Uploaded image for project: 'Crunch'
  1. Crunch
  2. CRUNCH-607

MemGroupedTable - iterator() can only be called once on this Iterable

    XMLWordPrintableJSON

    Details

    • Type: Bug
    • Status: Closed
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: 0.8.4
    • Fix Version/s: 0.15.0
    • Component/s: Core
    • Labels:
      None

      Description

      From the user mailing list:

      I'm running into a "java.lang.IllegalStateException: iterator() can only be called once on this Iterable" [1] when running a unit test that
      utilizes a MemCollection. The pipeline appears to runs fine when running on a cluster. I have a PGroupedTable that I am running multiple operations (mapValues, ungroup) [2] on that is causing the exception. The mapValues and the ungroup operations are run in separate jobs on the cluster, so I don't believe I should be running into iterator issues. This constraint was introduced by CRUNCH-192 [3].

      Gabriel Reid stated "Looks like the MemPipeline is doing something wrong when multiple PCollections are created from a single PCollection." [4]

      [1]
      apache-crunch-0.8.4 branch

      iterator() can only be called once on this Iterable
      java.lang.IllegalStateException: iterator() can only be called once on this Iterable
      at org.apache.crunch.impl.SingleUseIterable.iterator(SingleUseIterable.java:43)
      at org.apache.crunch.impl.mem.collect.MemGroupedTable$UngroupFn.process(MemGroupedTable.java:148)
      at org.apache.crunch.impl.mem.collect.MemGroupedTable$UngroupFn.process(MemGroupedTable.java:145)
      at org.apache.crunch.impl.mem.collect.MemCollection.parallelDo(MemCollection.java:155)
      at org.apache.crunch.impl.mem.collect.MemCollection.parallelDo(MemCollection.java:143)
      at org.apache.crunch.impl.mem.collect.MemGroupedTable.ungroup(MemGroupedTable.java:142)

      [2]
      PGroupedTable<String, Item> itemsByPersonId =
      AvroCollections.keyByAvroField(items, "person_id", Avros.strings()).groupByKey();

      PTable<String, Long> newestOrderByPersonId =
      itemsByPersonId
      .mapValues("Find latest order for each person", new MaxOrderMapFn(), Avros.longs());

      return itemsByPersonId.ungroup().join(newestOrderByPersonId).parallelDo(
      "Filter old items, leaving only current order items",
      new PreviousOrderItemFilter(),
      Avros.tableOf(Avros.strings(), Avros.specifics(Item.class)));

      [3] https://issues.apache.org/jira/browse/CRUNCH-192
      https://github.com/apache/crunch/commit/cbc7c2fb30ad0486e7ec60656c079c81e41eda2c
      [4] http://mail-archives.apache.org/mod_mbox/crunch-user/201604.mbox/date

        Attachments

        1. CRUNCH-607.patch
          7 kB
          Gabriel Reid

          Activity

            People

            • Assignee:
              gabriel.reid Gabriel Reid
              Reporter:
              nathan.schile@gmail.com Nathan Schile
            • Votes:
              0 Vote for this issue
              Watchers:
              3 Start watching this issue

              Dates

              • Created:
                Updated:
                Resolved: