> Pool Name Active Pending Completed Blocked All > time blocked > ReadStage 27 2166 3565927301 0
In general, "active" refers to work that is being executed right now, "pending" refers to work that is waiting to be executed (go into "active"), and completed is the cumulative all-time (since node start) count of the number of tasks executed. With the slicing, I'm not sure off the top of my head. I'm sure someone else can chime in. For e.g. a multi-get, they end up as independent tasks. Typically having pending persistently above 0 for ReadStage or MutationStage, especially if more than a hand-ful, means that you are having a performance issue - either capacity problem or something else, as incoming requests will have to wait to be services. Typically the most common effect is that you are bottlenecking on I/O and ReadStage pending shoots through the roof. There are exceptions. If you e.g. submit a really large multi-get of 5000, that will naturally lead to a spike (and if all 5000 of them need to go down to disk, the spike will survive for a bit). If you are ONLY doing these queries, that's not a problem per se. But if you are also expecting other requests to have low latency, then you want to avoid it. In general, batching is good - but don't overdo it, especially for reads, and especially if you're going to disk for the workload. -- / Peter Schuller (@scode, http://worldmodscode.wordpress.com)
