Uploaded image for project: 'Apache Arrow'
  1. Apache Arrow
  2. ARROW-7098

[Java] Improve the performance of comparing two memory blocks

    XMLWordPrintableJSON

Details

    • Improvement
    • Status: Resolved
    • Minor
    • Resolution: Fixed
    • None
    • 0.16.0
    • Java

    Description

      We often use the 8-4-1 paradigm to compare two blocks of memory:
      1. First compare by 8-byte blocks in a loop
      2. Then compare by 4-byte blocks in a loop
      3. Last compare by 1-byte blocks in a loop

      It can be proved that the second loop runs at most once. So we can replace the loop with a if statement, which will save us a comparison and two jump operations.

      According to the discussion in https://github.com/apache/arrow/pull/5508#discussion_r343973982, loop can be expensive.

      Attachments

        Issue Links

          Activity

            People

              fan_li_ya Liya Fan
              fan_li_ya Liya Fan
              Votes:
              0 Vote for this issue
              Watchers:
              2 Start watching this issue

              Dates

                Created:
                Updated:
                Resolved:

                Time Tracking

                  Estimated:
                  Original Estimate - Not Specified
                  Not Specified
                  Remaining:
                  Remaining Estimate - 0h
                  0h
                  Logged:
                  Time Spent - 50m
                  50m