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  1. ZooKeeper
  2. ZOOKEEPER-1285

make DataTree immutable

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Details

    • Improvement
    • Status: Open
    • Major
    • Resolution: Unresolved
    • None
    • None
    • None
    • None

    Description

      Having an immutable DataTree structure in the ZooKeeper server is an ambitious goal but is possible. Advantages would be:

      • No synchronization needed when accessing the DataTree.
      • The snapshotter thread gets an immutable datatree and will write a consistent DataTree to the disk.
      • No headaches whether multi transactions could lead to issues with (de)serialization.
      • Much better testability.
      • No concurrency - No headaches.
      • I hope for considerable speed improvements. Maybe also some memory savings, at least from refactorings possible after this step.
      • Statistical Data about the tree can be updated on every tree modification and is always consistent. The need to save statistical data in extra nodes for the quota feature goes away.

      Possible further improvements:

      Read requests actually don't need to enter the processor pipeline. Instead each server connection could get a reference to a (zxid, tree) tuple. Updates
      are delivered as (zxid, newTree, triggerWatchesCallback) to the server connections.
      The watches could be managed at each server connection instead of centrally at the DataTree.

      Attachments

        Issue Links

          depends upon

          Sub-task - The sub-task of the issue ZOOKEEPER-1228 Cleanup SessionTracker

          • Major - Major loss of function.
          • Open

          Sub-task - The sub-task of the issue ZOOKEEPER-1230 Cleanup FileTxnLog

          • Major - Major loss of function.
          • Open

          Sub-task - The sub-task of the issue ZOOKEEPER-1259 central mapping from type to txn record class

          • Major - Major loss of function.
          • Open

          Sub-task - The sub-task of the issue ZOOKEEPER-1255 unused fields in DataTree.ProcessTxnResult

          • Minor - Minor loss of function, or other problem where easy workaround is present.
          • Open

          Sub-task - The sub-task of the issue ZOOKEEPER-1276 ZKDatabase should not hold reference to FileTxnSnapLog

          • Minor - Minor loss of function, or other problem where easy workaround is present.
          • Open

          Sub-task - The sub-task of the issue ZOOKEEPER-1279 Only SessionTracker should hold reference to sessionsWithTimeouts

          • Minor - Minor loss of function, or other problem where easy workaround is present.
          • Open

          Sub-task - The sub-task of the issue ZOOKEEPER-1253 return value of DataTree.createNode is never used

          • Trivial - Cosmetic problem like misspelt words or misaligned text.
          • Resolved

          Sub-task - The sub-task of the issue ZOOKEEPER-1258 Move MultiResponse creation out of FinalRequestProcessor

          • Major - Major loss of function.
          • Patch Available
          supercedes

          Improvement - An improvement or enhancement to an existing feature or task. ZOOKEEPER-1092 get rid of pending changes

          • Minor - Minor loss of function, or other problem where easy workaround is present.
          • Open

          Activity

            People

              thkoch Thomas Koch
              thkoch Thomas Koch
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              Dates

                Created:
                Updated: