Re: [Caml-list] Size of .cmo / .cmi workload of the compiler

[Goswin von Brederlow <goswin-v-b@web.de>]

On Wed, Aug 19, 2015 at 05:38:12PM +0200, Christoph Höger wrote:
> Dear all,
> 
> I autogenerate a rather large (> 12k) set of ocaml modules containing
> classes which are parameterized over their final representation to allow
> for hierarchic classes with polymorphic open recursion.
> 
> My compilation scheme seems to work well in principle, but I am reaching
> a frustrating limit in practice: The compilation of the generated ml
> files seems to run superlinear (in fact it seems to depend on the
> hierarchical location of a class). As it turns out, the generated .cmo
> and .cmi files are quite large (up to several hundreds of kb). When I
> generate the .mli files or dump the .cmo files however, the output is
> quite small (several hundred instructions in the bytecode, the .mli file
> contains quite complex objects but still human readable).
> 
> Is there any known issue that leads to:
> 
> 1. non-linear runtime when compiling inter-module classes
> 2. huge .cmo files outside of the actual bytecode
> 
> The generated source code can be found here:
> 
> https://www.dropbox.com/s/cllc0xikv9zwu1k/doesnotscale.tar.bz2?dl=0
> 
> To test the behavior, unpack and run
> 
> ocamlbuild ModelicaXX5FElectricalXX5FMachines.cmo
> 
> (there might be type-errors in the generated files somewhere, though).
> 
> Any advice or comments are deeply appreciated.
> 
> Christoph

When you inherit a class the compiler has to parse that class and
everythig it inherits. So it is no surprise to get slower the longer
your inheritance chain gets. And I assume each step in the chain adds
some method so your interface gets bigger and bigger. Sounds like the
cmi file contains the full interface and not just a reference to the
inherited class(es) and the additional code while dumping the cmo file
only shows the additional code.

MfG
	Goswin