Re: timeout hitting a database url after launching compaction

[CGS]

I am not developer, but it's quite logic, I may say. Once you started 
the compaction, your CouchDB is not responsive while the database is 
preparing for compaction. Triggering immediately GET, the web instance 
responds with status code 500 (internal server error, meaning 
unresponsive server in this case). So, nothing unusual in my opinion.

Cheers,
CGS



On 10/17/2011 09:57 AM, Paolo Negri wrote:
IO activity is not monitored, there's only one db on the couchdb
instance and the described job is the only activity executed on this
machine.
Delaying the first request on the database url by 30 seconds did
actually prevent the problem from happening again.
So the issue seems to happen specifically at the moment right after
compaction is started.
The database is about 7GB big once compressed, the server is hosted on
ec2 with the database directory placed on his own dedicated ephemeral
storage.

Thanks,

Paolo

On Fri, Oct 14, 2011 at 9:05 PM, Paul Davis<paul.joseph.da...@gmail.com>  wrote:
Do you monitor IO activity or system responsiveness when you're doing
this. I've seen some compactions wallop a system when it switches over
due to removing large old files and such. It doesn't sound like this
is big enough for that case but it might be something worth checking.

On Fri, Oct 14, 2011 at 3:41 AM, Paolo Negri<paolo.ne...@wooga.net>  wrote:
Dear list,

We have a script that does the following (strictly sequentially)

1) update 300K docs in a db
2) launch compaction of the db
3) poll at a 30 sec frequency http://127.0.0.1:5984/database to know
when compaction completed

Last night we got a timeout error during 3, we think that this might
be because the first polling (GET  http://127.0.0.1:5984/database) is
done right after triggering compaction

I thought the dev team might be interested in knowing that this is happening

There's no other activity on the couchdb instance other than what
described in this email.

ERROR unexpectd response checking compaction db: {ok,"500",
                                                 [{"Server",

"CouchDB/1.3.0a-74613f5-git (Erlang OTP/R14B04)"},
                                                  {"Date",
                                                   "Fri, 14 Oct 2011
01:46:37 GMT"},
                                                  {"Content-Type",
                                                   "text/plain; charset=utf-8"},
                                                  {"Content-Length","350"},
                                                  {"Cache-Control",
                                                   "must-revalidate"}],

<<"{\"error\":\"{timeout,{gen_server,call,[<0.21934.9>,{open_ref_count,<0.4090.13>}]}}\",\"reason\":\"{gen_server,call,\\n
   [couch_server,\\n     {open,<<\\\"backup\\\">>,\\n
[{user_ctx,\\n              {user_ctx,null,\\n
[<<\\\"_admin\\\">>],\\n<<\\\"{couch_httpd_auth,
default_authentication_handler}\\\">>}}]},\\n     infinity]}\"}\n">>}


Thanks,

Paolo