8156871: Possible concurrency issue with JVM_AddModuleExports

[Christian Tornqvist]

Hi Lois,

I briefly looked at the test code and I have some concerns. I see the CompilerUtils class, what prevents you from using @compile in jtreg? 

Also, it's a testng test, in Runtime we've decided to not use testng to write our tests, is there a reason for using testng here?

Thanks,
Christian

-----Original Message-----
From: hotspot-runtime-dev [mailto:hotspot-runtime-dev-bounces at openjdk.java.net] On Behalf Of Lois Foltan
Sent: Friday, June 10, 2016 10:25 AM
To: hotspot-runtime-dev <hotspot-runtime-dev at openjdk.java.net>
Subject: RFR: 8156871: Possible concurrency issue with JVM_AddModuleExports

Hello,

Please review the work to finalize a concurrency issue when setting the exported state of a PackageEntry.  The work completed in bug
https://bugs.openjdk.java.net/browse/JDK-8152404 actually had the side effect of fixing this bug as well.  Prior to JDK-8152404, each PackageEntry determined its exported state via two flags, one of which was a general _is_exported flag followed by a another more specific state of exportability flag that determined if the package was exported qualifiedly or not to a given module.  Checking these two flags, as the
PackageEntry::is_* methods used to do without the Module_lock, was problematic and yielded a situation where a call to add a module to a PackageEntry's qualified exported entry list failed because it was determined that the package was unqualifiedly exported when it really was not.

To complete this fix, I have removed the is_unqual_exported call prior to setting a PackageEntry's exported list.  The method PackageEntry::set_exported determines what the current package export state is and acts correctly.  Also, the test case has been added in this webrev since it is a good stress test case for JVM module support.

Passes JPRT, java/lang, java/util RBT hotspot nightly.

Bug: https://bugs.openjdk.java.net/browse/JDK-8156871
Open webrev: http://cr.openjdk.java.net/~lfoltan/bug_jdk8156871/webrev/

Thanks,
Lois