[Caml-list] Attn: Development Editor, Latest OCaml Weekly News

[Alan Schmitt <alan.schmitt@polytechnique.org>]

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Here is the latest OCaml Weekly News, for the week of February 25 to
March 03, 2020.

Table of Contents
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OCaml 4.10 released
Summary of the Dune retreat 2020
Multicore OCaml: Feb 2020 update
Oplot 0.50
soupault: a static website generator based on HTML rewriting
Old CWN


OCaml 4.10 released
═══════════════════

  Archive: <https://discuss.ocaml.org/t/ocaml-4-10-released/5194/4>


Contnuing this thread, Anil Madhavapeddy said
─────────────────────────────────────────────

  Indeed, many thanks to everyone who leapt in to make 4.10 ready in
  opam in such record time!  Just a note that the CI Docker images are
  now also rebuilt for x86_64, arm32/64 and ppc64le to reflect the 4.10
  release, so feel free to start using
  them. <https://hub.docker.com/r/ocaml/opam2/tags>


Summary of the Dune retreat 2020
════════════════════════════════

  Archive:
  <https://discuss.ocaml.org/t/summary-of-the-dune-retreat-2020/5224/1>


Jérémie Dimino announced
────────────────────────

  We recently organised the second Dune retreat. If you'd like to see
  what is happening in the Dune world at the moment, please find a
  summary of what we discussed and work on in this blog post!

  <https://dune.build/blog/dune-retreat-2020/>


Multicore OCaml: Feb 2020 update
════════════════════════════════

  Archive:
  <https://discuss.ocaml.org/t/multicore-ocaml-feb-2020-update/5227/1>


Anil Madhavapeddy announced
───────────────────────────

  Welcome to the February 2020 news update from the Multicore OCaml
  team, spread across the UK, India, France and Switzerland! This
  follows on from [last month's] update, and has been put together by
  @shakthimaan and @kayceesrk.

  The [release of OCaml 4.10.0] has successfully pushed out some
  prerequisite features into the upstream compiler.  Our work in
  February has focussed on getting the multicore OCaml branch "feature
  complete" with respect to the complete OCaml language, and doing
  extensive benchmarking and stress testing to test our two minor heap
  implementations.

  To this end, a number of significant patches have been merged into the
  [Multicore OCaml trees] that essentially provide complete coverage of
  the language features. We encourage you to test the same for
  regressions and provide any improvements or report shortcomings to
  us. There are ongoing OCaml PRs and issues that are also under review,
  and we hope to complete those for the 4.11 release cycle. A new set of
  parallel benchmarks have been added to our [Sandmark benchmarking
  suite] (live instance [here]), including enhancements to the build
  setup.


[last month's]
<https://discuss.ocaml.org/t/multicore-ocaml-january-2020-update/5090>

[release of OCaml 4.10.0]
<https://discuss.ocaml.org/t/ocaml-4-10-released/5194>

[Multicore OCaml trees]
<https://github.com/ocaml-multicore/ocaml-multicore>

[Sandmark benchmarking suite] <https://github.com/ocaml-bench/sandmark>

[here] <http://bench2.ocamllabs.io>

Multicore OCaml
╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌

◊ Completed

  The following PRs have been merged into Multicore OCaml:

  • [ocaml-multicore/ocaml-multicore#281] Introduce `Forcing_tag' to fix
    concurrency bug with lazy values

    A `Forcing_tag' is used to implement lazy values to handle a
    concurrency bug. It behaves like a locked bit, and any concurrent
    access by a mutator will raise an exception on that domain.

  • [ocaml-multicore/ocaml-multicore#282] Safepoints

    A preliminary version of safe points has been merged into the
    Multicore OCaml trees. [ocaml-multicore/ocaml-multicore#187] also
    contains more discussion and background about how coverage can be
    improved in future PRs.

  • [ocaml-multicore/ocaml-multicore#285] Introduce an 'opportunistic'
    major collection slice

    An "opportunistic work credit" is implemented in this PR which forms
    a basis for doing mark and sweep work while waiting to synchronise
    with other domains.

  • [ocaml-multicore/ocaml-multicore#286] Do fflush and variable args in
    caml_gc_log

    The caml_gc_log() function has been updated to ensure that `fflush'
    is invoked only when GC logging is enabled.

  • [ocaml-multicore/ocaml-multicore#287] Increase EVENT_BUF_SIZE

    During debugging with event trace data it is useful to reduce the
    buffer flush times, and hence the `EVENT_BUF_SIZE' has now been
    increased.

  • [ocaml-multicore/ocaml-multicore#288] Write barrier optimization

    This PR closes the regression for the `chameneos_redux_lwt'
    benchmarking in Sandmark by using `intnat' to avoid sign extensions
    and cleans up `write_barrier' to improve overall performance.

  • [ocaml-multicore/ocaml-multicore#290] Unify sweep budget to be in
    word size

    The PR updates the sweep work units to all be in word size. This is
    to handle the differences between the budget for setup, sweep and
    for large allocations in blocks.


  [ocaml-multicore/ocaml-multicore#281]
  <https://github.com/ocaml-multicore/ocaml-multicore/pull/281>

  [ocaml-multicore/ocaml-multicore#282]
  <https://github.com/ocaml-multicore/ocaml-multicore/pull/282>

  [ocaml-multicore/ocaml-multicore#187]
  <https://github.com/ocaml-multicore/ocaml-multicore/issues/187>

  [ocaml-multicore/ocaml-multicore#285]
  <https://github.com/ocaml-multicore/ocaml-multicore/pull/285>

  [ocaml-multicore/ocaml-multicore#286]
  <https://github.com/ocaml-multicore/ocaml-multicore/pull/286>

  [ocaml-multicore/ocaml-multicore#287]
  <https://github.com/ocaml-multicore/ocaml-multicore/pull/287>

  [ocaml-multicore/ocaml-multicore#288]
  <https://github.com/ocaml-multicore/ocaml-multicore/pull/288>

  [ocaml-multicore/ocaml-multicore#290]
  <https://github.com/ocaml-multicore/ocaml-multicore/pull/290>


◊ Ongoing

  • A lot of work is ongoing for the implementation of a synchronised
    minor garbage collector for Multicore OCaml, including benchmarking
    for the stop-the-world (stw) branch.  We will publish the results of
    this in a future update, as we are assembling a currently
    comprehensive evaluation of the runtime against the mainstream
    runtime.


Benchmarking
╌╌╌╌╌╌╌╌╌╌╌╌

  [Sandmark] now has support to run parallel benchmarks. We can also now
  about GC latency measurements for both stock OCaml and Multicore OCaml
  compiler.

  • [ocaml-bench/sandmark#73] More parallel benchmarks

    A number of parallel benchmarks such as N-body, Quick Sort and
    matrix multiplication have now been added to Sandmark!

  • [ocaml-bench/sandmark#76] Promote packages. Unbreak CI.

    The Continuous Integration build can now execute after updating and
    promoting packages in Sandmark.

  • [ocaml-bench/sandmark#78] Add support for collecting information
    about GC pausetimes on trunk

    The PR now helps process the runtime log and produces a `.bench'
    file that captures the GC pause times. This works on both stock
    OCaml and in Multicore OCaml.

  • [ocaml-bench/sandmark#86] Read and write Irmin benchmark

    A test for measuring Irmin's merge capabilities with Git as its
    filesystem is being tested with different read and write rates.

  • A number of other parallel benchmarks like Merge sort,
    Floyd-Warshall matrix, prime number generation, parallel map, filter
    et. al. have been added to Sandmark.


[Sandmark] <http://bench2.ocamllabs.io/>

[ocaml-bench/sandmark#73]
<https://github.com/ocaml-bench/sandmark/pull/73>

[ocaml-bench/sandmark#76]
<https://github.com/ocaml-bench/sandmark/pull/76>

[ocaml-bench/sandmark#78]
<https://github.com/ocaml-bench/sandmark/pull/78>

[ocaml-bench/sandmark#86]
<https://github.com/ocaml-bench/sandmark/pull/86>


Documentation
╌╌╌╌╌╌╌╌╌╌╌╌╌

  • Examples using domainslib and modifying Domains are currently being
    worked upon for a chapter on Parallel Programming for Multicore
    OCaml. We will release an early draft to the community for your
    feedback.


OCaml
╌╌╌╌╌

  One PR opened to OCaml this month, which fixes up the marshalling
  scheme to be multicore compatible. The complete set of [upstream
  multicore prerequisites] are labelled in the compiler issue tracker.

  • [ocaml/ocaml#9293] Use addrmap hash table for marshaling

    The hash table (addrmap) implementation from Multicore OCaml has
    been ported to upstream OCaml to avoid using GC mark bits to
    represent visitedness.


[upstream multicore prerequisites]
<https://github.com/ocaml/ocaml/labels/multicore-prerequisite>

[ocaml/ocaml#9293] <https://github.com/ocaml/ocaml/pull/9293>


Acronyms
╌╌╌╌╌╌╌╌

  • CTF: Common Trace Format
  • CI: Continuous Integration
  • GC: Garbage Collector
  • PR: Pull Request

  As always, many thanks to our fellow OCaml developers and users who
  have reviewed our code, reported bugs or otherwise assisted this
  month.


Oplot 0.50
══════════

  Archive: <https://discuss.ocaml.org/t/ann-oplot-0-50/5235/1>


sanette announced
─────────────────

  I'm happy to annouce the revival of the `oplot' library.

  If you ever wanted to quickly draw the graph of an intriguing
  mathematical function, animate it by varying a parameter, or explore a
  3D surface, without leaving your favorite programming language, then
  `oplot' is for you.

  If you're familiar with LaTeX and want to produce nice mathematical
  graphics decorated with LaTeX formulas, that you can view onscreen,
  export to images or vector graphics (pdf, eps) then `oplot' is even
  more for you!

  • Installation: `opam install oplot'
  • documentation:
    <https://sanette.github.io/oplot/oplot/Oplot/index.html>
  • source code, issues, etc: <https://github.com/sanette/oplot>

  Drawing is hardware accelerated (opengl) thanks to the venerable
  `ocamlsdl' and `lablgl' libraries. I'm glad they still work perfectly.

  Happy plotting.


soupault: a static website generator based on HTML rewriting
════════════════════════════════════════════════════════════

  Archive:
  <https://discuss.ocaml.org/t/ann-soupault-a-static-website-generator-based-on-html-rewriting/4126/12>


Daniil Baturin announced
────────────────────────

  [1.9.0] release is now available.

  • `--index-only' option that makes soupault dump the site metadata to
    JSON and stop at that
  • Metadata extraction and index generation can now be limited to
    specific pages/section/path regexes, just like widgets
  • The `preprocess_element' widget now supports a list of selectors,
    e.g. `selector = ["code", "pre code"]'.
  • Plugin API now has functions for running external programs, and some
    more element tree access functions.
  • CSS selector parse errors are now handled gracefully ([lambdasoup
    PR#31]).
  • The `title' widget now correctly removes HTML tags from the supposed
    title string and doesn't add extra whitespace (fixes by [Thomas
    Letan]).


[1.9.0] <https://soupault.neocities.org/blog/soupault-1.9.0-release/>

[lambdasoup PR#31] <https://github.com/aantron/lambdasoup/pull/31>

[Thomas Letan] <https://soap.coffee/~lthms/>


Old CWN
═══════

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  [Alan Schmitt]


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