[xray] Users get no warning for infeasible tasks.

[robertnishihara]

Start Ray with

RAY_USE_XRAY=1 ray start --head --redis-port=6379 --num-gpus=0

Then start RAY_USE_XRAY=1 ipython and run

import ray

ray.init(redis_address='localhost:6379')

@ray.remote(num_gpus=1)
def f():
    return 1

f.remote()

f will never execute because it is infeasible, and yet the user will get no warning.

[atumanov]

what about this : https://github.com/ray-project/ray/blob/master/src/ray/raylet/scheduling_policy.cc#L110

[robertnishihara]

That's good, but it goes to a log file (assuming output is redirected, which is the default in the cluster setting). It'd be best for it to be pushed to the driver.