On Fri, 15 Apr 2022 11:45:01 GMT, Alan Bateman <[email protected]> wrote:
>> This is the implementation of JEP 425: Virtual Threads (Preview); TBD which
>> JDK version to target.
>>
>> We will refresh this PR periodically to pick up changes and fixes from the
>> loom repo.
>>
>> Most of the new mechanisms in the HotSpot VM are disabled by default and
>> require running with `--enable-preview` to enable.
>>
>> The patch has support for x64 and aarch64 on the usual operating systems
>> (Linux, macOS, and Windows). There are stubs (calling Unimplemented) for
>> zero and some of the other ports. Additional ports can be contributed via
>> PRs against the fibers branch in the loom repo.
>>
>> There are changes in many areas. To reduce notifications/mails, the labels
>> have been trimmed down for now to hotspot, serviceability and core-libs.
>> We'll add the complete set of labels when the PR is further along.
>>
>> The changes include a refresh of java.util.concurrent and ForkJoinPool from
>> Doug Lea's CVS. These changes will probably be proposed and integrated in
>> advance of this PR.
>>
>> The changes include some non-exposed and low-level infrastructure to support
>> the (in draft) JEPs for Structured Concurrency and Scope Locals. This is to
>> make life a bit easier and avoid having to separate VM changes and juggle
>> branches at this time.
>
> Alan Bateman has updated the pull request with a new target base due to a
> merge or a rebase. The incremental webrev excludes the unrelated changes
> brought in by the merge/rebase. The pull request contains five additional
> commits since the last revision:
>
> - Refresh
> - Refresh
> - Merge with jdk-19+18
> - Refresh
> - Initial push
src/java.base/share/classes/java/lang/Thread.java line 602:
> 600: } else {
> 601: // getContextClassLoader not trusted
> 602: ClassLoader cl = parent.contextClassLoader;
I might be misreading the comment on that line, but reading this if/else block
a few times, I'm unsure what the expectations here are.
It's my understanding that a call to `getContextClassLoader()` can't be trusted
if that method has been overridden by the passed `Thread` type. In such cases,
we don't call that method and instead just use the field value of
`contextClassLoader` (which is a private field on `Thread`). Is that
understanding correct? If yes, then the condition in the `if` block a few lines
above, looks odd. It seems to be calling the `getContextClassLoader()` if that
method is overridden by the passed `Thread` type, i.e. the untrusted case.
Should it instead be:
if (sm == null || !isCCLOverridden(parent.getClass())) {
return parent.getContextClassLoader();
}
(notice the negation)
-------------
PR: https://git.openjdk.java.net/jdk/pull/8166
