[agent][dogstatsd] Add support for changing niceness on POSIX systems

[armenb]

…ocesses on POSIX systems

let me know if you'd like a unit test for this, thanks :-)

[irabinovitch]

@armenb @armenfirespotter Thank you for the patch! Our team will review and be in touch soon with any feedback, most likely as part of the 5.7 release/review process. In the mean time, tests are always greatly appreciated!

[armenb]

Hi DD team, do you have any initial comments/questions/concerns regarding this patch? Thanks!

[remh]

Thanks this is an interesting patch.

I'm not sure it makes sense to have the agent governs itself like that.

I think it would make more sense to patch your /etc/dd-agent/supervisor.conf file with nice/ionice commands.

What do you think ?

[armenb]

remh - great idea, I think that's ultimately a better and simpler way to do this. However, I think there is an issue with upgrading the datadog-agent via apt after doing this - it seems that the supervisor.conf file gets overwritten.

[remh]

It does indeed. You could maybe manage this file through chef or something similar though.
Or we could pass the niceness as an environment variable.

DOGSTATSD_NICENESS=-5 /etc/init.d/datadog-agent restart

What do you think?
Meanwhile i'm closing this PR.

Thanks again for the feedback!

[olivielpeau]

Related: #3086