In org.apache.mina.core.filterchainDefaultIoFilterChain, code around line number 600,
<code>if (writeRequestQueue.size() == 0 )</code>
will raise performance problem in high concurrent situation, Mina default use ConcurrentLinkedQueue as writeRequestQueue, but size() of this queue is not a constant-time operation, suggest to use <code>if (writeRequestQueue.isEmpty(s))</code> instead of it.