[foreign-memaccess+abi] RFR: 8263018: Improve API for lifecycle of native resources [v2]

[Jorn Vernee]

On Wed, 10 Mar 2021 14:58:13 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

>> src/jdk.incubator.foreign/share/classes/jdk/internal/foreign/ArenaAllocator.java line 34:
>> 
>>> 32: 
>>> 33:     @Override
>>> 34:     public synchronized MemorySegment allocate(long bytesSize, long bytesAlignment) {
>> 
>> The synchronization here is a bit unfortunate I guess... Especially since the scope might be confined. We use this allocator as well for by-value struct copies.
>> 
>> Can we maybe change this to an explicit lock instead of using `synchronized` and then only use the lock when the scope we get is not confined?
>> 
>> (can save that for another day as well though)
>
> I was thinking that we could have a thread local arena based allocator - which would completely eliminate synchronization issues. I just didn't get to it. But there are options we can explore.

Ok that sounds like a good idea.

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PR: https://git.openjdk.java.net/panama-foreign/pull/466