On Sun, 17 Apr 2022 16:03:30 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 incrementally with one additional
> commit since the last revision:
>
> Refresh
src/java.base/share/classes/java/lang/System.java line 2173:
> 2171:
> 2172: // start Finalizer and Reference Handler threads
> 2173: SharedSecrets.getJavaLangRefAccess().startThreads();
I think it would avoid any confusion if `VM.initLevel(1)` is the last step in
`initPhase1`, i.e. call after this line. Previously, the finalizer starts
very early and it has to wait until initLevel is set to level 1 which
guarantees that `JavaLangAccess` is available. With this change,
`JavaLangAccess` is already set.
src/java.base/share/classes/java/lang/ref/ReferenceQueue.java line 61:
> 59: private final Condition notEmpty;
> 60:
> 61: void signal() { notEmpty.signalAll(); }
`signal()`, `await()` and `await(long)` methods are only used by
`ReferenceQueue`. Good to make them private.
src/jdk.management/share/classes/com/sun/management/HotSpotDiagnosticMXBean.java
line 138:
> 136: *
> 137: * @param outputFile the path to the file to create
> 138: * @param format the format to use (TEXT_PLAIN or JSON)
It's useful to link to `ThreadDumpFormat#TEXT_PLAN` and `ThreadDumpFormat#JSON`
-------------
PR: https://git.openjdk.java.net/jdk/pull/8166
