Hi Weihua, thanks for feedback. 1. Yes, only *Manually* is supported in this FLIP, but it's the first step towards auto-detection. 2. We wii print the blocked nodes in logs. Maybe also put it into the exception of insufficient resources. 3. No. This FLIP won't change the WebUI. The blocklist information can be obtained through REST API and metrics.
Best, Lijie Weihua Hu <huweihua....@gmail.com> 于2022年5月17日周二 21:41写道： > Hi, > Thanks for creating this FLIP. > We have implemented an automatic blocklist detection mechanism internally, > which is indeed very effective for handling node failures. > Due to the large number of nodes, although SREs already support automatic > offline failure nodes, the detection is not 100% accurate and there is some > delay. > So the blocklist mechanism can make flink job recover from failure much > faster. > > Here are some of my thoughts: > 1. In this FLIP, it needs users to locate machine failure manually, there > is a certain cost of use > 2. What happens if too many nodes are blocked, resulting in insufficient > resources? Will there be a special Exception for the user? > 3. Will we display the blocklist information in the WebUI? The blocklist > is for cluster level, and if multiple users share a cluster, some users may > be a little confused when resources are not enough, or when resources are > applied for more. > > Also, Looking forward to the next FLIP on auto-detection. > > Best, > Weihua > > > 2022年5月16日 下午11:22，Lijie Wang <wangdachui9...@gmail.com> 写道： > > > > Hi Konstantin, > > > > Maybe change it to the following: > > > > 1. POST: http://{jm_rest_address:port}/blocklist/taskmanagers/{id} > > Merge is not allowed. If the {id} already exists, return error. > Otherwise, > > create a new item. > > > > 2. POST: http://{jm_rest_address:port}/blocklist/taskmanagers/{id}:merge > > Merge is allowed. If the {id} already exists, merge. Otherwise, create a > > new item. > > > > WDYT? > > > > Best, > > Lijie > > > > Konstantin Knauf <kna...@apache.org> 于2022年5月16日周一 20:07写道： > > > >> Hi Lijie, > >> > >> hm, maybe the following is more appropriate in that case > >> > >> POST: http://{jm_rest_address:port}/blocklist/taskmanagers/{id}:merge > >> > >> Best, > >> > >> Konstantin > >> > >> Am Mo., 16. Mai 2022 um 07:05 Uhr schrieb Lijie Wang < > >> wangdachui9...@gmail.com>: > >> > >>> Hi Konstantin, > >>> thanks for your feedback. > >>> > >>> From what I understand, PUT should be idempotent. However, we have a > >>> *timeout* field in the request. This means that initiating the same > >> request > >>> at two different times will lead to different resource status > (timestamps > >>> of the items to be removed will be different). > >>> > >>> Should we use PUT in this case? WDYT? > >>> > >>> Best, > >>> Lijie > >>> > >>> Konstantin Knauf <kna...@apache.org> 于2022年5月13日周五 17:20写道： > >>> > >>>> Hi Lijie, > >>>> > >>>> wouldn't the REST API-idiomatic way for an update/replace be a PUT on > >> the > >>>> resource? > >>>> > >>>> PUT: http://{jm_rest_address:port}/blocklist/taskmanagers/{id} > >>>> > >>>> Best, > >>>> > >>>> Konstantin > >>>> > >>>> > >>>> > >>>> Am Fr., 13. Mai 2022 um 11:01 Uhr schrieb Lijie Wang < > >>>> wangdachui9...@gmail.com>: > >>>> > >>>>> Hi everyone, > >>>>> > >>>>> I've had an offline discussion with Becket Qin and Zhu Zhu, and made > >>> the > >>>>> following changes on REST API: > >>>>> 1. To avoid ambiguity, *timeout* and *endTimestamp* can only choose > >>> one. > >>>> If > >>>>> both are specified, will return error. > >>>>> 2. If the specified item is already there, the *ADD* operation has > >> two > >>>>> behaviors: *return error*(default value) or *merge/update*, and we > >>> add a > >>>>> flag to the request body to control it. You can find more details > >>> "Public > >>>>> Interface" section. > >>>>> > >>>>> If there is no more feedback, we will start the vote thread next > >> week. > >>>>> > >>>>> Best, > >>>>> Lijie > >>>>> > >>>>> Lijie Wang <wangdachui9...@gmail.com> 于2022年5月10日周二 17:14写道： > >>>>> > >>>>>> Hi Becket Qin, > >>>>>> > >>>>>> Thanks for your suggestions. I have moved the description of > >>>>>> configurations, metrics and REST API into "Public Interface" > >> section, > >>>> and > >>>>>> made a few updates according to your suggestion. And in this FLIP, > >>>> there > >>>>>> no public java Interfaces or pluggables that users need to > >> implement > >>> by > >>>>>> themselves. > >>>>>> > >>>>>> Answers for you questions: > >>>>>> 1. Yes, there 2 block actions: MARK_BLOCKED and. > >>>>>> MARK_BLOCKED_AND_EVACUATE_TASKS (has renamed). Currently, block > >> items > >>>> can > >>>>>> only be added through the REST API, so these 2 action are mentioned > >>> in > >>>>> the > >>>>>> REST API part (The REST API part has beed moved to public interface > >>>> now). > >>>>>> 2. I agree with you. I have changed the "Cause" field to String, > >> and > >>>>> allow > >>>>>> users to specify it via REST API. > >>>>>> 3. Yes, it is useful to allow different timeouts. As mentioned > >> above, > >>>> we > >>>>>> will introduce 2 fields : *timeout* and *endTimestamp* into the ADD > >>>> REST > >>>>>> API to specify when to remove the blocked item. These 2 fields are > >>>>>> optional, if neither is specified, it means that the blocked item > >> is > >>>>>> permanent and will not be removed. If both are specified, the > >> minimum > >>>> of > >>>>>> *currentTimestamp+tiemout *and* endTimestamp* will be used as the > >>> time > >>>> to > >>>>>> remove the blocked item. To keep the configurations more minimal, > >> we > >>>> have > >>>>>> removed the *cluster.resource-blocklist.item.timeout* configuration > >>>>>> option. > >>>>>> 4. Yes, the block item will be overridden if the specified item > >>> already > >>>>>> exists. The ADD operation is *ADD or UPDATE*. > >>>>>> 5. Yes. On JM/RM side, all the blocklist information is maintained > >> in > >>>>>> JMBlocklistHandler/RMBlocklistHandler. The blocklist handler(or > >>>>> abstracted > >>>>>> to other interfaces) will be propagated to different components. > >>>>>> > >>>>>> Best, > >>>>>> Lijie > >>>>>> > >>>>>> Becket Qin <becket....@gmail.com> 于2022年5月10日周二 11:26写道： > >>>>>> > >>>>>>> Hi Lijie, > >>>>>>> > >>>>>>> Thanks for updating the FLIP. It looks like the public interface > >>>> section > >>>>>>> did not fully reflect all the user sensible behavior and API. Can > >>> you > >>>>> put > >>>>>>> everything that users may be aware of there? That would include > >> the > >>>> REST > >>>>>>> API, metrics, configurations, public java Interfaces or pluggables > >>>> that > >>>>>>> users may see or implement by themselves, as well as a brief > >> summary > >>>> of > >>>>>>> the > >>>>>>> behavior of the public API. > >>>>>>> > >>>>>>> Besides that, I have a few questions: > >>>>>>> > >>>>>>> 1. According to the conversation in the discussion thread, it > >> looks > >>>> like > >>>>>>> the BlockAction will have "MARK_BLOCKLISTED" and > >>>>>>> "MARK_BLOCKLISTED_AND_EVACUATE_TASKS". Is that the case? If so, > >> can > >>>> you > >>>>>>> add > >>>>>>> that to the public interface as well? > >>>>>>> > >>>>>>> 2. At this point, the "Cause" field in the BlockingItem is a > >>> Throwable > >>>>> and > >>>>>>> is not reflected in the REST API. Should that be included in the > >>> query > >>>>>>> response? And should we change that field to be a String so users > >>> may > >>>>>>> specify the cause via the REST API when they block some nodes / > >> TMs? > >>>>>>> > >>>>>>> 3. Would it be useful to allow users to have different timeouts > >> for > >>>>>>> different blocked items? So while there is a default timeout, > >> users > >>>> can > >>>>>>> also override it via the REST API when they block an entity. > >>>>>>> > >>>>>>> 4. Regarding the ADD operation, if the specified item is already > >>>> there, > >>>>>>> will the block item be overridden? For example, if the user wants > >> to > >>>>>>> extend > >>>>>>> the timeout of a blocked item, can they just issue an ADD command > >>>>> again? > >>>>>>> > >>>>>>> 5. I am not quite familiar with the details of this, but is there > >> a > >>>>> source > >>>>>>> of truth for the blocked list? I think it might be good to have a > >>>> single > >>>>>>> source of truth for the blocked list and just propagate that list > >> to > >>>>>>> different components to take the action of actually blocking the > >>>>> resource. > >>>>>>> > >>>>>>> Thanks, > >>>>>>> > >>>>>>> Jiangjie (Becket) Qin > >>>>>>> > >>>>>>> On Mon, May 9, 2022 at 5:54 PM Lijie Wang < > >> wangdachui9...@gmail.com > >>>> > >>>>>>> wrote: > >>>>>>> > >>>>>>>> Hi everyone, > >>>>>>>> > >>>>>>>> Based on the discussion in the mailing list, I updated the FLIP > >>> doc, > >>>>> the > >>>>>>>> changes include: > >>>>>>>> 1. Changed the description of the motivation section to more > >>> clearly > >>>>>>>> describe the problem this FLIP is trying to solve. > >>>>>>>> 2. Only *Manually* is supported. > >>>>>>>> 3. Adopted some suggestions, such as *endTimestamp*. > >>>>>>>> > >>>>>>>> Best, > >>>>>>>> Lijie > >>>>>>>> > >>>>>>>> > >>>>>>>> Roman Boyko <ro.v.bo...@gmail.com> 于2022年5月7日周六 19:25写道： > >>>>>>>> > >>>>>>>>> Hi Lijie! > >>>>>>>>> > >>>>>>>>> > >>>>>>>>> > >>>>>>>>> > >>>>>>>>> *a) “Probably storing inside Zookeeper/Configmap might be > >>>>>>> helpfulhere.” > >>>>>>>>> Can you explain it in detail? I don't fully understand that. > >> In > >>>>>>>> myopinion, > >>>>>>>>> non-active and active are the same, and no special treatment > >>>>>>> isrequired.* > >>>>>>>>> > >>>>>>>>> Sorry this was a misunderstanding from my side. I thought we > >>> were > >>>>>>> talking > >>>>>>>>> about the HA mode (but not about Active and Standalone > >>>>>>> ResourceManager). > >>>>>>>>> And the original question was - how to handle the blacklisted > >>>> nodes > >>>>>>> list > >>>>>>>> at > >>>>>>>>> the moment of leader change? Should we simply forget about > >> them > >>> or > >>>>>>> try to > >>>>>>>>> pre-save that list on the remote storage? > >>>>>>>>> > >>>>>>>>> On Sat, 7 May 2022 at 10:51, Yang Wang <danrtsey...@gmail.com > >>> > >>>>> wrote: > >>>>>>>>> > >>>>>>>>>> Thanks Lijie and ZhuZhu for the explanation. > >>>>>>>>>> > >>>>>>>>>> I just overlooked the "MARK_BLOCKLISTED". For tasks level, > >> it > >>> is > >>>>>>> indeed > >>>>>>>>>> some functionalities the external tools(e.g. kubectl taint) > >>>> could > >>>>>>> not > >>>>>>>>>> support. > >>>>>>>>>> > >>>>>>>>>> > >>>>>>>>>> Best, > >>>>>>>>>> Yang > >>>>>>>>>> > >>>>>>>>>> Lijie Wang <wangdachui9...@gmail.com> 于2022年5月6日周五 22:18写道： > >>>>>>>>>> > >>>>>>>>>>> Thanks for your feedback, Jiangang and Martijn. > >>>>>>>>>>> > >>>>>>>>>>> @Jiangang > >>>>>>>>>>> > >>>>>>>>>>> > >>>>>>>>>>>> For auto-detecting, I wonder how to make the strategy > >> and > >>>>> mark a > >>>>>>>> node > >>>>>>>>>>> blocked? > >>>>>>>>>>> > >>>>>>>>>>> In fact, we currently plan to not support auto-detection > >> in > >>>> this > >>>>>>>> FLIP. > >>>>>>>>>> The > >>>>>>>>>>> part about auto-detection may be continued in a separate > >>> FLIP > >>>> in > >>>>>>> the > >>>>>>>>>>> future. Some guys have the same concerns as you, and the > >>>>>>> correctness > >>>>>>>>> and > >>>>>>>>>>> necessity of auto-detection may require further discussion > >>> in > >>>>> the > >>>>>>>>> future. > >>>>>>>>>>> > >>>>>>>>>>>> In session mode, multi jobs can fail on the same bad > >> node > >>>> and > >>>>>>> the > >>>>>>>>> node > >>>>>>>>>>> should be marked blocked. > >>>>>>>>>>> By design, the blocklist information will be shared among > >>> all > >>>>> jobs > >>>>>>>> in a > >>>>>>>>>>> cluster/session. The JM will sync blocklist information > >> with > >>>> RM. > >>>>>>>>>>> > >>>>>>>>>>> @Martijn > >>>>>>>>>>> > >>>>>>>>>>>> I agree with Yang Wang on this. > >>>>>>>>>>> As Zhu Zhu and I mentioned above, we think the > >>>>>>> MARK_BLOCKLISTED(Just > >>>>>>>>>> limits > >>>>>>>>>>> the load of the node and does not kill all the processes > >> on > >>>> it) > >>>>>>> is > >>>>>>>>> also > >>>>>>>>>>> important, and we think that external systems (*yarn > >> rmadmin > >>>> or > >>>>>>>> kubectl > >>>>>>>>>>> taint*) cannot support it. So we think it makes sense even > >>>> only > >>>>>>>>>> *manually*. > >>>>>>>>>>> > >>>>>>>>>>>> I also agree with Chesnay that magical mechanisms are > >>> indeed > >>>>>>> super > >>>>>>>>> hard > >>>>>>>>>>> to get right. > >>>>>>>>>>> Yes, as you see, Jiangang(and a few others) have the same > >>>>> concern. > >>>>>>>>>>> However, we currently plan to not support auto-detection > >> in > >>>> this > >>>>>>>> FLIP, > >>>>>>>>>> and > >>>>>>>>>>> only *manually*. In addition, I'd like to say that the > >> FLIP > >>>>>>> provides > >>>>>>>> a > >>>>>>>>>>> mechanism to support MARK_BLOCKLISTED and > >>>>>>>>>>> MARK_BLOCKLISTED_AND_EVACUATE_TASKS, > >>>>>>>>>>> the auto-detection may be done by external systems. > >>>>>>>>>>> > >>>>>>>>>>> Best, > >>>>>>>>>>> Lijie > >>>>>>>>>>> > >>>>>>>>>>> Martijn Visser <mart...@ververica.com> 于2022年5月6日周五 > >>> 19:04写道： > >>>>>>>>>>> > >>>>>>>>>>>>> If we only support to block nodes manually, then I > >> could > >>>> not > >>>>>>> see > >>>>>>>>>>>> the obvious advantages compared with current SRE's > >>>>> approach(via > >>>>>>>> *yarn > >>>>>>>>>>>> rmadmin or kubectl taint*). > >>>>>>>>>>>> > >>>>>>>>>>>> I agree with Yang Wang on this. > >>>>>>>>>>>> > >>>>>>>>>>>>> To me this sounds yet again like one of those magical > >>>>>>> mechanisms > >>>>>>>>>> that > >>>>>>>>>>>> will rarely work just right. > >>>>>>>>>>>> > >>>>>>>>>>>> I also agree with Chesnay that magical mechanisms are > >>> indeed > >>>>>>> super > >>>>>>>>> hard > >>>>>>>>>>> to > >>>>>>>>>>>> get right. > >>>>>>>>>>>> > >>>>>>>>>>>> Best regards, > >>>>>>>>>>>> > >>>>>>>>>>>> Martijn > >>>>>>>>>>>> > >>>>>>>>>>>> On Fri, 6 May 2022 at 12:03, Jiangang Liu < > >>>>>>>> liujiangangp...@gmail.com > >>>>>>>>>> > >>>>>>>>>>>> wrote: > >>>>>>>>>>>> > >>>>>>>>>>>>> Thanks for the valuable design. The auto-detecting can > >>>>> decrease > >>>>>>>>> great > >>>>>>>>>>> work > >>>>>>>>>>>>> for us. We have implemented the similar feature in our > >>>> inner > >>>>>>> flink > >>>>>>>>>>>>> version. > >>>>>>>>>>>>> Below is something that I care about: > >>>>>>>>>>>>> > >>>>>>>>>>>>> 1. For auto-detecting, I wonder how to make the > >>> strategy > >>>>> and > >>>>>>>>> mark a > >>>>>>>>>>>>> node > >>>>>>>>>>>>> blocked? Sometimes the blocked node is hard to be > >>>>> detected, > >>>>>>> for > >>>>>>>>>>>>> example, > >>>>>>>>>>>>> the upper node or the down node will be blocked when > >>>>> network > >>>>>>>>>>>>> unreachable. > >>>>>>>>>>>>> 2. I see that the strategy is made in JobMaster > >> side. > >>>> How > >>>>>>> about > >>>>>>>>>>>>> implementing the similar logic in resource manager? > >> In > >>>>>>> session > >>>>>>>>>> mode, > >>>>>>>>>>>>> multi > >>>>>>>>>>>>> jobs can fail on the same bad node and the node > >> should > >>>> be > >>>>>>>> marked > >>>>>>>>>>>>> blocked. > >>>>>>>>>>>>> If the job makes the strategy, the node may be not > >>>> marked > >>>>>>>> blocked > >>>>>>>>>> if > >>>>>>>>>>>>> the > >>>>>>>>>>>>> fail times don't exceed the threshold. > >>>>>>>>>>>>> > >>>>>>>>>>>>> > >>>>>>>>>>>>> Zhu Zhu <reed...@gmail.com> 于2022年5月5日周四 23:35写道： > >>>>>>>>>>>>> > >>>>>>>>>>>>>> Thank you for all your feedback! > >>>>>>>>>>>>>> > >>>>>>>>>>>>>> Besides the answers from Lijie, I'd like to share > >> some > >>> of > >>>>> my > >>>>>>>>>> thoughts: > >>>>>>>>>>>>>> 1. Whether to enable automatical blocklist > >>>>>>>>>>>>>> Generally speaking, it is not a goal of FLIP-224. > >>>>>>>>>>>>>> The automatical way should be something built upon > >> the > >>>>>>> blocklist > >>>>>>>>>>>>>> mechanism and well decoupled. It was designed to be a > >>>>>>>> configurable > >>>>>>>>>>>>>> blocklist strategy, but I think we can further > >> decouple > >>>> it > >>>>> by > >>>>>>>>>>>>>> introducing a abnormal node detector, as Becket > >>>> suggested, > >>>>>>> which > >>>>>>>>>> just > >>>>>>>>>>>>>> uses the blocklist mechanism once bad nodes are > >>> detected. > >>>>>>>> However, > >>>>>>>>>> it > >>>>>>>>>>>>>> should be a separate FLIP with further dev > >> discussions > >>>> and > >>>>>>>>> feedback > >>>>>>>>>>>>>> from users. I also agree with Becket that different > >>> users > >>>>>>> have > >>>>>>>>>>> different > >>>>>>>>>>>>>> requirements, and we should listen to them. > >>>>>>>>>>>>>> > >>>>>>>>>>>>>> 2. Is it enough to just take away abnormal nodes > >>>> externally > >>>>>>>>>>>>>> My answer is no. As Lijie has mentioned, we need a > >> way > >>> to > >>>>>>> avoid > >>>>>>>>>>>>>> deploying tasks to temporary hot nodes. In this case, > >>>> users > >>>>>>> may > >>>>>>>>> just > >>>>>>>>>>>>>> want to limit the load of the node and do not want to > >>>> kill > >>>>>>> all > >>>>>>>> the > >>>>>>>>>>>>>> processes on it. Another case is the speculative > >>>>> execution[1] > >>>>>>>>> which > >>>>>>>>>>>>>> may also leverage this feature to avoid starting > >> mirror > >>>>>>> tasks on > >>>>>>>>>> slow > >>>>>>>>>>>>>> nodes. > >>>>>>>>>>>>>> > >>>>>>>>>>>>>> Thanks, > >>>>>>>>>>>>>> Zhu > >>>>>>>>>>>>>> > >>>>>>>>>>>>>> [1] > >>>>>>>>>>>>>> > >>>>>>>>>>>>> > >>>>>>>>>>> > >>>>>>>>>> > >>>>>>>>> > >>>>>>>> > >>>>>>> > >>>>> > >>>> > >>> > >> > https://cwiki.apache.org/confluence/display/FLINK/FLIP-168%3A+Speculative+execution+for+Batch+Job > >>>>>>>>>>>>>> > >>>>>>>>>>>>>> Lijie Wang <wangdachui9...@gmail.com> 于2022年5月5日周四 > >>>>> 15:56写道： > >>>>>>>>>>>>>> > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> Hi everyone, > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> Thanks for your feedback. > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> There's one detail that I'd like to re-emphasize > >> here > >>>>>>> because > >>>>>>>> it > >>>>>>>>>> can > >>>>>>>>>>>>>> affect the value and design of the blocklist > >> mechanism > >>>>>>> (perhaps > >>>>>>>> I > >>>>>>>>>>> should > >>>>>>>>>>>>>> highlight it in the FLIP). We propose two actions in > >>>> FLIP: > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> 1) MARK_BLOCKLISTED: Just mark the task manager or > >>> node > >>>>> as > >>>>>>>>>> blocked. > >>>>>>>>>>>>>> Future slots should not be allocated from the blocked > >>>> task > >>>>>>>> manager > >>>>>>>>>> or > >>>>>>>>>>>>> node. > >>>>>>>>>>>>>> But slots that are already allocated will not be > >>>> affected. > >>>>> A > >>>>>>>>> typical > >>>>>>>>>>>>>> application scenario is to mitigate machine hotspots. > >>> In > >>>>> this > >>>>>>>>> case, > >>>>>>>>>> we > >>>>>>>>>>>>> hope > >>>>>>>>>>>>>> that subsequent resource allocations will not be on > >> the > >>>> hot > >>>>>>>>> machine, > >>>>>>>>>>> but > >>>>>>>>>>>>>> tasks currently running on it should not be affected. > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> 2) MARK_BLOCKLISTED_AND_EVACUATE_TASKS: Mark the > >> task > >>>>>>> manager > >>>>>>>> or > >>>>>>>>>>> node > >>>>>>>>>>>>> as > >>>>>>>>>>>>>> blocked, and evacuate all tasks on it. Evacuated > >> tasks > >>>> will > >>>>>>> be > >>>>>>>>>>>>> restarted on > >>>>>>>>>>>>>> non-blocked task managers. > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> For the above 2 actions, the former may more > >>> highlight > >>>>> the > >>>>>>>>> meaning > >>>>>>>>>>> of > >>>>>>>>>>>>>> this FLIP, because the external system cannot do > >> that. > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> Regarding *Manually* and *Automatically*, I > >> basically > >>>>> agree > >>>>>>>> with > >>>>>>>>>>>>> @Becket > >>>>>>>>>>>>>> Qin: different users have different answers. Not all > >>>> users’ > >>>>>>>>>> deployment > >>>>>>>>>>>>>> environments have a special external system that can > >>>>> perform > >>>>>>> the > >>>>>>>>>>> anomaly > >>>>>>>>>>>>>> detection. In addition, adding pluggable/optional > >>>>>>> auto-detection > >>>>>>>>>>> doesn't > >>>>>>>>>>>>>> require much extra work on top of manual > >> specification. > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> I will answer your other questions one by one. > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> @Yangze > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> a) I think you are right, we do not need to expose > >>> the > >>>>>>>>>>>>>> > >>> `cluster.resource-blocklist.item.timeout-check-interval` > >>>> to > >>>>>>>> users. > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> b) We can abstract the `notifyException` to a > >>> separate > >>>>>>>> interface > >>>>>>>>>>>>> (maybe > >>>>>>>>>>>>>> BlocklistExceptionListener), and the > >>>>>>>>> ResourceManagerBlocklistHandler > >>>>>>>>>>> can > >>>>>>>>>>>>>> implement it in the future. > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> @Martijn > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> a) I also think the manual blocking should be done > >> by > >>>>>>> cluster > >>>>>>>>>>>>> operators. > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> b) I think manual blocking makes sense, because > >>>> according > >>>>>>> to > >>>>>>>> my > >>>>>>>>>>>>>> experience, users are often the first to perceive the > >>>>> machine > >>>>>>>>>> problems > >>>>>>>>>>>>>> (because of job failover or delay), and they will > >>> contact > >>>>>>>> cluster > >>>>>>>>>>>>> operators > >>>>>>>>>>>>>> to solve it, or even tell the cluster operators which > >>>>>>> machine is > >>>>>>>>>>>>>> problematic. From this point of view, I think the > >>> people > >>>>> who > >>>>>>>>> really > >>>>>>>>>>> need > >>>>>>>>>>>>>> the manual blocking are the users, and it’s just > >>>> performed > >>>>> by > >>>>>>>> the > >>>>>>>>>>>>> cluster > >>>>>>>>>>>>>> operator, so I think the manual blocking makes sense. > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> @Chesnay > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> We need to touch the logic of JM/SlotPool, because > >>> for > >>>>>>>>>>>>> MARK_BLOCKLISTED > >>>>>>>>>>>>>> , we need to know whether the slot is blocklisted > >> when > >>>> the > >>>>>>> task > >>>>>>>> is > >>>>>>>>>>>>>> FINISHED/CANCELLED/FAILED. If so, SlotPool should > >>>> release > >>>>>>> the > >>>>>>>>> slot > >>>>>>>>>>>>>> directly to avoid assigning other tasks (of this job) > >>> on > >>>>> it. > >>>>>>> If > >>>>>>>> we > >>>>>>>>>>> only > >>>>>>>>>>>>>> maintain the blocklist information on the RM, JM > >> needs > >>> to > >>>>>>>> retrieve > >>>>>>>>>> it > >>>>>>>>>>> by > >>>>>>>>>>>>>> RPC. I think the performance overhead of that is > >>>> relatively > >>>>>>>> large, > >>>>>>>>>> so > >>>>>>>>>>> I > >>>>>>>>>>>>>> think it's worth maintaining the blocklist > >> information > >>> on > >>>>>>> the JM > >>>>>>>>>> side > >>>>>>>>>>>>> and > >>>>>>>>>>>>>> syncing them. > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> @Роман > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> a) “Probably storing inside Zookeeper/Configmap > >>>> might > >>>>>>> be > >>>>>>>>>> helpful > >>>>>>>>>>>>>> here.” Can you explain it in detail? I don't fully > >>>>>>> understand > >>>>>>>>> that. > >>>>>>>>>>> In > >>>>>>>>>>>>> my > >>>>>>>>>>>>>> opinion, non-active and active are the same, and no > >>>> special > >>>>>>>>>> treatment > >>>>>>>>>>> is > >>>>>>>>>>>>>> required. > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> b) I agree with you, the `endTimestamp` makes > >> sense, > >>> I > >>>>> will > >>>>>>>> add > >>>>>>>>> it > >>>>>>>>>>> to > >>>>>>>>>>>>>> FLIP. > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> @Yang > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> As mentioned above, AFAK, the external system > >> cannot > >>>>>>> support > >>>>>>>> the > >>>>>>>>>>>>>> MARK_BLOCKLISTED action. > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> Looking forward to your further feedback. > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> Best, > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> Lijie > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> Yang Wang <danrtsey...@gmail.com> 于2022年5月3日周二 > >>>> 21:09写道： > >>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>> Thanks Lijie and Zhu for creating the proposal. > >>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>> I want to share some thoughts about Flink cluster > >>>>>>> operations. > >>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>> In the production environment, the SRE(aka Site > >>>>>>> Reliability > >>>>>>>>>>> Engineer) > >>>>>>>>>>>>>>>> already has many tools to detect the unstable > >> nodes, > >>>>> which > >>>>>>>>> could > >>>>>>>>>>> take > >>>>>>>>>>>>>> the > >>>>>>>>>>>>>>>> system logs/metrics into consideration. > >>>>>>>>>>>>>>>> Then they use graceful-decomission in YARN and > >> taint > >>>> in > >>>>>>> K8s > >>>>>>>> to > >>>>>>>>>>>>> prevent > >>>>>>>>>>>>>> new > >>>>>>>>>>>>>>>> allocations on these unstable nodes. > >>>>>>>>>>>>>>>> At last, they will evict all the containers and > >> pods > >>>>>>> running > >>>>>>>> on > >>>>>>>>>>> these > >>>>>>>>>>>>>> nodes. > >>>>>>>>>>>>>>>> This mechanism also works for planned maintenance. > >>> So > >>>> I > >>>>> am > >>>>>>>>> afraid > >>>>>>>>>>>>> this > >>>>>>>>>>>>>> is > >>>>>>>>>>>>>>>> not the typical use case for FLIP-224. > >>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>> If we only support to block nodes manually, then I > >>>> could > >>>>>>> not > >>>>>>>>> see > >>>>>>>>>>>>>>>> the obvious advantages compared with current SRE's > >>>>>>>> approach(via > >>>>>>>>>>> *yarn > >>>>>>>>>>>>>>>> rmadmin or kubectl taint*). > >>>>>>>>>>>>>>>> At least, we need to have a pluggable component > >>> which > >>>>>>> could > >>>>>>>>>> expose > >>>>>>>>>>>>> the > >>>>>>>>>>>>>>>> potential unstable nodes automatically and block > >>> them > >>>> if > >>>>>>>>> enabled > >>>>>>>>>>>>>> explicitly. > >>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>> Best, > >>>>>>>>>>>>>>>> Yang > >>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>> Becket Qin <becket....@gmail.com> 于2022年5月2日周一 > >>>> 16:36写道： > >>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>> Thanks for the proposal, Lijie. > >>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>> This is an interesting feature and discussion, > >> and > >>>>>>> somewhat > >>>>>>>>>>> related > >>>>>>>>>>>>>> to the > >>>>>>>>>>>>>>>>> design principle about how people should operate > >>>>> Flink. > >>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>> I think there are three things involved in this > >>>> FLIP. > >>>>>>>>>>>>>>>>> a) Detect and report the unstable node. > >>>>>>>>>>>>>>>>> b) Collect the information of the unstable > >>> node > >>>>> and > >>>>>>>>> form a > >>>>>>>>>>>>>> blocklist. > >>>>>>>>>>>>>>>>> c) Take the action to block nodes. > >>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>> My two cents: > >>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>> 1. It looks like people all agree that Flink > >>> should > >>>>> have > >>>>>>>> c). > >>>>>>>>> It > >>>>>>>>>>> is > >>>>>>>>>>>>>> not only > >>>>>>>>>>>>>>>>> useful for cases of node failures, but also > >> handy > >>>> for > >>>>>>> some > >>>>>>>>>>> planned > >>>>>>>>>>>>>>>>> maintenance. > >>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>> 2. People have different opinions on b), i.e. > >> who > >>>>>>> should be > >>>>>>>>> the > >>>>>>>>>>>>> brain > >>>>>>>>>>>>>> to > >>>>>>>>>>>>>>>>> make the decision to block a node. I think this > >>>>> largely > >>>>>>>>> depends > >>>>>>>>>>> on > >>>>>>>>>>>>>> who we > >>>>>>>>>>>>>>>>> talk to. Different users would probably give > >>>> different > >>>>>>>>> answers. > >>>>>>>>>>> For > >>>>>>>>>>>>>> people > >>>>>>>>>>>>>>>>> who do have a centralized node health management > >>>>>>> service, > >>>>>>>> let > >>>>>>>>>>> Flink > >>>>>>>>>>>>>> do just > >>>>>>>>>>>>>>>>> do a) and c) would be preferred. So essentially > >>>> Flink > >>>>>>> would > >>>>>>>>> be > >>>>>>>>>>> one > >>>>>>>>>>>>> of > >>>>>>>>>>>>>> the > >>>>>>>>>>>>>>>>> sources that may detect unstable nodes, report > >> it > >>> to > >>>>>>> that > >>>>>>>>>>> service, > >>>>>>>>>>>>>> and then > >>>>>>>>>>>>>>>>> take the command from that service to block the > >>>>>>> problematic > >>>>>>>>>>> nodes. > >>>>>>>>>>>>> On > >>>>>>>>>>>>>> the > >>>>>>>>>>>>>>>>> other hand, for users who do not have such a > >>>> service, > >>>>>>>> simply > >>>>>>>>>>>>> letting > >>>>>>>>>>>>>> Flink > >>>>>>>>>>>>>>>>> be clever by itself to block the suspicious > >> nodes > >>>>> might > >>>>>>> be > >>>>>>>>>>> desired > >>>>>>>>>>>>> to > >>>>>>>>>>>>>>>>> ensure the jobs are running smoothly. > >>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>> So that indicates a) and b) here should be > >>>> pluggable / > >>>>>>>>>> optional. > >>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>> In light of this, maybe it would make sense to > >>> have > >>>>>>>> something > >>>>>>>>>>>>>> pluggable > >>>>>>>>>>>>>>>>> like a UnstableNodeReporter which exposes > >> unstable > >>>>> nodes > >>>>>>>>>>> actively. > >>>>>>>>>>>>> (A > >>>>>>>>>>>>>> more > >>>>>>>>>>>>>>>>> general interface should be JobInfoReporter<T> > >>> which > >>>>>>> can be > >>>>>>>>>> used > >>>>>>>>>>> to > >>>>>>>>>>>>>> report > >>>>>>>>>>>>>>>>> any information of type <T>. But I'll just keep > >>> the > >>>>>>> scope > >>>>>>>>>>> relevant > >>>>>>>>>>>>> to > >>>>>>>>>>>>>> this > >>>>>>>>>>>>>>>>> FLIP here). Personally speaking, I think it is > >> OK > >>> to > >>>>>>> have a > >>>>>>>>>>> default > >>>>>>>>>>>>>>>>> implementation of a reporter which just tells > >>> Flink > >>>> to > >>>>>>> take > >>>>>>>>>>> action > >>>>>>>>>>>>> to > >>>>>>>>>>>>>> block > >>>>>>>>>>>>>>>>> problematic nodes and also unblocks them after > >>>>> timeout. > >>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>> Thanks, > >>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>> Jiangjie (Becket) Qin > >>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>> On Mon, May 2, 2022 at 3:27 PM Роман Бойко < > >>>>>>>>>> ro.v.bo...@gmail.com > >>>>>>>>>>>> > >>>>>>>>>>>>>> wrote: > >>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>> Thanks for good initiative, Lijie and Zhu! > >>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>> If it's possible I'd like to participate in > >>>>>>> development. > >>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>> I agree with 3rd point of Konstantin's reply - > >>> we > >>>>>>> should > >>>>>>>>>>> consider > >>>>>>>>>>>>>> to move > >>>>>>>>>>>>>>>>>> somehow the information of blocklisted > >> nodes/TMs > >>>>> from > >>>>>>>>> active > >>>>>>>>>>>>>>>>>> ResourceManager to non-active ones. Probably > >>>> storing > >>>>>>>> inside > >>>>>>>>>>>>>>>>>> Zookeeper/Configmap might be helpful here. > >>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>> And I agree with Martijn that a lot of > >>>> organizations > >>>>>>>> don't > >>>>>>>>>> want > >>>>>>>>>>>>> to > >>>>>>>>>>>>>> expose > >>>>>>>>>>>>>>>>>> such API for a cluster user group. But I think > >>>> it's > >>>>>>>>> necessary > >>>>>>>>>>> to > >>>>>>>>>>>>>> have the > >>>>>>>>>>>>>>>>>> mechanism for unblocking the nodes/TMs anyway > >>> for > >>>>>>>> avoiding > >>>>>>>>>>>>> incorrect > >>>>>>>>>>>>>>>>>> automatic behaviour. > >>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>> And another one small suggestion - I think it > >>>> would > >>>>> be > >>>>>>>>> better > >>>>>>>>>>> to > >>>>>>>>>>>>>> extend > >>>>>>>>>>>>>>>>> the > >>>>>>>>>>>>>>>>>> *BlocklistedItem* class with the > >> *endTimestamp* > >>>>> field > >>>>>>> and > >>>>>>>>>> fill > >>>>>>>>>>> it > >>>>>>>>>>>>>> at the > >>>>>>>>>>>>>>>>>> item creation. This simple addition will allow > >>> to: > >>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>> - > >>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>> Provide the ability to users to setup the > >>> exact > >>>>>>> time > >>>>>>>> of > >>>>>>>>>>>>>> blocklist end > >>>>>>>>>>>>>>>>>> through RestAPI > >>>>>>>>>>>>>>>>>> - > >>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>> Not being tied to a single value of > >>>>>>>>>>>>>>>>>> *cluster.resource-blacklist.item.timeout* > >>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>> On Mon, 2 May 2022 at 14:17, Chesnay Schepler > >> < > >>>>>>>>>>>>> ches...@apache.org> > >>>>>>>>>>>>>>>>> wrote: > >>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>> I do share the concern between blurring the > >>>> lines > >>>>> a > >>>>>>>> bit. > >>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>> That said, I'd prefer to not have any > >>>>> auto-detection > >>>>>>>> and > >>>>>>>>>> only > >>>>>>>>>>>>>> have an > >>>>>>>>>>>>>>>>>>> opt-in mechanism > >>>>>>>>>>>>>>>>>>> to manually block processes/nodes. To me > >> this > >>>>> sounds > >>>>>>>> yet > >>>>>>>>>>> again > >>>>>>>>>>>>>> like one > >>>>>>>>>>>>>>>>>>> of those > >>>>>>>>>>>>>>>>>>> magical mechanisms that will rarely work > >> just > >>>>> right. > >>>>>>>>>>>>>>>>>>> An external system can leverage way more > >>>>> information > >>>>>>>>> after > >>>>>>>>>>> all. > >>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>> Moreover, I'm quite concerned about the > >>>> complexity > >>>>>>> of > >>>>>>>>> this > >>>>>>>>>>>>>> proposal. > >>>>>>>>>>>>>>>>>>> Tracking on both the RM/JM side; syncing > >>> between > >>>>>>>>>> components; > >>>>>>>>>>>>>>>>> adjustments > >>>>>>>>>>>>>>>>>>> to the > >>>>>>>>>>>>>>>>>>> slot and resource protocol. > >>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>> In a way it seems overly complicated. > >>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>> If we look at it purely from an active > >>> resource > >>>>>>>>> management > >>>>>>>>>>>>>> perspective, > >>>>>>>>>>>>>>>>>>> then there > >>>>>>>>>>>>>>>>>>> isn't really a need to touch the slot > >> protocol > >>>> at > >>>>>>> all > >>>>>>>> (or > >>>>>>>>>> in > >>>>>>>>>>>>> fact > >>>>>>>>>>>>>> to > >>>>>>>>>>>>>>>>>>> anything in the JobMaster), > >>>>>>>>>>>>>>>>>>> because there isn't any point in keeping > >>> around > >>>>>>> blocked > >>>>>>>>> TMs > >>>>>>>>>>> in > >>>>>>>>>>>>> the > >>>>>>>>>>>>>>>>> first > >>>>>>>>>>>>>>>>>>> place. > >>>>>>>>>>>>>>>>>>> They'd just be idling, potentially shutting > >>> down > >>>>>>> after > >>>>>>>> a > >>>>>>>>>>> while > >>>>>>>>>>>>> by > >>>>>>>>>>>>>> the > >>>>>>>>>>>>>>>>> RM > >>>>>>>>>>>>>>>>>>> because of > >>>>>>>>>>>>>>>>>>> it (unless we _also_ touch that logic). > >>>>>>>>>>>>>>>>>>> Here the blocking of a process (be it by > >>>> blocking > >>>>>>> the > >>>>>>>>>> process > >>>>>>>>>>>>> or > >>>>>>>>>>>>>> node) > >>>>>>>>>>>>>>>>> is > >>>>>>>>>>>>>>>>>>> equivalent with shutting down the blocked > >>>>>>> process(es). > >>>>>>>>>>>>>>>>>>> Once the block is lifted we can just spin it > >>>> back > >>>>>>> up. > >>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>> And I do wonder whether we couldn't apply > >> the > >>>> same > >>>>>>> line > >>>>>>>>> of > >>>>>>>>>>>>>> thinking to > >>>>>>>>>>>>>>>>>>> standalone resource management. > >>>>>>>>>>>>>>>>>>> Here being able to stop/restart a > >> process/node > >>>>>>> manually > >>>>>>>>>>> should > >>>>>>>>>>>>> be > >>>>>>>>>>>>>> a > >>>>>>>>>>>>>>>>> core > >>>>>>>>>>>>>>>>>>> requirement for a Flink deployment anyway. > >>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>> On 02/05/2022 08:49, Martijn Visser wrote: > >>>>>>>>>>>>>>>>>>>> Hi everyone, > >>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>> Thanks for creating this FLIP. I can > >>>> understand > >>>>>>> the > >>>>>>>>>> problem > >>>>>>>>>>>>> and > >>>>>>>>>>>>>> I see > >>>>>>>>>>>>>>>>>>> value > >>>>>>>>>>>>>>>>>>>> in the automatic detection and > >>> blocklisting. I > >>>>> do > >>>>>>>> have > >>>>>>>>>> some > >>>>>>>>>>>>>> concerns > >>>>>>>>>>>>>>>>>> with > >>>>>>>>>>>>>>>>>>>> the ability to manually specify to be > >>> blocked > >>>>>>>>> resources. > >>>>>>>>>> I > >>>>>>>>>>>>> have > >>>>>>>>>>>>>> two > >>>>>>>>>>>>>>>>>>>> concerns; > >>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>> * Most organizations explicitly have a > >>>>> separation > >>>>>>> of > >>>>>>>>>>>>> concerns, > >>>>>>>>>>>>>>>>> meaning > >>>>>>>>>>>>>>>>>>> that > >>>>>>>>>>>>>>>>>>>> there's a group who's responsible for > >>>> managing a > >>>>>>>>> cluster > >>>>>>>>>>> and > >>>>>>>>>>>>>> there's > >>>>>>>>>>>>>>>>> a > >>>>>>>>>>>>>>>>>>> user > >>>>>>>>>>>>>>>>>>>> group who uses that cluster. With the > >>>>>>> introduction of > >>>>>>>>>> this > >>>>>>>>>>>>>> mechanism, > >>>>>>>>>>>>>>>>>> the > >>>>>>>>>>>>>>>>>>>> latter group now can influence the > >>>>> responsibility > >>>>>>> of > >>>>>>>>> the > >>>>>>>>>>>>> first > >>>>>>>>>>>>>> group. > >>>>>>>>>>>>>>>>>> So > >>>>>>>>>>>>>>>>>>> it > >>>>>>>>>>>>>>>>>>>> can be possible that someone from the user > >>>> group > >>>>>>>> blocks > >>>>>>>>>>>>>> something, > >>>>>>>>>>>>>>>>>> which > >>>>>>>>>>>>>>>>>>>> causes an outage (which could result in > >>> paging > >>>>>>>>> mechanism > >>>>>>>>>>>>>> triggering > >>>>>>>>>>>>>>>>>> etc) > >>>>>>>>>>>>>>>>>>>> which impacts the first group. > >>>>>>>>>>>>>>>>>>>> * How big is the group of people who can > >> go > >>>>>>> through > >>>>>>>> the > >>>>>>>>>>>>> process > >>>>>>>>>>>>>> of > >>>>>>>>>>>>>>>>>>> manually > >>>>>>>>>>>>>>>>>>>> identifying a node that isn't behaving as > >> it > >>>>>>> should > >>>>>>>>> be? I > >>>>>>>>>>> do > >>>>>>>>>>>>>> think > >>>>>>>>>>>>>>>>> this > >>>>>>>>>>>>>>>>>>>> group is relatively limited. Does it then > >>> make > >>>>>>> sense > >>>>>>>> to > >>>>>>>>>>>>>> introduce > >>>>>>>>>>>>>>>>> such > >>>>>>>>>>>>>>>>>> a > >>>>>>>>>>>>>>>>>>>> feature, which would only be used by a > >>> really > >>>>>>> small > >>>>>>>>> user > >>>>>>>>>>>>> group > >>>>>>>>>>>>>> of > >>>>>>>>>>>>>>>>>> Flink? > >>>>>>>>>>>>>>>>>>> We > >>>>>>>>>>>>>>>>>>>> still have to maintain, test and support > >>> such > >>>> a > >>>>>>>>> feature. > >>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>> I'm +1 for the autodetection features, but > >>> I'm > >>>>>>>> leaning > >>>>>>>>>>>>> towards > >>>>>>>>>>>>>> not > >>>>>>>>>>>>>>>>>>> exposing > >>>>>>>>>>>>>>>>>>>> this to the user group but having this > >>>> available > >>>>>>>>> strictly > >>>>>>>>>>> for > >>>>>>>>>>>>>> cluster > >>>>>>>>>>>>>>>>>>>> operators. They could then also set up > >> their > >>>>>>>>>>>>>> paging/metrics/logging > >>>>>>>>>>>>>>>>>>> system > >>>>>>>>>>>>>>>>>>>> to take this into account. > >>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>> Best regards, > >>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>> Martijn Visser > >>>>>>>>>>>>>>>>>>>> https://twitter.com/MartijnVisser82 > >>>>>>>>>>>>>>>>>>>> https://github.com/MartijnVisser > >>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>> On Fri, 29 Apr 2022 at 09:39, Yangze Guo < > >>>>>>>>>>> karma...@gmail.com > >>>>>>>>>>>>>> > >>>>>>>>>>>>>> wrote: > >>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>> Thanks for driving this, Zhu and Lijie. > >>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>> +1 for the overall proposal. Just share > >>> some > >>>>>>> cents > >>>>>>>>> here: > >>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>> - Why do we need to expose > >>>>>>>>>>>>>>>>>>>>> > >>>>>>>> cluster.resource-blacklist.item.timeout-check-interval > >>>>>>>>>> to > >>>>>>>>>>>>> the > >>>>>>>>>>>>>> user? > >>>>>>>>>>>>>>>>>>>>> I think the semantics of > >>>>>>>>>>>>>> `cluster.resource-blacklist.item.timeout` > >>>>>>>>>>>>>>>>> is > >>>>>>>>>>>>>>>>>>>>> sufficient for the user. How to guarantee > >>> the > >>>>>>>> timeout > >>>>>>>>>>>>>> mechanism is > >>>>>>>>>>>>>>>>>>>>> Flink's internal implementation. I think > >> it > >>>>> will > >>>>>>> be > >>>>>>>>> very > >>>>>>>>>>>>>> confusing > >>>>>>>>>>>>>>>>> and > >>>>>>>>>>>>>>>>>>>>> we do not need to expose it to users. > >>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>> - ResourceManager can notify the > >> exception > >>>> of a > >>>>>>> task > >>>>>>>>>>>>> manager to > >>>>>>>>>>>>>>>>>>>>> `BlacklistHandler` as well. > >>>>>>>>>>>>>>>>>>>>> For example, the slot allocation might > >> fail > >>>> in > >>>>>>> case > >>>>>>>>> the > >>>>>>>>>>>>> target > >>>>>>>>>>>>>> task > >>>>>>>>>>>>>>>>>>>>> manager is busy or has a network jitter. > >> I > >>>>> don't > >>>>>>>> mean > >>>>>>>>> we > >>>>>>>>>>>>> need > >>>>>>>>>>>>>> to > >>>>>>>>>>>>>>>>> cover > >>>>>>>>>>>>>>>>>>>>> this case in this version, but we can > >> also > >>>>> open a > >>>>>>>>>>>>>> `notifyException` > >>>>>>>>>>>>>>>>> in > >>>>>>>>>>>>>>>>>>>>> `ResourceManagerBlacklistHandler`. > >>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>> - Before we sync the blocklist to > >>>>>>> ResourceManager, > >>>>>>>>> will > >>>>>>>>>>> the > >>>>>>>>>>>>>> slot of > >>>>>>>>>>>>>>>>> a > >>>>>>>>>>>>>>>>>>>>> blocked task manager continues to be > >>> released > >>>>> and > >>>>>>>>>>> allocated? > >>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>> Best, > >>>>>>>>>>>>>>>>>>>>> Yangze Guo > >>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>> On Thu, Apr 28, 2022 at 3:11 PM Lijie > >> Wang > >>> < > >>>>>>>>>>>>>>>>> wangdachui9...@gmail.com> > >>>>>>>>>>>>>>>>>>>>> wrote: > >>>>>>>>>>>>>>>>>>>>>> Hi Konstantin, > >>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>> Thanks for your feedback. I will > >> response > >>>>> your 4 > >>>>>>>>>> remarks: > >>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>> 1) Thanks for reminding me of the > >>>>> controversy. I > >>>>>>>>> think > >>>>>>>>>>>>>> “BlockList” > >>>>>>>>>>>>>>>>> is > >>>>>>>>>>>>>>>>>>>>> good > >>>>>>>>>>>>>>>>>>>>>> enough, and I will change it in FLIP. > >>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>> 2) Your suggestion for the REST API is a > >>>> good > >>>>>>> idea. > >>>>>>>>>> Based > >>>>>>>>>>>>> on > >>>>>>>>>>>>>> the > >>>>>>>>>>>>>>>>>>> above, I > >>>>>>>>>>>>>>>>>>>>>> would change REST API as following: > >>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>> POST/GET <host>/blocklist/nodes > >>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>> POST/GET <host>/blocklist/taskmanagers > >>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>> DELETE > >> <host>/blocklist/node/<identifier> > >>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>> DELETE > >>>>> <host>/blocklist/taskmanager/<identifier> > >>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>> 3) If a node is blocking/blocklisted, it > >>>> means > >>>>>>> that > >>>>>>>>> all > >>>>>>>>>>>>> task > >>>>>>>>>>>>>>>>> managers > >>>>>>>>>>>>>>>>>>> on > >>>>>>>>>>>>>>>>>>>>>> this node are blocklisted. All slots on > >>>> these > >>>>>>> TMs > >>>>>>>> are > >>>>>>>>>> not > >>>>>>>>>>>>>>>>> available. > >>>>>>>>>>>>>>>>>>> This > >>>>>>>>>>>>>>>>>>>>>> is actually a bit like TM losts, but > >> these > >>>> TMs > >>>>>>> are > >>>>>>>>> not > >>>>>>>>>>>>> really > >>>>>>>>>>>>>> lost, > >>>>>>>>>>>>>>>>>>> they > >>>>>>>>>>>>>>>>>>>>>> are in an unavailable status, and they > >> are > >>>>> still > >>>>>>>>>>> registered > >>>>>>>>>>>>>> in this > >>>>>>>>>>>>>>>>>>> flink > >>>>>>>>>>>>>>>>>>>>>> cluster. They will be available again > >> once > >>>> the > >>>>>>>>>>>>> corresponding > >>>>>>>>>>>>>>>>>> blocklist > >>>>>>>>>>>>>>>>>>>>> item > >>>>>>>>>>>>>>>>>>>>>> is removed. This behavior is the same in > >>>>>>>>>>> active/non-active > >>>>>>>>>>>>>>>>> clusters. > >>>>>>>>>>>>>>>>>>>>>> However in the active clusters, these > >> TMs > >>>> may > >>>>> be > >>>>>>>>>> released > >>>>>>>>>>>>> due > >>>>>>>>>>>>>> to > >>>>>>>>>>>>>>>>> idle > >>>>>>>>>>>>>>>>>>>>>> timeouts. > >>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>> 4) For the item timeout, I prefer to > >> keep > >>>> it. > >>>>>>> The > >>>>>>>>>> reasons > >>>>>>>>>>>>> are > >>>>>>>>>>>>>> as > >>>>>>>>>>>>>>>>>>>>> following: > >>>>>>>>>>>>>>>>>>>>>> a) The timeout will not affect users > >>> adding > >>>> or > >>>>>>>>> removing > >>>>>>>>>>>>> items > >>>>>>>>>>>>>> via > >>>>>>>>>>>>>>>>>> REST > >>>>>>>>>>>>>>>>>>>>> API, > >>>>>>>>>>>>>>>>>>>>>> and users can disable it by configuring > >> it > >>>> to > >>>>>>>>>>>>> Long.MAX_VALUE . > >>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>> b) Some node problems can recover after > >> a > >>>>>>> period of > >>>>>>>>>> time > >>>>>>>>>>>>>> (such as > >>>>>>>>>>>>>>>>>>> machine > >>>>>>>>>>>>>>>>>>>>>> hotspots), in which case users may > >> prefer > >>>> that > >>>>>>>> Flink > >>>>>>>>>> can > >>>>>>>>>>> do > >>>>>>>>>>>>>> this > >>>>>>>>>>>>>>>>>>>>>> automatically instead of requiring the > >>> user > >>>> to > >>>>>>> do > >>>>>>>> it > >>>>>>>>>>>>> manually. > >>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>> Best, > >>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>> Lijie > >>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>> Konstantin Knauf <kna...@apache.org> > >>>>>>> 于2022年4月27日周三 > >>>>>>>>>>>>> 19:23写道： > >>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>>> Hi Lijie, > >>>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>>> I think, this makes sense and +1 to > >> only > >>>>>>> support > >>>>>>>>>>> manually > >>>>>>>>>>>>>> blocking > >>>>>>>>>>>>>>>>>>>>>>> taskmanagers and nodes. Maybe the > >>> different > >>>>>>>>> strategies > >>>>>>>>>>> can > >>>>>>>>>>>>>> also be > >>>>>>>>>>>>>>>>>>>>>>> maintained outside of Apache Flink. > >>>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>>> A few remarks: > >>>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>>> 1) Can we use another term than > >>>> "bla.cklist" > >>>>>>> due > >>>>>>>> to > >>>>>>>>>> the > >>>>>>>>>>>>>>>>> controversy > >>>>>>>>>>>>>>>>>>>>> around > >>>>>>>>>>>>>>>>>>>>>>> the term? [1] There was also a Jira > >>> Ticket > >>>>>>> about > >>>>>>>>> this > >>>>>>>>>>>>> topic a > >>>>>>>>>>>>>>>>> while > >>>>>>>>>>>>>>>>>>>>> back > >>>>>>>>>>>>>>>>>>>>>>> and there was generally a consensus to > >>>> avoid > >>>>>>> the > >>>>>>>>> term > >>>>>>>>>>>>>> blacklist & > >>>>>>>>>>>>>>>>>>>>> whitelist > >>>>>>>>>>>>>>>>>>>>>>> [2]? We could use "blocklist" > >> "denylist" > >>> or > >>>>>>>>>>> "quarantined" > >>>>>>>>>>>>>>>>>>>>>>> 2) For the REST API, I'd prefer a > >>> slightly > >>>>>>>> different > >>>>>>>>>>>>> design > >>>>>>>>>>>>>> as > >>>>>>>>>>>>>>>>> verbs > >>>>>>>>>>>>>>>>>>>>> like > >>>>>>>>>>>>>>>>>>>>>>> add/remove often considered an > >>> anti-pattern > >>>>> for > >>>>>>>> REST > >>>>>>>>>>> APIs. > >>>>>>>>>>>>>> POST > >>>>>>>>>>>>>>>>> on a > >>>>>>>>>>>>>>>>>>>>> list > >>>>>>>>>>>>>>>>>>>>>>> item is generally the standard to add > >>>> items. > >>>>>>>> DELETE > >>>>>>>>> on > >>>>>>>>>>> the > >>>>>>>>>>>>>>>>>> individual > >>>>>>>>>>>>>>>>>>>>>>> resource is standard to remove an item. > >>>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>>> POST <host>/quarantine/items > >>>>>>>>>>>>>>>>>>>>>>> DELETE > >>>>> <host>/quarantine/items/<itemidentifier> > >>>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>>> We could also consider to separate > >>>>> taskmanagers > >>>>>>>> and > >>>>>>>>>>> nodes > >>>>>>>>>>>>> in > >>>>>>>>>>>>>> the > >>>>>>>>>>>>>>>>>> REST > >>>>>>>>>>>>>>>>>>>>> API > >>>>>>>>>>>>>>>>>>>>>>> (and internal data structures). Any > >>> opinion > >>>>> on > >>>>>>>> this? > >>>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>>> POST/GET <host>/quarantine/nodes > >>>>>>>>>>>>>>>>>>>>>>> POST/GET <host>/quarantine/taskmanager > >>>>>>>>>>>>>>>>>>>>>>> DELETE > >>> <host>/quarantine/nodes/<identifier> > >>>>>>>>>>>>>>>>>>>>>>> DELETE > >>>>>>> <host>/quarantine/taskmanager/<identifier> > >>>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>>> 3) How would blocking nodes behave with > >>>>>>> non-active > >>>>>>>>>>>>> resource > >>>>>>>>>>>>>>>>>> managers, > >>>>>>>>>>>>>>>>>>>>> i.e. > >>>>>>>>>>>>>>>>>>>>>>> standalone or reactive mode? > >>>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>>> 4) To keep the implementation even more > >>>>>>> minimal, > >>>>>>>> do > >>>>>>>>> we > >>>>>>>>>>>>> need > >>>>>>>>>>>>>> the > >>>>>>>>>>>>>>>>>>> timeout > >>>>>>>>>>>>>>>>>>>>>>> behavior? If items are added/removed > >>>> manually > >>>>>>> we > >>>>>>>>> could > >>>>>>>>>>>>>> delegate > >>>>>>>>>>>>>>>>> this > >>>>>>>>>>>>>>>>>>>>> to the > >>>>>>>>>>>>>>>>>>>>>>> user easily. In my opinion the timeout > >>>>> behavior > >>>>>>>>> would > >>>>>>>>>>>>> better > >>>>>>>>>>>>>> fit > >>>>>>>>>>>>>>>>>> into > >>>>>>>>>>>>>>>>>>>>>>> specific strategies at a later point. > >>>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>>> Looking forward to your thoughts. > >>>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>>> Cheers and thank you, > >>>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>>> Konstantin > >>>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>>> [1] > >>>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>> > >>>>>>>>>>>>> > >>>>>>>>>>> > >>>>>>>>>> > >>>>>>>>> > >>>>>>>> > >>>>>>> > >>>>> > >>>> > >>> > >> > https://en.wikipedia.org/wiki/Blacklist_(computing)#Controversy_over_use_of_the_term > >>>>>>>>>>>>>>>>>>>>>>> [2] > >>>>>>>>> https://issues.apache.org/jira/browse/FLINK-18209 > >>>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>>> Am Mi., 27. Apr. 2022 um 04:04 Uhr > >>> schrieb > >>>>>>> Lijie > >>>>>>>>> Wang > >>>>>>>>>> < > >>>>>>>>>>>>>>>>>>>>>>> wangdachui9...@gmail.com>: > >>>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>>>> Hi all, > >>>>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>>>> Flink job failures may happen due to > >>>> cluster > >>>>>>> node > >>>>>>>>>>> issues > >>>>>>>>>>>>>>>>>>>>> (insufficient > >>>>>>>>>>>>>>>>>>>>>>> disk > >>>>>>>>>>>>>>>>>>>>>>>> space, bad hardware, network > >>>> abnormalities). > >>>>>>>> Flink > >>>>>>>>>> will > >>>>>>>>>>>>>> take care > >>>>>>>>>>>>>>>>>> of > >>>>>>>>>>>>>>>>>>>>> the > >>>>>>>>>>>>>>>>>>>>>>>> failures and redeploy the tasks. > >>> However, > >>>>> due > >>>>>>> to > >>>>>>>>> data > >>>>>>>>>>>>>> locality > >>>>>>>>>>>>>>>>> and > >>>>>>>>>>>>>>>>>>>>>>> limited > >>>>>>>>>>>>>>>>>>>>>>>> resources, the new tasks are very > >> likely > >>>> to > >>>>> be > >>>>>>>>>>> redeployed > >>>>>>>>>>>>>> to the > >>>>>>>>>>>>>>>>>> same > >>>>>>>>>>>>>>>>>>>>>>>> nodes, which will result in continuous > >>>> task > >>>>>>>>>>> abnormalities > >>>>>>>>>>>>>> and > >>>>>>>>>>>>>>>>>> affect > >>>>>>>>>>>>>>>>>>>>> job > >>>>>>>>>>>>>>>>>>>>>>>> progress. > >>>>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>>>> Currently, Flink users need to > >> manually > >>>>>>> identify > >>>>>>>>> the > >>>>>>>>>>>>>> problematic > >>>>>>>>>>>>>>>>>>>>> node and > >>>>>>>>>>>>>>>>>>>>>>>> take it offline to solve this problem. > >>> But > >>>>>>> this > >>>>>>>>>>> approach > >>>>>>>>>>>>> has > >>>>>>>>>>>>>>>>>>>>> following > >>>>>>>>>>>>>>>>>>>>>>>> disadvantages: > >>>>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>>>> 1. Taking a node offline can be a > >> heavy > >>>>>>> process. > >>>>>>>>>> Users > >>>>>>>>>>>>> may > >>>>>>>>>>>>>> need > >>>>>>>>>>>>>>>>> to > >>>>>>>>>>>>>>>>>>>>>>> contact > >>>>>>>>>>>>>>>>>>>>>>>> cluster administors to do this. The > >>>>> operation > >>>>>>> can > >>>>>>>>>> even > >>>>>>>>>>> be > >>>>>>>>>>>>>>>>> dangerous > >>>>>>>>>>>>>>>>>>>>> and > >>>>>>>>>>>>>>>>>>>>>>> not > >>>>>>>>>>>>>>>>>>>>>>>> allowed during some important business > >>>>> events. > >>>>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>>>> 2. Identifying and solving this kind > >> of > >>>>>>> problems > >>>>>>>>>>> manually > >>>>>>>>>>>>>> would > >>>>>>>>>>>>>>>>> be > >>>>>>>>>>>>>>>>>>>>> slow > >>>>>>>>>>>>>>>>>>>>>>> and > >>>>>>>>>>>>>>>>>>>>>>>> a waste of human resources. > >>>>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>>>> To solve this problem, Zhu Zhu and I > >>>> propose > >>>>>>> to > >>>>>>>>>>>>> introduce a > >>>>>>>>>>>>>>>>>> blacklist > >>>>>>>>>>>>>>>>>>>>>>>> mechanism for Flink to filter out > >>>>> problematic > >>>>>>>>>>> resources. > >>>>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>>>> You can find more details in > >>> FLIP-224[1]. > >>>>>>> Looking > >>>>>>>>>>> forward > >>>>>>>>>>>>>> to your > >>>>>>>>>>>>>>>>>>>>>>> feedback. > >>>>>>>>>>>>>>>>>>>>>>>> [1] > >>>>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>> > >>>>>>>>>>>>> > >>>>>>>>>>> > >>>>>>>>>> > >>>>>>>>> > >>>>>>>> > >>>>>>> > >>>>> > >>>> > >>> > >> > https://cwiki.apache.org/confluence/display/FLINK/FLIP-224%3A+Blacklist+Mechanism > >>>>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>>>> Best, > >>>>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>>>>>>> Lijie > >>>>>>>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>> > >>>>>>>>>>>>> > >>>>>>>>>>>> > >>>>>>>>>>> > >>>>>>>>>> > >>>>>>>>> > >>>>>>>>> > >>>>>>>>> -- > >>>>>>>>> Best regards, > >>>>>>>>> Roman Boyko > >>>>>>>>> e.: ro.v.bo...@gmail.com > >>>>>>>>> > >>>>>>>> > >>>>>>> > >>>>>> > >>>>> > >>>> > >>>> > >>>> -- > >>>> https://twitter.com/snntrable > >>>> https://github.com/knaufk > >>>> > >>> > >> > >> > >> -- > >> https://twitter.com/snntrable > >> https://github.com/knaufk > >> > >
