# \#ocaml5 **URL:** https://discuss.ocaml.org/tag/ocaml5/536.md [Latest](https://discuss.ocaml.org/latest.md) · [Categories](https://discuss.ocaml.org/categories.md) · [Tags](https://discuss.ocaml.org/tags.md) --- ## [\[ANN\] CS6868 Concurrent Programming -- Course Materials](https://discuss.ocaml.org/t/ann-cs6868-concurrent-programming-course-materials/17932)
**Author:** [@kayceesrk](https://discuss.ocaml.org/u/kayceesrk)\ **Replies:** 0\ **Last updated:** [March 28, 2026, 5:10am UTC](https://discuss.ocaml.org/t/ann-cs6868-concurrent-programming-course-materials/17932 "2026-03-28T05:10:35Z")
I’m currently teaching a course called “CS6868: Concurrent Programming” at IIT Madras. The goal of the course is to teach concurrent and parallel programming using OCaml 5, and then introduce OxCaml for safe and fast par… --- ## [OCaml 5 FFI, use of \`Int\_val\` inside \`caml\_enter\_blocking\_section()\`](https://discuss.ocaml.org/t/ocaml-5-ffi-use-of-int-val-inside-caml-enter-blocking-section/17872)
**Author:** [@lindig](https://discuss.ocaml.org/u/lindig)\ **Replies:** 8\ **Last updated:** [March 8, 2026, 3:37pm UTC](https://discuss.ocaml.org/t/ocaml-5-ffi-use-of-int-val-inside-caml-enter-blocking-section/17872 "2026-03-08T15:37:54Z")
Pull requests for the compiler suggest that Int\_val should not be used inside caml\_enter\_blocking\_section(), and in particular not in a parameter position of an FFI call like close\_unix.c- caml\_enter\_blocking\_section()… --- ## [Multi-domain, multi-scheduler Lwt](https://discuss.ocaml.org/t/multi-domain-multi-scheduler-lwt/16834)
**Author:** [@raphael-proust](https://discuss.ocaml.org/u/raphael-proust)\ **Replies:** 0\ **Last updated:** [June 17, 2025, 12:42pm UTC](https://discuss.ocaml.org/t/multi-domain-multi-scheduler-lwt/16834 "2025-06-17T12:42:56Z")
I have started working on changing Lwt to allow multiple schedulers to run in parallel in separate domains. The current status is early work-in-progress with some actual tests that actually use the multi-scheduler featur… --- ## [\[BLOG\] Using Property-Based Testing to Test OCaml 5](https://discuss.ocaml.org/t/blog-using-property-based-testing-to-test-ocaml-5/14550)
**Author:** [@jmid](https://discuss.ocaml.org/u/jmid)\ **Replies:** 1\ **Last updated:** [December 24, 2024, 8:45am UTC](https://discuss.ocaml.org/t/blog-using-property-based-testing-to-test-ocaml-5/14550 "2024-12-24T08:45:51Z")
Here’s a blog post about how we have been using property-based testing to test OCaml 5: --- ## [Eio fiber hangs instead of "index out of bounds" exception: bug or feature?](https://discuss.ocaml.org/t/eio-fiber-hangs-instead-of-index-out-of-bounds-exception-bug-or-feature/15511)
**Author:** [@yashrk](https://discuss.ocaml.org/u/yashrk)\ **Replies:** 6\ **Last updated:** [October 28, 2024, 9:19am UTC](https://discuss.ocaml.org/t/eio-fiber-hangs-instead-of-index-out-of-bounds-exception-bug-or-feature/15511 "2024-10-28T09:19:47Z")
Hi. I’ve noticed some strange behavior in Eio fibers. Consider the following simple program: let producer stream = while true do Eio.Stream.add stream "asdfasdfasdf\\n" done let consumer stream = while true d… --- ## [OCaml 5: forcing objects to be collected and finalized](https://discuss.ocaml.org/t/ocaml-5-forcing-objects-to-be-collected-and-finalized/12492)
**Author:** [@rwmjones](https://discuss.ocaml.org/u/rwmjones)\ **Replies:** 4\ **Last updated:** [June 27, 2023, 3:27pm UTC](https://discuss.ocaml.org/t/ocaml-5-forcing-objects-to-be-collected-and-finalized/12492 "2023-06-27T15:27:48Z")
In a real set of bindings we have a C finalizer that closes the handle automatically. When testing this we have code which looks something like the simplified example below: let handle\_closed = ref 0 let final \_ = incr… --- ## [Fatal error: Fatal error during lock: Resource deadlock avoided](https://discuss.ocaml.org/t/fatal-error-fatal-error-during-lock-resource-deadlock-avoided/12457)
**Author:** [@rwmjones](https://discuss.ocaml.org/u/rwmjones)\ **Replies:** 25\ **Last updated:** [June 26, 2023, 3:47pm UTC](https://discuss.ocaml.org/t/fatal-error-fatal-error-during-lock-resource-deadlock-avoided/12457 "2023-06-26T15:47:57Z")
With OCaml 5 (not 4) my program deadlocks in caml\_acquire\_runtime\_system (aka caml\_leave\_blocking\_section). The example below demonstrates what I mean: test.ml contains: Printf.eprintf "hello from OCaml\\n%!" test-oca… --- ## [【Q】Why is it 0?](https://discuss.ocaml.org/t/q-why-is-it-0/11688)
**Author:** [@anzhi0708](https://discuss.ocaml.org/u/anzhi0708)\ **Replies:** 2\ **Last updated:** [March 17, 2023, 9:58am UTC](https://discuss.ocaml.org/t/q-why-is-it-0/11688 "2023-03-17T09:58:35Z")
Hello! I’m both an OCaml beginner and a CS beginner AKA a noob. I was expecting variable money’s value to equal to 0 since race condition but its value was still 0. Can someone explain? Thanks a lot :3 let money = ref… --- ## [Need help for understanding a segmentation fault with OCaml 5.0](https://discuss.ocaml.org/t/need-help-for-understanding-a-segmentation-fault-with-ocaml-5-0/10265)
**Author:** [@thierry-martinez](https://discuss.ocaml.org/u/thierry-martinez)\ **Replies:** 2\ **Last updated:** [August 6, 2022, 12:20pm UTC](https://discuss.ocaml.org/t/need-help-for-understanding-a-segmentation-fault-with-ocaml-5-0/10265 "2022-08-06T12:20:24Z")
I had a hard time trying to reduce a segmentation fault observed with OCaml 5.0: I would prefer not to fill an issue before having something smaller to reproduce and before checking for sure that the fault is not in my c…