Cap the number of samples in node-datadog-metrics

[dbader]

node-datadog-metrics/lib/metrics.js

Lines 133 to 136 in 10d3b29

	// The number of samples recorded is unbounded at the moment.
	// If this becomes a problem we might want to limit how many
	// samples we keep.
	this.samples.push(val);

If ddog is down this will hog a lot of memory.

[csabapalfi]

Have you considered using https://github.com/circonus-labs/circllhist.js ?

[dbader]

Personally, I'd be in favor of a simple solution like dropping new/old samples if the buffer is full. Especially for a first implementation to plug the memory issue.

Under normal operation it should be quite rare we encounter this situation. For my use cases, it would be okay to drop samples.