On 10/11/14 12:56, David Holmes wrote:
On 10/11/2014 9:52 PM, Chris Hegarty wrote:
Aleksey,
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.
Very quick response, but IIRC this has been examined in the past and
there were reasons why it can't/shouldn't be done. Will try to dig out
more details in the morning.
If there was previous discussion on this, that revealed some substantial
issue, that would be great, but I can't recall, or find, it now.
Hotspot express, and the desire for hotspot to run with different
library versions, would certainly cause complication, but I don't
believe that is an issue now.
Just on that, the library changes are minimal, and if this were to
proceed then they can accompany the hotspot change, as they make their
way into jdk9/dev.
Anyway, this should await your reply.
-Chris.
If String construction is a bottleneck just cache it.
David
-----
Trivially, after your changes will NPE be thrown if setName(null), as it
is today ?
-Chris.
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.
