RFR (S) 8059677: Thread.getName() instantiates Strings

Chris Hegarty chris.hegarty at oracle.com
Mon Nov 10 11:52:08 UTC 2014


I have only looked at the libraries changes, and I think they make sense 
. As in, I can find no reason why the name cannot be changed to be a String.

Trivially, after your changes will NPE be thrown if setName(null), as it 
is today ?


On 09/11/14 18:45, Aleksey Shipilev wrote:
> Hi,
> Thread.getName() returns String, and does new String instantiation every
> time, because the thread name is stored in char[]. Even though we use a
> private String constructor that shares the char[] array without copying
> it, this still hurts some use cases (think extra-fast logging). To the
> extent some people actually maintain Map<Thread, String> to avoid it.
>   https://bugs.openjdk.java.net/browse/JDK-8059677
> Here's the attempt to maintain String instead of char[]:
>   http://cr.openjdk.java.net/~shade/8059677/webrev.01.jdk/
>   http://cr.openjdk.java.net/~shade/8059677/webrev.01.hs/
> JDK changes are trivial, but HS changes require some rewiring, since VM
> treats Thread.name specially. However, it turns out we can make a
> contained change, since the getter is used sparingly, and setter seems
> to be not used at all. Any trouble with this change?
> Testing: JPRT, manual tests, jdk/test/java/lang/Thread jtreg,
> hotspot/test/runtime/ jtreg, vm.quick.testlist, nsk.jvmti.testlist,
> svc.quick.testlist
> Thanks,
> -Aleksey.

More information about the core-libs-dev mailing list