Major Clojure 1.10 performance degredation on JDK11

Alex Miller alex at
Wed Feb 6 16:17:01 GMT 2019

While in general, those are all good comments, in this case I think
something is pretty obviously wrong. The time doesn't vary that much for
just reading and printing a string.

On Wed, Feb 6, 2019 at 10:07 AM Tom Marble <tmarble at> wrote:

> Elana Hashman <elana at> writes:
> > Mm, given all that, my guess is that this is an AOT compilation issue.
> I'll
> > have to dig deeper into where that's coming from.
> Having had this role of measuring JVM performance I can tell you
> that this type of "cold start" is tricky to measure accurately.
> Obviously we have to factor out machine speed. In the automated
> tests we did at Sun we also unmounted the filesystem with the JVM
> artifacts to ensure that the file system cache was cold.
> It may be that Openjdk 11 has made some startup time tradeoffs
> (e.g. more eagerness in favor of better HotSpot behavior).
> And Clojure itself may have to initialize a bunch of infrastructure
> before evaluating "hi".
> Everybody cares about cold start performance, but it will require
> more analysis. Getting a set of Clojure tools that work (at any speed)
> is a priority for Buster.
> Regards,
> --Tom
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