RFR: 8199717: Avoid calculating primordial thread stack bounds on VM startup
robbin.ehn at oracle.com
Tue Mar 27 11:36:25 UTC 2018
Hi Claes, looks good.
Personally taste would be to instantiate the bool explicit (to true) like the
On 03/27/2018 12:02 PM, Claes Redestad wrote:
> on linux, we scan /proc/self/maps to be able to tell if the current thread is
> the "primordial" one.
> However, when initializing the VM, all the java launchers spawn a new thread
> rather than initializing the VM on the primordial thread, so we can deduce that
> none of the threads we'll run on will be the primordial thread if started by one
> of the standard java launchers. This enables us to skip reading the
> /proc/self/maps entirely.
> Bug: https://bugs.openjdk.java.net/browse/JDK-8199717
> Webrev: http://cr.openjdk.java.net/~redestad/8199717/open.00/
> This patch uses the Arguments::created_by_java_launcher(), which checks is the
> sun.java.launcher property has been set or not. There is a small risk third
> party launchers sets the sun.java.launcher property even when not conforming to
> the behavior of the standard java launchers; if so the existing
> created_by_java_launcher() method might need to be re-examined in a follow up.
> This shaves ~0.7ms off of startup on my linux machine.
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