apache/hadoop · error · IllegalArgumentException

invalid args: {}

Error message

invalid args: {}

What it means

JMXGet ('hdfs jmxget') parses its command line with commons-cli GnuParser in stop-at-non-option mode. Any ParseException — unknown option, an option like -port missing its value, malformed flags — is caught, the usage is printed, and an IllegalArgumentException prefixed 'invalid args:' wrapping the parser's reason is thrown.

Source

Thrown at hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/tools/JMXGet.java:283

        .argName("VM's connector url").hasArg()
        .desc("connect to the VM on the same machine;"
        + "\n use:\n jstat -J-Djstat.showUnsupported=true -snap <vmpid> | "
        + "grep sun.management.JMXConnectorServer.address\n "
        + "to find the url").build();

    opts.addOption(jmxServer);
    opts.addOption(jmxHelp);
    opts.addOption(jmxService);
    opts.addOption(jmxPort);
    opts.addOption(jmxLocalVM);

    CommandLine commandLine = null;
    CommandLineParser parser = new GnuParser();
    try {
      commandLine = parser.parse(opts, args, true);
    } catch (ParseException e) {
      printUsage(opts);
      throw new IllegalArgumentException("invalid args: " + e.getMessage());
    }
    return commandLine;
  }

  public static void main(String[] args) {
    int res = -1;

    // parse arguments
    Options opts = new Options();
    CommandLine commandLine = null;
    try {
      commandLine = parseArgs(opts, args);
    } catch (IllegalArgumentException iae) {
      commandLine = null;
    }

    if (commandLine == null) {
      // invalid arguments

View on GitHub (pinned to 2add963021)

Solutions

1. Run 'hdfs jmxget -help' and rebuild the command with only supported options: -server, -port, -service, -localVM.
2. Give every value-taking option an explicit non-empty value (e.g. -server localhost -port 8004).
3. If embedding in scripts, fail early on empty variables rather than letting the parser see a dangling option.

Example fix

# before
hdfs jmxget -server localhost -prot 8004
# invalid args: Unrecognized option: prot

# after
hdfs jmxget -server localhost -port 8004

// Pre-validate with the same parser instead of invoking main directly
try {
  CommandLine cl = new GnuParser().parse(buildJmxOptions(), args, true);
  for (Option o : cl.getOptions()) {
    if (o.hasArg() && (o.getValue() == null || o.getValue().isEmpty())) {
      throw new IllegalArgumentException("option -" + o.getOpt() + " needs a value");
    }
  }
} catch (ParseException pe) {
  throw new IllegalArgumentException("fix jmxget args: " + pe.getMessage(), pe);
}
JMXGet.main(args);

try {
  JMXGet.main(args);
} catch (IllegalArgumentException e) {
  if (e.getMessage().startsWith("invalid args")) {
    // usage was already printed; surface parser reason to caller/script
    System.err.println("jmxget argument error: " + e.getMessage());
    System.exit(1);
  }
  throw e;
}

When it happens

Trigger: Running 'hdfs jmxget' with a misspelled option (e.g. -prot instead of -port), an option that requires a value but is last on the line, or a stray token before recognized options depending on parse order.

Common situations: Wrong port/service combination while scraping NameNode JMX; scripts passing empty variables for -port/-service so the next token is consumed as its value; option order copied from a different Hadoop version.

Related errors

• Invalid or extra Arguments: {}
• Did not expect argument: {}
• usage: -confKey [key]
• Unknown processor {} (valid processors: xml, binary, stats)
• Illegal option {}

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/4abdae02047f981e. Report an issue: GitHub.