[jboss-jira] [JBoss JIRA] Resolved: (JGRP-1049) Concurrent hashmaps: set parameters via system properties

[Bela Ban (JIRA)]

     [ https://jira.jboss.org/browse/JGRP-1049?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Bela Ban resolved JGRP-1049.
----------------------------

    Resolution: Done


The 3 properties can now be set via system properties cchm.initial_capacity, cchm.load_factor and cchm.concurrency_level. The helper method to create hashmaps is Util.createConcurrentMap()

> Concurrent hashmaps: set parameters via system properties
> ---------------------------------------------------------
>
>                 Key: JGRP-1049
>                 URL: https://jira.jboss.org/browse/JGRP-1049
>             Project: JGroups
>          Issue Type: Feature Request
>            Reporter: Bela Ban
>            Assignee: Bela Ban
>             Fix For: 2.11
>
>
> 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 system 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

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