[infinispan-issues] [JBoss JIRA] (ISPN-4842) Shared consistent hash

[Dan Berindei (JIRA)]

    [ https://issues.jboss.org/browse/ISPN-4842?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13011990#comment-13011990 ] 

Dan Berindei commented on ISPN-4842:
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Takayoshi, the JGroups channel is already shared. There are probably some per-cache threads that could be merged, like the TXCleanupService thread that you already issued a PR for, however most threads should be shared.

Sharing the consistent hash would require all those caches to be symmetric - i.e. if cache {{c}} is running on one node, it must also run on all the other nodes in the cluster. We are considering allowing only symmetric caches for 8.0 (adding support for multiple cache managers on FORKed JChannels instead), which should allow sharing the consistent hash. 

However, 8.0 is quite far away, so I would focus on reducing cost of computing the consistent hash (e.g. [TopologyAware]SyncConsistentHash results may be cached) and the merging per-cache threads into global threads. Please create separate issues for other per-cache threads that you've found.

> Shared consistent hash
> ----------------------
>
>                 Key: ISPN-4842
>                 URL: https://issues.jboss.org/browse/ISPN-4842
>             Project: Infinispan
>          Issue Type: Feature Request
>          Components: Core
>    Affects Versions: 7.0.0.CR1
>            Reporter: Takayoshi Kimura
>
> A user is testing 500 nodes cluster with 500 dist caches defined, and plans to expand it to 3000 caches.
> Infinispan manages consistent hash per cache, uses a JGroups channel per cache and uses several threads per cache. It gives significant overhead with this large size cluster. When tested with this size, Infinispan easily exhausted all threads in the thread pools and deadlocks, and requires several thousands threads to handle massive JOIN requests - the coord receives 499 * 3000 JOIN requests.
> It would be great if we can share the consistent hash and resources between caches. For example, define a "master" dist cache and allow other caches to refer to the master cache for resource sharing.



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