Release thread attr handles and block default route on compression

Release the thread attributes where were created with pthread_attr_init. According to the manual: "When a thread attributes object is no longer required, it should be destroyed using the pthread_attr_destroy() function. Destroying a thread attributes object has no effect on threads that were created using that object.". For the configuration of the compression add the default switch to block accidental invalid configuration settings since this would use an uninitialized variable.