[erlang-bugs] Allow code upgrade for the code_server itself

Siri Hansen <>
Thu Jun 19 11:26:28 CEST 2014

Hi Stavros, I'm sorry for the very long delay! Are you still struggling
with this problem or did you find a way around it? Would a code_change
system message while the process is suspended possibly solve the problem?

2014-03-10 23:02 GMT+01:00 Stavros Aronis <>:

> Hello!
> I am playing around with code instrumentation and trying to hack the code
> server so that it applies some transformation whenever it loads *any*
> module. The hack itself is relatively simple:
> 1) Instrument and reload any already loaded modules (come to think about
> it, during this process more modules may be loaded, but let's assume a
> fixpoint). This is to avoid the case where in order to load A, you have to
> instrument A, and the instrumenter itself needs a call to X, which is not
> yet loaded so you have to load X, so you have to instrument X, etc...
> 2) Get the Core Erlang code of the codeserver and wrap the second argument
> of erlang:load_module (Line 1264) with a call to my instrumenter (which is
> a function from binary() -> binary())
> 3) Load the patched code_server code
> 4) Move the code_server process from the old code to the new one.
> I am having trouble with the last step. As far as I understand it, the
> reason is that the call to system_continue (Line 184) is not qualified, as
> is the similar call in sys.erl (Line 324).
> Is there a reason why this is so? Is there any possibility for this to be
> patched?
> Cheers,
> Stavros
> _______________________________________________
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> http://erlang.org/mailman/listinfo/erlang-bugs
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