[jira] [Created] (HBASE-11267) Dynamic metrics2 metrics may consume large amount of heap memory

["Ted Yu (JIRA)" <ji...@apache.org>]

Ted Yu created HBASE-11267:
------------------------------

             Summary: Dynamic metrics2 metrics may consume large amount of heap memory
                 Key: HBASE-11267
                 URL: https://issues.apache.org/jira/browse/HBASE-11267
             Project: HBase
          Issue Type: Bug
            Reporter: Ted Yu


User sunweiei provided the following jmap output in 0.96 deployment:
{code}
 num     #instances         #bytes  class name
----------------------------------------------
   1:      14917882     3396492464  [C
   2:       1996994     2118021808  [B
   3:      43341650     1733666000  java.util.LinkedHashMap$Entry
   4:      14453983     1156550896  [Ljava.util.HashMap$Entry;
   5:      14446577      924580928  org.apache.hadoop.metrics2.lib.Interns$CacheWith2Keys$2
{code}
Heap consumption by Interns$CacheWith2Keys$2 could be due to calls to Interns.info() in DynamicMetricsRegistry.
This scenario would arise when large number of regions are tracked through metrics2.
Interns class doesn't provide API to remove entries in its internal Map.
Meaning, DynamicMetricsRegistry#clearMetrics() is unable to reclaim that part of heap.



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