Finally managed to get a thread dump from the process - I've attached it.
Also, thanks to a helpful tip from #glassfish freenode irc, i added
<jvm-options>-Dcom.sun.enterprise.server.ss.ASQuickStartup=false</jvm-options>
to my domain's domain.xml, which seemed to start the server up faster but still arrived at the same point and 100% cpu.
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