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 > > >
