Memory leak when using threads #11289
Description
This bug has been tested with OCaml 4.13.0. I am in the process of testing it with 5.0.0 (on a m1 mac)
The following program:
let rec f () =
let th = Thread.create (fun () ->
let b = Bytes.make (10*4096) ' ' in
Printf.printf "New Thread with %d bytes\n%!" (Bytes.length b);
Unix.sleepf 0.1) ()
in
Thread.join th;
f ()
let () = f ()Seems to leave the memory allocated in the thread for too long. In my test, the program quickly rose to ~60Mo of RAM within minutes:
The same program with a call to full_major does not exhibit the issue:
let rec f () =
let th = Thread.create (fun () ->
let b = Bytes.make (10*4096) ' ' in
Printf.printf "New Thread with %d bytes\n%!" (Bytes.length b);
Unix.sleepf 0.1) ()
in
Thread.join th;
Gc.full_major();
f ()
let () = f ()
This seems to indicate that the GC is underestimating the amount of memory waiting to be cleaned up from the thread's allocations.