Memory leak in Lwt_unix.files_of_directory

[samoht]

The following simple program shows how to reproduce:

(* test.ml *)
open Lwt.Infix

let list_files dir =
  let s = Lwt_unix.files_of_directory dir in
  let s = Lwt_stream.filter (fun s -> s <> "." && s <> "..") s in
  let s = Lwt_stream.map (Filename.concat dir) s in
  Lwt_stream.to_list s

let rec loop () =
  Gc.full_major ();
  list_files "." >>= fun _l ->
  loop ()

let () = Lwt_main.run (loop ())

To compile:

$ ocamlfind ocamlopt -package lwt.unix test.ml -linkpkg -o test

Then look at how fast the memory consumption grow.

[samoht]

Actually @talex5 has an even shorter repro-case:

open Lwt

let rec loop () =
  Lwt_unix.opendir "/" >>= fun handle ->
  Lwt_unix.readdir_n handle 1024 >>= fun entries ->
  Lwt_unix.closedir handle >>= fun () ->
  ignore entries;
  loop ()

let () =
  Lwt_main.run (loop ())

[talex5]

I guess it's missing a call to lwt_unix_free_job in the success branch here:

lwt/src/unix/lwt_unix_unix.c

Line 1498 in ebd0a99

static value result_readdir_n(struct job_readdir_n *job)