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Posted to common-issues@hadoop.apache.org by "Ted Yu (JIRA)" <ji...@apache.org> on 2014/05/30 02:55:02 UTC

[jira] [Created] (HADOOP-10642) Provide option to limit heap memory consumed by dynamic metrics2 metrics

Ted Yu created HADOOP-10642:
-------------------------------

             Summary: Provide option to limit heap memory consumed by dynamic metrics2 metrics
                 Key: HADOOP-10642
                 URL: https://issues.apache.org/jira/browse/HADOOP-10642
             Project: Hadoop Common
          Issue Type: Improvement
            Reporter: Ted Yu


User sunweiei provided the following jmap output in HBase 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 (and indirectly by [C) could be due to calls to Interns.info() in DynamicMetricsRegistry which was cloned off metrics2/lib/MetricsRegistry.java.
This scenario would arise when large number of regions are tracked through metrics2 dynamically.
Interns class doesn't provide API to remove entries in its internal Map.

One solution is to provide an option that allows skipping calls to Interns.info() in metrics2/lib/MetricsRegistry.java



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