JDK-8243971 : Deprecate -XX:ForceNUMA option
  • Type: CSR
  • Component: hotspot
  • Sub-Component: gc
  • Priority: P4
  • Status: Closed
  • Resolution: Approved
  • Fix Versions: 15
  • Submitted: 2020-04-28
  • Updated: 2020-08-12
  • Resolved: 2020-04-29
Related Reports
CSR :  
JDK-8243628 - Deprecate -XX:ForceNUMA option
Relates :  
JDK-8251463 - Obsolete -XX:ForceNUMA option
Description
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.
Comments
Moving to Approved for JDK 15.
29-04-2020