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  1. Hadoop HDFS
  2. HDFS-16821

Fix regression in HDFS-13522 that enables observer reads by default.

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Details

    • Bug
    • Status: Resolved
    • Major
    • Resolution: Fixed
    • 3.4.0
    • 3.4.0
    • hdfs
    • Reviewed

    Description

      Serving reads consistently from Observer Namenodes is a feature that was introduced in HDFS-12943.

      Clients opt-into this feature by configuring the ObserverReadProxyProvider. It is important that the opt-in is explicit because for third-party reads to remain consistent, these clients then need to perform an msync before reads.

      In HDFS-13522, the ClientGSIContext is implicitly added to the DFSClient thus enabling Observer reads for all clients by default. This breaks consistency guarantees for clients that haven't opted into observer reads.

      https://github.com/apache/hadoop/pull/4883/files#diff-a627e2c1f3e68235520d3c28092f4ae8a41aa4557cc530e4e6862c318be7e898R352-R354

      We need to return to the old behavior of only using the ClientGSIContext when users have explicitly opted into Observer reads.

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            simbadzina Simbarashe Dzinamarira
            simbadzina Simbarashe Dzinamarira
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