[Caml-list] Java JVM is becoming more strict

[Matthieu Dubuget <matthieu.dubuget@gmail.com>]

Hello,

this post is just a short story for the archives of the mailing-list… 
This is about a three days (successful) fight against a bug.

Since more than three year, my colleague is using one DLL of mine. This 
DLL was produced with ocaml, from some caml modules and one hand written 
C file. My colleague is not perfect: he is calling this DLL from one 
Java application.

Last week, for some technical constraints, he had to upgrade the Java 
virtual machine toward a >= 1.6 version.
Since this upgrade, he experienced one exception violation on the first 
call to the DLL (ie when calling caml_startup).

It appeared that some other OCaml DLL were still working fine. We made a 
test, replacing the Caml modules with a minimal .ml file, returning 
static values: this worked without violation exception. After that, we 
printed the dependencies (ocamldep -modules) of the modules.

The problem was that some (unused) debugging code was still there in one 
of them: this module had a dependency toward Printf module. Once this 
dependency was removed, we got read of the exception violation. I wonder 
if this is a bug in OCaml, in the JVM, or a mis-use of the JVM?

Salutations

Matthieu