[jira] [Created] (FLINK-19112) No access to metric group in ScalarFunction when optimizing

[Shang Yuanchun (Jira)]

Nico Kruber created FLINK-19112:
-----------------------------------

             Summary: No access to metric group in ScalarFunction when optimizing
                 Key: FLINK-19112
                 URL: https://issues.apache.org/jira/browse/FLINK-19112
             Project: Flink
          Issue Type: Bug
          Components: Table SQL / Runtime
    Affects Versions: 1.11.1
            Reporter: Nico Kruber
         Attachments: MetricsGroupBug.java

Under some circumstances, I cannot access {{context.getMetricGroup()}} in a {{ScalarFunction}} like this (full job attached):
{code:java}
  public static class MyUDF extends ScalarFunction {
    @Override
    public void open(FunctionContext context) throws Exception {
      super.open(context);
      context.getMetricGroup();
    }

    public Integer eval(Integer id) {
      return id;
    }
  }
{code}
which leads to this exception:
{code:java}
Exception in thread "main" java.lang.UnsupportedOperationException: getMetricGroup is not supported when optimizing
        at org.apache.flink.table.planner.codegen.ConstantFunctionContext.getMetricGroup(ExpressionReducer.scala:249)
        at com.ververica.MetricsGroupBug$MyUDF.open(MetricsGroupBug.java:57)
        at ExpressionReducer$2.open(Unknown Source)
        at org.apache.flink.table.planner.codegen.ExpressionReducer.reduce(ExpressionReducer.scala:118)
        at org.apache.calcite.rel.rules.ReduceExpressionsRule.reduceExpressionsInternal(ReduceExpressionsRule.java:696)
        at org.apache.calcite.rel.rules.ReduceExpressionsRule.reduceExpressions(ReduceExpressionsRule.java:618)
        at org.apache.calcite.rel.rules.ReduceExpressionsRule$ProjectReduceExpressionsRule.onMatch(ReduceExpressionsRule.java:303)
        at org.apache.calcite.plan.AbstractRelOptPlanner.fireRule(AbstractRelOptPlanner.java:328)
        at org.apache.calcite.plan.hep.HepPlanner.applyRule(HepPlanner.java:562)
        at org.apache.calcite.plan.hep.HepPlanner.applyRules(HepPlanner.java:427)
        at org.apache.calcite.plan.hep.HepPlanner.executeInstruction(HepPlanner.java:264)
        at org.apache.calcite.plan.hep.HepInstruction$RuleInstance.execute(HepInstruction.java:127)
        at org.apache.calcite.plan.hep.HepPlanner.executeProgram(HepPlanner.java:223)
        at org.apache.calcite.plan.hep.HepPlanner.findBestExp(HepPlanner.java:210)
        at org.apache.flink.table.planner.plan.optimize.program.FlinkHepProgram.optimize(FlinkHepProgram.scala:69)
        at org.apache.flink.table.planner.plan.optimize.program.FlinkHepRuleSetProgram.optimize(FlinkHepRuleSetProgram.scala:87)
        at org.apache.flink.table.planner.plan.optimize.program.FlinkChainedProgram.$anonfun$optimize$1(FlinkChainedProgram.scala:62)
        at scala.collection.TraversableOnce.$anonfun$foldLeft$1(TraversableOnce.scala:156)
        at scala.collection.TraversableOnce.$anonfun$foldLeft$1$adapted(TraversableOnce.scala:156)
        at scala.collection.Iterator.foreach(Iterator.scala:937)
        at scala.collection.Iterator.foreach$(Iterator.scala:937)
        at scala.collection.AbstractIterator.foreach(Iterator.scala:1425)
        at scala.collection.IterableLike.foreach(IterableLike.scala:70)
        at scala.collection.IterableLike.foreach$(IterableLike.scala:69)
        at scala.collection.AbstractIterable.foreach(Iterable.scala:54)
        at scala.collection.TraversableOnce.foldLeft(TraversableOnce.scala:156)
        at scala.collection.TraversableOnce.foldLeft$(TraversableOnce.scala:154)
        at scala.collection.AbstractTraversable.foldLeft(Traversable.scala:104)
        at org.apache.flink.table.planner.plan.optimize.program.FlinkChainedProgram.optimize(FlinkChainedProgram.scala:58)
        at org.apache.flink.table.planner.plan.optimize.StreamCommonSubGraphBasedOptimizer.optimizeTree(StreamCommonSubGraphBasedOptimizer.scala:164)
        at org.apache.flink.table.planner.plan.optimize.StreamCommonSubGraphBasedOptimizer.doOptimize(StreamCommonSubGraphBasedOptimizer.scala:84)
        at org.apache.flink.table.planner.plan.optimize.CommonSubGraphBasedOptimizer.optimize(CommonSubGraphBasedOptimizer.scala:77)
        at org.apache.flink.table.planner.delegation.PlannerBase.optimize(PlannerBase.scala:279)
        at org.apache.flink.table.planner.delegation.PlannerBase.translate(PlannerBase.scala:164)
        at org.apache.flink.table.api.internal.TableEnvironmentImpl.translate(TableEnvironmentImpl.java:1264)
        at org.apache.flink.table.api.internal.TableEnvironmentImpl.executeInternal(TableEnvironmentImpl.java:700)
        at org.apache.flink.table.api.internal.TableImpl.executeInsert(TableImpl.java:565)
        at org.apache.flink.table.api.internal.TableImpl.executeInsert(TableImpl.java:549)
        at com.ververica.MetricsGroupBug.main(MetricsGroupBug.java:50)
{code}
I also tried to work around this with a try-catch, assuming that this method is called once during optimisation and another time at runtime. However, it seems as if {{open()}} is actually only called once (during optimization) thus giving me no choice to access the metrics group.



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