[infinispan-dev] Concurrent hashmaps parameters

[Christian Vest Hansen]

Using NonBlockingHashMap from highscalelib could be another option.

On Tue, Sep 15, 2009 at 5:59 PM, Bela Ban <bban at redhat.com> wrote:
> FYI,
>
> This might be important for you guys as well (if you haven't done so):
> I'll add code to configure ConcurrentHashMaps based on system
> properties, e.g. capacity, load factory etc.
>
> This will be important for large clusters. E.g. when we have 1000 nodes
> in the cluster, most hashmaps in JGroups will contain 1000 entries, and
> if we only have 16 buckets (the default IIRC), there would be a lot of
> contention.
>
>
> https://jira.jboss.org/jira/browse/JGRP-1049
>
> ConcurrentHashMap
> -----------------
>
> CCHMs have a default initial capacity (16), load factor (0.75) and
> concurrency level (16). These are OK for most
> scenarios, but we have to investigate whether these values are
> sufficient for 1000 node clusters.
>
> When for example 1000 threads from different senders access the same
> CCHM, we need to make sure we don't have high
> contention, ie. by spreading a 1000 senders over 16 buckets.
>
> Investigate whether we should add CCHM initial sizes, load factors and
> concurrency levels as properties.
>
> With ergonomics [1], we could for example set bucket sizes for CCHMs
> dynamically, e.g. based on cluster size.
>
>
>
> [1] https://jira.jboss.org/jira/browse/JGRP-1037
>
> --
> Bela Ban
> Lead JGroups / Clustering Team
> JBoss
>
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>



-- 
Venlig hilsen / Kind regards,
Christian Vest Hansen.