I see what you mean. I think this is a good feature, and I will summarize this into the design doc.
If you have any good suggestions，please let me know. Sheng Wu <[email protected]> 于2019年12月13日周五 下午10:24写道： > Hi Han Liu > > One more reminder, a trace id in one instance could have multiple threads > sampling in theory, such as across threads scenarios. We also should set a > threshold for this. Max 3 threads for one trace id maybe? > > Sheng Wu 吴晟 > Twitter, wusheng1108 > > > Sheng Wu <[email protected]> 于2019年12月13日周五 下午1:03写道： > > > Hi Han Liu and everyone > > > > I have submitted a design draft to the doc. Please take a look, if you > > have an issue, please let me known. We could set up a online meeting too. > > > > Sheng Wu <[email protected]>于2019年12月12日 周四下午8:49写道： > > > >> Hi Han Liu > >> > >> I have replied the design with the most important key points I expect. > >> Let's discuss those. After we are on the same page, we could continue on > >> more details. > >> > >> Sheng Wu 吴晟 > >> Twitter, wusheng1108 > >> > >> > >> han liu <[email protected]> 于2019年12月12日周四 下午2:26写道： > >> > >>> Due to formatting issues with previous mailboxes, they have been > replaced > >>> with new ones. > >>> > >>> I have completed some of the features in the google doc, and can > provide > >>> your comments and improvements. I will continue to improve the > following > >>> functions in the documentation. > >>> The documentation is the same as you previously sent me. To prevent > >>> trouble, I'll post the link again here. > >>> > >>> > https://docs.google.com/document/d/1rxMf1WN3PaFaZp7r8JmtwfdkmjLTcFW_ETAZv5FIU-s/edit# > >>> > >>> Sheng Wu <[email protected]> 于2019年12月10日周二 上午10:46写道： > >>> > >>> > 741550557 <[email protected]> 于2019年12月9日周一 下午9:42写道： > >>> > > >>> > > Thank for your reply, the issues you mentioned are very critical > and > >>> > > meaningful. > >>> > > There I will answer what you mentioned. Sorry, I'm not good at > >>> comment > >>> > > mode, so I use different colors and “ “ prefix to QA. > >>> > > > >>> > > > >>> > > As we already have designed limit mechanism at backend and agent > >>> > > side(according to your design), also the number would not be > big(10 > >>> most > >>> > > likely), we just need a list to storage the trace-id(s) > >>> > > > >>> > > > >>> > > If just need a list to storage trace-id(s), so how can I map to the > >>> > > thread? I hope to use the map to quickly find thread info from > >>> trace-id. > >>> > > How can I get thread-stack information from your way? Could you > >>> please > >>> > > help elaborate? > >>> > > > >>> > > >>> > Why do you need to do that? You just save a list of thread ids which > >>> should > >>> > do thread dump, or remove some thread id from them when the trace id > is > >>> > finished. > >>> > This is easy to do this by doing a loop search in the list. Right? > >>> > Thread-stack is in the list, they are stored in an element. Also, > they > >>> are > >>> > in a list too. > >>> > > >>> > I think you were thinking the same all stack in a single map? That > will > >>> > cause a very dangerous memory and GC risk. > >>> > > >>> > > >>> > > >>> > > > >>> > > > >>> > > Could you explain the (2), what do you mean `stop`? I think if > your > >>> > > sampling mechanism should include the sampling duration. > >>> > > > >>> > > > >>> > > As far as the communication between the sniffer and the OAP > server, I > >>> > hope > >>> > > the sniffer only needs to obtain the thread-monitor task that needs > >>> to be > >>> > > monitored at this time. The termination condition can be stopped by > >>> the > >>> > > sniffer or the OAP server. > >>> > > If It’s just an OAP server notification, it may be more > complicated. > >>> > Cause > >>> > > OAP server need record sniffer has received the current command, > and > >>> > > sniffer is not stable, such as sniffer has shutdown when receiving > >>> the > >>> > > command, at this time, no thread information I have been collected. > >>> > > > >>> > > > >>> > > I think that the active calculation termination by the OAP server > can > >>> > make > >>> > > the monitoring more controllable, of course, the client can also > >>> actively > >>> > > report the end. > >>> > > I think it’s necessary to provide a protection mechanism for the > >>> sniffer > >>> > > side, and it can be released quickly when the business peak period > >>> or the > >>> > > probe suddenly occupies a lot of CPU / memory resources. Therefore, > >>> the > >>> > > function of stopping monitoring can be provided in the UI > interface, > >>> so > >>> > > that the sniffer can recover. > >>> > > Sampling duration is required, but only as a default termination > >>> > > thread-monitor condition. > >>> > > > >>> > > >>> > But you should know, in the real case, the thread dump monitor is a > >>> > sampling mechanism, you are even hard to know where they are > happening. > >>> > Then you have to send the stop notification to every instance. > >>> > Even you could send the notification, but could you explain how you > >>> know to > >>> > stop? > >>> > The scenario is, you are facing an issue, which trace and metrics > can't > >>> > explain, so you active thread dump, right? At the same time, you want > >>> to > >>> > stop? > >>> > > >>> > CPU and memory resources should be guaranteed by design level, such > as > >>> > 1. Limited thread dump task for one service. > >>> > 2. Limited thread dump traces in the certain time window. > >>> > For example, the OAP backend/UI would say, you only could > >>> > 1. Set 3 thread dump commands in the same time window. > >>> > 2. Every command will require the sampling thread dump number should > be > >>> > less than 5 traces. At the same time, in order to make this sampling > >>> works, > >>> > only active sampling thread dump after the trace executed more than > >>> > 200ms(value is an example only). > >>> > 3. Thread dump could be sent to the backend duration sampling to > >>> reduce the > >>> > memory cache. > >>> > 4. Thread dump period should not less than 5ms, recommend 20ms > >>> > 5. How depth the thread dump should do > >>> > > >>> > We need a very detailed design, above are just my thoughts, in order > to > >>> > share the idea, the safe of the agent should not be by UI button. > >>> > Otherwise, your online system will be very dangerous, which is not > the > >>> > design goal of SkyWalking. > >>> > > >>> > > >>> > > >>> > > > >>> > > > >>> > > The sampling period depends on how you are going to visualize it. > >>> > > > >>> > > > >>> > > Yes, I agree. I hope can provide a select/input let trace count and > >>> time > >>> > > windows can be configurable in UI. Of course, this is my current > >>> idea, > >>> > and > >>> > > if there have other plains, I will adopt it. > >>> > > > >>> > > > >>> > > Highly doubt about this, reduce the memory, maybe, only reduce if > >>> the > >>> > > codes > >>> > > are running the loop or facing lock issue. But if it is neither of > >>> these > >>> > > two, they are different. > >>> > > Also, please consider the CPU cost of the comparison of the stack. > >>> You > >>> > > need > >>> > > a performance benchmark to verify if you want this. > >>> > > > >>> > > > >>> > > I didn’t understand that first sentence. In my personal experience, > >>> most > >>> > > of the cases are blocking in the lock(socket/local) and running > >>> loop. I > >>> > > have not imagined any other cases? > >>> > > For the second sentence, I think I can add a thread-stack-element > >>> field > >>> > to > >>> > > storage the top-level element of last stack information. When get > >>> stack > >>> > > information next time, I can compare the current top-level element > >>> that > >>> > is > >>> > > the same with that field. > >>> > > I do this mainly to reduce duplicate thread-stack information form > >>> taking > >>> > > up too much memory space, this is a way to optimizing memory space. > >>> It > >>> > can > >>> > > consider remove it, or do you have a better memory-saving solution? > >>> After > >>> > > all, memory and CPU resources are very valuable in the sniffer. > >>> > > > >>> > > >>> > I know you mean about reducing the memory, but do you consider how > >>> much CPU > >>> > you will cost do a full thread dump comparison? The thread dump could > >>> > easily be hundreds of lines in Java. > >>> > I mean this is a tradeoff, CPU or memory. If you are just using > limited > >>> > memory, before you could send the snapshot to backend while > collecting > >>> new, > >>> > even could save into the disk(if really necessary). > >>> > In my experience, compress is always very high risk in the agent, if > >>> you > >>> > want to do that, you need a benchmark test to improve that, this CPU > >>> cost > >>> > is small enough. > >>> > > >>> > > >>> > > >>> > > > >>> > > > >>> > > The trace number and time window should be configurable, that is I > >>> mean > >>> > > more complex. Inthe current SamplingServcie, only n traces per 3 > >>> > seconds. > >>> > > But here, it is a dynamic rule. > >>> > > > >>> > > > >>> > > I expect that it can be configured at the UI level for special > trace > >>> > count > >>> > > and time windows as I said above. > >>> > > For SamplingService, my previous tech design was not rigorous > >>> enough, and > >>> > > there were indeed problems. > >>> > > Maybe we need to extend a new SamplingService, build a mapping base > >>> on > >>> > > endpoint-id and AtomicInteger. > >>> > > For `first 5 traces of this endpoint in the next 5 mins`, just need > >>> to > >>> > > increment it. > >>> > > For sampling, maybe use another schedule task to reset > AtomicInteger > >>> > value. > >>> > > > >>> > > >>> > You could avoid map, by using ArrayList with > >>> RangeAtomicInteger(SkyWalking > >>> > provides that) to let the trace context to get the slot. > >>> > Also, you are considering `active sampling after trace execution time > >>> more > >>> > than xxx ms`, you should add remove mechanism during runtime. > >>> > Anyway, try your best to avoid using Map, especially this map could > be > >>> > changed in the runtime. > >>> > > >>> > > >>> > > >>> > > > >>> > > > >>> > > I think at least should be a level one new page called > >>> configuration or > >>> > > command page, which could set up the multiple sampling rule and > >>> > visualize > >>> > > the existing tasks and related sampling data. > >>> > > > >>> > > > >>> > > I think it’s necessary to add a new page to the configuration > >>> > > thread-monitor task, I think the specific UI display should be > >>> designed > >>> > in > >>> > > detail. > >>> > > For example, what I expected is similar to the trace page. The left > >>> side > >>> > > displays the configuration, and the right side quickly displays the > >>> > related > >>> > > trace list. When clicked, it quickly links to the trace page and > >>> displays > >>> > > the sidebox display. > >>> > > I ’m not good at this. Do you have any good plans? > >>> > > > >>> > > >>> > UI is the thing that is hard to discuss by text, so I am pretty sure, > >>> we > >>> > need some demo(could not be the codes, that is I mean drew by a tool) > >>> > It is OK to show a trace with thread dumps on another page, even > better > >>> > linking to your task ID. > >>> > But this kind of abstract description is hard to continue, no > details I > >>> > mean. > >>> > > >>> > > >>> > > >>> > > And I feel that the two of us have a different understanding of the > >>> > > configuration object. I think it is more of a task than a command. > I > >>> > don't > >>> > > know which way is better? > >>> > > I suddenly thought of a problem. I think that some real problems > are > >>> > often > >>> > > triggered at a specific period, such as a fixed business peak > >>> period, and > >>> > > we cannot guarantee that the user will operate on the UI. > >>> > > So should the task mechanism be adopted to ensure that it can be > run > >>> at a > >>> > > specific period? > >>> > > > >>> > > >>> > This makes sense to me, and it is a just enhance feature. It is just > a > >>> > start time sampling rule. > >>> > > >>> > > >>> > > >>> > > > >>> > > > >>> > > We don't have separated thread monitor view table, how about we > add > >>> an > >>> > > icon > >>> > > at the segment list, and add icon at the first span of this > segment > >>> in > >>> > > trace detail view? > >>> > > I think the latter one should be an entrance of the thread view. > >>> > > > >>> > > > >>> > > I think it's a good idea. The link I mentioned in one of the > answers > >>> > > above, I think it is also a convenient entry point. > >>> > > The switch button I mentioned earlier is only a data filtering item > >>> in > >>> > the > >>> > > query of the trace list and does not need a separate table UI. > >>> > > > >>> > > >>> > As you intend to have a separated page for thread sampling, it is OK > to > >>> > > >>> > > >>> > > > >>> > > > >>> > > If you have some visualization idea, drawn by any tool you like > >>> > supporting > >>> > > comment, we could discuss it there. In my mind, we should support > >>> > > visualize > >>> > > the thread dump stack through the time windows, and support > >>> aggregate > >>> > them > >>> > > by choosing the continued stack snapshots on the time window. > >>> > > > >>> > > > >>> > > I think we should find a front-end who is better at discussing > >>> together > >>> > > because this depends on how the front-end UI can be displayed. > >>> > > BTW: I can provide code for the OAP server and sniffer, and the > >>> frontend > >>> > > may need to look for help in the community alone. Hope that any > >>> front-end > >>> > > friends can participate in the topic discussion. > >>> > > > >>> > > >>> > Once you have the demo, I could loop our UI committers in for UI side > >>> > development. But UI committers may not be familiar with thread dump > >>> context > >>> > story. We need to resolve that first. > >>> > Let's start up a demo, such as some slides on Google doc? > >>> > > >>> > > >>> > > > >>> > > > >>> > > > >>> > > > >>> > > The above is my answer to all the questions, and I look forward to > >>> your > >>> > > reply at any time. As more and more discussions took place, the > >>> details > >>> > > became more and more complete. This is good. > >>> > > Everyone is welcome to discuss together if you have any questions > or > >>> good > >>> > > ideas, please let me know. > >>> > > > >>> > > >>> > I think we could move the discussion to the design doc as the next > >>> step. > >>> > > >>> > Please use this > >>> > > >>> > > >>> > https://docs.google.com/document/d/1rxMf1WN3PaFaZp7r8JmtwfdkmjLTcFW_ETAZv5FIU-s/edit# > >>> > Trite the design including > >>> > 1. Key features > >>> > 2. Protocol > >>> > 3. Work mechanism > >>> > 4. UI design, prototype > >>> > and anything you think important before writing codes. > >>> > > >>> > This is SkyWalking CLI design doc, you could use it as a reference. > >>> > > >>> > > >>> > https://docs.google.com/document/d/1WBnRNF0ABxaSdBZo6Gv2hMzCQzj04YAePUdOyLWHWew/edit# > >>> > > >>> > > >>> > > > >>> > > > >>> > > 原始邮件 > >>> > > 发件人:Sheng [email protected] > >>> > > 收件人:[email protected] > >>> > > 发送时间:2019年12月9日(周一) 10:50 > >>> > > 主题:Re: A proposal for Skywalking(thread monitor) > >>> > > > >>> > > > >>> > > Hi Thanks for writing this proposal with a detailed design. My > >>> comments > >>> > > are inline. 741550557 [email protected] 于2019年12月8日周日 下午11:22写道： > >>> Thanks > >>> > > for your reply, I have carefully read these issues you mentioned, > >>> and > >>> > > these issues mentioned are very meaningful and critical. I will > >>> give you > >>> > > technical details about the issues you mentioned below. I find > these > >>> > > issues are related, so I will explain them in different > dimensions. > >>> > use > >>> > > a different protocol to transmission trace and thread-stack: 1. > add > >>> a > >>> > > boolean field in segment data, to record has thread monitored. and > >>> is > >>> > good > >>> > > for filter monitored trace in UI. 2. add new BootService, storage > >>> Map to > >>> > > record relate trace-id and trace-stack information. As we already > >>> have > >>> > > designed limit mechanism at backend and agent side(according to > your > >>> > > design), also the number would not be big(10 most likely), we just > >>> need a > >>> > > list to storage the trace-id(s) 3. listen > >>> > > TracingContextListener#afterFinished if the current segment has > >>> thread > >>> > > monitored, mark current trace-id don’t need to monitor anymore. > >>> (Cause > >>> > if > >>> > > for-each the step 2 map, the remove operation will fail and throw > >>> > > exception). 4. when thread-monitor main thread running, It will > >>> for-each > >>> > > step 2 map and check is it don’t need monitor anymore, I will put > >>> data > >>> > > into new data carrier. 5. generate new thread-monitor gRPC > >>> protocol to > >>> > > send data from the data carrier. The agent side design seems > pretty > >>> > good. > >>> > > the server receives thread-stack logic: 1. storage stack-stack > >>> > > informations and trace-id/segment-id relations on a different > >>> table. 2. > >>> > > check thread-monitor is need to be stop on receiving data or > >>> schedule. > >>> > > Could you explain the (2), what do you mean `stop`? I think if your > >>> > > sampling mechanism should include the sampling duration. reduce > >>> CPU > >>> > and > >>> > > memory in sniffer: 1. through the configuration of thread > >>> monitoring in > >>> > > the UI, you can configure the performance loss. For example, set > the > >>> > > monitoring level: fast monitoring (100ms), medium speed monitoring > >>> > > (500ms), slow speed monitoring (1000ms). The sampling period > >>> depends on > >>> > > how you are going to visualize it. 2. add new integer field on per > >>> > > thread-stack, if current thread-stack last element same as last > >>> time, > >>> > > don’t need storage, just increment it. I think it will save a lot > of > >>> > > memory space. Highly doubt about this, reduce the memory, maybe, > only > >>> > > reduce if the codes are running the loop or facing lock issue. But > >>> if it > >>> > is > >>> > > neither of these two, they are different. Also, please consider the > >>> CPU > >>> > > cost of the comparison of the stack. You need a performance > >>> benchmark to > >>> > > verify if you want this. 3. create new VM args to setting > >>> thread-monitor > >>> > > pool size, It dependence on user, maybe default 3? (this can be > >>> > discussed > >>> > > later) I think UI limit is enough. 3 seems good to me. 4. limit > >>> > > thread-stack-element size to 100, I think it can resolve most of > the > >>> > > scenes already. It also can create a new VM args if need. > multiple > >>> > > sampling methods can choose :(just my current thoughts, can add > >>> more) > >>> > 1. > >>> > > base on current client SamplingServcie, extra a new factor holder > to > >>> > > increment, and reset on schedule. Yours may be a little more > complex > >>> > than > >>> > > the current SamplingServcie, right? Based on the next rule. 2. > >>> `first 5 > >>> > > traces of this endpoint in the next 5 mins`, it a good idea. My > >>> > > understanding is that within a few minutes, each instance can send > a > >>> > > specified number of traces. The trace number and time window > should > >>> be > >>> > > configurable, that is I mean more complex. Inthe current > >>> SamplingServcie, > >>> > > only n traces per 3 seconds. But here, it is a dynamic rule. UI > >>> > settings > >>> > > and sniffer perception: 1. create a new button on the dashboard > >>> page, It > >>> > > can create or stop a thread-monitor. It can be dynamic load > >>> > thread-monitor > >>> > > status when reselecting endpoint. I think at least should be a > >>> level > >>> > one > >>> > > new page called configuration or command page, which could set up > the > >>> > > multiple sampling rule and visualize the existing tasks and related > >>> > > sampling data. 2. sniffer creates a new scheduled task to check > the > >>> > > current service has need monitor endpoint each 5 seconds. (I see > >>> current > >>> > > sniffer has command functions, feel that principle is the same as > >>> the > >>> > > scheduler) Seems reasonable. thread-monitor on the UI:(That’s > >>> just my > >>> > > initial thoughts, I think there will have a better way to show) > 1. > >>> When > >>> > > switch to the trace page, I think we need to add a new switch > >>> button to > >>> > > filter thread-monitor trace. 2. make a new thread-monitor icon on > >>> the > >>> > same > >>> > > segment. It means it has thread-stack information. We don't have > >>> > > separated thread monitor view table, how about we add an icon at > the > >>> > > segment list, and add icon at the first span of this segment in > trace > >>> > > detail view? I think the latter one should be an entrance of the > >>> thread > >>> > > view. 3. show on the information sidebox when the user clicks the > >>> > > thread-monitor segment(any span). create a new tab, like the log > >>> tab. > >>> > If > >>> > > you have some visualization idea, drawn by any tool you like > >>> supporting > >>> > > comment, we could discuss it there. In my mind, we should support > >>> > visualize > >>> > > the thread dump stack through the time windows, and support > aggregate > >>> > them > >>> > > by choosing the continued stack snapshots on the time window. > >>> They're > >>> > > just a description of my current implementation details for > >>> > thread-monitor > >>> > > if these seem to work. I can do some time planning for these > tasks. > >>> > Sorry, > >>> > > my English is not very well, hope you can understand. Maybe these > >>> seem > >>> > to > >>> > > have some problem, any good idea or suggestion are welcome. Very > >>> > > appreciated you to lead this new direction. It is a long term task > >>> but > >>> > > should be interesting. :) Good work, carry on. 原始邮件 发件人:Sheng > >>> > > [email protected] 收件人:[email protected] > >>> > > 发送时间:2019年12月8日(周日) 08:31 主题:Re: A proposal for Skywalking(thread > >>> > > monitor) First of all, thanks for your proposal. Thread > >>> monitoring is > >>> > > super important for application performance. So basically, I agree > >>> with > >>> > > this proposal. But for tech details, I think we need more > >>> discussion in > >>> > > the following ways 1. Do you want to add thread status to the > >>> trace? If > >>> > > so, why don't consider this as a UI level join? Because we could > >>> know > >>> > > thread id in the trace when we create a span, right? Then we have > >>> all > >>> > the > >>> > > thread dump(if), we could ask UI to query specific thread context > >>> based > >>> > > on timestamp and thread number(s). 2. For thread dump, I don't > know > >>> > > whether you do the performance evaluation for this OP. From my > >>> > > experiences, `get all need thread monitor segment every 100 > >>> > milliseconds` > >>> > > is a very high cost in your application and agent. So, you may > need > >>> to > >>> > be > >>> > > careful about doing this. 3. Endpoint related thread dump with > some > >>> > > sampling mechanisms makes more sense to me. And this should be > >>> activated > >>> > > by UI. We should only provide a conditional thread dump sampling > >>> > > mechanism, such as `first 5 traces of this endpoint in the next 5 > >>> mins`. > >>> > > Jian Tan I think DaoCloud also has customized this feature in your > >>> > > internal SkyWalking. Could you share what you do? Sheng Wu 吴晟 > >>> Twitter, > >>> > > wusheng1108 741550557 [email protected] 于2019年12月8日周日 上午12:14写道： > >>> Hello > >>> > > everyone, I would like to share a new feature with skywalking, > >>> called > >>> > > “thread monitor”. Background When our company used skywalking to > APM > >>> > > earlier, we found that many traces did not have enough span to > fill > >>> up, > >>> > > doubting whether there were some third-party frameworks that we > >>> didn't > >>> > > enhance or programmers API usage errors such as java CountDown > >>> number > >>> > is 3 > >>> > > but there are only 2 countdowns. So we decide to write a new > >>> feature to > >>> > > monitor executing trace thread stack, then we can get more > >>> information > >>> > on > >>> > > the trace, quick known what’s happening on that trace. Structure > >>> > > Agent(thread monitor) — gRPC protocol — OAP Server(Storage) — > >>> > > Skywalking-Rocketbot-UI More detail OAP Server: 1. Storage witch > >>> traces > >>> > > need to monitor(i suggest storage on the endpoint, add new boolean > >>> field > >>> > > named needThreadMonitor) 2. Provide GraphQL API to change endpoint > >>> > monitor > >>> > > status. 3. Monitor Trace parse, storage thread stack if the > segment > >>> has > >>> > > any thread info. Skywalking-Rocketbot-UI: 1. Add a new switch > >>> button on > >>> > > the dashboard, It can read or modify endpoint status. 2. It will > >>> show > >>> > > every thread stack on click trace detail. Agent: 1. setup two new > >>> > > BootService: 1) find any need thread monitor endpoint in current > >>> > service, > >>> > > start on a new schedule take and works on each minute. 2) start > new > >>> > > schedule task to get all need thread monitor segment each 100 > >>> > > milliseconds, and put a new thread dump task to a global thread > >>> > > pool(fixed, count number default 3). 2. check endpoint need thread > >>> > monitor > >>> > > on create entry/local span(TracingConext#createEntry/LocalSpan). > If > >>> > need, > >>> > > It will be marked and put into thread monitor map. 3. when > >>> > TraceingContext > >>> > > finishes, It will get thread has monitored, and send all thread > >>> stack to > >>> > > server. Finally, I don’t know it is a good idea to get more > >>> information > >>> > on > >>> > > trace? If you have any good ideas or suggestions on this, please > >>> let me > >>> > > know. Mrpro > >>> > > >>> > >> -- > > Sheng Wu 吴晟 > > > > Apache SkyWalking > > Apache Incubator > > Apache ShardingSphere, ECharts, DolphinScheduler podlings > > Zipkin > > Twitter, wusheng1108 > > >
