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https://issues.apache.org/jira/browse/HIVE-22161?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Gopal V updated HIVE-22161:
---------------------------
    Labels: concurrency performance  (was: performance)

> UDF: FunctionRegistry synchronizes on org.apache.hadoop.hive.ql.udf.UDFType 
> class
> ---------------------------------------------------------------------------------
>
>                 Key: HIVE-22161
>                 URL: https://issues.apache.org/jira/browse/HIVE-22161
>             Project: Hive
>          Issue Type: Bug
>          Components: UDF
>    Affects Versions: 1.2.2, 4.0.0, 3.1.2
>            Reporter: Gopal V
>            Assignee: Gopal V
>            Priority: Major
>              Labels: concurrency, performance
>             Fix For: 4.0.0
>
>         Attachments: HIVE-22161.1.patch
>
>
> There's a hidden synchronization across threads when looking up isStateful 
> and isDeterministic.
> https://github.com/apache/hive/blob/master/common/src/java/org/apache/hive/common/util/AnnotationUtils.java#L27
> {code}
>   // to avoid https://bugs.openjdk.java.net/browse/JDK-7122142
>   public static <T extends Annotation> T getAnnotation(Class<?> clazz, 
> Class<T> annotationClass) {
>     synchronized (annotationClass) {
>       return clazz.getAnnotation(annotationClass);
>     }
>   }
> {code}
> This is serializing multiple threads initializing UDFs (or checking them 
> during compilation) & also being locked across threads for each instance of 
> GenericUDFOpEqual in the specific scenario.
> https://bugs.openjdk.java.net/browse/JDK-7122142 is fixed in jdk8+



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