Re: String.interning is surprisingly cpu-consuming.

[Dr Heinz M. Kabutz]

Funny coincidence, I mention this in todays' "Java Specialists'
Newsletter": https://www.javaspecialists.eu/archive/Issue254.html

And I believe they improved this in Java 9 :-)
Regards

Heinz
-- 
Dr Heinz M. Kabutz (PhD CompSci)
Author of "The Java™ Specialists' Newsletter" - www.javaspecialists.eu
Java Champion - www.javachampions.org
Oracle Developer Champion - www.twitter.com/dev_champions
JavaOne Rock Star - www.oracle.com/javaone/rock-star-wall-of-fame.html
Tel: +30 69 75 595 262
Skype: kabutz



John Hening wrote:

  Hello! 
  
I have the very simple Utils function: 
  
  
  public static Unsafe getUnsafe(){
      Field f = Unsafe.class.getDeclaredField("theUnsafe");
      f.setAccessible(true);
      return (Unsafe) f.get(null);
  }
  
  
  
And, as it turned out from my analysis with perf it is a bottleneck in
my "scheme" of the program. That funciton is called in main loop. It is
a scheme so it wasn't optimized (I know that I should do it better).
Nevertheless, perf points that `String::intern` is
cpu-cylcle-consuming. 
I cannot understand why that method wasn't compiled to something like
that:
  
("theUnsafe" was placed in permgen)
and now:
  
  
  
load string_theUnsafe_from_permgen
call Unsafe.class.getDeclaredField
  ..
  
  
  
  
instead of
  
  public static getUnsafe()Lsun/misc/Unsafe;
    ...
   L0
    LDC Lsun/misc/Unsafe;.class
    LDC "theUnsafe"
    INVOKEVIRTUAL java/lang/Class.getDeclaredField
  (Ljava/lang/String;)Ljava/lang/reflect/Field;
    ...
  }
  
  
  
Especially, I don't see where method
  
  
  String.intern
  
  
is called? I suppose that it is called by interpreter on
  
  
  LDC "theUnsafe"
  
  
  
  
Explain me that, please.
  
Greetings,
  
John
  
-- 
You received this message because you are subscribed to the Google
Groups "mechanical-sympathy" group.
To unsubscribe from this group and stop receiving emails from it, send
an email to mechanical-sympathy+unsubscr...@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.






-- 
You received this message because you are subscribed to the Google Groups "mechanical-sympathy" group.
To unsubscribe from this group and stop receiving emails from it, send an email to mechanical-sympathy+unsubscr...@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

String.interning is surprisingly cpu-consuming.

[John Hening]

Hello! 

I have the very simple Utils function: 

public static Unsafe getUnsafe(){
  Field f = Unsafe.class.getDeclaredField("theUnsafe");
  f.setAccessible(true);
  return (Unsafe) f.get(null);
}

And, as it turned out from my analysis with perf it is a bottleneck in my 
"scheme" of the program. That funciton is called in main loop. It is a 
scheme so it wasn't optimized (I know that I should do it better). 
Nevertheless, perf points that `String::intern` is cpu-cylcle-consuming. 
I cannot understand why that method wasn't compiled to something like that:

("theUnsafe" was placed in permgen)
and now:


load string_theUnsafe_from_permgen
call Unsafe.class.getDeclaredField
..



instead of
public static getUnsafe()Lsun/misc/Unsafe;
...
   L0
LDC Lsun/misc/Unsafe;.class
LDC "theUnsafe"
INVOKEVIRTUAL java/lang/Class.getDeclaredField (Ljava/lang/String;)Ljava
/lang/reflect/Field;
...
}

Especially, I don't see where method

String.intern

is called? I suppose that it is called by interpreter on

LDC "theUnsafe"


Explain me that, please.

Greetings,

John

-- 
You received this message because you are subscribed to the Google Groups 
"mechanical-sympathy" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to mechanical-sympathy+unsubscr...@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.