Opened an issue NIFI-4638 <https://issues.apache.org/jira/plugins/servlet/mobile#issue/NIFI-4638>
On Wed, 22 Nov 2017 at 20:39 Omer Hadari <[email protected]> wrote: > Yes we were thinking in that direction as well, that’s why I mentioned the > 1ms part. I do not know how events are assigned an ordinal though, so it’s > unclear to me whether the disordering is constant but is usually “hidden” > since there is no rollover, or maybe there is some kind of a race > condition. You’ll probably be able to answer these questions quicker than > me, I’ll open a jira as soon as I get home later today. > > Thanks again! > > On Wed, 22 Nov 2017 at 20:34 Mark Payne <[email protected]> wrote: > >> Omer, >> >> Yes, I think that is sufficient. I think the issue is that the framework >> is creating both the >> ATTRIBUTES_MODIFIED and DROP events, and the generation of these objects >> is >> very fast. But if the timestamp happens to 'rollover' from millisecond 1 >> to millisecond 2, >> for example, those events get different timestamps. So I think it's just >> a timing thing that >> will be somewhat difficult to reproduce reliably. But just a description >> of the behavior that >> you're experiencing should be fine. >> >> Thanks >> -Mark >> >> On Nov 22, 2017, at 1:04 PM, Omer Hadari <[email protected]> wrote: >> >> I’ll be glad to open a jira, though the problem is hardly coherent imo, >> what would you like to see there? Simply “Disordering of drop events” and >> the explanation I have here? Sadly I cannot provide a concrete example >> since the problem does not reproduce. >> >> On Wed, 22 Nov 2017 at 18:23 Joe Witt <[email protected]> wrote: >> >>> also - awesome find! And glad you're at such a level with provenance >>> data to catch that. Thanks Omer! >>> >>> On Wed, Nov 22, 2017 at 11:21 AM, Mark Payne <[email protected]> >>> wrote: >>> > Omer, >>> > >>> > This is likely an issue related to the order in which we generate >>> those events in the framework. >>> > Do you mind filing a JIRA? >>> > >>> > Thanks >>> > -Mark >>> > >>> > >>> >> On Nov 22, 2017, at 10:51 AM, Omer Hadari <[email protected]> >>> wrote: >>> >> >>> >> Hi! >>> >> We’ve been using NiFi for a while now, and we save all provenance >>> events for logging purposes and such. We encountered an issue while looking >>> at lineages of some flow files, which showed drop events as if they >>> happened before another event, that in fact preceded it (and indeed has a >>> lower event ordinal). >>> >> >>> >> For example in a split json processor, the original FlowFile is >>> dropped after all splits happen and are assigned fragment counts, but still >>> the timestamp of the drop event is earlier than the timestamp of the >>> attributes modified event. That causes the graph to look as if the >>> attributes modified event comes out of the drop event, which doesn’t really >>> make sense to us (should it?). It’s probably worth noting that the drop >>> event ordinal is higher than the attributes modified event ordinal. Also we >>> noticed that >>> >> 1. This only happens every once per a few thousand events. >>> >> 2. This does not reproduce by replaying. >>> >> 3. The drop event’s timestamp is earlier by 1ms in the cases we >>> encountered, and the ordinal is always larger by one. >>> >> >>> >> This might be an error with the split json processor or a more >>> general one. We’d love any clues or corrections to misconceptions we might >>> have (maybe this is not a problem and drop events can precede other events?) >>> >> >>> >> Thank you! >>> > >>> >> >>
