I've got myself an Amazon ec2 Micro Instance (A VPN Server) to play around with.
The problem is that Amazon charges you for every disc IO you do in a Micro Instance.
The instance is running Amazon Linux a flavour of CentOS.
I've started a Scala application in Play 2.0(.2) framework on the server and I'm the only one who connects to the application.
I have observed that every few second something on the server commits IO transactions, to narrow it down I installed a Linux program called iotop.
Here is output after a couple of seconds.
TID PRIO USER DISK READ DISK WRITE SWAPIN IO>
23333 be/4 root 0.00 B/s 11.91 K/s 0.00 % 0.00 %
COMMAND java -Dsbt.ivy.home=/usr/play-2.0.2/framework/../repository -Djava.runtime.name=OpenJDK ~/jars/slf4j-api.jar:/usr/play-2.0.2/repository/local/org.slf4j/jul-to-slf4j/1.6.4/jars/j
A cat from the log file
2012-07-05 11:43:31,881 - [INFO] - from play in main
Listening for HTTP on port 9000...
So Play doesn't write anything to the log file.
The first question have I understood the iotop correct and that Play indeed is the disc IO thief.
If so why do play use IO?
My application is a simple WebSocket example. In essence it echos the input to the output. The IO occurs even thou nothing is pushed thru WebSockets.