When running the tests, a tremendous number of connections are put into TIME_WAIT.

When you run the test suite and monitor the number of connections in TIME_WAIT, it appears that a very large number of connections do not end up with a proper connection close lifecycle or perhaps proper reuse.

Given connections can stay in TIME_WAIT from 1-4 minutes depending on OS/Env, running the tests faster or with more tests in parallel increases the TIME_WAIT connection buildup. Some tests spin up a very, very large number of connections and if the wrong ones run at the same time, this can also greatly increase the number of connections put into TIME_WAIT. This can have a dramatic affect on performance (as it can take longer to create a new connection) or flat out fail or timeout.

In my experience, a much, much smaller number of connections in a test suite would end up in TIME_WAIT when connection handling is all correct.

Notes to come in comments below.