[jira] [Resolved] (HBASE-13903) Speedup IdLock

["Andrew Kyle Purtell (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HBASE-13903?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Andrew Kyle Purtell resolved HBASE-13903.
-----------------------------------------
    Resolution: Abandoned

> Speedup IdLock
> --------------
>
>                 Key: HBASE-13903
>                 URL: https://issues.apache.org/jira/browse/HBASE-13903
>             Project: HBase
>          Issue Type: Improvement
>          Components: regionserver
>    Affects Versions: 1.0.1, 1.1.0, 0.98.13, 2.0.0
>            Reporter: Matteo Bertozzi
>            Priority: Minor
>         Attachments: HBASE-13903-v0.patch, IdLockPerf.java
>
>
> while testing the read path, I ended up with the profiler showing a lot of time spent in IdLock.
> The IdLock is used by the HFileReader and the BucketCache, so you'll see a lot of it when you have an hotspot on a hfile.
> we end up locked by that synchronized() and with too many calls to map.putIfAbsent()
> {code}
> public Entry getLockEntry(long id) throws IOException {
>   while ((existing = map.putIfAbsent(entry.id, entry)) != null) {
>     synchronized (existing) {
>       ...
>     }
>     // If the entry is not locked, it might already be deleted from the
>     // map, so we cannot return it. We need to get our entry into the map
>     // or get someone else's locked entry.
>   }
> }
> public void releaseLockEntry(Entry entry) {
>   synchronized (entry) {
>     ...
>   }
> }
> {code}



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