And that last issue was mine. My setting override was not picked up and it was using GroupByContainerCount instead. -Thanks, Thunder
-----Original Message----- From: Thunder Stumpges Sent: Monday, March 19, 2018 20:58 To: dev@samza.apache.org Cc: Jagadish Venkatraman <jagadish1...@gmail.com>; t...@recursivedream.com; yi...@linkedin.com; Yi Pan <nickpa...@gmail.com> Subject: RE: Old style "low level" Tasks with alternative deployment model(s) Well I figured it out. My specific issue was due to a simple dependency problem where I had gotten an older version of the Jackson-mapper library. However the code was throwing NoSuchMethodError (an Error instead of Exception) and being silently dropped. I created a pull request to handle any Throwable in ScheduleAfterDebounceTime. https://github.com/apache/samza/pull/450 I'm now running into an issue with the generation of the JobModel and the ProcessorId. The ZkJobCoordinator has a ProcessorId that is a Guid, but when GroupByContainerIds class (my TaskNameGrouper) creates the ContainerModels, it is using the ContainerId (a numeric value, 0,1,2,etc) as the ProcessorId (~ line 105). This results in the JobModel that is generated and published immediately causing the processor to quit with this message: INFO o.apache.samza.zk.ZkJobCoordinator - New JobModel does not contain pid=38c637bf-9c2b-4856-afc4-5b1562711cfb. Stopping this processor. I was assuming I should be using GroupByContainerIds as my TaskNameGrouper. I don't see any other promising implementations. Am I just missing something? Thanks, Thunder JobModel { "config" : { ... }, "containers" : { "0" : { "tasks" : { "Partition 0" : { "task-name" : "Partition 0", "system-stream-partitions" : [ { "system" : "kafka", "partition" : 0, "stream" : "test_topic1" }, { "system" : "kafka", "partition" : 0, "stream" : "test_topic2" } ], "changelog-partition" : 0 }, "Partition 1" : { "task-name" : "Partition 1", "system-stream-partitions" : [ { "system" : "kafka", "partition" : 1, "stream" : "test_topic1" }, { "system" : "kafka", "partition" : 1, "stream" : "test_topic2" } ], "changelog-partition" : 1 } }, "container-id" : 0, "processor-id" : "0" } }, "max-change-log-stream-partitions" : 2, "all-container-locality" : { "0" : null } } -----Original Message----- From: Thunder Stumpges [mailto:tstump...@ntent.com] Sent: Friday, March 16, 2018 18:21 To: dev@samza.apache.org Cc: Jagadish Venkatraman <jagadish1...@gmail.com>; t...@recursivedream.com; yi...@linkedin.com; Yi Pan <nickpa...@gmail.com> Subject: RE: Old style "low level" Tasks with alternative deployment model(s) Attached. I don't see any threads actually running this code which is odd. There's my main thread that's waiting for the whole thing to finish, the "debounce-thread-0" (which logged the other surrounding messages below) has this: "debounce-thread-0" #18 daemon prio=5 os_prio=0 tid=0x00007fa0fd719800 nid=0x21 waiting on condition [0x00007fa0d0d45000] java.lang.Thread.State: WAITING (parking) at sun.misc.Unsafe.park(Native Method) - parking to wait for <0x00000006f166e350> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject) at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175) at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039) at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:1081) at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:809) at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1067) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1127) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) at java.lang.Thread.run(Thread.java:745) Locked ownable synchronizers: - None Thanks for having a look. Thunder -----Original Message----- From: Prateek Maheshwari [mailto:prateek...@gmail.com] Sent: Friday, March 16, 2018 17:02 To: dev@samza.apache.org Cc: Jagadish Venkatraman <jagadish1...@gmail.com>; t...@recursivedream.com; yi...@linkedin.com; Yi Pan <nickpa...@gmail.com> Subject: Re: Old style "low level" Tasks with alternative deployment model(s) Hi Thunder, Can you please take and attach a thread dump with this? Thanks, Prateek On Fri, Mar 16, 2018 at 4:47 PM, Thunder Stumpges <tstump...@ntent.com> wrote: > It appears it IS hung while serializing the JobModel... very strange! > I added some debug statements around the calls: > > LOG.debug("Getting object mapper to serialize job model"); // > this IS printed > ObjectMapper mmapper = SamzaObjectMapper.getObjectMapper(); > LOG.debug("Serializing job model"); // this IS printed > String jobModelStr = mmapper.writerWithDefaultPrettyPrinter > ().writeValueAsString(jobModel); > LOG.info("jobModelAsString=" + jobModelStr); // this is NOT printed! > > Another thing I noticed is that "getObjectMapper" actually creates the > object mapper twice! > > 2018-03-16 23:09:24 logback 24985 [debounce-thread-0] DEBUG > org.apache.samza.zk.ZkUtils - Getting object mapper to serialize job > model > 2018-03-16 23:09:24 logback 24994 [debounce-thread-0] DEBUG > o.a.s.s.model.SamzaObjectMapper > - Creating new object mapper and simple module > 2018-03-16 23:09:24 logback 25178 [debounce-thread-0] DEBUG > o.a.s.s.model.SamzaObjectMapper > - Adding SerDes and mixins > 2018-03-16 23:09:24 logback 25183 [debounce-thread-0] DEBUG > o.a.s.s.model.SamzaObjectMapper > - Adding custom ContainerModel deserializer > 2018-03-16 23:09:24 logback 25184 [debounce-thread-0] DEBUG > o.a.s.s.model.SamzaObjectMapper > - Setting up naming strategy and registering module > 2018-03-16 23:09:24 logback 25187 [debounce-thread-0] DEBUG > o.a.s.s.model.SamzaObjectMapper > - Done! > 2018-03-16 23:09:24 logback 25187 [debounce-thread-0] DEBUG > o.a.s.s.model.SamzaObjectMapper > - Creating new object mapper and simple module > 2018-03-16 23:09:24 logback 25187 [debounce-thread-0] DEBUG > o.a.s.s.model.SamzaObjectMapper > - Adding SerDes and mixins > 2018-03-16 23:09:24 logback 25187 [debounce-thread-0] DEBUG > o.a.s.s.model.SamzaObjectMapper > - Adding custom ContainerModel deserializer > 2018-03-16 23:09:24 logback 25187 [debounce-thread-0] DEBUG > o.a.s.s.model.SamzaObjectMapper > - Setting up naming strategy and registering module > 2018-03-16 23:09:24 logback 25187 [debounce-thread-0] DEBUG > o.a.s.s.model.SamzaObjectMapper > - Done! > 2018-03-16 23:09:24 logback 25187 [debounce-thread-0] DEBUG > org.apache.samza.zk.ZkUtils - Serializing job model > > Could this ObjectMapper be a singleton? I see there is a private > static instance, but getObjectMapper creates a new one every time... > > Anyway, then it takes off to serialize the job model and never comes > back... > > Hoping someone has some idea here... the implementation for this > mostly comes from Jackson-mapper-asl, and I have the version that is > linked in the > 0.14.0 tag: > | | | +--- org.codehaus.jackson:jackson-mapper-asl:1.9.13 > | | | | \--- org.codehaus.jackson:jackson-core-asl:1.9.13 > > Thanks! > Thunder > > -----Original Message----- > From: Thunder Stumpges [mailto:tstump...@ntent.com] > Sent: Friday, March 16, 2018 15:29 > To: dev@samza.apache.org; Jagadish Venkatraman > <jagadish1...@gmail.com> > Cc: t...@recursivedream.com; yi...@linkedin.com; Yi Pan < > nickpa...@gmail.com> > Subject: RE: Old style "low level" Tasks with alternative deployment > model(s) > > So, my investigation starts at StreamProcessor.java. Line 294 in > method > onNewJobModel() logs an INFO message that it's starting a container. > This message never appears. > > I see that ZkJobCoordinator calls onNewJobModel from its > onNewJobModelConfirmed method which also logs an info message stating > "version X of the job model got confirmed". I never see this message > either, so I go up the chain some more. > > I DO see: > > 2018-03-16 21:43:58 logback 20498 > [ZkClient-EventThread-13-10.0.127.114:2181] > INFO o.apache.samza.zk.ZkJobCoordinator - > ZkJobCoordinator::onBecomeLeader > - I became the leader! > And > 2018-03-16 21:44:18 logback 40712 [debounce-thread-0] INFO > o.apache.samza.zk.ZkJobCoordinator - > pid=91e07d20-ae33-4156-a5f3-534a95642133Generated > new Job Model. Version = 1 > > Which led me to method onDoProcessorChange line 210. I see that line, > but not the line below " Published new Job Model. Version =" so > something in here is not completing: > > LOG.info("pid=" + processorId + "Generated new Job Model. Version = " > + nextJMVersion); > > // Publish the new job model > zkUtils.publishJobModel(nextJMVersion, jobModel); > > // Start the barrier for the job model update > barrier.create(nextJMVersion, currentProcessorIds); > > // Notify all processors about the new JobModel by updating > JobModel Version number > zkUtils.publishJobModelVersion(currentJMVersion, nextJMVersion); > > LOG.info("pid=" + processorId + "Published new Job Model. Version = " > + nextJMVersion); > > As I mentioned, after the line "Generated new Job Model. Version = 1" > I just get repeated zk ping responses.. no more application logging. > > The very next thing that's run is zkUtils.publishJobModel() which only > has two lines before another log statement (which I don't see): > > public void publishJobModel(String jobModelVersion, JobModel jobModel) { > try { > ObjectMapper mmapper = SamzaObjectMapper.getObjectMapper(); > String jobModelStr = mmapper.writerWithDefaultPrettyPrinter > ().writeValueAsString(jobModel); > LOG.info("jobModelAsString=" + jobModelStr); > ... > > Could it really be getting hung up on one of these two lines? (seems > like it must be, but I don't see anything there that seems like it > would just hang). I'll keep troubleshooting, maybe add some more debug > logging and try again. > > Thanks for any guidance you all might have. > -Thunder > > > -----Original Message----- > From: Thunder Stumpges [mailto:tstump...@ntent.com] > Sent: Friday, March 16, 2018 14:43 > To: dev@samza.apache.org; Jagadish Venkatraman > <jagadish1...@gmail.com> > Cc: t...@recursivedream.com; yi...@linkedin.com; Yi Pan < > nickpa...@gmail.com> > Subject: RE: Old style "low level" Tasks with alternative deployment > model(s) > > Well I have my stand-alone application in docker and running in > kubernetes. I think something isn't wired up all the way though, > because my task never actually gets invoked. I see no errors, however > I'm not getting the usual startup logs (checking existing offsets, > "entering run loop"...) My logs look like this: > > 2018-03-16 21:05:55 logback 50797 [debounce-thread-0] INFO > kafka.utils.VerifiableProperties > - Verifying properties > 2018-03-16 21:05:55 logback 50797 [debounce-thread-0] INFO > kafka.utils.VerifiableProperties > - Property client.id is overridden to samza_admin-test_stream_task-1 > 2018-03-16 21:05:55 logback 50798 [debounce-thread-0] INFO > kafka.utils.VerifiableProperties > - Property metadata.broker.list is overridden to > test-kafka-kafka.test-svc:9092 > 2018-03-16 21:05:55 logback 50798 [debounce-thread-0] INFO > kafka.utils.VerifiableProperties > - Property request.timeout.ms is overridden to 30000 > 2018-03-16 21:05:55 logback 50799 [debounce-thread-0] INFO > kafka.client.ClientUtils$ - Fetching metadata from broker > BrokerEndPoint(0,test-kafka-kafka.test-svc,9092) with correlation id 0 > for 1 topic(s) Set(dev_k8s.samza.test.topic) > 2018-03-16 21:05:55 logback 50800 [debounce-thread-0] DEBUG > kafka.network.BlockingChannel - Created socket with SO_TIMEOUT = 30000 > (requested 30000), SO_RCVBUF = 179680 (requested -1), SO_SNDBUF = > 102400 (requested 102400), connectTimeoutMs = 30000. > 2018-03-16 21:05:55 logback 50800 [debounce-thread-0] INFO > kafka.producer.SyncProducer - Connected to > test-kafka-kafka.test-svc:9092 for producing > 2018-03-16 21:05:55 logback 50804 [debounce-thread-0] INFO > kafka.producer.SyncProducer - Disconnecting from > test-kafka-kafka.test-svc:9092 > 2018-03-16 21:05:55 logback 50804 [debounce-thread-0] DEBUG > kafka.client.ClientUtils$ - Successfully fetched metadata for 1 > topic(s) > Set(dev_k8s.samza.test.topic) > 2018-03-16 21:05:55 logback 50813 [debounce-thread-0] INFO > o.a.s.coordinator.JobModelManager$ - SystemStreamPartitionGrouper > org.apache.samza.container.grouper.stream.GroupByPartition@1a7158cc > has grouped the SystemStreamPartitions into 10 tasks with the > following > taskNames: [Partition 1, Partition 0, Partition 3, Partition 2, > Partition 5, Partition 4, Partition 7, Partition 6, Partition 9, > Partition 8] > 2018-03-16 21:05:55 logback 50818 [debounce-thread-0] INFO > o.a.s.coordinator.JobModelManager$ - New task Partition 0 is being > assigned changelog partition 0. > 2018-03-16 21:05:55 logback 50819 [debounce-thread-0] INFO > o.a.s.coordinator.JobModelManager$ - New task Partition 1 is being > assigned changelog partition 1. > 2018-03-16 21:05:55 logback 50820 [debounce-thread-0] INFO > o.a.s.coordinator.JobModelManager$ - New task Partition 2 is being > assigned changelog partition 2. > 2018-03-16 21:05:55 logback 50820 [debounce-thread-0] INFO > o.a.s.coordinator.JobModelManager$ - New task Partition 3 is being > assigned changelog partition 3. > 2018-03-16 21:05:55 logback 50820 [debounce-thread-0] INFO > o.a.s.coordinator.JobModelManager$ - New task Partition 4 is being > assigned changelog partition 4. > 2018-03-16 21:05:55 logback 50820 [debounce-thread-0] INFO > o.a.s.coordinator.JobModelManager$ - New task Partition 5 is being > assigned changelog partition 5. > 2018-03-16 21:05:55 logback 50820 [debounce-thread-0] INFO > o.a.s.coordinator.JobModelManager$ - New task Partition 6 is being > assigned changelog partition 6. > 2018-03-16 21:05:55 logback 50820 [debounce-thread-0] INFO > o.a.s.coordinator.JobModelManager$ - New task Partition 7 is being > assigned changelog partition 7. > 2018-03-16 21:05:55 logback 50820 [debounce-thread-0] INFO > o.a.s.coordinator.JobModelManager$ - New task Partition 8 is being > assigned changelog partition 8. > 2018-03-16 21:05:55 logback 50820 [debounce-thread-0] INFO > o.a.s.coordinator.JobModelManager$ - New task Partition 9 is being > assigned changelog partition 9. > 2018-03-16 21:05:55 logback 50838 [main-SendThread(10.0.127.114:2181)] > DEBUG org.apache.zookeeper.ClientCnxn - Reading reply > sessionid:0x1622c8b5fc01ac7, packet:: clientPath:null serverPath:null > finished:false header:: 23,4 replyHeader:: 23,14024,0 request:: > '/app-test_stream_task-1/dev_test_stream_task-1-coordinationData/ > JobModelGeneration/jobModelVersion,T response:: > ,s{13878,13878,1521234010089,1521234010089,0,0,0,0,0,0,13878} > 2018-03-16 21:05:55 logback 50838 [debounce-thread-0] INFO > o.apache.samza.zk.ZkJobCoordinator - > pid=a14a0434-a238-4ff6-935b-c78d906fe80dGenerated > new Job Model. Version = 1 > 2018-03-16 21:06:05 logback 60848 [main-SendThread(10.0.127.114:2181)] > DEBUG org.apache.zookeeper.ClientCnxn - Got ping response for sessionid: > 0x1622c8b5fc01ac7 after 2ms > 2018-03-16 21:06:15 logback 70856 [main-SendThread(10.0.127.114:2181)] > DEBUG org.apache.zookeeper.ClientCnxn - Got ping response for sessionid: > 0x1622c8b5fc01ac7 after 1ms > 2018-03-16 21:06:25 logback 80865 [main-SendThread(10.0.127.114:2181)] > DEBUG org.apache.zookeeper.ClientCnxn - Got ping response for sessionid: > 0x1622c8b5fc01ac7 after 2ms ... > > The zk ping responses continue every 10 seconds, but no other activity > or messages occur. > It looks like it gets as far as confirming the JobModel and grouping > the partitions, but nothing actually starts up. > > Any ideas? > Thanks in advance! > Thunder > > > -----Original Message----- > From: Thunder Stumpges [mailto:tstump...@ntent.com] > Sent: Thursday, March 15, 2018 16:35 > To: Jagadish Venkatraman <jagadish1...@gmail.com> > Cc: dev@samza.apache.org; t...@recursivedream.com; yi...@linkedin.com; > Yi Pan <nickpa...@gmail.com> > Subject: RE: Old style "low level" Tasks with alternative deployment > model(s) > > Thanks a lot for the info. I have something basically working at this > point! I have not integrated it with Docker nor Kubernetes yet, but it > does run from my local machine. > > I have determined that LocalApplicationRunner does NOT do config > rewriting. I had to write my own little “StandAloneApplicationRunner” > that handles the “main” entrypoint. It does command parsing using > CommandLine, load config from ConfigFactory, and perform rewriting > before creating the new instance of LocalApplicationRunner. This is > all my StandAloneApplicationRunner contains: > > > object StandAloneSamzaRunner extends App with LazyLogging { > > // parse command line args just like JobRunner. > val cmdline = new ApplicationRunnerCommandLine > val options = cmdline.parser.parse(args: _*) > val config = cmdline.loadConfig(options) > > val runner = new LocalApplicationRunner(Util.rewriteConfig(config)) > runner.runTask() > runner.waitForFinish() > } > > The only config settings I needed to make to use this runner were > (easily configured due to our central Consul config system and our rewriter) : > > # use the ZK based job coordinator > job.coordinator.factory=org.apache.samza.zk.ZkJobCoordinatorFactory > # need to use GroupByContainerIds instead of GroupByContainerCount > task.name.grouper.factory=org.apache.samza.container.grouper.task. > GroupByContainerIdsFactory > # ZKJC config > job.coordinator.zk.connect=<our_zk_connection> > > I did run into one potential problem; as you see above, I have started > the task using runTask() and then to prevent my main method from > returning, I have called waitForFinish(). The first time I ran it, the > job itself failed because I had forgotten to override the task > grouper, and container count was pulled from our staging environment. > There are some failures logged and it appears the JobCoordinator > fails, but it never returns from waitForFinish. Stack trace and continuation > of log is below: > > 2018-03-15 22:34:32 logback 77786 [debounce-thread-0] ERROR > o.a.s.zk.ScheduleAfterDebounceTime > - Execution of action: OnProcessorChange failed. > java.lang.IllegalArgumentException: Your container count (4) is larger > than your task count (2). Can't have containers with nothing to do, so > aborting. > at org.apache.samza.container.grouper.task.GroupByContainerCount. > validateTasks(GroupByContainerCount.java:212) > at org.apache.samza.container.grouper.task. > GroupByContainerCount.group(GroupByContainerCount.java:62) > at org.apache.samza.container.grouper.task.TaskNameGrouper. > group(TaskNameGrouper.java:56) > at org.apache.samza.coordinator.JobModelManager$.readJobModel( > JobModelManager.scala:266) > at org.apache.samza.coordinator.JobModelManager.readJobModel( > JobModelManager.scala) > at org.apache.samza.zk.ZkJobCoordinator.generateNewJobModel( > ZkJobCoordinator.java:306) > at org.apache.samza.zk.ZkJobCoordinator.doOnProcessorChange( > ZkJobCoordinator.java:197) > at org.apache.samza.zk.ZkJobCoordinator$LeaderElectorListenerImpl. > lambda$onBecomingLeader$0(ZkJobCoordinator.java:318) > at org.apache.samza.zk.ScheduleAfterDebounceTime. > lambda$getScheduleableAction$0(ScheduleAfterDebounceTime.java:134) > at java.util.concurrent.Executors$RunnableAdapter. > call$$$capture(Executors.java:511) > at java.util.concurrent.Executors$RunnableAdapter. > call(Executors.java) > at java.util.concurrent.FutureTask.run$$$capture( > FutureTask.java:266) > at java.util.concurrent.FutureTask.run(FutureTask.java) > at java.util.concurrent.ScheduledThreadPoolExecutor$ > ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180) > at java.util.concurrent.ScheduledThreadPoolExecutor$ > ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293) > at java.util.concurrent.ThreadPoolExecutor.runWorker( > ThreadPoolExecutor.java:1142) > at java.util.concurrent.ThreadPoolExecutor$Worker.run( > ThreadPoolExecutor.java:617) > at java.lang.Thread.run(Thread.java:745) > 2018-03-15 22:34:32 logback 77787 [debounce-thread-0] DEBUG > o.a.samza.processor.StreamProcessor - Container is not instantiated yet. > 2018-03-15 22:34:32 logback 77787 [debounce-thread-0] DEBUG > org.I0Itec.zkclient.ZkClient - Closing ZkClient... > 2018-03-15 22:34:32 logback 77789 > [ZkClient-EventThread-15-10.0.127.114:2181] > INFO org.I0Itec.zkclient.ZkEventThread - Terminate ZkClient event thread. > > And then the application continues on with metric reporters, and other > debug logging (not actually running the task though) > > Thanks in advance for the guidance, this has been easier than I imagined! > I’ll report back when I get more of the Dockerization/Kubernetes > running and test it a bit more. > Cheers, > Thunder > > > From: Jagadish Venkatraman [mailto:jagadish1...@gmail.com] > Sent: Thursday, March 15, 2018 14:46 > To: Thunder Stumpges <tstump...@ntent.com> > Cc: dev@samza.apache.org; t...@recursivedream.com; yi...@linkedin.com; > Yi Pan <nickpa...@gmail.com> > Subject: Re: Old style "low level" Tasks with alternative deployment > model(s) > > >> Thanks for the info on the tradeoffs. That makes a lot of sense. I > >> am > on-board with using ZkJobCoordinator, sounds like some good benefits > over just the Kafka high-level consumer. > > This certainly looks like the simplest alternative. > > For your other questions, please find my answers inline. > > >> Q1: If I use LocalApplicationRunner, It does not use > "ProcessJobFactory" (or any StreamJob or *Job classes) correct? > > Your understanding is correct. It directly instantiates the > StreamProcessor, which in-turn creates and runs the SamzaContainer. > > >> Q2: If I use LocalApplicationRunner, I will need to code myself the > loading and rewriting of the Config that is currently handled by > JobRunner, correct? > > I don't think you'll need to do this. IIUC, the LocalApplicationRunner > should automatically invoke rewriters and do the right thing. > > >> Q3: Do I need to also handle coordinator stream(s) and storing of > config that is done in JobRunner (I don’t think so as the ? > > I don't think this is necessary either. The creation of coordinator > stream and persisting configuration happens in the > LocalApplicationRunner (more specifically in StreamManager#createStreams). > > >> Q4: Where/How do I specify the Container ID for each instance? Is > >> there > a config setting that I can pass, (or pull from an env variable and > add to the config) ? I am assuming it is my responsibility to ensure > that each instance is started with a unique container ID..? > > Nope, If you are using the ZkJobCoordinator, you need not have to > worry about assigning IDs for each instance. The framework will > automatically take care of generating IDs and reaching consensus by > electing a leader. If you are curious please take a look at > implementations of the ProcessorIdGenerator interface. > > Please let us know should you have further questions! > > Best, > Jagdish > > On Thu, Mar 15, 2018 at 11:48 AM, Thunder Stumpges > <tstump...@ntent.com <mailto:tstump...@ntent.com>> wrote: > > Thanks for the info on the tradeoffs. That makes a lot of sense. I am > on-board with using ZkJobCoordinator, sounds like some good benefits > over just the Kafka high-level consumer. > > > > To that end, I have made some notes on possible approaches based on > the previous thread, and from my look into the code. I’d love to get feedback. > > > > Approach 1. Configure jobs to use “ProcessJobFactory” and run > instances of the job using run-job.sh or using JobRunner directly. > > I don’t think this makes sense from what I can see for a few reasons: > > * JobRunner is concerned with stuff I don't *think* we need: > > * coordinatorSystemProducer|Consumer, > * writing/reading the configuration to the coordinator streams > > * ProcessJobFactory hard-codes the ID to “0” so I don’t think that > will work for multiple instances. > > > > Approach 2. Configure ZkJobCoordinator, GroupByContainerIds, and > invoke > LocalApplicationRunner.runTask() > > > > Q1: If I use LocalApplicationRunner, It does not use > "ProcessJobFactory" (or any StreamJob or *Job classes) correct? > > Q2: If I use LocalApplicationRunner, I will need to code myself > the loading and rewriting of the Config that is currently handled by > JobRunner, correct? > > Q3: Do I need to also handle coordinator stream(s) and storing of > config that is done in JobRunner (I don’t think so as the ? > > Q4: Where/How do I specify the Container ID for each instance? Is > there a config setting that I can pass, (or pull from an env variable > and add to the config) ? I am assuming it is my responsibility to > ensure that each instance is started with a unique container ID..? > > I am getting started on the above (Approach 2.), and looking closer at > the code so I may have my own answers to my questions, but figured I > should go ahead and ask now anyway. Thanks! > > -Thunder > > > From: Jagadish Venkatraman [mailto:jagadish1...@gmail.com<mailto: > jagadish1...@gmail.com>] > Sent: Thursday, March 15, 2018 1:41 > To: dev@samza.apache.org<mailto:dev@samza.apache.org>; Thunder > Stumpges < tstump...@ntent.com<mailto:tstump...@ntent.com>>; > t...@recursivedream.com <mailto:t...@recursivedream.com> > Cc: yi...@linkedin.com<mailto:yi...@linkedin.com>; Yi Pan < > nickpa...@gmail.com<mailto:nickpa...@gmail.com>> > > Subject: Re: Old style "low level" Tasks with alternative deployment > model(s) > > >> You are correct that this is focused on the higher-level API but > >> doesn't > preclude using the lower-level API. I was at the same point you were > not long ago, in fact, and had a very productive conversation on the > list > > Thanks Tom for linking the thread, and I'm glad that you were able to > get Kubernetes integration working with Samza. > > >> If it is helpful for everyone, once I get the low-level API + > >> ZkJobCoordinator + Docker + > K8s working, I'd be glad to formulate an additional sample for hello-samza. > > @Thunder Stumpges: > We'd be thrilled to receive your contribution. Examples, demos, > tutorials etc. > contribute a great deal to improving the ease of use of Apache Samza. > I'm happy to shepherd design discussions/code-reviews in the > open-source including answering any questions you may have. > > > >> One thing I'm still curious about, is what are the drawbacks or > >> complexities of leveraging the Kafka High-level consumer + > >> PassthroughJobCoordinator in a stand-alone setup like this? We do > >> have Zookeeper (because of kafka) so I think either would work. The > >> Kafka High-level consumer comes with other nice tools for > >> monitoring offsets, lag, etc > > > @Thunder Stumpges: > > Samza uses a "Job-Coordinator" to assign your input-partitions among > the different instances of your application s.t. they don't overlap. A > typical way to solve this "partition distribution" > problem is to have a single instance elected as a "leader" and have > the leader assign partitions to the group. > The ZkJobCoordinator uses Zk primitives to achieve this, while the > YarnJC relies on Yarn's guarantee that there will be a > singleton-AppMaster to achieve this. > > A key difference that separates the PassthroughJC from the Yarn/Zk > variants is that it does _not_ attempt to solve the "partition > distribution" problem. As a result, there's no leader-election involved. > Instead, it pushes the problem of "partition distribution" to the > underlying consumer. > > The PassThroughJc supports these 2 scenarios: > > 1. Consumer-managed partition distribution: When using the Kafka > high-level consumer (or an AWS KinesisClientLibrary consumer) with > Samza, the consumer manages partitions internally. > > 2. Static partition distribution: Alternately, partitions can be > managed statically using configuration. You can achieve static > partition assignment by implementing a custom > SystemStreamPartitionGrouper<h > ttps://samza.apache.org/learn/documentation/0.8/api/ > javadocs/org/apache/samza/container/grouper/stream/ > SystemStreamPartitionGrouper.html> and TaskNameGrouper<https:// > github.com/apache/samza/blob/master/samza-core/src/main/ > java/org/apache/samza/container/grouper/task/TaskNameGrouper.java>. > Solutions in this category will typically require you to distinguish > the various processors in the group by providing an "id" for each. > Once the "id"s are decided, you can then statically compute > assignments using a function (eg: modulo N). > You can rely on the following mechanisms to provide this id: > - Configure each instance differently to have its own id > - Obtain the id from the cluster-manager. For instance, Kubernetes > will provide each POD an unique id in the range [0,N). AWS ECS should > expose similar capabilities via a REST end-point. > > >> One thing I'm still curious about, is what are the drawbacks or > complexities of leveraging the Kafka High-level consumer + > PassthroughJobCoordinator in a stand-alone setup like this? > > Leveraging the Kafka High-level consumer: > > The Kafka high-level consumer is not integrated into Samza just yet. > Instead, Samza's integration with Kafka uses the low-level consumer > because > i) It allows for greater control in fetching data from individual brokers. > It is simple and performant in-terms of the threading model to have > one-thread pull from each broker. > ii) It is efficient in memory utilization since it does not do > internal-buffering of messages. > iii) There's no overhead like Kafka-controller heart-beats that are > driven by consumer.poll > > Since there's no built-in integration, you will have to build a new > SystemConsumer if you need to integrate with the Kafka High-level consumer. > Further, there's more a fair bit of complexity to manage in checkpointing. > > >> The Kafka High-level consumer comes with other nice tools for > >> monitoring offsets, lag, etc > > Samza exposes<https://github.com/apache/samza/blob/master/ > samza-kafka/src/main/scala/org/apache/samza/system/kafka/ > KafkaSystemConsumerMetrics.scala> the below metrics for lag-monitoring: > - The current log-end offset for each partition > - The last check-pointed offset for each partition > - The number of messages behind the highwatermark of the partition > > Please let us know if you need help discovering these or integrating > these with other systems/tools. > > > Leveraging the Passthrough JobCoordinator: > > It's helpful to split this discussion on tradeoffs with PassthroughJC > into > 2 parts: > > 1. PassthroughJC + consumer managed partitions: > > - In this model, Samza has no control over partition-assignment since > it's managed by the consumer. This means that stateful operations like > joins that rely on partitions being co-located on the same task will not work. > Simple stateless operations (eg: map, filter, remote lookups) are fine. > > - A key differentiator between Samza and other frameworks is our > support for "host > affinity<https://samza.apache.org/learn/documentation/0.14/ > yarn/yarn-host-affinity.html>". Samza achieves this by assigning > partitions to hosts taking data-locality into account. If the consumer > can arbitrarily shuffle partitions, it'd be hard to support this > affinity/locality. Often this is a key optimization when dealing with > large stateful jobs. > > 2. PassthroughJC + static partitions: > > - In this model, it is possible to make stateful processing (including > host affinity) work by carefully choosing how "id"s are assigned and > computed. > > Recommendation: > > - Owing to the above subtleties, I would recommend that we give the > ZkJobCoordinator + the built-in low-level Kafka integration a try. > - If we hit snags down this path, we can certainly explore the > approach with PassthroughJC + static partitions. > - Using the PassthroughJC + consumer-managed distribution would be > least preferable owing to the subtleties I outlined above. > > Please let us know should you have more questions. > > Best, > Jagdish > > On Wed, Mar 14, 2018 at 9:24 PM, Thunder Stumpges <tstump...@ntent.com > <mailto:tstump...@ntent.com>> wrote: > Wow, what great timing, and what a great thread! I definitely have > some good starters to go off of here. > > If it is helpful for everyone, once I get the low-level API + > ZkJobCoordinator + Docker + K8s working, I'd be glad to formulate an > additional sample for hello-samza. > > One thing I'm still curious about, is what are the drawbacks or > complexities of leveraging the Kafka High-level consumer + > PassthroughJobCoordinator in a stand-alone setup like this? We do have > Zookeeper (because of kafka) so I think either would work. The Kafka > High-level consumer comes with other nice tools for monitoring > offsets, lag, etc.... > > Thanks guys! > -Thunder > > -----Original Message----- > From: Tom Davis [mailto:t...@recursivedream.com<mailto: > t...@recursivedream.com>] > Sent: Wednesday, March 14, 2018 17:50 > To: dev@samza.apache.org<mailto:dev@samza.apache.org> > Subject: Re: Old style "low level" Tasks with alternative deployment > model(s) > > Hey there! > > You are correct that this is focused on the higher-level API but > doesn't preclude using the lower-level API. I was at the same point > you were not long ago, in fact, and had a very productive conversation on the > list: > you should look for "Question about custom StreamJob/Factory" in the > list archive for the past couple months. > > I'll quote Jagadish Venkatraman from that thread: > > > For the section on the low-level API, can you use > > LocalApplicationRunner#runTask()? It basically creates a new > > StreamProcessor and runs it. Remember to provide task.class and set > > it to your implementation of StreamTask or AsyncStreamTask. Please > > note that this is an evolving API and hence, subject to change. > > I ended up just switching to the high-level API because I don't have > any existing Tasks and the Kubernetes story is a little more straight > forward there (there's only one container/configuration to deploy). > > Best, > > Tom > > Thunder Stumpges <tstump...@ntent.com<mailto:tstump...@ntent.com>> writes: > > > Hi all, > > > > We are using Samza (0.12.0) in about 2 dozen jobs implementing > > several processing pipelines. We have also begun a significant move > > of other services within our company to Docker/Kubernetes. Right now > > our Hadoop/Yarn cluster has a mix of stream and batch "Map Reduce" > > jobs > (many reporting and other batch processing jobs). We would really like > to move our stream processing off of Hadoop/Yarn and onto Kubernetes. > > > > When I just read about some of the new progress in .13 and .14 I got > > really excited! We would love to have our jobs run as simple > > libraries in our own JVM, and use the Kafka High-Level-Consumer for > > partition > distribution and such. This would let us "dockerfy" our application > and run/scale in kubernetes. > > > > However as I read it, this new deployment model is ONLY for the > > new(er) High Level API, correct? Is there a plan and/or resources > > for adapting this back to existing low-level tasks ? How complicated > > of a > task is that? Do I have any other options to make this transition easier? > > > > Thanks in advance. > > Thunder > > > > -- > Jagadish V, > Graduate Student, > Department of Computer Science, > Stanford University > > > > -- > Jagadish V, > Graduate Student, > Department of Computer Science, > Stanford University >
