How to configure keep-alive timeout in playframework 2

Question

I use playframework 2.0 in production and I see a rapidly growing number of files open by the corresponding java process. I changed the default allowed number of open files for a process from 1024 to 4096, but this just delays a problem and after some time the number of open files becomes so big, that the server slows down and sometimes even a java.net.SocketException "too many open files" appears in a log.

I use ubuntu server 12.04, sun jdk 1.7.0_09.

lsof command demonstrates that almost all of open files are sockets created for user connections, so I make a conclusion that the Netty server that is used by playframework keeps alive a lot of open connections. As far as I understand I should change the keep-alive behaviour of the Netty server, for example, to set a low keep-alive timeout. How can I configure this in playframework 2.0? Or may be the problem is in something else? I can provide any configuration if needed.

UPD: here is a bit of output of lsof -aPn -p 12251. I censored some parts of ips with ***

COMMAND   PID USER   FD   TYPE             DEVICE SIZE/OFF   NODE NAME
java    12251 root  324u  IPv6             279502      0t0    TCP 10.127.0.***:80->***.***.65.137:51506 (ESTABLISHED)
java    12251 root  325u  IPv6             286749      0t0    TCP 10.127.0.***:80->***.***.18.121:1624 (ESTABLISHED)
java    12251 root  327u  IPv6             287220      0t0    TCP 10.127.0.***:80->***.***.126.210:49244 (ESTABLISHED)
java    12251 root  330u  IPv6             279289      0t0    TCP 10.127.0.***:80->***.***.65.155:12444 (ESTABLISHED)
java    12251 root  331u  IPv6             285609      0t0    TCP 10.127.0.***:80->***.***.33.233:2552 (ESTABLISHED)
java    12251 root  332u  IPv6             285610      0t0    TCP 10.127.0.***:80->***.***.33.233:2554 (ESTABLISHED)
java    12251 root  333u  IPv6             287236      0t0    TCP 10.127.0.***:80->***.***.90.20:16040 (ESTABLISHED)
java    12251 root  334u  IPv6             284047      0t0    TCP 10.127.0.***:80->***.***.195.2:1175 (ESTABLISHED)
java    12251 root  335u  IPv6             279357      0t0    TCP 10.127.0.***:80->***.***.65.137:51273 (ESTABLISHED)
java    12251 root  336u  IPv6             279988      0t0    TCP 10.127.0.***:80->***.***.65.137:51287 (ESTABLISHED)

Answer 1

If you're using Play without any HTTP server you can manipulate the response headers before sending the Result (Scala version) , otherwise you need to check settings of the front-end server.

response().setHeader(CONNECTION, "Keep-Alive");
response().setHeader("Keep-Alive", "timeout=3, max=10");
return ok(index.render());

Note, that these values are sample and I don't know if they will fit your needs.