Thread dumps are a common problem diagnosis tool. The request.log gives a picture of the activity the server is receiving retroactively.
Jetty Server delegates request processing to threads in its thread pool. These threads start with "qtp".
While a thread dump will show you the thread id and its stack, what is virtually impossible to map is what request in the request.log ( assuming the thread finishes ) was associated wth the thread in a thread dump.
If the request qtp threadid name was included in each request.log line as a field, one could in theory retroactively compare thread dumps + the timestamp it was taken to a request.log and isolate the specific requests contributing to some problem.
Include the thread id name of the request processing thread in the request.log by default.