JVM在Java 6中被吊死了几秒钟

Question

After upgrading our application(Mindalign) from jdk 1.4 to jdk 1.6 , it was found that JVM often gets hanged for few seconds.

Observation:

During startup, Application does a lot of I/O operations (ie loading xml file, sending data to Tcp/Ip socket) There is a gap of around 2 second can be observed during these operations.

Given below is the sample logs during the issue.

Compiled with JDK1.4

DEBUG 14Jan30 16:33:42108  digester.xml.AbstractDigestBinder/shutdown        | loading configuration: 
DEBUG 14Jan30 16:33:42218  gs.group_server.GroupServer/shutdown              | Maximum exception occurred within the timespan is set to 0

INFO  14Jan30 16:33:53153  rr.net.ConnectionManager/MessageHandler    | [IRC] << :groupserver. RPLWHOREG
INFO  14Jan30 16:33:53153  rr.net.ConnectionManager/MessageHandler    | [IRC] << :groupserver. RPLWHOREG


Compiled with JDK1.6

DEBUG 14Feb05 14:22:45801  digester.xml.AbstractDigestBinder/shutdown        | loading configuration: 
DEBUG 14Feb05 14:22:47205  gs.group_server.GroupServer/shutdown              | Maximum exception occurred within the timespan is set to 0

DEBUG 14Feb05 14:22:54599  rr.net.ConnectionManager/MessageHandler       | [IRC] << :groupserver. RPLWHOREG
DEBUG 14Feb05 14:22:56502  rr.net.ConnectionManager/MessageHandler                | [IRC] << :groupserver. RPLWHOREG

Please suggest me, how to troubleshoot this issue. strong text

Can it be related with xms value (heap size) of java..?

Answer 1

Use a profiler and/or VisualVM to look at what your application is doing.

Turn on garbage collection debugging to see if there is anything going on there.

Use a debugger to "pause" the application during one of these stalls and then investigate to see what it's doing or waiting for.

I don't actually see huge differences in the two timings though:

:42 to :53 is :11 difference, in the second case :47 to :54 is :07 difference. It's actually got faster...which is to be expected as the 1.6 JVM is smarter than the 1.4 one.