When your JAVA process started to spin your CPU, you need to immediately issue following two commands and get the invaluable information required to tackle the issue.
1. jstack <pid> > thread-dump.txt
2. ps -C java -L -o pcpu,cpu,nice,state,cputime,pid,tid > thread-usage.txt
After getting those two files, what you can do is,
1. find the thread ID (which belongs to the corresponding PID ) which takes the highest CPU usage by examine thread-usage.txt file.
%CPU CPU NI S TIME PID TID
..........
0.0 - 0 S 00:00:00 1519 1602
0.0 - 0 S 00:00:00 1519 1603
24.8 - 0 R 00:06:19 1519 1604
2.4 - 0 S 00:00:37 1519 1605
0.0 - 0 S 00:00:00 1519 1606
..........
2. convert the decimal value (in this case 1604) to hexadecimal - (online converter - http://easycalculation.com/decimal-converter.php)
Hex - 644
3. search for the hexadecimal obtained (in this case 644) in the thread-dump.txt (thread-dump.txt should have that value as a thread id of one thread) and that is the thread which spins.
4. that thread usually has a stack trace, and that's the lead to find the culprit.
In this case the stack trace of the thread that spins is:
"HTTPS-Sender I/O dispatcher-1" prio=10 tid=0x00007fb54c010000 nid=0x644 runnable [0x00007fb534e20000] java.lang.Thread.State: RUNNABLE at org.apache.http.impl.nio.reactor.IOSessionImpl.getEventMask(IOSessionImpl.java:139) - locked <0x00000006cd91fef8> (a org.apache.http.impl.nio.reactor.IOSessionImpl) at org.apache.http.nio.reactor.ssl.SSLIOSession.updateEventMask(SSLIOSession.java:300) at org.apache.http.nio.reactor.ssl.SSLIOSession.inboundTransport(SSLIOSession.java:402) - locked <0x00000006cd471df8> (a org.apache.http.nio.reactor.ssl.SSLIOSession) at org.apache.http.impl.nio.reactor.AbstractIODispatch.inputReady(AbstractIODispatch.java:121) at org.apache.http.impl.nio.reactor.BaseIOReactor.readable(BaseIOReactor.java:160) at org.apache.http.impl.nio.reactor.AbstractIOReactor.processEvent(AbstractIOReactor.java:342) at org.apache.http.impl.nio.reactor.AbstractIOReactor.processEvents(AbstractIOReactor.java:320) at org.apache.http.impl.nio.reactor.AbstractIOReactor.execute(AbstractIOReactor.java:280) at org.apache.http.impl.nio.reactor.BaseIOReactor.execute(BaseIOReactor.java:106) at org.apache.http.impl.nio.reactor.AbstractMultiworkerIOReactor$Worker.run(AbstractMultiworkerIOReactor.java:604) at java.lang.Thread.run(Thread.java:722)Hope this helps!
