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

Per Liden per.liden at oracle.com
Wed Mar 16 07:49:55 UTC 2016


On 2016-03-15 23:38, Jon Masamitsu wrote:

On 3/15/2016 6:48 AM, 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/ Changes look good.

Thanks Jon.

Not part of your changes bug should this code mostly be under INCLUDEALLGCS?

It could be, but given that this is a small function I'm not sure it's worth the additional #if/#endif we would need in at lease two places.

thanks, Per

Jon

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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