[erlang-questions] How to upgrade running applications repeatedly
Fri Jun 8 10:54:58 CEST 2007
> Hello All.
> I have tried without success to be able to update my running applications. The code below is a very simple example in which there is a loop, that will always call itself with ?MODULE:loop(L) which according to the documentation should always call the latest version of itself, but this is what happens:
> 1) I start the app with test1:start().
> 2) I compile it and send some message to it, everything works
> 3) I repeat step 2 and the program fails
Ok, so the problem turned out to be that old code was still running on
the second code load (which happened implicitly as part of the
- Take a look at code:soft_purge/1
- By default, use spawn_link() or proc_lib:spawn_link() and not
plain spawn. Most of the time, you don't want processes to die
silently. (Ulf Wiger already suggested this)
- Don't be "too clever" with funs. There are a few gotchas which
affect code loading. You can read a bit more here, under "Do
funs behave during a code change?"
Experimenting with the basics, e.g. writing a 'server' process from
scratch, is a great way to learn. And then you can forgive gen_server
for not being so pretty, because it gets the fiddly details right so
that you have to go out of your way to screw up code loading.
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