Neo4j server seems to drop connection when processing for 200 seconds

Question

I've been writing a Neo4j server extension (as described here, i.e. a managed server extension: http://docs.neo4j.org/chunked/stable/server-plugins.html). It should just get a string via POST (which in productivity would hold information the extension should process, but this is of no further concern here). It tried the extension with Neo4j 1.8.2 and 1.9.RC2, the outcome was the same.

Now my problem is that sometimes this extension does quite a lot of work which can take a couple of minutes. However, after exactly 200 seconds, the connection gets lost. I'm not absolutely sure what is happening, but it seems the server is dropping the connection.

To verify this behavior, I wrote a new, almost empty server extension which does nothing else but to wait 5 minutes (via Thread.sleep()). From a test-client-class, I POST some dummy data. I tested with Jersey, Apache HTTPcomponents and plain Java URL connections. Jersey and plain Java do a retry after exactly 200 seconds, the HTTPcomponents throw " org.apache.http.NoHttpResponseException: The target server failed to respond".

I think it's a server issue, first because the exception seems to stand for that in this context (there's a comment saying that in the httpcomponent's code) and second because when I set connection timeout and/or socket timeout to lower values than 200 seconds, I get just normal timeout exceptions.

Now there's one thing on top of that: I said I would POST some data. Seemingly this whole behavior depends on the amount of data sent. I pinned it down so far I can say, when sending a string of length ca. 4500 characters, the described behavior does NOT happen, but everything is alright and I get an HTTP 204 "no content" response which is correct. As soon as I send ca. 6000 characters or more, the mentioned connection drop occurs. The string I'm sending here is only dummy data. The sent string is only a sequence of 'a', i.e. "aaaaaaaa..." created with a for loop with 4500 or 6000 iterations, respectively.

In my productive code I would really like to wait until the server operation has finished, but I don't how to prevent the connection drop.

Is there an option on the Neo4j server to configure (I looked but didn't find anything) or isn't it the server's fault and my clients do something wrong? A bug somewhere?

Thanks for reading and any help or hints!

Not sure but I guess there is either some Jersey config option or it is a setting of the operating system. — Stefan Armbruster, May 10 '13 at 21:11
Hm, is there such a Jersey server side option? Couldn't find one. Which web server technology is Neo4j Server using anyway? Plain Jersey or some kind of embedded Jetty or...? — khituras, May 11 '13 at 13:37
Argh, sorry. I've meant Jetty in my previous comment. Jetty is used internally of course. — Stefan Armbruster, May 11 '13 at 16:51

score 0 · Answer 1 · answered Jun 15 '15 at 14:28

Just to wrap this up: I eventually found out that there exists a default timeout constant in Jetty (version 6.x was used by Neo4j back then, I think) set to exactly 200 seconds. This could be changed using the Jetty API but the Neo4j server did not appear to offer any possibility to configure this. Changing to Neo4j 2.x eventually solved the issue (why exactly is unknown). With those newer version of Neo4j the issue did not come up anymore.

Neo4j server seems to drop connection when processing for 200 seconds

1 Answers1