Packing 2 data points into 1 field in ThreadPoolExecutor
david.holmes at oracle.com
Tue Dec 2 02:32:20 UTC 2014
On 2/12/2014 3:44 AM, Alex Yursha wrote:
> 1. Do you mean 'the only way', except using a lock?
> 2. I also cant imagine how we can use long primitive type for CAS atomicity without a lock if only its not an AtomicLong. Any hint here, please?
AtomicFieldUpdater can apply atomic operations to plain (volatile) int
and long fields. The Unsafe API can also be used to do it more performantly.
> Sent from my iPhone
>> On Dec 1, 2014, at 20:27, Martin Buchholz <martinrb at google.com> wrote:
>> The only way to use atomic compare and set is to pack all your state
>> into a single primitive unit. The largest we have is "long". So we
>> regularly pack what the C folks would call bitfields into longs.
>>> On Sat, Nov 29, 2014 at 8:13 AM, Alex Yursha <alexyursha at gmail.com> wrote:
>>> Hi all,
>>> According to javadoc current implementation of ThreadPoolExecutor packs two conceptual fields ‘workerCount’ and ‘runState’ into one actual field ‘ctl’ of type AtomicInteger.
>>> Could you please explain are there any performance or other benefits for this? It seems to complicate the class design and I can’t find the positive side of this.
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