C3P0 apparent DEADLOCK when connection pooling is started!!! Error

after deploying a normal application on the Windows platform to a Linux server, the error has been: com.mchange.v2.async.threadpoolasynchronousrunner$ Deadlockdetector@bbd1b-apparent DEADLOCK!!! Creating Emergency threads for unassigned pending tasks!

check a lot of forums, found that with iptables rules have a lot of relationship, try to close iptables, can solve this problem. Then iptables can not be kept closed, in addition to security considerations, there are some NAT and forwarding to be done by iptables, so iptables is necessary to open, then we need to see what rules to add to solve the problem,

Here are my steps to try:
1. Close Iptables
2. Start Tomcat (the connection pool is automatically started when the Deploy app)
3. View MySQL process, connect MySQL address: localhost
4. Add rule in iptables: iptables-a input-s 127.0.0.1/32-jaccept This rule means: Accept all accesses originating from this machine, according to my present experience, does not increase the obvious security hidden danger;
5. Restart Iptables
6. Restart Tomcat, check the log: The connection pool was found to be ready for success and the issue was resolved.

Outside: Iptables changed, the original Tomcat can not normally shut down the problem has been resolved, it is estimated that Tomcat access to the 8005 port of the machine was blocked by iptables, Tomcat waiting for 8005 port response time-out, resulting in a stop service failure;