Hi Piotr, Thanks for the clarification. Looking forward to the great feature!
Best regards, Jing On Mon, Nov 20, 2023 at 10:03 AM Piotr Nowojski <pnowoj...@apache.org> wrote: > Hi Jing! > > > the upcoming OpenTelemetry based TraceReporter will use the same Span > > implementation and will not support trace_id and span_id. Does it make > > sense to at least add the span_id into the current Span design? The > default > > implementation could follow your suggestion: > jobId#attemptId#checkpointId. > > Those IDs (jobId, checkpointId) will be accessible to the humans via > attributes, > so there is no need to encode them at the moment in the span/trace ids. At > the > same time, at the moment, I don't know for sure how the concept of span > parent ids should be exposed to the user of this API. Whether it should be > plain > text, or some pojo generating the trace id/span id. Also I'm not sure how > would > this have to work for other reporting systems other than OTEL. Due to those > reasons I thought that keeping the API as simple as possible would be the > best > option. > > > 1. The sample code shows that the scope of Span will be the CanonicalName > > of a class. If there are other cases that could be used as the scope too, > a > > javadoc about Span scope would be helpful. If the CanonicalName of a > class > > is the best practice, removing the scope from the builder constructor and > > adding setScope(Class) might ease the API usage. The Span.getScope() can > > still return String. > > I like the idea with `#setScope(Class)`. I will adjust the FLIP :) > > > 2. The sample code in the FLIP is not consistent. The first example used > > Span.builder(..) and the second example used new Span() with setters. > > I will fix that, I've forgotten to upgrade the second `new Span()` usage to > the > builder. > > > 3. I guess the constructor of SpanBuilder class is a typo. > > Yes! Thanks for noting. > > Best, > Piotrek > > > czw., 16 lis 2023 o 15:12 Roman Khachatryan <ro...@apache.org> napisał(a): > > > Thanks for the proposal, > > > > Starting with the minimal functionality and expanding if necessary as the > > FLIP describes makes a lot of sense to me. > > > > Regards, > > Roman > > > > On Wed, Nov 15, 2023, 9:31 PM Jing Ge <j...@ververica.com.invalid> > wrote: > > > > > Hi Piotr, > > > > > > Sorry for the late reply and thanks for the proposal, it looks awesome! > > > > > > In the discussion, you pointed out that it is difficult to build true > > > distributed traces. afaiu from FLIP-384 and FLIP-385, the > > > upcoming OpenTelemetry based TraceReporter will use the same Span > > > implementation and will not support trace_id and span_id. Does it make > > > sense to at least add the span_id into the current Span design? The > > default > > > implementation could follow your suggestion: > > jobId#attemptId#checkpointId. > > > > > > Some other NIT questions: > > > 1. The sample code shows that the scope of Span will be the > CanonicalName > > > of a class. If there are other cases that could be used as the scope > > too, a > > > javadoc about Span scope would be helpful. If the CanonicalName of a > > class > > > is the best practice, removing the scope from the builder constructor > and > > > adding setScope(Class) might ease the API usage. The Span.getScope() > can > > > still return String. > > > 2. The sample code in the FLIP is not consistent. The first example > used > > > Span.builder(..) and the second example used new Span() with setters. > > > 3. I guess the constructor of SpanBuilder class is a typo. > > > > > > Really a nice idea to introduce the trace report! Thanks again! > > > > > > Best regards, > > > Jing > > > > > > On Tue, Nov 14, 2023 at 3:16 PM Piotr Nowojski <pnowoj...@apache.org> > > > wrote: > > > > > > > Hi All, > > > > > > > > Thanks for the answers! > > > > > > > > Unless there are some objections or suggestions, I will open a voting > > > > thread later this > > > > week. > > > > > > > > > My original thought was to show how much time a sampled record is > > > > processed > > > > > within each operator in stream processing. By saying 'sampled', I > > mean > > > we > > > > > won't generate a trace for every record due to the high cost > > involved. > > > > > Instead, we could only trace ONE record from source when the user > > > > requests > > > > > it (via REST API or Web UI) or when triggered periodically at a > very > > > low > > > > > frequency. > > > > > > > > That would be useful, but another issue is that we can not measure > time > > > > reliably at the > > > > granularity of a single record. Time to process a single record by > the > > > > whole operator > > > > chain is usually faster compared to the syscalls to measure time. > > > > > > > > So I think we are stuck with sample based profilers, like Flame > Graphs > > > > generated by > > > > the Flink WebUI. > > > > > > > > Best, Piotrek > > > > > > > > czw., 9 lis 2023 o 05:32 Rui Fan <1996fan...@gmail.com> napisał(a): > > > > > > > > > Hi Piotr: > > > > > > > > > > Thanks for your reply! > > > > > > > > > > > About structured logging (basically events?) I vaguely remember > > some > > > > > > discussions about that. It might be a much larger topic, so I > would > > > > > prefer > > > > > > to leave it out of the scope of this FLIP. > > > > > > > > > > Sounds make sense to me! > > > > > > > > > > > I think those could be indeed useful. If you would like to > > contribute > > > > to > > > > > them > > > > > > in the future, I would be happy to review the FLIP for it :) > > > > > > > > > > Thank you, after this FLIP, I or my colleagues can pick it up! > > > > > > > > > > Best, > > > > > Rui > > > > > > > > > > On Thu, Nov 9, 2023 at 11:39 AM Zakelly Lan <zakelly....@gmail.com > > > > > > wrote: > > > > > > > > > > > Hi Piotr, > > > > > > > > > > > > Thanks for your detailed explanation! I could see the challenge > of > > > > > > implementing traces with multiple spans and agree to put it in > the > > > > future > > > > > > work. I personally prefer the idea of generating multi span > traces > > > for > > > > > > checkpoints on the JM only. > > > > > > > > > > > > > I'm not sure if I understand the proposal - I don't know how > > traces > > > > > could > > > > > > > be used for this purpose? > > > > > > > Traces are perfect for one of events (like checkpointing, > > recovery, > > > > > etc), > > > > > > > not for continuous monitoring > > > > > > > (like processing records). That's what metrics are. Creating > > trace > > > > and > > > > > > > span(s) per each record would > > > > > > > be prohibitively expensive. > > > > > > > > > > > > My original thought was to show how much time a sampled record is > > > > > processed > > > > > > within each operator in stream processing. By saying 'sampled', I > > > mean > > > > we > > > > > > won't generate a trace for every record due to the high cost > > > involved. > > > > > > Instead, we could only trace ONE record from source when the user > > > > > requests > > > > > > it (via REST API or Web UI) or when triggered periodically at a > > very > > > > low > > > > > > frequency. However after re-thinking my idea, I realized it's > hard > > to > > > > > > define the whole lifecycle of a record since it is transformed > into > > > > > > different forms among operators. We could discuss this in future > > > after > > > > > the > > > > > > basic trace is implemented in Flink. > > > > > > > > > > > > > Unless you mean in batch/bounded jobs? Then yes, we could > create > > a > > > > > > bounded > > > > > > > job trace, with spans > > > > > > > for every stage/task/subtask. > > > > > > > > > > > > Oh yes, batch jobs could definitely leverage the trace. > > > > > > > > > > > > Best, > > > > > > Zakelly > > > > > > > > > > > > > > > > > > On Wed, Nov 8, 2023 at 9:18 PM Jinzhong Li < > > lijinzhong2...@gmail.com > > > > > > > > > > wrote: > > > > > > > > > > > > > Hi Piotr, > > > > > > > > > > > > > > Thanks for driving this proposal! I strongly agree that the > > > > existing > > > > > > > metric APIs are not suitable for monitoring restore/checkpoint > > > > > behavior! > > > > > > > > > > > > > > I think the TM-level recovery/checkpointing traces are > necessary > > in > > > > the > > > > > > > future. In our production environment, we sometimes encounter > > that > > > > job > > > > > > > recovery time is very long (30min+), due to several subTask > heavy > > > > disk > > > > > > > traffic. The TM-level recovery trace is helpful for > > troubleshooting > > > > > such > > > > > > > issues. > > > > > > > > > > > > > > Best > > > > > > > Jinzhong > > > > > > > > > > > > > > On Wed, Nov 8, 2023 at 5:09 PM Piotr Nowojski < > > > pnowoj...@apache.org> > > > > > > > wrote: > > > > > > > > > > > > > > > Hi Zakelly, > > > > > > > > > > > > > > > > Thanks for the comments. Quick answer for both of your > > questions > > > > > would > > > > > > be > > > > > > > > that it probably should be > > > > > > > > left as a future work. For more detailed answers please take > a > > > look > > > > > > below > > > > > > > > :) > > > > > > > > > > > > > > > > > Does it mean the inclusion and subdivision relationships of > > > spans > > > > > > > defined > > > > > > > > > by "parent_id" are not supported? I think it is a very > > > necessary > > > > > > > feature > > > > > > > > > for the trace. > > > > > > > > > > > > > > > > Yes exactly, that is the current limitation. This could be > > solved > > > > > > somehow > > > > > > > > one way or another in the future. > > > > > > > > > > > > > > > > Support for reporting multi span traces all at once - for > > example > > > > > > > > `CheckpointStatsTracker` running JM, > > > > > > > > could upon checkpoint completion create in one place the > whole > > > > > > structure > > > > > > > of > > > > > > > > parent spans, to have for > > > > > > > > example one span per each subtask. This would be a relatively > > > easy > > > > > > follow > > > > > > > > up. > > > > > > > > > > > > > > > > However, if we would like to create true distributed traces, > > with > > > > > spans > > > > > > > > reported from many different > > > > > > > > components, potentially both on JM and TM, the problem is a > bit > > > > > deeper. > > > > > > > The > > > > > > > > issue in that case is how > > > > > > > > to actually fill out `parrent_id` and `trace_id`? Passing > some > > > > > context > > > > > > > > entity as a java object would be > > > > > > > > unfeasible. That would require too many changes in too many > > > > places. I > > > > > > > think > > > > > > > > the only realistic way > > > > > > > > to do it, would be to have a deterministic generator of > > > `parten_id` > > > > > and > > > > > > > > `trace_id` values. > > > > > > > > > > > > > > > > For example we could create the parent trace/span of the > > > checkpoint > > > > > on > > > > > > > JM, > > > > > > > > and set those ids to > > > > > > > > something like: `jobId#attemptId#checkpointId`. Each subtask > > then > > > > > could > > > > > > > > re-generate those ids > > > > > > > > and subtasks' checkpoint span would have an id of > > > > > > > > `jobId#attemptId#checkpointId#subTaskId`. > > > > > > > > Note that this is just an example, as most likely distributed > > > spans > > > > > for > > > > > > > > checkpointing do not make > > > > > > > > sense, as we can generate them much easier on the JM anyway. > > > > > > > > > > > > > > > > > In addition to checkpoint and recovery, I believe the trace > > > would > > > > > > also > > > > > > > be > > > > > > > > > valuable for performance tuning. If Flink can trace and > > > visualize > > > > > the > > > > > > > > time > > > > > > > > > cost of each operator and stage for a sampled record, users > > > would > > > > > be > > > > > > > able > > > > > > > > > to easily determine the end-to-end latency and identify > > > > performance > > > > > > > > issues > > > > > > > > > for optimization. Looking forward to seeing these in the > > > future. > > > > > > > > > > > > > > > > I'm not sure if I understand the proposal - I don't know how > > > traces > > > > > > could > > > > > > > > be used for this purpose? > > > > > > > > Traces are perfect for one of events (like checkpointing, > > > recovery, > > > > > > etc), > > > > > > > > not for continuous monitoring > > > > > > > > (like processing records). That's what metrics are. Creating > > > trace > > > > > and > > > > > > > > span(s) per each record would > > > > > > > > be prohibitively expensive. > > > > > > > > > > > > > > > > Unless you mean in batch/bounded jobs? Then yes, we could > > create > > > a > > > > > > > bounded > > > > > > > > job trace, with spans > > > > > > > > for every stage/task/subtask. > > > > > > > > > > > > > > > > Best, > > > > > > > > Piotrek > > > > > > > > > > > > > > > > > > > > > > > > śr., 8 lis 2023 o 05:30 Zakelly Lan <zakelly....@gmail.com> > > > > > > napisał(a): > > > > > > > > > > > > > > > > > Hi Piotr, > > > > > > > > > > > > > > > > > > Happy to see the trace! Thanks for this proposal. > > > > > > > > > > > > > > > > > > One minor question: It is mentioned in the interface of > Span: > > > > > > > > > > > > > > > > > > Currently we don't support traces with multiple spans. Each > > > span > > > > is > > > > > > > > > > self-contained and represents things like a checkpoint or > > > > > recovery. > > > > > > > > > > > > > > > > > > > > > > > > > > > Does it mean the inclusion and subdivision relationships of > > > spans > > > > > > > defined > > > > > > > > > by "parent_id" are not supported? I think it is a very > > > necessary > > > > > > > feature > > > > > > > > > for the trace. > > > > > > > > > > > > > > > > > > In addition to checkpoint and recovery, I believe the trace > > > would > > > > > > also > > > > > > > be > > > > > > > > > valuable for performance tuning. If Flink can trace and > > > visualize > > > > > the > > > > > > > > time > > > > > > > > > cost of each operator and stage for a sampled record, users > > > would > > > > > be > > > > > > > able > > > > > > > > > to easily determine the end-to-end latency and identify > > > > performance > > > > > > > > issues > > > > > > > > > for optimization. Looking forward to seeing these in the > > > future. > > > > > > > > > > > > > > > > > > Best, > > > > > > > > > Zakelly > > > > > > > > > > > > > > > > > > > > > > > > > > > On Tue, Nov 7, 2023 at 6:27 PM Piotr Nowojski < > > > > > pnowoj...@apache.org> > > > > > > > > > wrote: > > > > > > > > > > > > > > > > > > > Hi Rui, > > > > > > > > > > > > > > > > > > > > Thanks for the comments! > > > > > > > > > > > > > > > > > > > > > 1. I see the trace just supports Span? Does it support > > > trace > > > > > > > events? > > > > > > > > > > > I'm not sure whether tracing events is reasonable for > > > > > > > TraceReporter. > > > > > > > > > > > If it supports, flink can report checkpoint and > > checkpoint > > > > path > > > > > > > > > > proactively. > > > > > > > > > > > Currently, checkpoint lists or the latest checkpoint > can > > > only > > > > > be > > > > > > > > > fetched > > > > > > > > > > > by external components or platforms. And report is more > > > > timely > > > > > > and > > > > > > > > > > > efficient than fetch. > > > > > > > > > > > > > > > > > > > > No, currently the `TraceReporter` that I'm introducing > > > supports > > > > > > only > > > > > > > > > single > > > > > > > > > > span traces. > > > > > > > > > > So currently neither events on their own, nor events > inside > > > > spans > > > > > > are > > > > > > > > not > > > > > > > > > > supported. > > > > > > > > > > This is done just for the sake of simplicity, and test > out > > > the > > > > > > basic > > > > > > > > > > functionality. But I think, > > > > > > > > > > those currently missing features should be added at some > > > point > > > > in > > > > > > > > > > the future. > > > > > > > > > > > > > > > > > > > > About structured logging (basically events?) I vaguely > > > remember > > > > > > some > > > > > > > > > > discussions about > > > > > > > > > > that. It might be a much larger topic, so I would prefer > to > > > > leave > > > > > > it > > > > > > > > out > > > > > > > > > of > > > > > > > > > > the scope of this > > > > > > > > > > FLIP. > > > > > > > > > > > > > > > > > > > > > 2. This FLIP just monitors the checkpoint and task > > > recovery, > > > > > > right? > > > > > > > > > > > > > > > > > > > > Yes, it only adds single span traces for checkpointing > and > > > > > > > > > > recovery/initialisation - one > > > > > > > > > > span per whole job per either recovery/initialization > > process > > > > or > > > > > > per > > > > > > > > each > > > > > > > > > > checkpoint. > > > > > > > > > > > > > > > > > > > > > Could we add more operations in this FLIP? In our > > > production, > > > > > we > > > > > > > > > > > added a lot of trace reporters for job starts and > > scheduler > > > > > > > > operation. > > > > > > > > > > > They are useful if some jobs start slowly, because they > > > will > > > > > > affect > > > > > > > > > > > the job availability. For example: > > > > > > > > > > > - From JobManager process is started to JobGraph is > > created > > > > > > > > > > > - From JobGraph is created to JobMaster is created > > > > > > > > > > > - From JobMaster is created to job is running > > > > > > > > > > > - From start request tm from yarn or kubernetes to all > > tms > > > > are > > > > > > > ready > > > > > > > > > > > - etc > > > > > > > > > > > > > > > > > > > > I think those could be indeed useful. If you would like > to > > > > > > contribute > > > > > > > > > them > > > > > > > > > > in the future, > > > > > > > > > > I would be happy to review the FLIP for it :) > > > > > > > > > > > > > > > > > > > > > Of course, this FLIP doesn't include them is fine for > me. > > > The > > > > > > first > > > > > > > > > > version > > > > > > > > > > > only initializes the interface and common operations, > and > > > we > > > > > can > > > > > > > add > > > > > > > > > > > more operations in the future > > > > > > > > > > > > > > > > > > > > Yes, that's exactly my thinking :) > > > > > > > > > > > > > > > > > > > > Best, > > > > > > > > > > Piotrek > > > > > > > > > > > > > > > > > > > > wt., 7 lis 2023 o 10:05 Rui Fan <1996fan...@gmail.com> > > > > > napisał(a): > > > > > > > > > > > > > > > > > > > > > Hi Piotr, > > > > > > > > > > > > > > > > > > > > > > Thanks for driving this proposal! The trace reporter is > > > > useful > > > > > to > > > > > > > > > > > check a lot of duration monitors inside of Flink. > > > > > > > > > > > > > > > > > > > > > > I have some questions about this proposal: > > > > > > > > > > > > > > > > > > > > > > 1. I see the trace just supports Span? Does it support > > > trace > > > > > > > events? > > > > > > > > > > > I'm not sure whether tracing events is reasonable for > > > > > > > TraceReporter. > > > > > > > > > > > If it supports, flink can report checkpoint and > > checkpoint > > > > path > > > > > > > > > > > proactively. > > > > > > > > > > > Currently, checkpoint lists or the latest checkpoint > can > > > only > > > > > be > > > > > > > > > fetched > > > > > > > > > > > by external components or platforms. And report is more > > > > timely > > > > > > and > > > > > > > > > > > efficient than fetch. > > > > > > > > > > > > > > > > > > > > > > 2. This FLIP just monitors the checkpoint and task > > > recovery, > > > > > > right? > > > > > > > > > > > Could we add more operations in this FLIP? In our > > > production, > > > > > we > > > > > > > > > > > added a lot of trace reporters for job starts and > > scheduler > > > > > > > > operation. > > > > > > > > > > > They are useful if some jobs start slowly, because they > > > will > > > > > > affect > > > > > > > > > > > the job availability. For example: > > > > > > > > > > > - From JobManager process is started to JobGraph is > > created > > > > > > > > > > > - From JobGraph is created to JobMaster is created > > > > > > > > > > > - From JobMaster is created to job is running > > > > > > > > > > > - From start request tm from yarn or kubernetes to all > > tms > > > > are > > > > > > > ready > > > > > > > > > > > - etc > > > > > > > > > > > > > > > > > > > > > > Of course, this FLIP doesn't include them is fine for > me. > > > The > > > > > > first > > > > > > > > > > version > > > > > > > > > > > only initializes the interface and common operations, > and > > > we > > > > > can > > > > > > > add > > > > > > > > > > > more operations in the future. > > > > > > > > > > > > > > > > > > > > > > Best, > > > > > > > > > > > Rui > > > > > > > > > > > > > > > > > > > > > > On Tue, Nov 7, 2023 at 4:31 PM Piotr Nowojski < > > > > > > > pnowoj...@apache.org> > > > > > > > > > > > wrote: > > > > > > > > > > > > > > > > > > > > > > > Hi all! > > > > > > > > > > > > > > > > > > > > > > > > I would like to start a discussion on FLIP-384: > > Introduce > > > > > > > > > TraceReporter > > > > > > > > > > > and > > > > > > > > > > > > use it to create checkpointing and recovery traces > [1]. > > > > > > > > > > > > > > > > > > > > > > > > This proposal intends to improve observability of > > Flink's > > > > > > > > > Checkpointing > > > > > > > > > > > and > > > > > > > > > > > > Recovery/Initialization operations, by adding support > > for > > > > > > > reporting > > > > > > > > > > > traces > > > > > > > > > > > > from Flink. In the future, reporting traces can be of > > > > course > > > > > > used > > > > > > > > for > > > > > > > > > > > other > > > > > > > > > > > > use cases and also by users. > > > > > > > > > > > > > > > > > > > > > > > > There are also two other follow up FLIPS, FLIP-385 > [2] > > > and > > > > > > > FLIP-386 > > > > > > > > > > [3], > > > > > > > > > > > > which expand the basic functionality introduced in > > > FLIP-384 > > > > > > [1]. > > > > > > > > > > > > > > > > > > > > > > > > Please let me know what you think! > > > > > > > > > > > > > > > > > > > > > > > > Best, > > > > > > > > > > > > Piotr Nowojski > > > > > > > > > > > > > > > > > > > > > > > > [1] > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > https://cwiki.apache.org/confluence/display/FLINK/FLIP-384%3A+Introduce+TraceReporter+and+use+it+to+create+checkpointing+and+recovery+traces > > > > > > > > > > > > [2] > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > https://cwiki.apache.org/confluence/display/FLINK/FLIP-385%3A+Add+OpenTelemetryTraceReporter+and+OpenTelemetryMetricReporter > > > > > > > > > > > > [3] > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > https://cwiki.apache.org/confluence/display/FLINK/FLIP-386%3A+Support+adding+custom+metrics+in+Recovery+Spans > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >
