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Hi guys,


I have a big problem here. Very often my unit tests fail. I have asked
about this problem some time ago - but couldn't find that thread
anymore...

I have upgrade couchdb to 1.2.0 and run Wireshark to locate the problem.


Ok. I am uploading my design documents before each unit tests.
Sometimes (about 1 in 100) I get an 409 from couchdb.

The problem is, that there are two PUTs instead of just one. Of course
the second one fails with a 409.

But my client is *not* aware that it is sending the request twice.


Here is the relevant part of the couchdb.log:


[Sat, 26 May 2012 09:52:59 GMT] [info] [<0.23835.0>] 127.0.0.1 - - GET
/collustra_test$attachments/_design/rating 404
[Sat, 26 May 2012 09:52:59 GMT] [debug] [<0.23835.0>] httpd 404 error
response:
 {"error":"not_found","reason":"missing"}

[Sat, 26 May 2012 09:52:59 GMT] [debug] [<0.23813.0>] 'PUT'
/collustra_test$attachments/_design/rating {1,1} from "127.0.0.1"
Headers: [{'Accept',"text/html, image/gif, image/jpeg, *; q=.2, */*;
q=.2"},
          {'Connection',"keep-alive"},
          {'Content-Length',"4910"},
          {'Content-Type',"text/plain"},
          {'Host',"localhost:5984"},
          {"Millis","1338025979060"},
          {'User-Agent',"Java/1.6.0_26"}]
[Sat, 26 May 2012 09:52:59 GMT] [debug] [<0.23813.0>] OAuth Params: []
[Sat, 26 May 2012 09:52:59 GMT] [debug] [<0.23836.0>] 'PUT'
/collustra_test$attachments/_design/rating {1,1} from "127.0.0.1"
Headers: [{'Accept',"text/html, image/gif, image/jpeg, *; q=.2, */*;
q=.2"},
          {'Connection',"keep-alive"},
          {'Content-Length',"4910"},
          {'Content-Type',"text/plain"},
          {'Host',"localhost:5984"},
          {"Millis","1338025979060"},
          {'User-Agent',"Java/1.6.0_26"}]
[Sat, 26 May 2012 09:52:59 GMT] [debug] [<0.23836.0>] OAuth Params: []
[Sat, 26 May 2012 09:52:59 GMT] [info] [<0.23813.0>] 127.0.0.1 - - PUT
/collustra_test$attachments/_design/rating 201
[Sat, 26 May 2012 09:52:59 GMT] [debug] [<0.23836.0>] Minor error in
HTTP request: conflict
[Sat, 26 May 2012 09:52:59 GMT] [debug] [<0.23836.0>] Stacktrace:
[{couch_db,update_doc,4,
                                    [{file,

"/tmp/a/build-couchdb/dependencies/couchdb/src/couchdb/couch_db.erl"},
                                     {line,429}]},
                                   {couch_httpd_db,update_doc,6,
                                    [{file,

"/tmp/a/build-couchdb/dependencies/couchdb/src/couchdb/couch_httpd_db.erl"},
                                     {line,931}]},
                                   {couch_httpd_db,do_db_req,2,
                                    [{file,

"/tmp/a/build-couchdb/dependencies/couchdb/src/couchdb/couch_httpd_db.erl"},
                                     {line,230}]},
                                   {couch_httpd,handle_request_int,5,
                                    [{file,

"/tmp/a/build-couchdb/dependencies/couchdb/src/couchdb/couch_httpd.erl"},
                                     {line,317}]},
                                   {mochiweb_http,headers,5,
                                    [{file,

"/tmp/a/build-couchdb/dependencies/couchdb/src/mochiweb/mochiweb_http.erl"},
                                     {line,136}]},
                                   {proc_lib,init_p_do_apply,3,
                                    [{file,"proc_lib.erl"},{line,227}]}]
[Sat, 26 May 2012 09:52:59 GMT] [info] [<0.23836.0>] 127.0.0.1 - - PUT
/collustra_test$attachments/_design/rating 409
[Sat, 26 May 2012 09:52:59 GMT] [debug] [<0.23836.0>] httpd 409 error
response:
 {"error":"conflict","reason":"Document update conflict."}

[Sat, 26 May 2012 09:52:59 GMT] [debug] [<0.23837.0>] 'GET'
/collustra_test$attachments {1,1} from "127.0.0.1"
Headers: [{'Accept',"text/html, image/gif, image/jpeg, *; q=.2, */*;
q=.2"},
          {'Connection',"keep-alive"},
          {'Host',"localhost:5984"},
          {'User-Agent',"Java/1.6.0_26"}]


Now that seems to be very obvious...
But: On the client side I see just *1* PUT. I am using Jersey Client
API (Java).

Wiresharks shows that there are - in fact - two PUT.
But there is *no* response on the first PUT. Instead there are several
TCP errors (RST, ACK).

http://pastebin.com/17jV8MnA


So I have:

Client (Jersey): PUT
Wireshark: PUT, Errors but no response, PUT, response
CouchdB: PUT, (No Response?), PUT, Response



So I think the problem is, that the response to the first PUT is lost
somewhere - but executed successfully. And my client resends the
request and gets the 409...

So my question is basically: Does anybody have an idea how/why the
response is lost?



Thanks,

Johannes

- -- 
Johannes Schneider - blog.cedarsoft.com
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