I don't suppose that's the developers' choice. That's more like W3C choice when they defined the standard codes. In your case, the code is returned by cURL (or whatever application you use for triggering the predicate GET). I am not so sure the developers can do anything about that because the database file on the disk is replaced with the new database file in which the history is no longer kept (if I understood well the compaction process). The only thing the developers may be able to do is to offer you a 404 code (file not found) during that time. But I suppose that's more alarming then 500. :)

Nevertheless, that's their choice and it's good that you provided this piece of information for the rest of us to know about it and to know how to handle these situations.

Cheers,
CGS



On 10/17/2011 10:29 AM, Paolo Negri wrote:
I agree on the fact that what happens is pretty clear to explain, I
still thought it would be useful for the developers to know since
offering a 500 status code for a known system condition is probably
something that can be improved.

Thanks,

Paolo

On Mon, Oct 17, 2011 at 10:24 AM, CGS<[email protected]>  wrote:
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<[email protected]>
  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<[email protected]>
  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






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