RFR: 8291555: Implement alternative fast-locking scheme [v71]

[Daniel D. Daugherty]

On Thu, 4 May 2023 20:59:58 GMT, Roman Kennke <rkennke at openjdk.org> wrote:

>> src/hotspot/share/runtime/lockStack.inline.hpp line 53:
>> 
>>> 51:   bool is_owning = &JavaThread::cast(thread)->lock_stack() == this;
>>> 52:   assert(is_owning == (get_thread() == thread), "is_owning sanity");
>>> 53:   return is_owning;
>> 
>> This is going to require a re-test just to make sure that we don't have
>> a code path into here from the VMThread when it is doing some
>> JVM/TI stuff (again...).
>
> I don't think so. That code did use JavaThread::cast(thread) before which would have fired. But that means I can leave out the JavaThread::cast() now. Let me do that change.

Agreed! I read thru the diffs so fast I missed the "JavaThread::cast(thread)" part of this:

> bool is_self = &JavaThread::cast(thread)->lock_stack() == this;

I'll still do a round of testing on v70 just because more runs are better for
shaking out anything that might be racy...

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PR Review Comment: https://git.openjdk.org/jdk/pull/10907#discussion_r1185529131