Jürgen Thomann created HIVE-13531:
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             Summary: Cache in json_tuple UDF grows larger than it should
                 Key: HIVE-13531
                 URL: https://issues.apache.org/jira/browse/HIVE-13531
             Project: Hive
          Issue Type: Bug
          Components: UDF
    Affects Versions: 1.1.0
         Environment: CDH 5.5.0 with Java 1.8.0_45
            Reporter: Jürgen Thomann
            Assignee: Jason Dere
            Priority: Minor


According to the code in 
ql/src/java/org/apache/hadoop/hive/ql/udf/generic/GenericUDTFJSONTuple.java the 
HashCache should never grow larger than 16 entries. In the last OOM of Hive 
Server 2 I found this HashCache with over 1 million 
java.util.LinkedHashMap$Entry objects.

The code looks right and works single threaded as it should when I tested it 
isolated. The only problem I can imagine with my limited Hive source code 
knowledge that it is accessed concurrently and somewhere the cleanup with 
removeEldestEntry is not working in that case.

I had this problem with Hive 1.1.0 but the current implementation in master 
looks the same for the HashCache.



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