The DisableReuse + JKOption is recommended because of how mod_jk handles connections. Typically the DisableReuse option is recommended when there are issues with keeping a connection alive.
mod_jk has built in health checks:
Both of them do the same thing. They send a PING to Tomcat. Tomcat responds with a PONG. And only then the connection is used as it is considered healthy.
Why active threads remain high after load decreases using the Blocking IO connector
There are a number of different http connectors that can be used with Tomcat. They are:
• Blocking IO
• Non-blocking IO
• Native/Apache Portable Runtime (APR)
The blocking IO connector is the default http connector. With this connector each request is handled by a dedicated thread (obtained from a pool) until the request is complete at which point the thread is returned to the pool to be re-used by another request.