signature.asc
Description: PGP signature
Hello
Here is the latest OCaml Weekly News, for the week of June 30 to July 07, 2020. Table of Contents ───────────────── Releases of ringo Multicore OCaml: June 2020 Time expression demo Interactive OCaml development with utop in Emacs Old CWN Releases of ringo ═════════════════ Archive: [https://discuss.ocaml.org/t/ann-releases-of-ringo/5605/5] Continuing this thread, Raphaël Proust said ─────────────────────────────────────────── Ringo provides bounded-size key-value stores. More specifically, it provides a functor similar to `Hastbl.Make' except that the number of bindings held by the tables is limited: inserting additional bindings when the limit has been reached causes some previously inserted binding to be removed. More more specifically, Ringo provides a function `map_maker' that takes parameters to customise the policies that determine the behaviour of the cache when supernumerary bindings are inserted, and returns the functor described above. Once a module `Cache' is instantiated using this functor, it can be used as follows: ┌──── │ let cache = Cache.create size │ let fetch_data uri = │ match Cache.find_opt cache uri with │ | Some data -> data │ | None -> │ let data = really_fetch_data uri in │ Cache.replace cache uri data; │ data └──── The cache will only hold up to [size] bindings, which avoids leaking memory. Additionally, the parameters for `map_maker' allow you to customise: • The replacement policy: which binding is removed when a supernumerary is inserted (currently supports least-recently used and first-in first-out). • The overflow policy: whether the cache can weakly hold some supernumerary elements (if so, the cache may hold more but the GC can always collect them if space is lacking). • The accounting precision: whether to keep precise track of removed/replaced elements. In addition, Ringo also provide set-caches: i.e., sets (rather than maps) with bounded size and all the same properties as above. Also note Ringo-Lwt (`ringo-lwt') provides Lwt wrappers around Ringo caches. If you have suggestions for a different concise synopsis for `opam', feel free to send them this way. Use cases are, I guess, caches. In particular those that might receive many elements not all of which you can hold in memory. We use it in a few places in the Tezos project to hold resources (blocks, operations, etc.) that are fetched from the P2p layer: it avoids having to fetch them again from the network. I think `anycache', `lru', and `lru-cache' are all alternatives available on opam. Raphaël Proust later added ────────────────────────── The documentation is now available online at [https://nomadic-labs.gitlab.io/ringo/index.html] Of particular interest: • [The signature for a `ringo' key-value cache] • [The entry point for the `ringo' library] (allowing you to instantiate modules with the above signature as well as simple value caches) • [The signature for `ringo-lwt' cache] [The signature for a `ringo' key-value cache] https://nomadic-labs.gitlab.io/ringo/ringo/Ringo/module-type-CACHE_MAP/index.html [The entry point for the `ringo' library] https://nomadic-labs.gitlab.io/ringo/ringo/Ringo/index.html [The signature for `ringo-lwt' cache] https://nomadic-labs.gitlab.io/ringo/ringo-lwt/Ringo_lwt/Sigs/module-type-CACHE_MAP/index.html Multicore OCaml: June 2020 ══════════════════════════ Archive: [https://discuss.ocaml.org/t/multicore-ocaml-june-2020/6047/1] Anil Madhavapeddy announced ─────────────────────────── Welcome to the June 2020 [Multicore OCaml] report! As with [previous updates], many thanks to @shakthimaan and @kayceesrk for collating the updates for the month of June 2020. /This is an incremental update; new readers may find it helpful to flick through the previous posts first./ This month has seen a tremendous surge of activity on the upstream OCaml project to prepare for multicore integration, as @xavierleroy and the core team have driven a number of initiatives to prepare the OCaml project for the full multicore featureset. To reflect this, from next month we will have a status page on the ocaml-multicore wiki with the current status of both our multicore branch and the upstream OCaml project itself. Why not from this month? Well, there's good news and bad news. [Last month], I observed that we are a PR away from most of the opam ecosystem working with the multicore branch. The good news is that we are still a single PR away from it working, but it's a different one :-) The retrofitting of the `Threads' library has brought up [some design complexities], and so rather than putting in a "bandaid" fix, we are integrating a comprehensive solution that will work with system threads, domains and (eventually) fibres. That work has taken some time to get right, and I hope to be able to update you all on an opam-friendly OCaml 4.10.0+multicore in a few weeks. Aside from this, there have been a number of other improvements going into the multicore branches: [mingw Windows support], [callstack improvements], [fixing the Unix module] and so on. The full list is in the detailed report later in this update. [Multicore OCaml] https://github.com/ocaml-multicore/ocaml-multicore [previous updates] https://discuss.ocaml.org/tag/multicore-monthly [Last month] https://discuss.ocaml.org/t/multicore-ocaml-may-2020-update/5898 [some design complexities] https://github.com/ocaml-multicore/ocaml-multicore/pull/342 [mingw Windows support] https://github.com/ocaml-multicore/ocaml-multicore/pull/351 [callstack improvements] https://github.com/ocaml-multicore/ocaml-multicore/pull/363 [fixing the Unix module] https://github.com/ocaml-multicore/ocaml-multicore/pull/346 Sandmark benchmarks ╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌ A major milestone in this month has been the upgrade to the latest dune.2.6.0 to build Multicore OCaml 4.10.0 for the Sandmark benchmarking project. A number of new OPAM packages have been added, and the existing packages have been upgraded to their latest versions. The Multicore OCaml code base has seen continuous performance improvements and enhancements which can be observed from the various PRs mentioned in the report. We would like to thank: • @xavierleroy for working on a number of multicore-prequisite PRs to make stock OCaml ready for Multicore OCaml. • @camlspotter has reviewed and accepted the camlimages changes and made a release of camlimages.5.0.3 required for Sandmark. • @dinosaure for updating the decompress test benchmarks for Sandmark to build and run with dune.2.6.0 for Multicore OCaml 4.10.0. A chapter on Parallel Programming in Multicore OCaml with topics on task pool, channels section, profiling with code examples is being written. We shall provide an early draft version of the document to the community for your valuable feedback. Papers ╌╌╌╌╌╌ Our "Retrofitting Parallism onto OCaml" paper has been officially accepted at [ICFP 2020] which will be held virtually between August 23-28, 2020. A [preprint] of the paper was made available earlier, and will be updated in a few days with the camera-ready version for ICFP. Please do feel free to send on comments and queries even after the paper is published, of course. Excitingly, another multicore-related paper on [Cosmo: A Concurrent Separation Logic for Multicore OCaml] will also be presented at the same conference. The Multicore OCaml updates are first listed in our report, which are followed by improvements to the Sandmark benchmarking project. Finally, the changes made to upstream OCaml which include both the ongoing and completed tasks are mentioned for your reference. [ICFP 2020] https://icfp20.sigplan.org/track/icfp-2020-papers#event-overview [preprint] https://arxiv.org/abs/2004.11663 [Cosmo: A Concurrent Separation Logic for Multicore OCaml] http://gallium.inria.fr/~fpottier/publis/mevel-jourdan-pottier-cosmo-2020.pdf Multicore OCaml ╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌ ◊ Ongoing • [ocaml-multicore/ocaml-multicore#339] Proposal for domain-local storage An RFC proposal to implement a domain-local storage in Multicore OCaml. Kindly review the idea and share your feedback! • [ocaml-multicore/ocaml-multicore#342] Implementing the threads library with Domains An effort to rebase @jhwoodyatt's implementation of the Thread library for Domains. • [ocaml-multicore/ocaml-multicore#357] Implementation of systhreads with pthreads Exploring the possibilty of implementing systhreads with pthreads, while still maintaining compatibility with the existing solution. • [ocaml/dune#3548] Dune fails to pick up secondary compiler The `ocaml-secondary-compiler' fails to install with dune.2.6.0. This is required as Multicore OCaml cannot build the latest dune without systhreads support. [ocaml-multicore/ocaml-multicore#339] https://github.com/ocaml-multicore/ocaml-multicore/issues/339 [ocaml-multicore/ocaml-multicore#342] https://github.com/ocaml-multicore/ocaml-multicore/pull/342 [ocaml-multicore/ocaml-multicore#357] https://github.com/ocaml-multicore/ocaml-multicore/issues/357 [ocaml/dune#3548] https://github.com/ocaml/dune/issues/3548 ◊ Completed • [ocaml-multicore/multicore-opam#22] Update dune to 2.6.0 The dune version in the Multicore OPAM repository is now updated to use the latest 2.6.0. • [ocaml-multicore/ocaml-multicore#338] Introduce Lazy.try_force and Lazy.try_force_val An implementation of `Lazy.try_force' and `Lazy.try_force_val' functions to implement concurrent lazy abstractions. • [ocaml-multicore/ocaml-multicore#340] Fix Atomic.exchange in concurrent_minor_gc A patch that introduces `Atomic.exchange' through `Atomic.get' that provides the appropriate read barrier for correct exchange semantics for `caml_atomic_exchange' in `memory.c'. • [ocaml-multicore/ocaml-multicore#343] Fix extcall noalloc DWARF The DWARF information emitted for `extcall noalloc' had broken backtraces and this PR fixes the same. • [ocaml-multicore/ocaml-multicore#345] Absolute exception stack The representation of the exception stack is changed from relative addressing to absolute addressing and the results are promising. The Sandmark serial benchmark results after the change is illustrated in the following graph: [https://aws1.discourse-cdn.com/standard11/uploads/ocaml/optimized/2X/b/b385409b3f9e44cbfef98de668b0b4d0ed403472_2_1380x436.png] • [ocaml-multicore/ocaml-multicore#347] Turn on -Werror by default Adds a `--enable-warn-error' option to `configure' to treat C compiler warnings as errors. • [ocaml-multicore/ocaml-multicore#353] Poll for interrupts in cpu_relax without locking Use `Caml_check_gc_interrupt' first to poll for interrupts without locking, and then proceeding to handle the interrupt with the lock. • [ocaml-multicore/ocaml-multicore#354] Add Caml_state_field to domain_state.h The `Caml_state_field' macro definition in domain_state.h is required for base-v0.14.0 to build for Multicore OCaml 4.10.0 with dune.2.6.0. • [ocaml-multicore/ocaml-multicore#355] One more location to poll for interrupts without lock Another use of `Caml_check_gc_interrupt' first to poll for interrupts without lock, similar to [ocaml-multicore/ocaml-multicore#353]. • [ocaml-multicore/ocaml-multicore#356] Backup threads for domain Introduces `backup threads' to perform GC and handle service interrupts when the domain is blocked in the kernel. • [ocaml-multicore/ocaml-multicore#358] Fix up bad CFI information in amd64.S Add missing `CFI_ADJUST' directives in `runtime/amd64.S' for `caml_call_poll' and `caml_allocN'. • [ocaml-multicore/ocaml-multicore#359] Inline caml_domain_alone The PR makes `caml_domain_alone' an inline function to improve performance for `caml_atomic_cas_field' and other atomics in `memory.c'. • [ocaml-multicore/ocaml-multicore#360] Parallel minor GC inline mask rework The inline mask rework for the promotion path to the `parallel_minor_gc' branch gives a 3-5% performance improvement for `test_decompress' sandmark benchmark, and a decrease in the executed instructions for all other benchmarks. • [ocaml-multicore/ocaml-multicore#361] Mark stack push work credit The PR improves the Multicore mark work accounting to be in line with stock OCaml. • [ocaml-multicore/ocaml-multicore#362] Iloadmut does not clobber rax and rdx when we do not have a read barrier A code clean-up to free the registers `rax' and `rdx' for OCaml code when `Iloadmut' is used. [ocaml-multicore/multicore-opam#22] https://github.com/ocaml-multicore/multicore-opam/pull/22 [ocaml-multicore/ocaml-multicore#338] https://github.com/ocaml-multicore/ocaml-multicore/pull/338 [ocaml-multicore/ocaml-multicore#340] https://github.com/ocaml-multicore/ocaml-multicore/pull/340 [ocaml-multicore/ocaml-multicore#343] https://github.com/ocaml-multicore/ocaml-multicore/pull/343 [ocaml-multicore/ocaml-multicore#345] https://github.com/ocaml-multicore/ocaml-multicore/pull/345 [ocaml-multicore/ocaml-multicore#347] https://github.com/ocaml-multicore/ocaml-multicore/pull/347 [ocaml-multicore/ocaml-multicore#353] https://github.com/ocaml-multicore/ocaml-multicore/pull/353 [ocaml-multicore/ocaml-multicore#354] https://github.com/ocaml-multicore/ocaml-multicore/pull/354 [ocaml-multicore/ocaml-multicore#355] https://github.com/ocaml-multicore/ocaml-multicore/pull/355 [ocaml-multicore/ocaml-multicore#356] https://github.com/ocaml-multicore/ocaml-multicore/pull/356 [ocaml-multicore/ocaml-multicore#358] https://github.com/ocaml-multicore/ocaml-multicore/pull/358 [ocaml-multicore/ocaml-multicore#359] https://github.com/ocaml-multicore/ocaml-multicore/pull/359 [ocaml-multicore/ocaml-multicore#360] https://github.com/ocaml-multicore/ocaml-multicore/pull/360 [ocaml-multicore/ocaml-multicore#361] https://github.com/ocaml-multicore/ocaml-multicore/pull/361 [ocaml-multicore/ocaml-multicore#362] https://github.com/ocaml-multicore/ocaml-multicore/pull/362 Benchmarking ╌╌╌╌╌╌╌╌╌╌╌╌ ◊ Ongoing • [ocaml-bench/sandmark#8] Ability to run compiler variants in Sandmark A feature to specify configure options when building compiler variants such as `flambda' is useful for development and testing. This feature is being worked upon. • [ocaml-bench/sandmark#107] Add Coq benchmarks We are continuing to add more benchmarks to Sandmark for Multicore OCaml and investigating adding the [Coq] benchmarks to our repertoire! • [ocaml-bench/sandmark#124] User configurable paramwrapper added to Makefile A `PARAMWRAPPER' environment variable can be passed as an argument by specifying the `--cpu-list' to be used for parallel benchmark runs. • [ocaml-bench/sandmark#131] Update decompress benchmarks Thanks to @dinosaure for updating the decompress benchmarks in order to run them with dune.2.6.0 for Multicore OCaml 4.10.0. • [ocaml-bench/sandmark#132] Update dependency packages to use dune.2.6.0 and Multicore OCaml 4.10.0 Sandmark has been running with dune.1.11.4, and we need to move to the latest dune.2.6.0 for using Multicore OCaml 4.10.0 and beyond, as mentioned in [Promote dune to > 2.0]. The PR updates over 30 dependency packages and successfully builds both serial and parallel benchmarks! [ocaml-bench/sandmark#8] https://github.com/ocaml-bench/sandmark/issues/8 [ocaml-bench/sandmark#107] https://github.com/ocaml-bench/sandmark/issues/107 [Coq] https://coq.inria.fr/ [ocaml-bench/sandmark#124] https://github.com/ocaml-bench/sandmark/pull/124 [ocaml-bench/sandmark#131] https://github.com/ocaml-bench/sandmark/pull/131 [ocaml-bench/sandmark#132] https://github.com/ocaml-bench/sandmark/pull/132 [Promote dune to > 2.0] https://github.com/ocaml-bench/sandmark/issues/106 ◊ Completed • [camlspotter/camlimages#1] Use dune-configurator instead of configurator for camlimages A new release of `camlimages.5.0.3' was made by @camlspotter after accepting the changes to camlimages.opam in order to build with dune.2.6.0. • [ocaml-bench/sandmark#115] Task API Port: LU-Decomposition, Floyd Warshall, Mandelbrot, Nbody The changes to use the `Domainslib.Task' API for the listed benchmarks have been merged. • [ocaml-bench/sandmark#121] Mention sudo access for run_all_parallel.sh script The README.md file has been updated with the necessary `sudo' configuration steps to execute the `run_all_parallel.sh' script for nightly builds. • [ocaml-bench/sandmark#125] Add cubicle benchmarks The `German PFS' and `Szymanski's mutual exclusion algorithm' cubicle benchmarks have been included in Sandmark. • [ocaml-bench/sandmark#126] Update ocaml-versions README to reflect 4.10.0+multicore The README has now been updated to reflect the latest 4.10.0 Multicore OCaml compiler and its variants. • [ocaml-bench/sandmark#129] Add target to run parallel benchmarks in the CI The .drone.yml file used by the CI has been updated to run both the serial and parallel benchmarks. • [ocaml-bench/sandmark#130] Add missing dependencies in multicore-numerical The `domainslib' library has been added to the dune file for the multicore-numerical benchmark. [camlspotter/camlimages#1] https://gitlab.com/camlspotter/camlimages/-/merge_requests/1 [ocaml-bench/sandmark#115] https://github.com/ocaml-bench/sandmark/pull/115 [ocaml-bench/sandmark#121] https://github.com/ocaml-bench/sandmark/pull/121 [ocaml-bench/sandmark#125] https://github.com/ocaml-bench/sandmark/pull/125 [ocaml-bench/sandmark#126] https://github.com/ocaml-bench/sandmark/pull/126 [ocaml-bench/sandmark#129] https://github.com/ocaml-bench/sandmark/pull/129 [ocaml-bench/sandmark#130] https://github.com/ocaml-bench/sandmark/pull/130 OCaml ╌╌╌╌╌ ◊ Ongoing • [ocaml/ocaml#9541] Add manual page for the instrumented runtime The [instrumented runtime] has been merged to OCaml 4.11.0. A manual for the same has been created and is under review. • [sadigqj/ocaml#1] GC colours change This PR removes the grey colour used in stock OCaml to match the scheme used by the Multicore major collector. The performance and considerations are included for review. [ocaml/ocaml#9541] https://github.com/ocaml/ocaml/pull/9541 [instrumented runtime] https://github.com/ocaml/ocaml/pull/9082 [sadigqj/ocaml#1] https://github.com/sadiqj/ocaml/pull/1 ◊ Completed • [ocaml/ocaml#9619] A self-describing representation for function closures The PR provides a way to record the position of the environment for each entry point for function closures. • [ocaml/ocaml#9649] Marshaling for the new closure representation The `output_value' marshaler has been updated to use the new closure representation. There is no change required for the `input_value' unmarshaler. • [ocaml/ocaml#9655] Introduce type Obj.raw_data and functions Obj.raw_field, Obj.set_raw_field to manipulate out-of-heap pointers The PR introduces a type `Obj.bits', and functions `Obj.field_bits' and `Obj.set_field_bits' to read and write bit representation of block fields to support the no-naked-pointer operation. • [ocaml/ocaml#9678] Reimplement Obj.reachable_word using a hash table to detect sharing The `caml_obj_reachable_words' now uses a hash table instead of modifying the mark bits of block headers to detect sharing. This is required for compatibility with Multicore OCaml. • [ocaml/ocaml#9680] Naked pointers and the bytecode interpreter The bytecode interpreter implementation is updated to support the no-naked-pointers mode operation as required by Multicore OCaml. • [ocaml/ocaml#9682] Signal handling in native code without the page table The patch uses the code fragment table instead of a page table lookup for signal handlers to know whether the signal came from ocamlopt-generated code. • [ocaml/ocaml#9683] globroots.c: adapt to no-naked-pointers mode The patch considers out-of-heap pointers as major-heap pointers in no-naked-pointers mode for global roots management. • [ocaml/ocaml#9689] Generic hashing for the new closure representation The hashing functions have been updated to use the latest closure representation from [ocaml/ocaml#9619] for the no-naked-pointers mode. • [ocaml/ocaml#9698] The end of the page table is near The PR eliminates some of the use of the page tables in the runtime system when built with no-naked-pointers mode. Our thanks to all the OCaml developers and users in the community for their continued support and contribution to the project. Stay safe! [ocaml/ocaml#9619] https://github.com/ocaml/ocaml/pull/9619 [ocaml/ocaml#9649] https://github.com/ocaml/ocaml/pull/9649 [ocaml/ocaml#9655] https://github.com/ocaml/ocaml/pull/9655 [ocaml/ocaml#9678] https://github.com/ocaml/ocaml/pull/9678 [ocaml/ocaml#9680] https://github.com/ocaml/ocaml/pull/9680 [ocaml/ocaml#9682] https://github.com/ocaml/ocaml/pull/9682 [ocaml/ocaml#9683] https://github.com/ocaml/ocaml/pull/9683 [ocaml/ocaml#9689] https://github.com/ocaml/ocaml/pull/9689 [ocaml/ocaml#9698] https://github.com/ocaml/ocaml/pull/9698 Acronyms ╌╌╌╌╌╌╌╌ • API: Application Programming Interface • CFI: Call Frame Information • CI: Continuous Integration • DWARF: Debugging With Attributed Record Formats • GC: Garbage Collector • ICFP: International Conference on Functional Programming • OPAM: OCaml Package Manager • PR: Pull Request • RFC: Request for Comments Time expression demo ════════════════════ Archive: [https://discuss.ocaml.org/t/time-expression-demo/6052/1] Darren announced ──────────────── An interactive demo for a small part of our time stuff and schedule handling library is available here: [https://daypack-dev.github.io/time-expr-demo/] Time expression is in essence a language for specifying time points or time slots precisely and concisely, while trying to mimic natural language. The implementation of the demo core itself can be seen here: [https://github.com/daypack-dev/time-expr-demo/blob/master/src/demo.ml] , where the usage of Daypack-lib is shown. Lastly, the library is still a prototype, so expect some faults in the outputs of the demo here and there. Interactive OCaml development with utop in Emacs ════════════════════════════════════════════════ Archive: [https://discuss.ocaml.org/t/interactive-ocaml-development-with-utop-in-emacs/6058/1] Samarth Kishor announced ──────────────────────── I made a [blog post] about REPL driven development with utop in Emacs a few months ago. Please let me know if you found it useful or have anything to add! I'm a bit new to OCaml so any feedback helps. There was a [similar post about REPL driven development] last year and my post addresses a lot of those points. I wish I'd seen that post before I wrote this since there's a ton of useful information in the comments. [blog post] https://samarthkishor.github.io/posts/interactive_ocaml_development/ [similar post about REPL driven development] https://discuss.ocaml.org/t/ocaml-repl-driven-development/4068 Old CWN ═══════ If you happen to miss a CWN, you can [send me a message] and I'll mail it to you, or go take a look at [the archive] or the [RSS feed of the archives]. If you also wish to receive it every week by mail, you may subscribe [online]. [Alan Schmitt] [send me a message] mailto:alan.schm...@polytechnique.org [the archive] http://alan.petitepomme.net/cwn/ [RSS feed of the archives] http://alan.petitepomme.net/cwn/cwn.rss [online] http://lists.idyll.org/listinfo/caml-news-weekly/ [Alan Schmitt] http://alan.petitepomme.net/
_______________________________________________ caml-news-weekly mailing list caml-news-weekly@lists.idyll.org http://lists.idyll.org/listinfo/caml-news-weekly
