RFR 7149320: Move sun.misc.VM.booted() to end of System.initializeSystemClass()

Alan Bateman Alan.Bateman at oracle.com
Wed Feb 29 14:41:59 UTC 2012

On 28/02/2012 03:57, Mike Duigou wrote:
> Hello all;
> This issue is a patch for review that I have split out of a larger issue I'll be submitting later.
> WEBREV @ http://cr.openjdk.java.net/~mduigou/7149320/0/webrev/
> sun.misc.VM.booted() is currently called before setJavaLangAccess(). For code which uses the JavaLangAccess shared secrets it's convenient to be able to check whether the secrets are initialized without having to call sun.misc.SharedSecrets.getJavaLangAccess() every time the secrets are used and checking for null. In particular with the static inner class holder idiom it would be desirable to do :
> static class Holder {
>    final sun.misc.JavaLangAccess ACCESS = sun.misc.SharedSecrets.getJavaLangAccess();
> }
> ...
> if(sun.misc.VM.isBooted()&&  Holder.ACCESS...
> In my research on this issue I was unable to determine why sun.misc.VM.booted() isn't the currently the last activity in System.initSystemClass(). Neither of the two tasks which currently follow it depend upon booted state in any way that I could determine. I am tempted, thinking about it, to add a comment to System.initSystemClass before the call to sun.misc.VM.booted() asking future maintainers to leave boot() as the last activity or explain why not.
> I have done JTReg runs on linux x86, linux x64 and Solaris 64 which incorporated this change without any problems encountered. It's rather difficult to write a unit test for this issue as it requires a class that is initialized after java.lang.System but before java.lang.System.initSystemClass() and uses JavaLangAccess.
> Thanks,
> Mike
We do need to take great care in System.initSystemClass. I think the 
safest thing would be to just move setJavaLangAccess to before the call 
to VM.booted(). At one point the access to java.lang was setup 
immediately after the system properties were initialized so we've been 
there before.


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