Queue depth
Also known as Queue length, Work queue depth
Definition
Queue depth is the count of items waiting for the same processing step, capacity slot, approval, or dependency at a particular time. It is a snapshot of accumulation, not a measure of how long items have waited.
How many are waiting now?
Queue depth is a count at a point in time. It answers how much work is waiting, while queue time answers how long work waits. Both are needed: a queue of ten new items may be less urgent than a queue of one item that has exceeded its service expectation.
A concrete example
An illustrative review queue contains seven pull requests at 9 a.m. A second snapshot at noon contains nine. The increase signals accumulation, but the team should inspect item age, reviewer capacity, and arrival rate before deciding what changed.
Watch the trend
Track depth over time and segment by work class or stage. Rising depth with stable arrival may indicate lower service rate. Falling depth with rising cycle time may indicate items are being closed or moved without finishing the underlying work.
Limitations
Counts hide size, risk, and age. Queue depth also changes with snapshot timing and state definitions. Never use it alone as a performance score or capacity forecast.
How this relates to Weave
Weave can help teams investigate changes and review events associated with an observed queue. Use it with the system that records all work and with age data, because a shallow queue can still contain one dangerously old item.
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