Re: [infinispan-dev] Concurrent hashmaps parameters

NonBlockingHashMap is great *except* that it relies on sun.misc.Unsafe, which makes portability a bit iffy. I *think* that it could be ported to use Atomic* instead, but it looked like quite a bit of work to do so (not to mention testing). The problem with CHM is that they are *big*, so you don't want to have a lot of them - *especially* if you're using a high concurrency level, because they get even bigger in that case. - DML On 09/15/2009 11:59 AM, Christian Vest Hansen wrote: > Using NonBlockingHashMap from highscalelib could be another option. > > On Tue, Sep 15, 2009 at 5:59 PM, Bela Ban <bban(a)redhat.com&gt; 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 >> >> _______________________________________________ >> infinispan-dev mailing list >> infinispan-dev(a)lists.jboss.org >> https://lists.jboss.org/mailman/listinfo/infinispan-dev >> > > > _______________________________________________ infinispan-dev mailing list infinispan-dev(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/infinispan-dev