by active references to it and by related
> active operations (like compaction):
> https://github.com/apache/couchdb/blob/master/src/couchdb/couch_db.erl#L1115
> CouchDB uses LRU cache to manage opened databases and frees idle by 
> demand:
> https://github.com/apache/couchdb/blob/master/src/couchdb/couch_server.erl#L490
> leads to:
> https://github.com/apache/couchdb/blob/master/src/couchdb/couch_server.erl#L261
>
> There is nothing need to be configured.
> --
> ,,,^..^,,,
>
>
> On Tue, Jun 24, 2014 at 7:01 PM, Herman Chan <hermanccw@gmail.com> 
> wrote:
>> Hi there,
>>
>> In the description of max_db_open, it says "CouchDB reference counts
>> database accesses internally and will close idle databases when it 
>> must."  I
>> was wondering what's consider idle in couchdb and if the idle time is
>> configurable?
>>
>> Herman

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