worker thread pool of 1, gremlin pool of 1 and boss thread pool of 1 ?

Hello - I have an remote gremlin setup backend as cassandra, In my gremlin remote logs I see a log statement "INFO org.apache.tinkerpop.gremlin.server.GremlinServer - Gremlin Server configured with worker thread pool of 1, gremlin pool of 1 and boss thread pool of 1." Can some help me understand what does it meant by worker thread pool of 1, gremlin pool of 1 and boss thread pool of 1 ?