[PYTHON][RABIT] calling rabit.init multiple times exits the process

[TomAugspurger]

Environment info

Operating System: macOS 10.12.6

Compiler: gcc

Package used (python/R/jvm/C++): python

xgboost version used: 0.6

If installing from source, please provide

1. The commit hash (git rev-parse HEAD) 78c4188

2. Logs will be helpful (If logs are large, please upload as attachment).

If you are using python package, please provide

1. The python version and distribution: 0.6, source

Steps to reproduce

In [1]: import xgboost as xgb
In [2]: xgb.rabit.init()

In [3]: xgb.rabit.init()
rabit::Init is already called in this thread

(and the process exits)

---

Would it be possible to avoid this, say by storing a global or threadlocal variable? It seems like https://github.com/dmlc/rabit/blob/a764d45cfb438cc9f15cf47ce586c02ff2c65d0f/python/rabit.py#L46-L52 intends to do something like that, but even then, the init will still continue to run, since it doesn't check the result and continues unconditionally.

I'm happy to submit a patch for this, but I'm not sure whether to make it in the rabit repo or here. My local copy picks up the version of rabit in xgboost/python-package/xgboost/rabit.py, so I've made the issue here.

[TomAugspurger]

Was this fixed in rabit?

[hcho3]

This issue was closed due to the current triaging. We try to aggressive close issues from now on so opened issues can get attended to. I went ahead and re-opened it.

[tqchen]

please send a PR to the rabit repo