Serious performance issue with JavaScript target

I am new to antlr4 and have a relatively simple recursive grammar (with separate lexer/parser) for a project that runs in both Java and JavaScript. Everything works as expected for short expressions. For longer ones, Java works as expected with parses on the order of 50-100ms, while JavaScript takes many, many seconds for medium length expression and simply hangs and/or does not complete for longer ones. Some simple performance metrics rule out the lexing and visiting phases which take only a few milliseconds. I am at a loss as to how to investigate further…

In the demo below, the output parse-tree is identical, but while the Java parse takes 91 ms the JavaScript parse takes 46 seconds!!

If I increase the length of the string any further, the JavaScript hangs and does not complete.

Java: https://github.com/dhowe/rita4j/tree/master/src/main/java/rita/antlr JS: https://github.com/dhowe/ritajs/tree/master/grammar

Simple demo (js):

$ git clone https://github.com/dhowe/ritajs.git
$ cd ritajs && git checkout perf
$ npm install
$ node perf-test.js

OUTPUT:
[lexing] 0ms
(script (line (expr (chars Lorem   ipsum   dolor   sit   amet,  ) (choice ( (wexpr (expr (chars consectetur   adipiscing   elit))) )) (chars   morbi   ullamcorper   porttitor   lorem,   in   faucibus   velit   ultrices   nec .   Curabitur   convallis   luctus   felis,   sed   posuere   turpis   mollis   quis .   Suspendisse   euismod   vel   tellus   sit   amet   tempus .   Nullam   pretium   tincidunt   pellentesque .   Vestibulum   tempus   eget   eros   non   dignissim .   Nullam   faucibus   et   augue   a   commodo .   Curabitur   tellus   est,   elementum   sit   amet   finibus   a,   posuere   in   nunc .   In   libero   metus,   tempor   nec   tincidunt   eu,   vulputate   a   ex .   Aliquam   id   tincidunt   sapien .   In   pharetra   condimentum   lacus,   non   congue   arcu   tempor   nec .   Nullam   faucibus   odio   id   diam   dapibus   volutpat   sed   in   quam .   Vivamus   ex   quam,   efficitur   sit   amet   ante   eu,   congue   blandit   arcu .   Suspendisse   molestie   sit   amet   diam   ac   tristique .))) <EOF>)
[parsing] 46028ms
[visiting] 1ms

Same demo (java):

$ git clone https://github.com/dhowe/rita4j.git
$ cd rita4j && git checkout perf
$ mvn compile test-compile  exec:java  -Dexec.mainClass="rita.test.PerfTest" -Dexec.classpathScope=test 

OUTPUT:
[lexing] 50ms
(script (line (expr (chars Lorem   ipsum   dolor   sit   amet,  ) (choice ( (wexpr (expr (chars consectetur   adipiscing   elit))) )) (chars   morbi   ullamcorper   porttitor   lorem,   in   faucibus   velit   ultrices   nec .   Curabitur   convallis   luctus   felis,   sed   posuere   turpis   mollis   quis .   Suspendisse   euismod   vel   tellus   sit   amet   tempus .   Nullam   pretium   tincidunt   pellentesque .   Vestibulum   tempus   eget   eros   non   dignissim .   Nullam   faucibus   et   augue   a   commodo .   Curabitur   tellus   est,   elementum   sit   amet   finibus   a,   posuere   in   nunc .   In   libero   metus,   tempor   nec   tincidunt   eu,   vulputate   a   ex .   Aliquam   id   tincidunt   sapien .   In   pharetra   condimentum   lacus,   non   congue   arcu   tempor   nec .   Nullam   faucibus   odio   id   diam   dapibus   volutpat   sed   in   quam .   Vivamus   ex   quam,   efficitur   sit   amet   ante   eu,   congue   blandit   arcu .   Suspendisse   molestie   sit   amet   diam   ac   tristique .))) <EOF>)
[parsing] 91ms
[visiting] 18ms

Any suggestions would be very much appreciated.

[ericvergnaud]

3 to 4 times slower is in line with what you can expect. See https://benchmarksgame-team.pages.debian.net/benchmarksgame/performance/knucleotide.html, a benchmark which like ANTLR spends most of its time manipulating hash maps.

Can I close this?

[dhowe]

This issue should not (imho) be closed, without at least creating separate issues, b/c there are still 2 real problems:

1. There is huge bug in the current public release for JS, and no good workaround
2. The JS releases do not support the most common/basic workflows (as described above)