Investigate use of `arguments` in logger. about cloud-diagnostics-common-nodejs

[cristiancavalli]

@matthewloring @ofrobots can this be closed? Seems like it was implemented already

[matthewloring]

This bug was opened to investigate the performance impact of arguments used here: https://github.com/GoogleCloudPlatform/cloud-diagnostics-common-nodejs/blob/master/lib/logger.js#L99. If it is causing deopts or poor performance we may want to rework this section.

[matthewloring]

We observed deopts in join (https://github.com/GoogleCloudPlatform/cloud-diagnostics-common-nodejs/blob/master/lib/logger.js#L73) and slice (https://github.com/GoogleCloudPlatform/cloud-diagnostics-common-nodejs/blob/master/lib/logger.js#L99) but nothing associated with arguments. It will be difficult to avoid these deopts as logs can be called on arbitrary numbers of arguments (though it would be good to investigate V8 changes to avoid these). We can do a more detailed analysis of logging performance if needed. Closing this for now.