Ann: SWI-Prolog 9.3.3

Dear SWI-Prolog user,

SWI-Prolog 9.3.3 is ready for download. This release comes with many
fixes, although most will affect few users. They are mostly the
result the website (notably SWISH) reorganization, @peter.ludemann
work on cpp and @ridgeworks work on clpBNR. Highlights:

  • Several issues wrt. the “standard” streams could result in
    crashes and memory leaks.
  • Several improvements to help/1 for loaded (documented)
  • @brebs fixed an old issue with accasionally failing tests for
    HTTP proxy processing
  • Preserve properties of foreign predicates when creating a
    saved state.
  • Make coverage analysis deal with include/1.
  • Possibly incorrect handling for C-stack limit.
  • Various enhancements to HTTP server session management, notably
    for the Redis plugin.
  • thread_exit/1 has been dropped from the Windows version after
    comments by @mgondan.
  • Added library(http/http_server_health), providing /health to
    return a JSON document with configurable keys with health
    related data. Now active on all SWI-Prolog’s public services.
  • PlDoc enhancements or included files and user predicates.
    @peter.ludemann fixed closing quotes in LaTeX based docs to
    use proper Unicode quotes.

Eventually, this will probably all be merged into 9.2.3 (stable).
Considering the complexity of notably the I/O stream changes it
is safer to wait a little.

And, on suggestion by @nicos, there are some more sponsor buttons
spread over the website and SWISH. In particular institutional and
commercial users are kindly requested to donate and help making
SWI-Prolog more sustainable.

Enjoy --- Jan

SWI-Prolog Changelog since version 9.3.2

  • FIXED: tell/1: properly manage standard stream references.

  • FIXED: Stream reference counting and reset when closing a standard

  • FIXED: Memory leak in string_bytes/3.

  • FIXED: Properly close temporary redirect to a string
    tellString()/toldString() could fail to reclaim the temporary stream

  • ENHANCED: Use a segmented stack for dealing with findall/3.
    This avoids memory fragmentatation when findall/3 is deeply nested.
    Although that is a rare occasion, deeply nested findall/3 leads to
    poor memory reuse. As activating and deactivating is stacked anyway,
    a segstack avoids the fragmentation.

  • ADDED: help(Name/Arity): handle user predicates.

  • FIXED: xref_source/2: keep processing PlDoc commands after including
    a file.

  • ADDED: help/1: give help on a specific user predicate using Module:PI.

  • ENHANCED: help/1: filter user predicates on the module class.
    This use to filter on whether they are documented in the manual,
    making it impossible to show documentation for loaded predicates that
    conflict with something defined in the manual.

  • FIXED: Thread I/O streams may be invalid If a thread is created
    using thread_create/3 with the inherit_from(Thread) option or using
    PL_thread_attach_engine() (which inherits from main), we may copy
    current_input or current_output from a temporary redirect.

    The reference counting when copying the streams was broken, possibly
    causing memory corruption. This is improved, but not 100% safe.
    we now set the current_input and current_output to user_input and
    user_output, which typically never change.

  • FIXED: help/1 to deal with help on public predicates in included files.
    help/1 finds the predicate and, if necessary, reloads the file in
    which it is defined to get the documentation. If the predicate is
    defined in an include file it should reload the main file to get the
    module context right.

  • ENHANCED: trace/1,2 and friends. - Code cleanup - Support conditional
    trace using trace(Head, Port(Condition))

  • FIXED: Ensure correct setting file handle for std streams. This was
    broken after adding the fileno field to the IOSTREAM struct.

  • MODIFIED: Discontinue thread_exit/1 on Windows The implementation was
    broken for some time. The reason is not entirely clear, but possibly
    related to issues in pthread-win32. As the predicate is unsafe and
    deprecated anyway, it has now been removed from the Windows version.

  • FIXED: pack metadata checking for prolog:Feature requirements.

  • FIXED: make stream_property(S, file_no(N)) safe. This used to be
    subject to race conditions between the enumerating thread and threads
    that close the underlying stream. We now copy the file handle as it
    was found when creating the stream to the main stream structure.

  • CLARIFIED: PL_free_blob() can be called multiple times. This patch
    changes subsequent calls to a no-op that returns FALSE and document
    this is valid. After comment by Peter Ludemann.

  • CLEANUP: Do not call blob release() on GC or cleanup after

  • ENHANCED: Answer/query expansion. Toplevel variable ($Var) handing
    is now always handled, regardless of the user:expand_query/4 or
    user:expand_answer/2 hooks. The user:expand_answer/2 hook is
    superseded by prolog:expand_answer/3.

  • DOC: Deprecate format/3 with a non-list 3th argument.

  • FIXED: Setting the C-stack limit to values not a multiple of the page
    size Causes problems on some platforms.

  • DOC: Use ASCII LaTeX ``word’’

  • FIXED: Preserve atributes set on foreign functions for saved states.
    This bug causes http_stream:stream_range_open/3 not be to transparent
    when reloaded from a saved state. This in turn raises an error with
    http_open/3 on HTTPS and chunked streams.

  • ENHANCED: coverage/2: analyze and annotate included files.
    The coverage analyzer now deals with files that are included. Files
    that are included multiple times in different modules get their
    numbers aggregated.

  • FIXED: Crash when using ‘$cov_data’/3 if there is no coverage data.

Package cpp

  • DOC: improve non-det example (and tests)

  • DOC: Use ASCII LaTeX ``word’'.

Package http

  • TEST: Don’t reuse original test port for HTTP proxy Instead, use port
    assigned by OS.

    Intention is to prevent intermittent build test failure on Linux
    armv7, and Mac M1.

    The HTTP, HTTPS, SOCKS and “unused” ports are still reused, though.

    Original build failure report:
    Swi-prolog 9.2.2 fails http:proxy test on armv7

  • FIXED: Make http session GC thread inherit from main This thread is
    started lazily from an HTTP worker and would by default interit the
    temporary CGI stream as current_output. By interiting from main we
    can safely print debug messages and avoid stream existence exceptions.

  • FIXED: HTTP Sessions using Redis to properly handle concurrent delete.
    Multiple participants may decide to delete a session. By checking
    the removal from the timeout queue we avoid that two nodes delete
    the same session.

  • ADDED: HTTP session management granularity This setting controls
    how precisely we manage idle time updated and session timeouts.
    This is notably important when using an external (Redis) database
    for sharing session information to reduce traffic.

  • ENHANCED: http_upgrade_to_websocket/3: discard a websocket on failure.
    When using the guarded(false) option, the created web socket is now
    only left open if the passed Goal succeeds.

  • DOC: http_server/2: Explictly mention the possible use of AF_UNIX

  • ENHANCED: Implementation of open_files in server stats.

  • ADDED: Extended /health with CPU time and thread satistics.
    Also allows asking for specific keys only in the HTTP request, e.g.

  • ADDED: http_workers/2: mode (?,-) (was (+,-)) Also point at
    library(http/http_dyn_workers) in docs and improve the implementation
    by using aggregate_all/3 rather than findall/3 and length/2.

  • ADDED: library(http_server_health)

Package ltx2htm

  • FIXED: handling of final single quote

  • ENHANCED: Warn on non-ASCII characters. We can’t handle these.

Package pldoc

  • ENHANCED: Better ordering of predicates comming from other files.
    pldoc for “re-exported” predicates are now ordered by position, i.e.,
    file name and line number.

Package plunit

  • FIXED: Report tests where the setup goal fail as failed and print

Package semweb

  • FIXED: #110 Allow blank nodes as graph in TRiG format.

Package swipl-win

  • FIXED: Reset fileno for stdio streams
1 Like

This release hangs on Windows 10. Doesn’t show the sermon and
then the prompt, just a blank window, when using the GUI console.

I hangs somewhere, doesn’t get past this here:


The previous version works fine:

Thanks for reporting. Fixed and updated the binaries on the download page.

1 Like