Thanks Jeanfrancois Arcand!
I use mod_proxy instead of mod_jk, followed the instruction
http://www.manorrock.com/documents/glassfish/proxy.html, and this time the exception "java.lang.IllegalStateException: Grizzly Comet hasn't been registered" is gone, but new problem occured.
The problem is the message window doesn't display anything, no matter how many words I inputed in below window, just like the picture I captured in attachment. And after timeout, all the words I inputed appeared at once.
Thanks!
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