This is asked in a context to better understand why a submitted share by a miner might be rejected.
I know when a new block gets solved that would require a work update, which is approximately every 10 mins on average. Are there any other circumstances where miners in a pool would get new work from the pool server?
I'm mainly asking this question to better understand the explanation given here:
The cause of this problem is low overall hashrate. Phoenix maintains a work queue to reduce hashrate disruptions caused by momentary connection problems. This works great on faster hardware like the ATI 5870, but it can cause issues with miners that get <100 Mhash or so. The reason for "unknown-work" rejects is that those shares were from work that has been sitting in the queue for long periods of time(>1 min). Some pools "forget" about assigned work after very short time periods (1 minute for example) and any results returned based on that work are rejected as unknown...
It sounds like a pool ignores submitted shares that's over a 1 min even if no new blocks were solved in that time. The submitted share clearly shouldn't be considered stale yet so why would a pool do this?