On Tue, 10 Nov 2020 16:46:10 GMT, Coleen Phillimore <cole...@openjdk.org> wrote:
>> Daniel D. Daugherty has updated the pull request incrementally with one
>> additional commit since the last revision:
>>
>> dholmes-ora - convert inner while loop to do-while loop in
>> unlink_deflated().
>
> src/hotspot/share/runtime/monitorDeflationThread.cpp line 85:
>
>> 83: // visible to external suspension.
>> 84:
>> 85: ThreadBlockInVM tbivm(jt);
>
> Does this have to be a JavaThread? Could it be a non-java thread since
> deflating monitors doesn't have to call any Java code? You'd have to lock
> down the Monitor list maybe, but couldn't this be a NamedThread? This isn't
> a request to change it right now.
Ummm... we use a JavaThread because we have to stop async deflation
during safepoints so that we're not messing with Object headers during GC.
Yes, it's possible to use a non-JavaThread because this is "just software",
but I don't want to try to figure out those races...
> src/hotspot/share/runtime/synchronizer.cpp line 1641:
>
>> 1639:
>> 1640: // Do the final audit and print of ObjectMonitor stats; must be done
>> 1641: // by the VMThread (at VM exit time).
>
> Can you take (at VM exit time) out of parenthesis? it made me wonder when
> else is this called.
Okay.
> src/hotspot/share/runtime/objectMonitor.cpp line 509:
>
>> 507: //
>> 508: bool ObjectMonitor::deflate_monitor() {
>> 509: if (is_busy()) {
>
> is_busy should be checked != 0 since it doesn't return a bool.
Nice catch! That has been there for many, many years...
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PR: https://git.openjdk.java.net/jdk/pull/642
