RFR(S): 8068579: Running with -XX:-UseParallelGC does not turn ParalleGC off (original) (raw)

Per Liden per.liden at oracle.com
Wed Mar 16 08:12:21 UTC 2016

Hi Dima,

On 2016-03-15 17:38, Dmitry Fazunenko wrote:

Hi Per,

A couple of comments: 1) globalsextension.hpp.frames.html requires copyright update 2) such fix should go with a regression test, it could be done separately.

Good point. I was about to add a test for this just now and realized that the new semantics is not kept for minimal VMs (i.e. when INCLUDE_ALL_GCS==0). I'll rework the patch a bit to have the same semantics also on minimal VMs. New webrev coming.

thanks, Per

Thanks, Dima

On 15.03.2016 16:48, Per Liden wrote: Summary: Explicitly disabling the default collector, without specifying another collector, will silently re-enable the default collector. This is a bit counter intuitive. A better approach would be for the VM to complain about the situation.

Bug: https://bugs.openjdk.java.net/browse/JDK-8068579 Webrev: http://cr.openjdk.java.net/~pliden/8068579/webrev.0/ Testing: manual, jprt Example (assuming it's a platform/configuration with G1 as default): $ java -XX:-UseG1GC ... Today, the above command will happily start a VM with G1 enabled. With this patch the VM will instead complain, like this: $ java -XX:-UseG1GC ... Error occurred during initialization of VM Garbage collector not selected (default collector explicitly disabled) And of course, we're good with disabling the default collector as long as you specify some other collector, e.g.: $ java -XX:-UseG1GC -XX:+UseParallelGC ... cheers, Per

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