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From "Li Lu (JIRA)" <j...@apache.org>
Subject [jira] [Resolved] (YARN-3595) Performance optimization using connection cache of Phoenix timeline writer
Date Wed, 22 Jul 2015 17:50:04 GMT

     [ https://issues.apache.org/jira/browse/YARN-3595?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Li Lu resolved YARN-3595.
    Resolution: Later

Since we're moving phoenix storage to aggregation side, we need to fix this after we have
a full story of the offline (time-based) aggregation. 

> Performance optimization using connection cache of Phoenix timeline writer
> --------------------------------------------------------------------------
>                 Key: YARN-3595
>                 URL: https://issues.apache.org/jira/browse/YARN-3595
>             Project: Hadoop YARN
>          Issue Type: Sub-task
>          Components: timelineserver
>            Reporter: Li Lu
>            Assignee: Li Lu
> The story about the connection cache in Phoenix timeline storage is a little bit long.
In YARN-3033 we planned to have shared writer layer for all collectors in the same collector
manager. In this way we can better reuse the same heavy-weight storage layer connection, therefore
it's more friendly to conventional storage layer connections which are typically heavy-weight.

> Phoenix, on the other hand, implements its own connection interface layer to be light-weight,
thread-unsafe. To make these connections work with our "multiple collector, single writer"
model, we're adding a thread indexed connection cache. However, many performance critical
factors are yet to be tested. 
> In this JIRA we're tracing performance optimization efforts using this connection cache.
Previously we had a draft, but there was one implementation challenge on cache evictions:
There may be races between Guava cache's removal listener calls (which close the connection)
and normal references to the connection. We need to carefully define the way they synchronize.

> Performance-wise, at the very beginning stage we may need to understand:
> # If the current, thread-based indexing is an appropriate approach, or we can use some
better ways to index the connections. 
> # the best size of the cache, presumably as the proposed default value of a configuration.

> # how long we need to preserve a connection in the cache. 
> Please feel free to add this list. 

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