Uploaded image for project: 'JDK'
  1. JDK
  2. JDK-8180421

Change default value of BiasedLockingStartupDelay to 0

    XMLWordPrintable

Details

    • Enhancement
    • Status: Resolved
    • P4
    • Resolution: Fixed
    • 10
    • 10
    • hotspot
    • b21

    Description

      The current default value for BiasedLockingStartupDelay is 4000, which means that biased locking won't be enabled until after 4 seconds of runtime.

      This will have the effect that all objects created before biased locking is enabled will have a different mark word value than the one used after biased locking has been enabled. This is a bit problematic for GCs using the mark word, since the mark then will have to be saved and later restored when the GC is done.

      There is not much documentation around why this delay was added, but the idea seems to have been to improve performance later on in the run or possibly improve startup time.

      Recent performance measurements doesn't show any significant changes in either startup or steady state performance between using the current delay or having no delay at all.

      Attachments

        Issue Links

          There are no Sub-Tasks for this issue.

          Activity

            People

              rehn Robbin Ehn
              sjohanss Stefan Johansson
              Votes:
              0 Vote for this issue
              Watchers:
              3 Start watching this issue

              Dates

                Created:
                Updated:
                Resolved: