CODEWITHSUNDEEP
javafilejava-io
Jan-Willem Gmelig Meyling
Jan-Willem Gmelig Meyling

Reputation: 3913

Clean files queued for deletion through File.deleteOnExit

I have some library code that uses File.deleteOnExit(). As this piece of code is called a lot in my application, memory keeps piling up in DeleteOnExitHook. This causes my heap to grow indefinitely and eventually causes OutOfMemoryErrors. As the class is completely package protected, there seems trivial mechanism to intermediately delete the files enqueued for deletion. Can I get this empty this list with some reflection magic?

Upvotes: 0

Views: 352

Answers (1)

user319799
user319799

Reputation:

As I understand, you need a dirty hack, so this should suffice. You need to restore files field value so that normal shutdown (or next time you use this hack) works fine.

Note: will delete everything, including files scheduled by other libraries. Make sure to check it is safe in your case.

    java.lang.reflect.Method  run   = Class.forName ("java.io.DeleteOnExitHook").getDeclaredMethod ("runHooks");
    java.lang.reflect.Field   files = Class.forName ("java.io.DeleteOnExitHook").getDeclaredField  ("files");

    run.setAccessible (true);
    files.setAccessible (true);

    run.invoke (null);
    files.set (null, new java.util.LinkedHashSet <String> ());

Alternatively, just retrieve the scheduled files with

    files.get (null)

iterate the set and delete the files manually, also deleting the names from the set as you go. This way you can decide which files to delete yourself.

Upvotes: 1

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