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))))

#-quicklisp

(let ((quicklisp-init

"/lrde/home/jnewton/quicklisp/setup.lisp"))

  (if (probe-file quicklisp-init)

      (load quicklisp-init)

      (error "file not found ~S" quicklisp-init)))

(asdf:load-system :lisp-types-test)

On 23 Jan 2018, at 12:47, Pascal Bourguignon <pjb@informatimago.com> wrote:

On 23 Jan 2018, at 12:00, Jim Newton <jnewton@lrde.epita.fr> wrote:

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?

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?

Or is there some better way to handle this which is build into asdf?

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!

-- 
__Pascal J. Bourguignon__