诊断工具:
http://docs.oracle.com/javase/8/docs/technotes/guides/troubleshoot/
调优参数
http://docs.oracle.com/javase/8/docs/technotes/guides/vm/gctuning/
jvm
http://docs.oracle.com/javase/8/docs/technotes/guides/vm/index.html
http://docs.oracle.com/javase/8/docs/technotes/tools/unix/java.html