[concurrency-interest] ConcurrentHashMap footprint and contention improvements

Rodrigo Kumpera kumpera at gmail.com
Fri Apr 15 16:42:05 EDT 2011


On Fri, Apr 15, 2011 at 8:04 AM, Doug Lea <dl at cs.oswego.edu> wrote:

> Thanks everyone for on- and off-list feedback.
> A few follow-ups:
>
>
> On 04/14/11 15:52, Rodrigo Kumpera wrote:
>
>> Did you consider other lock free algorithms such as Shalev-Shavit
>> Split-Ordered List based hashtable?
>>
>
> Yes. Some variant of Shalev & Shavit is probably the best bet for
> an overhaul. The main challenges are finding ways of dealing with
> bit reversal and marker-based list deletion without adding per-node
> time and space overhead (that would negate main goal of reducing
> footprint).
>

My experience with Shalev & Shavit is that bit reversals using a per byte
table are fast enough. For Marker-based list deletion it would be a matter
of pushing JVM engineering to make AtomicMarkedReference usable. This
is the approach I plan on using to reduce the footprint on mono.
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