Thanks, Alan. Good to hear that this is on the radar. In the meantime, I think I can solve our performance problem by using the /packages namespace to route lookups to the relevant module(s) to avoid so many negative lookups in the first place.
Regards, Jason On Thu, 16 Feb 2017 at 18:44 Alan Bateman <alan.bate...@oracle.com> wrote: > On 16/02/2017 08:15, Jason Zaugg wrote: > > > Recently I modified the Scala compiler to read class files > > jrt:/ filesystem, rather than relying on rt.jar. > > > > I noticed a slowdown when running on JDK 9 ea and exercising this code. > > Profiles suggest that the bottleneck is in calls to Files.exists. > > JrtFileSystemProvider inherits an implementation which needs to > construct, > > throw and catch NoSuchFileException to answer in the negative. > > > > It is possible that I'm calling this more often than needed, and could > > implement a caching layer. But it seems worthwhile for jrtfs to > implement a > > fast path for exists, as is done in UnixFileSystemProvider. > > > > Possibly related bug "Startup regression with Jython": > > https://bugs.openjdk.java.net/browse/JDK-8166236 > > > As it happens, we a similar issue with the zip provider. It's something > that I was looking at with Sherman recently and we have a proposal to > push the exists down to the provider interface so that it can be > overridden. > > So a different issues to JDK-8166236 - that one is that Jython seems to > create a cache on first usage of all classes that it finds in rt.jar. I > assume that if/when Jython adds support for JDK 9 and jrtfs that they > will be able to integrate it with their caching. > > -Alan >
