Uploaded image for project: 'JDK'
  1. JDK
  2. JDK-8227019

CompletableFuture.waitingGet shouldn't call Runtime.availableProcessors in a tight loop

    Details

    • Type: Enhancement
    • Status: Closed
    • Priority: P4
    • Resolution: Duplicate
    • Affects Version/s: 8
    • Fix Version/s: None
    • Component/s: core-libs
    • Labels:

      Description

      As described in JDK-8227006 the addition of container support has slowed down the execution of Runtime.availableProcessors. By calling this function in its spin-loop waitingGet() can also suffer from a severe slowdown in performance.

                      spins = (Runtime.getRuntime().availableProcessors() > 1) ?
                          1 << 8 : 0; // Use brief spin-wait on multiprocessors

      As we only care about >1 processors we can cache this value in a field. The only problem case would be a >1 to 1 transition which is an unlikely change. If it did occur it would only result in a small performance hit anyway.

      This fix is only needed for 8u as 9 and later have different code due to JDK-8157522

        Attachments

          Issue Links

            Activity

              People

              • Assignee:
                Unassigned
                Reporter:
                dholmes David Holmes
              • Votes:
                0 Vote for this issue
                Watchers:
                1 Start watching this issue

                Dates

                • Created:
                  Updated:
                  Resolved: