Which version of Racket are you using? I think Ryan pushed some custodian related improvements to the db library recently. <div> <div>Robby On Friday, December 26, 2014, Dmitry Pavlov <<a href="mailto:dpavlov@ipa.nw.ru">dpavlov@ipa.nw.ru</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hello, Let us say I put this program into DrRacket's Definitions window: ----------------------------------------------------------------- #lang racket (require db) (define path "aaa.db") (when (file-exists? path) (delete-directory/files path)) (define conn (sqlite3-connect #:database path #:mode 'create)) ----------------------------------------------------------------- and then press the "Run" button. After that, I play with conn in the Interactions window. When I have played enough, I press the "Run" button again. Here is what I get: delete-file: cannot delete file path: [...]\aaa.db system error: Permission denied; errno=13 The reason is that I forgot to (disconnect conn) in the end. (I get that only on Windows; Linux is OK with removing opened files). How do I disconnect automatically? Putting the (disconnect conn) into the Definitions window is not a solution, as I want to use conn in the Interactions (also I want to be safe against the "Stop" button pressed in the middle of the program before the disconnect happens) I tried to use a will executor: ----------------------------------------------------------------- (define an-executor (make-will-executor)) (void (thread (lambda () (let loop () (will-execute an-executor) (loop))))) (define (executor-proc v) (printf "I am now garbage\n") (disconnect v)) (will-register an-executor conn executor-proc) ----------------------------------------------------------------- Surprisingly, it did not work for the database connection (while it does work for other kinds of objects), and I have no idea why. It does not work even with I call the GC explicitly: ----------------------------------------------------------------- (set! conn #f) (collect-garbage) ----------------------------------------------------------------- Is it possible to make the will executor work? Generally speaking, what is the recommended way to do this kind of thing? Best regards, Dmitry ____________________ Racket Users list: <a href="http://lists.racket-lang.org/users" target="_blank">http://lists.racket-lang.org/users</a> </blockquote></div></div>