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Re: [JAVA,libtool] Big libjava is biiiig.


Andrew Haley wrote:
> Dave Korn wrote:
> 
>> 1)  Would this be a reasonable approach, specifically i) in adding a configure
>> option to cause sublibraries to be built, and ii) in using gmake's $(filter)
>> construct to crudely subdivide the libraries like this?
> 
> At program startup the first library would be loaded, it would load
> the next, and so on.  There are a few parts of libgcj that are truly
> independent, but I suspect that you'd always load almost all of it.
> So, you'd have longer startup time for loading all those files.

  Compared to a single DLL that is unusably malformed because it exceeds
system limits, that's still an improvement :)

> With regard to GNU libc platforms:
> 
> You'd no longer be able to make so much use of fast calls between
> functions in the same library; you'd have to go via the PLT.
> 
> Also, dl_iterate_phdr() is used a great deal (for finding exception
> regions, garbage collection, etc.) and it linearly scans the libraries
> that are loaded.  So, the more libraries you have loaded, the slower
> it goes.
> 
> Now, I don't know how much of these characteristics are shared by
> Windows, but I imagine some of them are.

  Yes, the inter-library calls would have to be dllimports and go through
stubs (one extra indirect branch).  I don't know how dl_iterate_phdr works on
win32 but I imagine that it's also linear in the number of libs.

> So, I suspect your best bet would be to split libgcj into core and
> non-core libraries and not slice much more thinly than that.  I can
> advise you what is core and what isn't.

  Please do, I'll happily try that approach since it might significantly
simplify my inter-dependences problems.

    cheers,
      DaveK


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