First of all it's better to attach such content as a file instead of pasting it on the post.
Anyway, what I see in your case there are few errors:
- session with id cannot be found that indicates that you used this application server for other (probably default) data base and that's why it saved the session id it used.
- at some point your task server (exposed via hornetq) throw out of memory error
- could not connect to task client
As it comes to the first one you can either ignore it or make sure you remove jbpmSessionId.ser file from jboss tem directory (jboss_home/standalone/tmp). Second issue was a root cause of the third one. Just make sure that you assign enough resources for jboss server while running it.
HTH