Re: Patch: replace mutex with object synchronization

[Andrew Haley <aph at redhat dot com>]

Bryce McKinlay writes:
 > Andrew Haley wrote:
 > 
 > > > Andrew, I'm not suggesting we change the way offset tables are accessed 
 > > > by our code at all.
 > >
 > >But Tom is.  If the same class binary is to be used more than once,
 > >its otables will be resolved differently in each class loader context:
 > >that means they can't be common; and that means they can't be
 > >statically allocated; and that means they can't be accessed in the way
 > >they are at the moment.
 > >  
 > >
 > 
 > I see. Yes, that would certainly be a problem if the otable entries 
 > resolve to different classes in each context. Is loading multiple 
 > instances of the same class (in the same binary) into different class 
 > loaders a common requirement?

Very much so.  Application servers like JOnAS depend on it.  Don't
think of an application server as "one binary".  It's a bunch of
different communicating processes in a single VM, each process with
its own dependencies.

 > Example: 1.7 million string comparisons to start up OpenOffice.org, with 
 > an average symbol length of 58 characters. This is aggrivated due to the 
 > large number of .so's, but a large Java program linked against libgcj.so 
 > is probably not all that far removed from these numbers.
 > 
 > Its hard to imagine that we can't do better(*)

Right.  Let's show 'em how it should be done.  :-)

Andrew.