clojure's compile function leaks file descriptors, i.e. it relies on garbage collection to close the files. I'm trying to use boot [1] on windows and ran into the problem, that files could not be deleted intermittently [2]. The problem is that clojure's compile function, or rather clojure.lang.RT.lastModified() relies on garbage collection to close files. lastModified() looks like:

Here's the stacktrace from file leak detector [3]:

Cause: getLastModified() opens the URLConnection's InputStream but does not close it.

Approach: On Stackoverflow [4] there's a discussion on how to close the URLConnection correctly.

On non-Windows operating systems this shouldn't be much of a problem. But on windows this hurts very much, since you can't delete files that are opened by some process.

Patch: clj-1659-v3.patch

Screened by: Alex Miller

[1] http://boot-clj.com/
[2] https://github.com/boot-clj/boot/issues/117
[3] http://file-leak-detector.kohsuke.org/
[4] http://stackoverflow.com/questions/9150200/closing-urlconnection-and-inputstream-correctly