問題文
A team needs to record the current number of items waiting in an in-memory work queue. The value goes up when work arrives and down when a worker takes an item. Which instrument kind fits?
選択肢
- Counter, because a queue length is a running total that the backend can then differentiate over time to recover the current value of the queue.
- UpDownCounter, because it accumulates over time but can also go down again.
- Histogram, because the interesting question is the distribution of queue lengths.
- Asynchronous Counter, because the value is only known at export time.