(Sorry for delayed response)
: Jim Newton If I run several sbcl processes on different nodes in my compute cluster, it might happen that two different runs notice the same file needs to be recompiled (via asdf), and they might try to compile it at the same time. What is the best way to prevent this?
You mean that this machines share the same host directory? Interesting.
"Normal" rules of ASDF compile to a temporary file and rename the output at the end, thus providing some kind of race resistance. But for backward-compatibility reasons, this requires every extension to manually follow a protocol for ASDF to remain robust.
I see in the asdf documentation that there is an asdf:*user-cache* variable whose value is the path name of the directory where asdf compiles into. Would it be advisable for my to arrange so that asdf:*user-cache* is a function of the pid and hostname and perhaps thread-id (if such a thing exists) to avoid such collisions?
That's an option. It is expensive, though: it means no sharing of fasl files between hosts. If you have cluster of 200 machines, that means 200x the disk space.
What about instead building your application as an executable and delivering that to the cluster?
My rule of thumb is that there is one home directory per human, and the human is only interactively building one thing at a time (and/or can set several accounts and/or $HOME variants for as many "personalities"). Thus you only need one fasl cache for interactive compilation. If you want non-interactive deployment, use tools like bazel, nix, etc., to build your software deterministically.
Or is there some better way to handle this which is build into asdf?
You can have different ASDF_OUTPUT_TRANSLATIONS or asdf:*output-translations-parameter* on each machine, or you can indeed have the user cache depend on uiop:hostname and more.
The Right Thing™ is still to build and test then deploy, rather than deploy then build. Using Bazel, you might even be able to build in parallel on your cluster.
: pjb I had requested that ASDF includes the hostname (or machine-instance), in the built path for the cache. Unfortunately, for some reason, the maintainers of ASDF thought it was a good read to remove it. There you are!
I still think it's a bad idea. If your $HOME is shared by many machines, you probably want what's in $HOME to be shared, too. Go build in /var/tmp or use Bazel or whatever. Or use uiop:hostname in your ASDF configuration.
On Tue, Jan 23, 2018 at 7:51 AM, Jim Newton jnewton@lrde.epita.fr wrote:
Apparently, this approach seems to work. I’m not sure if it is the best approach. Here is what my code looks like. It creates a directory in /tmp/ and asdf:load-system seems to compile the .fasl files into there.
(require :asdf) (require :sb-posix) (let ((home (directory-namestring (user-homedir-pathname))) (uid (sb-posix:getuid)) (pid (sb-posix:getpid))) (setf asdf::*user-cache* (ensure-directories-exist (format nil "/tmp~A~D/~D/" home uid pid))))
I still don't understand why your use case uses deploy-then-build rather than build-then-deploy.
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