[Java] support python worker command in raylet

[chuxi]

What do these changes do?

support raylet, which is started by java runManager, to start python default_worker.py .

So when doing local test of java call python task, it helps auto start python worker.

Related issue number

[AmplabJenkins]

Test FAILed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/Ray-PRB/8755/
Test FAILed.

[chuxi]

... @AmplabJenkins restart?

How to apply the privilege to restart the failed ci test? ;(

[raulchen]

@chuxi you can close and reopen this PR to trigger CI

[raulchen]

@chuxi you can close and reopen this PR to trigger CI

[chuxi]

@raulchen get it. Thank you!

[raulchen]

hmm, weird that the last CI job kept failing... let me try again

[raulchen]

hmm, weird that the last CI job kept failing... let me try again

[AmplabJenkins]

Test FAILed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/Ray-PRB/8794/
Test FAILed.

[AmplabJenkins]

Test FAILed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/Ray-PRB/8801/
Test FAILed.

[chuxi]

@raulchen ...

why you always post two same comments ... :p

The ray test is broken actually. I will rebase master and push again.

[AmplabJenkins]

Test FAILed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/Ray-PRB/8822/
Test FAILed.

[chuxi]

@robertnishihara

... so is the master branch ci broken? I did not change any code except java, but the failed tests are python's ... :(

[robertnishihara]

The Jenkins failure should be fixed in #3112. Some of the Travis tests are a little flakey.

[AmplabJenkins]

Test PASSed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/Ray-PRB/8827/
Test PASSed.

[chuxi]

rerun failed test or merge directly ?