A new upstream version of PV should be released within the next couple of months. The patch kindly provided in this thread was originally sent to me directly two years ago, so I apologise profusely for the delay.
There have been a couple of other patch submissions around this issue which I'll need to understand before getting a release together, along with multiple other TODOs which need organising, but I hope that I have now sorted out my time management enough that this will not take long. If anyone can think of a relatively simple and reliable way to test the behaviour of ETA / rate calculation with bursty input such that it can be added to "make test", but which doesn't take ages to run, please let me know. On Sat, May 23, 2020 at 07:46:20PM +0200, lemonsqueeze wrote: > Package: pv > Version: 1.6.6-1 > Severity: normal > Tags: upstream patch > > Hello, > > This was reported upstream some time ago but it doesn't seem new pv > versions are coming out so reporting here instead, maybe we can do > something about it in debian. > > This was found on ubuntu initially, sorry I haven't tested debian per se > but from what I can see it's affected as well as package sources are > identical. > > Consider following scenario: > > I was running a really long task that generates a 800Mb file at about > 50k/s. Something like: > > while true ; do ls -l /* ; sleep 1 ; done > /tmp/file > > Sometime after it started I thought of using pv to keep track of > progress with: > > tail -n +1 -f /tmp/file | pv -s 800m >/dev/null > > I was interested in ETA mostly, unfortunately if you do this after a few > mb have been generated the ETA is wildly wrong for a very long time: > transfer rate is really fast initially and fools pv into thinking we're > going to get something like that over time, and it takes a really long > time for the average rate to drop back to 50k/s which is all we're > getting actually. > > It'd be nice to have an ETA based on current rate average here, say over > last 30s or last 10s, instead of global rate average. > > I've been playing with this patch on top of pv 1.6.6 > (also at https://github.com/lemonsqueeze/pv) > > Which keeps track of history periodically over a given time window and uses > that to compute current average rate for ETA. Looks like it works pretty > well in this case. Also added a --rate-window option to change time window > (default: last 10s) (name isn't great, maybe could find a better one). -- Andrew Wood
