I'm running my application on the single cpu machine in the 100MBit LAN.
Other three workstations in the LAN are emulating multiple clients.
The server uses custom protocol codec filter and custom handler. The
configuration is: manual thread model, one thread for SocketAcceptor, no
ExecutorFilter in the filterchain (because with the ExecutorFilter the total
thread count increases rapidly up tho hundreds!! why?..)
The fifth workstation in the LAN is running test application also emulating
a client and measures server echo response timeout.
The average results are:
1 client - 300 ms
333 cleints - 400-500 ms
666 clients - 1000-1500 ms
1000 clients - strange fluctuations in 7-20 s range
So we can clearly see the problem comes when the client count increases.
After i've thoroughly done the profiling i've managed to eliminate all hot
spots from my own code (anyway, almost nothing changed) and then the
performance has stuck to the
sun.nio.ch.WindowsSelectorImpl$SubSelector.poll0(long, int, int[], int[],
int[], long) method taking 64% of total execution time. It's enourmous
because my own logic thread takes only 16% of total, and the asynchronous
writing thread (that responds to clients) takes 11%.
The call tree descending to the mentioned method is:
java.lang.Thread.run() 71 %
java.util.concurrent.ThreadPoolExecutor$Worker.run()
71 %
java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Runnable) 71 %
org.apache.mina.util.NamePreservingRunnable.run() 71 %
org.apache.mina.transport.socket.nio.SocketIoProcessor$Worker.run()
71 %
sun.nio.ch.SelectorImpl.select(long) 70 %
sun.nio.ch.SelectorImpl.lockAndDoSelect(long) 70 %
sun.nio.ch.WindowsSelectorImpl.doSelect(long) 70 %
sun.nio.ch.WindowsSelectorImpl$SubSelector.access$400(WindowsSelectorImpl$SubSelector)
64 %
sun.nio.ch.WindowsSelectorImpl$SubSelector.poll() 64 %
sun.nio.ch.WindowsSelectorImpl$SubSelector.poll0(long, int,
int[], int[], int[], long) 64 %
Is there any workaround? Maybe somehow configure SocketIoProcessor or
smth?.. How should it scale on a multiple cpu machine?
Thanks for any kind of help in advance!
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