XGBoost4j-spark Build fail because NPE about xgboost

[trivialfis]

Hi, could you please make sure python3 is the default Python?

[CrazyBinXXX]

Hi, I've tried to alias python=python3 and ensured that pythonExec is "python3" in "RabitTracker.java" but the exception still happened. I wonder does the code exec python in sudo mode?

BTW I think python refers to python3 might be a little confusing. Shouldn't we replace "python" with "python3" in our .pom files and pythonExec default value?

[wbo4958]

@CrazyBinXXX, Can you hack startTrackerProcess to print the cmd in RabitTracker.java, and then run it in another terminal to see if it can work as expected?

  private boolean startTrackerProcess() {
    try {
      String cmd = getRabitTrackerCommand();
      trackerProcess.set(Runtime.getRuntime().exec(cmd));
      loadEnvs(trackerProcess.get().getInputStream());
      return true;
    } catch (IOException ioe) {
      ioe.printStackTrace();
      return false;
    }
  }

[CrazyBinXXX]

Actually I've hacked it.

!!!!!!!!!!!!!!!!!BIN LOG!!!!!!!!!!!!!!!!!
python3 /var/folders/ql/ld6nvq6d02z974sl6y8p2t7m0000gn/T/tracker1198335420923130425.py --log-level=DEBUG --num-workers=2
Process info: java.lang.UNIXProcess@2b62dddf
Process info: true
Process info: java.lang.UNIXProcess$ProcessPipeInputStream@6ecf25e
null

It seems to execute something in a temporary folder. I tried to execute it in another terminal and it gives me "can't open file '/var/folders/ql/ld6nvq6d02z974sl6y8p2t7m0000gn/T/tracker1198335420923130425.py': [Errno 2] No such file or directory"

[wbo4958]

Try python3 xgboost4j/src/main/resources/tracker.py --log-level=DEBUG --num-workers=2

[wbo4958]

BTW, the recent PR #10112 will revise the whole Rabit part, where there will be no tracker.py anymore.

[CrazyBinXXX]

I finally solved it by a weird way --- running "cat /etc/hosts"

[wbo4958]

That's interesting.