I work on Spring Boot which uses Tomcat (or Jetty or Undertow) as an embedded servlet container. We've seen a number of complaints from users that their application hangs during startup, most often on a newly booted VPS. The root cause is a lack of entropy which causes Tomcat's use of SecureRandom for session ID generation to block.
Users that choose to use Undertow rather than Tomcat aren't affected by this problem during startup. Like Tomcat, Undertow uses SecureRandom to generate session IDs. However, unlike Tomcat, Undertow does so lazily. This defers the problem till the first request that uses a session and permanently if the application does not make use of HTTP sessions. Can we please explore the possibility of making Tomcat behave in a similar way to Undertow? Thanks, Andy
