recreatePool
Recreates the Jedis connection pool.
Note that pool recreation might not be run on the same thread as the caller of the this method. For example, if a second recreatePool is called while the first still has the lock acquired, the second invocation of recreatePool will be a no-op. In other words, with reference to the second call of recreatePool, although after the method has returned the pool is recreated, the pool is not specifically recreated by that call.
Return
The instance to the previously used pool, or null if the pool is not recreated by this invocation of the method. The caller should be responsible for closing the previously used pool.