[jira] [Created] (HIVE-21971) HS2 leaks classload due to `ReflectionUtils::CONSTRUCTOR_CACHE` with temporary functions + GenericUDF

["Rajesh Balamohan (JIRA)" <ji...@apache.org>]

Rajesh Balamohan created HIVE-21971:
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             Summary: HS2 leaks classload due to `ReflectionUtils::CONSTRUCTOR_CACHE` with temporary functions + GenericUDF
                 Key: HIVE-21971
                 URL: https://issues.apache.org/jira/browse/HIVE-21971
             Project: Hive
          Issue Type: Bug
          Components: HiveServer2
    Affects Versions: 2.3.4
            Reporter: Rajesh Balamohan


https://issues.apache.org/jira/browse/HIVE-10329 helped in moving away from hadoop's ReflectionUtils constructor cache issue (https://issues.apache.org/jira/browse/HADOOP-10513).

However, there are corner cases where hadoop's {{ReflectionUtils}} is in use and this causes gradual build up of memory in HS2.

I have observed this in Hive 2.3. But the codepath in master for this has not changed much.

Easiest way to repro would be to add a temp function which extends {{GenericUDF}}. In {{FunctionRegistry::cloneGenericUDF,}} this would 
end up using {{org.apache.hadoop.util.ReflectionUtils.newInstance}} which in turn lands up in COSNTRUCTOR_CACHE of ReflectionUtils. 


{noformat}

CREATE TEMPORARY FUNCTION dummy AS 'com.hive.test.DummyGenericUDF' USING JAR 'file:///home/test/udf/dummy.jar';

select dummy();

	at org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:107)
	at org.apache.hadoop.hive.ql.exec.FunctionRegistry.cloneGenericUDF(FunctionRegistry.java:1353)
	at org.apache.hadoop.hive.ql.exec.FunctionInfo.getGenericUDF(FunctionInfo.java:122)
	at org.apache.hadoop.hive.ql.parse.TypeCheckProcFactory$DefaultExprProcessor.getXpathOrFuncExprNodeDesc(TypeCheckProcFactory.java:983)
	at org.apache.hadoop.hive.ql.parse.TypeCheckProcFactory$DefaultExprProcessor.process(TypeCheckProcFactory.java:1359)
	at org.apache.hadoop.hive.ql.lib.DefaultRuleDispatcher.dispatch(DefaultRuleDispatcher.java:90)
	at org.apache.hadoop.hive.ql.lib.DefaultGraphWalker.dispatchAndReturn(DefaultGraphWalker.java:105)
	at org.apache.hadoop.hive.ql.lib.DefaultGraphWalker.dispatch(DefaultGraphWalker.java:89)
	at org.apache.hadoop.hive.ql.lib.ExpressionWalker.walk(ExpressionWalker.java:76)
	at org.apache.hadoop.hive.ql.lib.DefaultGraphWalker.startWalking(DefaultGraphWalker.java:120)
{noformat}

Note: Reflection based invocation of hadoop's `ReflectionUtils::clear` was removed in 2.x. 



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