[prev in list] [next in list] [prev in thread] [next in thread] 

List:       openjdk-hotspot-gc-use
Subject:    Re: YGC time increasing suddenly
From:       "Bernd Eckenfels" <bernd-2013 () eckenfels ! net>
Date:       2013-12-21 19:45:46
Message-ID: op.w8gjukm5tc8ri4 () eckenfels02 ! seeburger ! de
[Download RAW message or body]

Am 21.12.2013, 17:15 Uhr, schrieb Luciano Molinari <lucmolinari@gmail.com>:
> I noticed that many Strings in the heap are equals..shouldn't JVM keep
> only different Strings and re-use the equals?

When a string is interned (all constants in your classes are interned)  
then there is only one instance for a string. However if you (or a  
library) construct a new string from bytes/characters then it will not be  
automatically interned and therefore created with multiple instances  
(basically if you use "new String" you get what you ask for :)

You can use .intern() on a String to get its unique instance, but be sure  
to do this only for the most common/often used strings. This does  
essentially a hash lookup, so it is most often not a good idea to do it  
(unless you know you keep them around for long and/or equal() them very  
often. (For example it sometimes make sense to intern() all element names  
of Dom Trees but not the (too many different) values).

Gruss
Bernd
-- 
http://bernd.eckenfels.net
_______________________________________________
hotspot-gc-use mailing list
hotspot-gc-use@openjdk.java.net
http://mail.openjdk.java.net/mailman/listinfo/hotspot-gc-use
[prev in list] [next in list] [prev in thread] [next in thread]