SpanProcessor incorrect calls to SpanExporter::forceFlush()

[Nevay]

• SimpleSpanProcessor::forceFlush() has to force-flush exporter
• BatchSpanProcessor::onEnd() shouldn't force-flush exporter

[brettmc]

I agree with SimpleSpanProcessor::forceFlush(), but the conditional flush in BatchSpanProcessor::onEnd() seems critical to the batching functionality. Is the issue that we're using the forceFlush() mechanism not for its intended purpose?

[Nevay]

The batching functionality doesn't depend on force-flushing; the batch processor should still call ::export() with the batch in ::onEnd(), just without calling ::forceFlush() afterwards.

SpanExporter::forceFlush()

ForceFlush SHOULD only be called in cases where it is absolutely necessary, such as when using some FaaS providers that may suspend the process after an invocation, but before the exporter exports the completed spans.

[amber0612]

I would like to work on this one. Can you please assign it to me. thanks

[brettmc]

Fixed by #788