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  1. Hadoop Common
  2. HADOOP-11274

ConcurrentModificationException in Configuration Copy Constructor

    Details

    • Type: Bug
    • Status: Closed
    • Priority: Blocker
    • Resolution: Duplicate
    • Affects Version/s: None
    • Fix Version/s: None
    • Component/s: conf
    • Labels:
      None
    • Target Version/s:

      Description

      Exception as below happens in doing some configuration update in parallel:

      java.util.ConcurrentModificationException
      	at java.util.HashMap$HashIterator.nextEntry(HashMap.java:922)
      	at java.util.HashMap$EntryIterator.next(HashMap.java:962)
      	at java.util.HashMap$EntryIterator.next(HashMap.java:960)
      	at java.util.HashMap.putAllForCreate(HashMap.java:554)
      	at java.util.HashMap.<init>(HashMap.java:298)
      	at org.apache.hadoop.conf.Configuration.<init>(Configuration.java:703)
      

      In a constructor of Configuration - public Configuration(Configuration other), the copy of updatingResource data structure in copy constructor is not synchronized properly.
      Configuration.get() eventually calls loadProperty() where updatingResource gets updated. So, whats happening here is one thread is trying to do copy of Configuration as demonstrated in stack trace and other thread is doing Configuration.get(key) and than ConcurrentModificationException occurs because copying of updatingResource is not synchronized in constructor.
      We should make the update to updatingResource get synchronized, and also fix other tiny synchronized issues there.

        Attachments

        1. HADOOP-11274-v4.patch
          5 kB
          Vinod Kumar Vavilapalli
        2. HADOOP-11274-v3.patch
          4 kB
          Vinod Kumar Vavilapalli
        3. HADOOP-11274-v2.patch
          5 kB
          Junping Du
        4. HADOOP-11274.patch
          2 kB
          Junping Du
        5. HADOOP-11274.003.patch
          5 kB
          Jing Zhao

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              • Assignee:
                vinodkv Vinod Kumar Vavilapalli
                Reporter:
                djp Junping Du
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                Dates

                • Created:
                  Updated:
                  Resolved: