Running Loom tests

Fabio Tudone fabtud at
Sat Oct 20 12:37:45 UTC 2018

Hi, some info from a brief experience (as well as some questions) about
running Loom tests.

As far as I can see existing tests are found in
"test/jdk/java/lang/[Continuation|Fiber]" and are TestNG-based but run via
JTReg (more info and download linke here
and "doc/testing.[md|html]" explains the new way JTReg tests can be run.
For example, I could run some tests with "make run-test
TEST=test/jdk/java/lang/Fiber/ JTREG="JOBS=1;VM_OPTIONS=-Xdebug

BTW enabling debugging slows down things a lot for some reason and I cannot
always connect, let alone halt in breakpoints; anyone has test debugging
info to offer and maybe some devenv setup wisdom as well? I usually use
IJIdea Community, what do you use and how? E.g. do you first write them in
a separate workspace and then adapt them for JTReg  and the JDK tree and
retry running them from there?

As a side note, I think the Graal guys are really doing the collaboration
right, e.g. (apart from the cool website) and and I'd
really love if Loom got closer to that kind of setup (and I'd be glad to
help with that).

Also it looks like some tests fail unless the build has debug enabled (due
to missing "-XX:+SafepointALot": I suppose it adds more safepoints than
usual but why and where?) so the build should be configured with something
like "sh configure --with-jtreg=/opt/my_jtreg_bin_untar/ --enable-debug".
If you already built one I suggest you just delete everything in "build"
and start over with debug enabled because it is just easier, else you'll
need to specify the configuration you want to use for every target (and I'm
not sure at all how it would work with tests).

Anyway "java/lang/Continuation/Driver" fails anyway here due to a timeout
error (attaching trace), has someone already encountered that?

@Ron any chance that you or someone with access can include such info the
project page?

Finally I understand that Duncan MacGregor has contributed Graal support
for Loom but I couldn't find that code, does someone have any pointers to

-- Fabio

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