I'm hitting this Jetty issue when running Solr's tests that spawn a Jetty:
It seems to be caused by this root cause:
Whereby, somehow, Jetty is trying to use cryptographically secure source of randomness to seed seed its HashSessionIdManager. My box doesn't have enough entropy so the read blocks for sometimes 10s of seconds!
If I forcefully symlink /dev/random -> /dev/urandom, that fixes the hang. Likewise, if I edit the JRE's java.security to set securerandom.source=file:/dev/./urandom, that also fixes it. But I think we can workaround this more "generally" by doing the workaround suggested in the Jetty issue (pass java.util.Random not java.security.SecureRandom).
However, it's still not clear how widespread / what evns this issue really affects (besides mine)...