Walter Su created HADOOP-12475:
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Summary: Replace guava Cache with ConcurrentHashMap for caching
Connection in ipc Client
Key: HADOOP-12475
URL: https://issues.apache.org/jira/browse/HADOOP-12475
Project: Hadoop Common
Issue Type: Sub-task
Reporter: Walter Su
Assignee: Walter Su
quote [~daryn] from HADOOP-11772:
{quote}
CacheBuilder is obscenely expensive for concurrent map, and it requires
generating unnecessary garbage even just to look up a key. Replace it with
ConcurrentHashMap.
I identified this issue that impaired my own perf testing under load. The
slowdown isn't just the sync. It's the expensive of Connection's ctor stalling
other connections. The expensive of ConnectionId#equals causes delays.
Synch'ing on connections causes unfair contention unlike a sync'ed method.
Concurrency simply hides this.
{quote}
BTW, guava Cache is heavyweight. Per local test, ConcurrentHashMap has better
overal performance.
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