Antlr4 failing to reach out to Maven repository

[Cazra]

This morning, I've been having trouble trying to do anything at all with Antlr4. I can't use it to build any of my grammars, and not even antlr4 --help works.

I get the following error output:

Traceback (most recent call last):
  File "/usr/local/bin/antlr4", line 8, in <module>
    sys.exit(tool())
  File "/usr/local/lib/python3.10/dist-packages/antlr4_tool_runner.py", line 141, in tool
    run_cli('org.antlr.v4.Tool')
  File "/usr/local/lib/python3.10/dist-packages/antlr4_tool_runner.py", line 132, in run_cli
    args, version = process_args()
  File "/usr/local/lib/python3.10/dist-packages/antlr4_tool_runner.py", line 126, in process_args
    args.version or os.environ.get("ANTLR4_TOOLS_ANTLR_VERSION") or latest_version()
  File "/usr/local/lib/python3.10/dist-packages/antlr4_tool_runner.py", line 27, in latest_version
    with urlopen(f"https://search.maven.org/solrsearch/select?q=a:antlr4-master+g:org.antlr", timeout=10) as response:
  File "/usr/lib/python3.10/urllib/request.py", line 216, in urlopen
    return opener.open(url, data, timeout)
  File "/usr/lib/python3.10/urllib/request.py", line 519, in open
    response = self._open(req, data)
  File "/usr/lib/python3.10/urllib/request.py", line 536, in _open
    result = self._call_chain(self.handle_open, protocol, protocol +
  File "/usr/lib/python3.10/urllib/request.py", line 496, in _call_chain
    result = func(*args)
  File "/usr/lib/python3.10/urllib/request.py", line 1391, in https_open
    return self.do_open(http.client.HTTPSConnection, req,
  File "/usr/lib/python3.10/urllib/request.py", line 1352, in do_open
    r = h.getresponse()
  File "/usr/lib/python3.10/http/client.py", line 1375, in getresponse
    response.begin()
  File "/usr/lib/python3.10/http/client.py", line 318, in begin
    version, status, reason = self._read_status()
  File "/usr/lib/python3.10/http/client.py", line 279, in _read_status
    line = str(self.fp.readline(_MAXLINE + 1), "iso-8859-1")
  File "/usr/lib/python3.10/socket.py", line 705, in readinto
    return self._sock.recv_into(b)
  File "/usr/lib/python3.10/ssl.py", line 1303, in recv_into
    return self.read(nbytes, buffer)
  File "/usr/lib/python3.10/ssl.py", line 1159, in read
    return self._sslobj.read(len, buffer)
TimeoutError: The read operation timed out

It appears to be timing out when it reaches out to its Maven repository.

[kaby76]

https://search.maven.org/solrsearch/select?q=a:antlr4-master+g:org.antlr. I mentioned this here. #4698 (comment). The change, which should be in the antlr4-tools repo, looks instead to https://repo1.maven.org/maven2/org/antlr/antlr4/, avoiding search.maven.org entirely, which is not robust, frequently down--more often than not!

[moogman]

antlr4 python is unusable again because there's an outage with https://status.maven.org/
This should be a soft failure with antlr4, warning instead of erroring out.
--help and --version should work even if maven is down, and we also should have a --skip-version-check cmdline option.

[moogman]

Duplicate of antlr/antlr4-tools#18 as this is a bug of antlr4-tools rather than antlr4 itself

[kaby76]

Yes, the current workaround is to always use the -v "option." But, you may want to use -v for another reason.

In grammars-v4, we always use the -v "option" because the tool and runtime versions must be kept in sync. So, while a new version of the tool may be released, the runtimes are released in a completely different timetable, sometimes up to a month after the release of the tool.

[moogman]

Cross referencing to antlr/antlr4-tools#18 (comment)
There's a fix that's not made it to a pip release yet, that errors cleanly when there's a timeout and automatically uses any current JRE as a fallback option.

In the meantime, you can add that manually in your envs:

.env/lib/python3.12/site-packages/antlr4_tool_runner.py:35
-    except (error.URLError, error.HTTPError) as e:
+    except (error.URLError, error.HTTPError, TimeoutError) as e: