[jira] [Created] (AVRO-3094) performance regression in SpecificData.getForClass() when run with code generated by older avro

["radai rosenblatt (Jira)" <ji...@apache.org>]

radai rosenblatt created AVRO-3094:
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             Summary: performance regression in SpecificData.getForClass() when run with code generated by older avro
                 Key: AVRO-3094
                 URL: https://issues.apache.org/jira/browse/AVRO-3094
             Project: Apache Avro
          Issue Type: Bug
          Components: java
    Affects Versions: 1.10.2, 1.9.2
            Reporter: radai rosenblatt


starting with 1.9, avro SpecificData supports per-class MODEL$ definitions, and looks for them on specific classes:
{code:java}
public static <T> SpecificData getForClass(Class<T> c) {
  if (SpecificRecordBase.class.isAssignableFrom(c)) {
    final Field specificDataField;
    try {
      specificDataField = c.getDeclaredField("MODEL$");
      specificDataField.setAccessible(true);
      return (SpecificData) specificDataField.get(null);
    } catch (NoSuchFieldException e) {
      // Return default instance
      return SpecificData.get();    <======= EXPENSIVE
    } catch (IllegalAccessException e) {
      throw new AvroRuntimeException(e);
    }
  }
  return SpecificData.get();
} {code}
when this is run vs specific record classes generated by older avro, which do not have field MODEL$ this reslts in a serious performance degradation. we've measured the impact on user code to be x3 slower in one case (see attached flame graph)

 

under java 7+ it should be completely possible to cache the existence (or lack thereof) of MODEL$ using [ClassValue|https://docs.oracle.com/javase/7/docs/api/java/lang/ClassValue.html] which would also speed this up when operating on classes generated by more modern avro since it would avoid reflection



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