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From Dave Cottlehuber <...@jsonified.com>
Subject Re: tinkering with limits while replicating
Date Tue, 05 Feb 2013 18:43:40 GMT
Hi Tibor,

Are you able to share your code? There's not much erlang examples around.

A+
Dave

On 5 February 2013 19:39, Tibor Gemes <tibber@gmail.com> wrote:
> I've rewritten my filters into erlang and the continuous filtered
> replications work faster with a few magnitude. T
> 2013.02.05. 19:23, "Nathan Vander Wilt" <nate-lists@calftrail.com> ezt írta:
>
>> Hi Stephen,
>>
>> I've been doing some tests related to replication lately too
>> (continuous+filtered in my case). I suspect the reason Futon hangs is
>> because your whole VM is running out of RAM due to your very high
>> os_process_limit. I went in to a bit more detail in
>> http://mail-archives.apache.org/mod_mbox/couchdb-dev/201302.mbox/%3c70278F4A-FD08-4818-89B7-EA1B0AF846F5@gmail.com%3ebut
this setting basically determines the size of the couchjs worker pool —
>> you'd probably rather have a bit of contention for the pool at a reasonable
>> size (maybe ~100 per GB free, tops?) than start paging.
>>
>> hth,
>> -natevw
>>
>>
>>
>> On Feb 4, 2013, at 5:15 PM, Stephen Bartell wrote:
>>
>> > Hi all,
>> >
>> > I'm hitting some limits while replicating , I'm hoping someone could
>> advise.
>> > Im running this in a VM on my macbook with the following allocated
>> resources:
>> > ubuntu 11.04
>> > 4 cores @ 2.3ghz
>> > 8 gb mem
>> >
>> > I'm doing a one-to-many replication.
>> > 1) I create one db named test.
>> > 2) Then create [test_0 .. test_99] databases.
>> > 3) I then set up replications from test -> [test_0 .. test_99].  100
>> replications total.
>> > 4) I finally go to test and create a doc, hit save.
>> >
>> > When I hit save, futon becomes completely unresponsive for around 10sec.
>>  It eventually returns to normal behavior.
>> >
>> > Tailing the couchdb log I find waves of the following errors:
>> > [Tue, 05 Feb 2013 00:46:26 GMT] [info] [<0.6936.1>] Retrying POST
>> request to http://admin:*****@localhost:5984/test_25/_revs_diff in 1.0
>> seconds due to error {code,503}
>> >
>> > I see that the replicator is finding the server to be unresponsive.  The
>> waves of these messages show that replicator retries in 0.25 sec, then 0.5
>> sec, then 1sec, then 2sec.  This is expected.  Everything settles done
>> after about 4 retries.
>> >
>> > So my first thought is resource limits.  I threw the book at it and set :
>> > 1) max_dbs_open: 500
>> > 2) os_process_limit: 5000
>> > 3) http_connections: 20000
>> > 4) ulimit -Sn 4096 (the hard limit is 4096)
>> >
>> > I really don't know whats reasonable for these values relative to how
>> many replications I am setting up.  So these values, save max_dbs_open,
>>  are all stabs in the dark.
>> >
>> > No change in performance.
>> >
>> > So, I'm at a loss now.  what can I do to get all this to work? Or what
>> am I doing wrong?  And note that this is only a test.  I aim to quadruple
>>  the amount of replications and have lots and lots of insertions on the so
>> called "test" database.  Actually, there will be several of these
>> one-to-many databases.
>> >
>> > I've heard people get systems up to thousands of dbs and replicators
>> running just fine.  So I hope Im just not offering to right sacrifices up
>> to couchdb yet.
>> >
>> > Thanks for any insight,
>> >
>> > sb
>> >
>>
>>

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