Failed to consult pl file

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1

I’m using: SWI-Prolog version 9.0.4 for x86_64-linux

In the Java web project, the third request to consult pl file threw the following error:

  ../src/pl-thread.c:8079: stack_avail___LD: Assertion failed: here > info->c_stack_base
  C-stack trace labeled "assert_fail":
    [0] save_backtrace() at /downloads/swipl/build/../src/os/pl-cstack.c:337 [0x7fe8a79eb2da]
    [1] __assert_fail() at /downloads/swipl/build/../src/pl-assert.c:105 [0x7fe8a79b437a]
    [2] pl_functor_table_in_use() at /downloads/swipl/build/../src/pl-thread.c:7866 (discriminator 1) [0x7fe8a79a21f7]
    [3] require_c_stack___LD() at /downloads/swipl/build/../src/pl-thread.c:8096 [0x7fe8a79a21c2]
    [4] callProlog() at /downloads/swipl/build/../src/pl-pro.c:425 [0x7fe8a7a0e55c]
    [5] pl_sig_atomic1_va() at /downloads/swipl/build/../src/pl-pro.c:361 [0x7fe8a7a0e7c4]
    [6] PL_next_solution___LD() at /downloads/swipl/build/../src/pl-vmi.c:4747 [0x7fe8a79f6825]
    [7] Java_org_jpl7_fli_Prolog_next_1solution() at /downloads/swipl/build/../packages/jpl/src/main/c/jpl.c:4188 [0x7fe87c0992a4]
  Prolog stack:
    [16] system:sig_atomic/1 [PC=1 in supervisor]
    [15] system:setup_call_catcher_cleanup/4 [PC=4 in clause 1]
    [11] system:$file_type_extensions/2 [PC=24 in clause 2]
    [10] system:absolute_file_name/3 [PC=56 in clause 2]
    [9] system:$resolve_source_path/3 [PC=54 in clause 1]
    [8] system:$load_file_e/3 [PC=21 in clause 3]
    [7] system:$load_file/3 [PC=12 in clause 1]
    [0] system:$c_call_prolog/0 [PC=0 in top query clause]

  Aborted

My code looks like this:

  @GetMapping("/test/swipl")
  public void testSwipl() {
      new Query("consult", new Term[]{new Atom("/data/pl/test.pl")}).hasSolution();
  }
2

It seems these two lines make sense and indicate you are running out of C stack. Or, looking at the assertion failure in stack_avail(), something weird is going on with the C stack. Surely it indeed grows down on X86_64 AFAIK.

It could really be running out of stack or the C stack availability checks are not properly working with JPL. It should not be too hard to figure that out using gdb and/or some print statements in the code trying to verify the C stack availability. If you want others to do that, please make complete source code available, so we can simply run your program and observe its behavior.

3

/data/pl/test.pl

  items('test').
4

If that is supposed to be the code to reproduce, I’m afraid this won’t do. What matters most is probably the Java code and how exactly this uses Prolog. With code, I mean something we can run to reproduce your problem. I think that means the Java code and Prolog code including instructions on how to get it running and reproduce the crash. This looks like something where the details matter.

5

The complete code has been uploaded to Google Cloud Drive：

https://drive.google.com/file/d/1fFnvXxowkk5ocoHcpNSzamE7wreH7FqF/view?usp=sharing
6

So far, so good. How do I use this? Don’t expect any knowledge about Java infrastructure on my side.

7

This is the packaged jar file

https://drive.google.com/file/d/1WRwRpDooUJ06deuOD8O5M-hQmDBGOWRw/view?usp=sharing

Debian 11.7, You need to first configure the Java environment, copy the test.pl file to /data/pl directory, run jar

java -jar swipl-test-1.0-SNAPSHOT.jar

and access it in the browser

http://ip:60001/test/swipl

The error will occur on the third request.

8

Thanks. That works and reproduced. Turns out that C-stack protection didn’t work when Prolog engines hop between threads as they do with JPL (and some other not-so-common scenarios). Required some redesign :frowning: Seems to work fine after commit 15f8cfd92949552b4e16c99723fc53e9fad7a3be to swipl-devel.git.

1 Like
9

Thank you, it can now be used normally