# Ann: SWI-Prolog 8.3.2 **URL:** \ **Category:** Releases\ **Created:** [June 18, 2020, 1:33pm UTC](https://swi-prolog.discourse.group/t/ann-swi-prolog-8-3-2/2536 "2020-06-18T13:33:04Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![jan](https://yyz2.discourse-cdn.com/free1/user_avatar/swi-prolog.discourse.group/jan/32/4_2.png) [@jan](https://swi-prolog.discourse.group/u/jan)\ **Post date:** [June 18, 2020, 1:33pm UTC](https://swi-prolog.discourse.group/t/ann-swi-prolog-8-3-2/2536/1 "2020-06-18T13:33:04Z")
Dear SWI-Prolog user, I’m happy to announce SWI-Prolog 8.3.2. Notably users of multi-threading are encouraged to update. Highlights: - Sebastian Sardina did a lot of work cleaning up JPL (the Java interface). Notably support Maven en reorganize and update the documentation. This version also supports SWI-Prolog’s dict objects. - Adrian Wong contributed yet another set of documentation patches. - wildcard\_match/2 and expand\_file\_name/2 provided proper support for ASCII only. Using Unicode patterns or targets could access memory outside allocated regions, causing crashes, leaking data or giving wrong result. Keri found this. I’ve reimplemented most of it to properly support full Unicode. - There was a bug in message queues that could cause thread\_get\_message/1,2 to block indefinitely despite a matching message arrived. Fixing this bug results in much more predictable timing of HTTP responses and the thread regression tests. - There was a race condition in temporary module handling that could cause SWISH to crash. - Another race was possible when two threads tried to compile the same file. - The HTTP server worker scheduling has been stress tested and improved considerably. This notably avoids starting far too many workers under heavy load. Most of this stuff should go into 8.2.1 as it addresses serious stability issues. Some of the patches are quite large though, so I first want to see how well they hold in the real world. ``` Enjoy --- Jan ``` P.s. The Macports update has failed due to a missing dependency. In theory that can be fixed by adding a patch file against the source. That is a bit too much work though, so unless someone wishes to become maintainer of the Macports version we can only hope we have more luck with 8.3.3. # SWI-Prolog Changelog since version 8.3.1 - FIXED: library(prolog\_codewalk): handle file/4 message terms. Matt Lilley. - FIXED: Location of jpl.jar in development tree to be able to run in the dev tree. - PORT: Windows: make condition variable abstraction compile again. - ADDED: Foreign API to reuse the internal lock-free hash table implementation. - DOC: Removed obsolete section on Boehm-GC support. - FIXED: Make module enumeration safe for temporary modules. This affects notably current\_predicate/1 in SWISH. current\_predicate/1 using an unbound module now skips enumeration of temporary modules. - FIXED: Possible race condition when two threads try to compile the same file. - FIXED: Possible inconsistent source file reference count. - CLEANUP: No longer create a source file object for a derived source. This doesn’t seem to be used anywhere and the new garbage collecting approach for source files would reclaim the file immediately anyway. - FIXED: Make source file admin use reference counts and delete no longer needed source file admin entries. Discarding them is needed by Pengines. The hard-coded discard from ‘$destroy\_module’/1 could cause a use-after-free issue in SWISH when using `:- include(file).`. The patch is rather involved. Probably there are easier ways to fix this particular issue. Usage based reclaim of source files is a step towards garbage collecting code in general though. - CLEANUP: Property balance ‘$start\_consult’/2 and ‘$end\_consult’/1. - ADDED: message\_queue\_property/2: property waiting(-Count) to find the number of threads waiting for this queue. - ENHANCED: thread\_send\_message/2: reduce time the queue mutex is held. - FIXED: thread\_get\_message/1,2 could not wakeup after a message arrived. - DEBUG: Improved debug channel MSG\_QUEUE, notably avoid printing to the possibly redirected current output using pl\_writeln(). - FIXED: destroying affected tables should first collect the network. Edward Schwartz - DOC: Format CMAKE.md \* Justify paragraphs - DOC: Fix typos in CMAKE.md - DOC: Fix typos in manual - ADDED: wildcard\_match/3. Required because wildcard\_match/2 no longer listens to case sensitivity of the file system. Suggested by Keri Harris. - FIXED: Missing error case for a non-terminated `[..` set. Included more test cases. - FIXED: wildcard\_match/2: peek after string on unmatched “{” - FIXED: wildcard\_match/2 and expand\_file\_name/2 used to print a warning and throw a domain\_error on an illegal pattern. It now throws a syntax\_error exception. - TEST: Added files test dir, now containing test\_glob.pl - FIXED: Memory leak in text canonicalization - FIXED: expand\_file\_name/2 and wildcard\_match/2 - Avoid a possible crash using Unicode patterns. Found by Keri harris. - Fully support Unicode in patterns and file names. - Remove the length limit for compiled patterns (used to be 1024 chars). - MODIFIED: wildcard\_match/2 used to be case insensitive if file names are case insensitive. Now wildcard\_match/2 is always case insensitive. - DOC: Remove duplicate license information \* Move the new license down to replace the old one ## Package cpp - ENHANCED: Add copy constructor. This prevents warnings from modern compilers and preserves the existing copy semantics. ## Package http - ENHANCED: HTTP workers for new connections to keep track of the activity rate and adjust to the best wait policy, trading time for memory minimisation. - ENHANCED: http server _backlog_ changed from 5 to 64. Probably doesn’t have much effect, but 5 seems old school. - FIXED: library(http/http\_dyn\_workers) could start far too many workers due to (1) waiting a negative time to check the queue was draining and (2) not respecting the max\_workers setting. ## Package jpl - IMPROVED: documentation, tutorials and initialization of engine - IMPROVED: doc pages, much better Development section - ADDED: Maven dependency for jpl.jar in doc - ADDED: Extended POM to deploy packages on GitHub - ADDED: Github Maven building process - UPDATED: Javadoc with Dict included - CLEANUP: Removed obsolete and unused code from org.jpl7.util - BUILD: Avoid warning if junit.jar is not present - ADDED: Maven support and dir layout - Upgraded to 7.6.1 - MODIFIED: move all examples to src/examples/ folder - Fixed #62 - ADDED: Dictionaries support - ADDED: Dictionary as a type of Term ## Package pengines - ADDED: Make pengines redirected I/O work on created threads. ## Package pldoc - FIXED: Manual to serve e.g., ``/pldoc/doc\_for?object=\*-\>/2’’. ## Package xpce - ENHANCED: Better visible current tab and better positioning of the label. ---
**Author:** ![peter.ludemann](https://yyz2.discourse-cdn.com/free1/user_avatar/swi-prolog.discourse.group/peter.ludemann/32/48_2.png) [@peter.ludemann](https://swi-prolog.discourse.group/u/peter.ludemann)\ **Post date:** [June 18, 2020, 7:14pm UTC](https://swi-prolog.discourse.group/t/ann-swi-prolog-8-3-2/2536/2 "2020-06-18T19:14:18Z")
There seems to be a file descriptor leak. I rolled back to V8.3.1 (278a4b032) and rebuilt to verify that it wasn’t a problem with my code. I tried rebuilding with the latest version (V8.3.2-3-gd0d08885e), but that broke even worse (weird messages about “Unknown procedure”. I’ll try rerunning with strace to try to figure out what’s going on. ---
**Author:** ![peter.ludemann](https://yyz2.discourse-cdn.com/free1/user_avatar/swi-prolog.discourse.group/peter.ludemann/32/48_2.png) [@peter.ludemann](https://swi-prolog.discourse.group/u/peter.ludemann)\ **Post date:** [June 20, 2020, 10:29pm UTC](https://swi-prolog.discourse.group/t/ann-swi-prolog-8-3-2/2536/3 "2020-06-20T22:29:55Z")
So, there seem to be two problems with 8.3.2. One is very rare; the other I’m not sure of. In both cases, I don’t have a simple test case. I’ll send more details separately to @jan (but not today). 1. (very rare) consulting a file sometimes gives a bogus “unknown procedure” message (there’s no missing procedure, and the procedure that’s claimed to be missing isn’t used). This is (I think) triggered by `wrap_procedure` and only shows up with `--threads=yes` (`--threads=no` works fine). I can reproduce it, but only with one particular source and goal. (I had a previous problem with compiling to a `.qlf` file that went away with `--threads=no`; but that mysteriously ceased to reproduce: [Cannot allocate memory (tcmalloc) building .qlf file + re\_replace crash](https://swi-prolog.discourse.group/t/cannot-allocate-memory-tcmalloc-building-qlf-file-re-replace-crash/2272)) - The likely change: `git difftool --tool=tkdiff 3314e0692fcd760d6935da4bf14f6fbdd50878e2 f91a985a3d7e3b3d37de616e9ffd72ea15b7d0a3` 1. FD leak - The likely change: `git difftool --tool=tkdiff cf00d089bcef49e5a00fd410f4dda0613601e27e 528d0b03e5fca71a42f8438164d9cb2c0d80634c` ---
**Author:** ![peter.ludemann](https://yyz2.discourse-cdn.com/free1/user_avatar/swi-prolog.discourse.group/peter.ludemann/32/48_2.png) [@peter.ludemann](https://swi-prolog.discourse.group/u/peter.ludemann)\ **Post date:** [June 23, 2020, 5:45pm UTC](https://swi-prolog.discourse.group/t/ann-swi-prolog-8-3-2/2536/4 "2020-06-23T17:45:06Z")
For the FD leak, I’ve opened a [github issue](https://github.com/SWI-Prolog/swipl-devel/issues/622) to track my progress. The leak only occurs sometimes, but so far I can’t identify the precise conditions that trigger it. It appears that the FD leak only happens when a file is loaded (using load\_files/2) that contains a directive to turn off autoloading. This triggers an infinite recursion of loading files from the library. I’m adding some instrumentation to the bootloader, to try to figure out what’s going on A simple work-around is: don’t disable autoloading. ---
**Author:** ![jan](https://yyz2.discourse-cdn.com/free1/user_avatar/swi-prolog.discourse.group/jan/32/4_2.png) [@jan](https://swi-prolog.discourse.group/u/jan)\ **Post date:** [June 25, 2020, 2:04pm UTC](https://swi-prolog.discourse.group/t/ann-swi-prolog-8-3-2/2536/5 "2020-06-25T14:04:04Z")
I think this should be fixed with 21e0a70e91d7aa9c5dd83b00f0d49e22c1ed8b60 Now I wonder whether it is a good idea to switch the `autoload` file from restarted saved state. The issue was due to poor interaction between explicit autoloading and implicit autoloading as performed by the saved state generation. ---
**Author:** ![peter.ludemann](https://yyz2.discourse-cdn.com/free1/user_avatar/swi-prolog.discourse.group/peter.ludemann/32/48_2.png) [@peter.ludemann](https://swi-prolog.discourse.group/u/peter.ludemann)\ **Post date:** [June 25, 2020, 9:00pm UTC](https://swi-prolog.discourse.group/t/ann-swi-prolog-8-3-2/2536/6 "2020-06-25T21:00:44Z")
> [@jan](#): > > I think this should be fixed with 21e0a70e91d7aa9c5dd83b00f0d49e22c1ed8b60 Confirmed that it’s fixed (and I’ve closed the issue on github). > [@jan](#): > > Now I wonder whether it is a good idea to switch the `autoload` file from restarted saved state. Maybe start a new discussion on this? I’ve read through the autoload, resources, and load\_files documentation, and it’s not entirely clear to me; also when I tried turning autoload off, I got various strange errors (I haven’t spent the time to look more deeply into them; I just left autoload on).