Tue Aug 13 13:25:28 CEST 2002
Richard Carlsson <> writes:
> - Is it necessary to be able to exchange any single module?
> (E.g., if your application consists of a number of modules,
> do you always replace all these modules anyway?)
I use this feature frequently while in development mode. Sometimes
even on production nodes to hot-fix bugs.
> - Could code migration be limited to specific functions, or
> is it necessary to be able to switch to a new version at all
> "remote" calls. (E.g., one could imagine a new declaration
> for specifying only certain functions as code update points.)
As I use generic behaviours almost exclusively, this has not been an
> - Do you always use the OTP release handler or similar to
> do code updates, or do you do it by hand, or with your own
> in-house tools, etc? Do you find it simple as it is today,
> or is code update so difficult that you try to avoid it?
We wrap our releases in Debian packages. I would like to have tight
integration between the OTP release handler and the Debian package
system. Most of the time, though, we just shut down the node while
> - How much of a problem are circular module dependencies in
Not much of a problem for me, yet.
> - Is the flexibility of being able to change any module at any
> time (even in production code) worth more to you than the
> speed of the code?
The speed of the code has not been an issue until now.
> - When you make a (remote) call that is expected to switch
> to new code whenever it has been loaded, could you guarantee
> that the call stack is empty at that point, i.e., you will
> not return to the old code, nor to the code that called it?
> (If so, the code purging stage would not have to scan the
> stacks of processes to find out if they must be killed.)
> This pretty much equals saying that code change always starts
> a fresh process, but keeps the old Pid.
I'm not sure. Would it be enough to only make qualified
intra-module-calls when they're tail-calls?
Gerd Flaig Technik
Bei Schlund + Partner AG Erbprinzenstr. 4-12 D-76133 Karlsruhe
Physics is like sex: sure, it may give some practical results,
but that's not why we do it. -- Richard Feynman
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