[jira] Commented: (HBASE-407) Client should cache region locations in an LRU structure

[stack (JIRA)]

    [ 
https://issues.apache.org/jira/browse/HBASE-407?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12567728#action_12567728
 ] 

stack commented on HBASE-407:
-----------------------------

You can't use ReferenceMap from commons collections because you want a 
SortedMap and ReferenceMap ?  Want me to make a little test to ensure this 
SoftReference value is actually working (I'd force the JVM to head for an OOME 
and add a ReferenceQueue implementation to the SortReference constructor and 
log its dequeues).

Otherwise, for the future, would suggest that you put together declarations and 
assignments as in:

{code}
@@ -116,7 +115,8 @@

     private HRegionLocation rootRegionLocation;

-    private Map<Text, SortedMap<Text, HRegionLocation>> cachedRegionLocations;
+    private Map<Text, SortedMap<Text, 
+      SoftReference<HRegionLocation>>> cachedRegionLocations;

     /**
      * constructor
@@ -147,7 +147,8 @@
       this.masterChecked = false;

       this.cachedRegionLocations =
-        new ConcurrentHashMap<Text, SortedMap<Text, HRegionLocation>>();
+        new ConcurrentHashMap<Text, SortedMap<Text, 
+          SoftReference<HRegionLocation>>>();
{code}

i.e. do private Map<Text, SortedMap<Text,  SoftReference<HRegionLocation>>> 
cachedRegionLocations = new ConcurrentHashMap<Text, SortedMap<Text, 
SoftReference<HRegionLocation>>>();

You might also be able to make cachedRegionLocations 'final' too.

These are for sure safe:

{code}
+          HRegionLocation rl = tableLocations.get(row).get();
{code}

and

{code}
+            matchingRegions.get(matchingRegions.lastKey()).get();
{code}

Otherwise, patch looks great.



> Client should cache region locations in an LRU structure
> --------------------------------------------------------
>
>                 Key: HBASE-407
>                 URL: https://issues.apache.org/jira/browse/HBASE-407
>             Project: Hadoop HBase
>          Issue Type: Improvement
>          Components: client
>            Reporter: Bryan Duxbury
>            Assignee: Bryan Duxbury
>         Attachments: 407-v2.patch, 407.patch
>
>
> Instead of keeping the region locations cached client side in a TreeMap, we 
> should use an LRU mechanism to help manage memory more dynamically.

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.