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  1. JDK
  2. JDK-8243971

Deprecate -XX:ForceNUMA option

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    • Icon: CSR CSR
    • Resolution: Approved
    • Icon: P4 P4
    • 15
    • hotspot
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    • gc
    • behavioral
    • low
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      Using -XX:+UseNUMA -XX:+ForceNUMA on Windows on non-NUMA hardware has failed an assertion for a long time. In a product build that would instead be a divide by zero. Also, the Windows implementation support for UseNUMA is a stub.

      A web search for "ForceNUMA" finds the usual lists of VM options. In addition, there are some old references like this one:
      https://www.oracle.com/technetwork/server-storage/hardware-solutions/o11-102-oos-webcenter-505718.pdf
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      Using -XX:+UseNUMA -XX:+ForceNUMA on Windows on non-NUMA hardware has failed an assertion for a long time. In a product build that would instead be a divide by zero. Also, the Windows implementation support for UseNUMA is a stub. A web search for "ForceNUMA" finds the usual lists of VM options. In addition, there are some old references like this one: https://www.oracle.com/technetwork/server-storage/hardware-solutions/o11-102-oos-webcenter-505718.pdf
    • add/remove/modify command line option
    • JDK

      Summary

      Deprecate the VM product option ForceNUMA.

      Problem

      The ForceNUMA option was added as part of the initial NUMA support (JDK-6779436). It provides a mechanism for forcing NUMA code paths to be used even if the execution hardware is single-node/UMA. There is no benefit from that behavior for end-users. That behavior is only useful for developers testing changes to the NUMA support code in the absence of NUMA hardware. And in that case there are better alternatives, based on virtualization, to have the appearance of NUMA hardware.

      Solution

      Deprecate the ForceNUMA option in JDK 15, and either make it a development option or obsolete it in JDK 16.

      Specification

      Use of -XX:+/-ForceNUMA will generate the usual warning for a deprecated VM option.

            kbarrett Kim Barrett
            kbarrett Kim Barrett
            Stefan Karlsson
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              Created:
              Updated:
              Resolved: