Hi For idle shards, I think restore from the previous not consumed data is ok, because Flink did not consume any data before, but for not idle shards this is problematic. From my experience of other connectors, could you check whether the "error" shards are newly split? maybe the newly split shards were not contained in the checkpoint.
Best, Congxian Steven Nelson <snel...@sourceallies.com> 于2019年10月17日周四 上午2:19写道： > In my situation I believe it's because we have idle shards (it's a testing > environment). I dug into the connector code and it looks like it only > updates the shard state when a record is processed or when the shard hits > shard_end. So, for an idle shard it would never get a checkpointed state. I > guess this is okay since in production we won't have idle shards, but it > might be better to send through a empty record that doesn't get emitted, > but it does trigger a state update. > > -Steve > > > On Wed, Oct 16, 2019 at 12:54 PM Ravi Bhushan Ratnakar < > ravibhushanratna...@gmail.com> wrote: > >> Do you know step by step process to reproduce this problem? >> >> -Ravi >> >> >> On Wed 16 Oct, 2019, 17:40 Steven Nelson, <snel...@sourceallies.com> >> wrote: >> >>> I have verified this behavior in 1.9.0, 1.8.1 and 1.7.2. >>> >>> About half my shards start over at trim horizon. Why would some shard >>> statuses appear to not exist in a savepoints? This seems like a big problem. >>> >>> -Steve >>> >>> On Wed, Oct 16, 2019 at 12:08 AM Ravi Bhushan Ratnakar < >>> ravibhushanratna...@gmail.com> wrote: >>> >>>> Hi, >>>> >>>> I am also facing the same problem. I am using Flink 1.9.0 and consuming >>>> from Kinesis source with retention of 1 day. I am observing that when the >>>> job is submitted with "latest" initial stream position, the job starts well >>>> and keep on processing data from all the shards for very long period of >>>> time without any lag. When the job fails then it also recovery well with >>>> last successful checkpointed state. But i am also experiencing that very >>>> rarely when the job fails and it recovers from the last successful >>>> checkpointed state, i noticed a hug lag( 1 day as per retention) on one of >>>> the stream. For me, to reproduce this issue is still unknown to defined a >>>> step by step process. >>>> >>>> So far now, as per the analysis i gathered some more information by >>>> customizing the FlinkKinesisConsumer to put additional log message, I >>>> noticed that the number of shards details which is loaded from checkpoint >>>> data during recovering is less than than the actual number of shards in the >>>> stream. I have fixed number of shards in kinesis stream. >>>> >>>> i added one line of debug log at line 408 to print the size of variable >>>> "sequenceNumsToRestore" which was populated with shard details from >>>> checkpoint data. >>>> >>>> https://github.com/apache/flink/blob/master/flink-connectors/flink-connector-kinesis/src/main/java/org/apache/flink/streaming/connectors/kinesis/FlinkKinesisConsumer.java#L408 >>>> >>>> In this consumer class, when the "run" method is called, it does >>>> following >>>> >>>> - it discover shards from kinesis stream and selects all those >>>> shards which a subtask can scheduled >>>> - then one by one it iterates over the discovers shards and checks >>>> that whether that shards state is available in recovered state >>>> "sequenceNumsToRestore" >>>> >>>> https://github.com/apache/flink/blob/master/flink-connectors/flink-connector-kinesis/src/main/java/org/apache/flink/streaming/connectors/kinesis/FlinkKinesisConsumer.java#L295 >>>> - if it is available then it scheduled that shard with the >>>> recovered state >>>> - if it is not available in the state then it shcedule that shard >>>> with "EARLIEST_SEQUENCE_NUMBER" >>>> >>>> https://github.com/apache/flink/blob/master/flink-connectors/flink-connector-kinesis/src/main/java/org/apache/flink/streaming/connectors/kinesis/FlinkKinesisConsumer.java#L308 >>>> >>>> As in my case, the recovered number of shard details from the >>>> checkpoint data is less than the actual number of shards which results into >>>> scheduling those shards with earliest stream position. >>>> I am suspecting that somehow the checkpoint is missing state for some >>>> of the shards. But if this is the case then that checkpoint should had >>>> failed. >>>> >>>> Any further information to resolve this issue would be highly >>>> appreciated... >>>> >>>> Regards, >>>> Ravi >>>> >>>> On Wed, Oct 16, 2019 at 5:57 AM Yun Tang <myas...@live.com> wrote: >>>> >>>>> Hi Steven >>>>> >>>>> If you restore savepoint/checkpoint successfully, I think this might >>>>> due to the shard wasn't discovered in the previous run, therefore it would >>>>> be consumed from the beginning. Please refer to the implementation here: >>>>> [1] >>>>> >>>>> [1] >>>>> https://github.com/apache/flink/blob/2c411686d23f456cdc502abf1c6b97a61070a17d/flink-connectors/flink-connector-kinesis/src/main/java/org/apache/flink/streaming/connectors/kinesis/FlinkKinesisConsumer.java#L307 >>>>> >>>>> Best >>>>> Yun Tang >>>>> ------------------------------ >>>>> *From:* Steven Nelson <snel...@sourceallies.com> >>>>> *Sent:* Wednesday, October 16, 2019 4:31 >>>>> *To:* user <user@flink.apache.org> >>>>> *Subject:* Kinesis Connector and Savepoint/Checkpoint restore. >>>>> >>>>> Hello, we currently use Flink 1.9.0 with Kinesis to process data. >>>>> >>>>> We have extended data retention on the Kinesis stream, which gives us >>>>> 7 days of data. >>>>> >>>>> We have found that when a savepoint/checkpoint is restored that it >>>>> appears to be restarting the Kinesis Consumer from the start of the >>>>> stream. >>>>> The >>>>> flink_taskmanager_job_task_operator_KinesisConsumer_stream_shardId_millisBehindLatest >>>>> property reports to Prometheus that it is behind by 7 days when the >>>>> process >>>>> starts back up from a savepoint. >>>>> >>>>> We have some logs that say: >>>>> >>>>> Subtask 3 will start consuming seeded shard >>>>> StreamShardHandle{streamName='TheStream', >>>>> shard='{ShardId: shardId-000000000083,HashKeyRange: {StartingHashKey: >>>>> 220651847300296034902031972006537199616,EndingHashKey: >>>>> 223310303291865866647839586127097888767},SequenceNumberRange: >>>>> {StartingSequenceNumber: >>>>> 49597946220601502339755334362523522663986150244033234226,}}'} from >>>>> sequence >>>>> number EARLIEST_SEQUENCE_NUM with ShardConsumer 20 >>>>> >>>>> This seems to indicate that this shard is starting from the beginning >>>>> of the stream >>>>> >>>>> and some logs that say: >>>>> Subtask 3 will start consuming seeded shard StreamShardHandle >>>>> {streamName=' TheStream ', shard='{ShardId: >>>>> shardId-000000000087,HashKeyRange: {StartingHashKey: >>>>> 231285671266575361885262428488779956224,EndingHashKey: >>>>> 233944127258145193631070042609340645375},SequenceNumberRange: >>>>> {StartingSequenceNumber: >>>>> 49597946220690705320549456855089665537076743690057155954,}}'} from >>>>> sequence >>>>> number 49599841594208637293623823226010128300928335129272649074 with >>>>> ShardConsumer 21 >>>>> >>>>> This shard seems to be resuming from a specific point. >>>>> >>>>> I am assuming that this might be caused by no data being available on >>>>> the shard for the entire stream (possible with this application stage). Is >>>>> this the expected behavior? I had thought it would checkpoint with the >>>>> most >>>>> recent sequence number, regardless of if it got data or not. >>>>> >>>>> -Steve >>>>> >>>>> >>>>>
