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From Susan Zhang <suchenz...@gmail.com>
Subject Re: Spark Streaming Checkpointing Restarts with 0 Event Batches
Date Wed, 26 Aug 2015 19:04:04 GMT
Compared offsets, and it continues from checkpoint loading:

15/08/26 11:24:54 INFO
DirectKafkaInputDStream$DirectKafkaInputDStreamCheckpointData: Restoring
KafkaRDD for time 1440612035000 ms [(install-json,5,826112083,826112446),
(install-json,4,825772921,825773536), (install-json,1,831654775,831655076),
(install-json,0,1296018451,1296018810),
(install-json,2,824785282,824785696), (install-json,3,
811428882,811429181)]

15/08/26 11:25:19 INFO kafka.KafkaRDD: Computing topic install-json,
partition 0 offsets 1296018451 -> 1296018810
15/08/26 11:25:28 INFO kafka.KafkaRDD: Computing topic install-json,
partition 4 offsets 825773536 -> 825907428
15/08/26 11:25:28 INFO kafka.KafkaRDD: Computing topic install-json,
partition 2 offsets 824785696 -> 824889957
15/08/26 11:25:28 INFO kafka.KafkaRDD: Computing topic install-json,
partition 3 offsets 811429181 -> 811529084
15/08/26 11:25:28 INFO kafka.KafkaRDD: Computing topic install-json,
partition 1 offsets 831655076 -> 831729964
...

But for some reason the streaming UI shows it as computing 0 events.

Removing the call to checkpoint does remove the queueing of 0 event
batches, since offsets just skip to the latest (checked that the first
part.fromOffset in the restarted job is larger than the last
part.untilOffset before restart).




On Wed, Aug 26, 2015 at 11:19 AM, Cody Koeninger <cody@koeninger.org> wrote:

> When the kafka rdd is actually being iterated on the worker, there should
> be an info line of the form
>
>     log.info(s"Computing topic ${part.topic}, partition ${part.partition}
> " +
>
>       s"offsets ${part.fromOffset} -> ${part.untilOffset}")
>
>
> You should be able to compare that to log of offsets during checkpoint
> loading, to see if they line up.
>
> Just out of curiosity, does removing the call to checkpoint on the stream
> affect anything?
>
>
>
> On Wed, Aug 26, 2015 at 1:04 PM, Susan Zhang <suchenzang@gmail.com> wrote:
>
>> Thanks for the suggestions! I tried the following:
>>
>> I removed
>>
>> createOnError = true
>>
>> And reran the same process to reproduce. Double checked that checkpoint
>> is loading:
>>
>> 15/08/26 10:10:40 INFO
>> DirectKafkaInputDStream$DirectKafkaInputDStreamCheckpointData: Restoring
>> KafkaRDD for time 1440608825000 ms [(install-json,5,825898270,825898528),
>> (install-json,4,825400856,825401058),
>> (install-json,1,831453228,831453396),
>> (install-json,0,1295759888,1295760378),
>> (install-json,2,824443526,824444409), (install-json,3,
>> 811222580,811222874)]
>> 15/08/26 10:10:40 INFO
>> DirectKafkaInputDStream$DirectKafkaInputDStreamCheckpointData: Restoring
>> KafkaRDD for time 1440608830000 ms [(install-json,5,825898528,825898791),
>> (install-json,4,825401058,825401249),
>> (install-json,1,831453396,831453603),
>> (install-json,0,1295760378,1295760809),
>> (install-json,2,824444409,824445510), (install-json,3,
>> 811222874,811223285)]
>> ...
>>
>> And the same issue is appearing as before (with 0 event batches getting
>> queued corresponding to dropped messages). Our kafka brokers are on version
>> 0.8.2.0, if that makes a difference.
>>
>> Also as a sanity check, I took out the ZK updates and reran (just in case
>> that was somehow causing problems), and that didn't change anything as
>> expected.
>>
>> Furthermore, the 0 event batches seem to take longer to process than
>> batches with the regular load of events: processing time for 0 event
>> batches can be upwards of 1 - 2 minutes, whereas processing time for ~2000
>> event batches is consistently < 1s. Why would that happen?
>>
>>
>> As for the checkpoint call:
>>
>> directKStream.checkpoint(checkpointDuration)
>>
>> was an attempt to set the checkpointing interval (at some multiple of the
>> batch interval), whereas StreamingContext.checkpoint seems like it will
>> only set the checkpoint directory.
>>
>>
>>
>> Thanks for all the help,
>>
>> Susan
>>
>>
>> On Wed, Aug 26, 2015 at 7:12 AM, Cody Koeninger <cody@koeninger.org>
>> wrote:
>>
>>> The first thing that stands out to me is
>>> createOnError = true
>>>
>>> Are you sure the checkpoint is actually loading, as opposed to failing
>>> and starting the job anyway?  There should be info lines that look like
>>>
>>> INFO DirectKafkaInputDStream$DirectKafkaInputDStreamCheckpointData:
>>> Restoring KafkaRDD for time 1440597180000 ms [(test,1,162,220)
>>>
>>>
>>> You should be able to tell from those whether the offset ranges being
>>> loaded from the checkpoint look reasonable.
>>>
>>> Also, is there a reason you're calling
>>>
>>> directKStream.checkpoint(checkpointDuration)
>>>
>>> Just calling checkpoint on the streaming context should be sufficient to
>>> save the metadata
>>>
>>>
>>>
>>> On Tue, Aug 25, 2015 at 2:36 PM, Susan Zhang <suchenzang@gmail.com>
>>> wrote:
>>>
>>>> Sure thing!
>>>>
>>>> The main looks like:
>>>>
>>>>
>>>> --------------------------------------------------------------------------------------------------
>>>>
>>>>
>>>> val kafkaBrokers = conf.getString(s"$varPrefix.metadata.broker.list")
>>>>
>>>> val kafkaConf = Map(
>>>>       "zookeeper.connect" -> zookeeper,
>>>>       "group.id" -> options.group,
>>>>       "zookeeper.connection.timeout.ms" -> "10000",
>>>>       "auto.commit.interval.ms" -> "1000",
>>>>       "rebalance.max.retries" -> "25",
>>>>       "bootstrap.servers" -> kafkaBrokers
>>>>     )
>>>>
>>>> val ssc = StreamingContext.getOrCreate(checkpointDirectory,
>>>>       () => {
>>>>         createContext(kafkaConf, checkpointDirectory, topic,
>>>> numThreads, isProd)
>>>>       }, createOnError = true)
>>>>
>>>> ssc.start()
>>>> ssc.awaitTermination()
>>>>
>>>>
>>>>
>>>> --------------------------------------------------------------------------------------------------
>>>>
>>>>
>>>> And createContext is defined as:
>>>>
>>>>
>>>>
>>>> --------------------------------------------------------------------------------------------------
>>>>
>>>>
>>>> val batchDuration = Seconds(5)
>>>> val checkpointDuration = Seconds(20)
>>>>
>>>> private val AUTO_OFFSET_COMMIT = "auto.commit.enable"
>>>>
>>>> def createContext(kafkaConf: Map[String, String],
>>>>                     checkpointDirectory: String,
>>>>                     topic: String,
>>>>                     numThreads: Int,
>>>>                     isProd: Boolean)
>>>>   : StreamingContext = {
>>>>
>>>>     val sparkConf = new SparkConf().setAppName("***")
>>>>     val ssc = new StreamingContext(sparkConf, batchDuration)
>>>>     ssc.checkpoint(checkpointDirectory)
>>>>
>>>>     val topicSet = topic.split(",").toSet
>>>>     val groupId = kafkaConf.getOrElse("group.id", "")
>>>>
>>>>     val directKStream = KafkaUtils.createDirectStream[String, String,
>>>> StringDecoder, StringDecoder](ssc, kafkaConf, topicSet)
>>>>     directKStream.checkpoint(checkpointDuration)
>>>>
>>>>     val table = ***
>>>>
>>>>     directKStream.foreachRDD { rdd =>
>>>>       val offsetRanges = rdd.asInstanceOf[HasOffsetRanges].offsetRanges
>>>>       rdd.flatMap(rec => someFunc(rec))
>>>>         .reduceByKey((i1: Long, i2: Long) => if (i1 > i2) i1 else i2)
>>>>         .foreachPartition { partitionRec =>
>>>>           val dbWrite = DynamoDBWriter()
>>>>           partitionRec.foreach {
>>>>             /* Update Dynamo Here */
>>>>           }
>>>>         }
>>>>
>>>>       /** Set up ZK Connection **/
>>>>       val props = new Properties()
>>>>       kafkaConf.foreach(param => props.put(param._1, param._2))
>>>>
>>>>       props.setProperty(AUTO_OFFSET_COMMIT, "false")
>>>>
>>>>       val consumerConfig = new ConsumerConfig(props)
>>>>       assert(!consumerConfig.autoCommitEnable)
>>>>
>>>>       val zkClient = new ZkClient(consumerConfig.zkConnect,
>>>> consumerConfig.zkSessionTimeoutMs,
>>>>         consumerConfig.zkConnectionTimeoutMs, ZKStringSerializer)
>>>>
>>>>       offsetRanges.foreach { osr =>
>>>>         val topicDirs = new ZKGroupTopicDirs(groupId, osr.topic)
>>>>         val zkPath = s"${topicDirs.consumerOffsetDir}/${osr.partition}"
>>>>         ZkUtils.updatePersistentPath(zkClient, zkPath,
>>>> osr.untilOffset.toString)
>>>>       }
>>>>     }
>>>>     ssc
>>>>   }
>>>>
>>>>
>>>>
>>>> On Tue, Aug 25, 2015 at 12:07 PM, Cody Koeninger <cody@koeninger.org>
>>>> wrote:
>>>>
>>>>> Sounds like something's not set up right... can you post a minimal
>>>>> code example that reproduces the issue?
>>>>>
>>>>> On Tue, Aug 25, 2015 at 1:40 PM, Susan Zhang <suchenzang@gmail.com>
>>>>> wrote:
>>>>>
>>>>>> Yeah. All messages are lost while the streaming job was down.
>>>>>>
>>>>>> On Tue, Aug 25, 2015 at 11:37 AM, Cody Koeninger <cody@koeninger.org>
>>>>>> wrote:
>>>>>>
>>>>>>> Are you actually losing messages then?
>>>>>>>
>>>>>>> On Tue, Aug 25, 2015 at 1:15 PM, Susan Zhang <suchenzang@gmail.com>
>>>>>>> wrote:
>>>>>>>
>>>>>>>> No; first batch only contains messages received after the
second
>>>>>>>> job starts (messages come in at a steady rate of about 400/second).
>>>>>>>>
>>>>>>>> On Tue, Aug 25, 2015 at 11:07 AM, Cody Koeninger <
>>>>>>>> cody@koeninger.org> wrote:
>>>>>>>>
>>>>>>>>> Does the first batch after restart contain all the messages
>>>>>>>>> received while the job was down?
>>>>>>>>>
>>>>>>>>> On Tue, Aug 25, 2015 at 12:53 PM, suchenzang <suchenzang@gmail.com
>>>>>>>>> > wrote:
>>>>>>>>>
>>>>>>>>>> Hello,
>>>>>>>>>>
>>>>>>>>>> I'm using direct spark streaming (from kafka) with
checkpointing,
>>>>>>>>>> and
>>>>>>>>>> everything works well until a restart. When I shut
down (^C) the
>>>>>>>>>> first
>>>>>>>>>> streaming job, wait 1 minute, then re-submit, there
is somehow a
>>>>>>>>>> series of 0
>>>>>>>>>> event batches that get queued (corresponding to the
1 minute when
>>>>>>>>>> the job
>>>>>>>>>> was down). Eventually, the batches would resume processing,
and I
>>>>>>>>>> would see
>>>>>>>>>> that each batch has roughly 2000 events.
>>>>>>>>>>
>>>>>>>>>> I see that at the beginning of the second launch,
the checkpoint
>>>>>>>>>> dirs are
>>>>>>>>>> found and "loaded", according to console output.
>>>>>>>>>>
>>>>>>>>>> Is this expected behavior? It seems like I might've
configured
>>>>>>>>>> something
>>>>>>>>>> incorrectly, since I would expect with checkpointing
that the
>>>>>>>>>> streaming job
>>>>>>>>>> would resume from checkpoint and continue processing
from there
>>>>>>>>>> (without
>>>>>>>>>> seeing 0 event batches corresponding to when the
job was down).
>>>>>>>>>>
>>>>>>>>>> Also, if I were to wait > 10 minutes or so before
re-launching,
>>>>>>>>>> there would
>>>>>>>>>> be so many 0 event batches that the job would hang.
Is this
>>>>>>>>>> merely something
>>>>>>>>>> to be "waited out", or should I set up some restart
behavior/make
>>>>>>>>>> a config
>>>>>>>>>> change to discard checkpointing if the elapsed time
has been too
>>>>>>>>>> long?
>>>>>>>>>>
>>>>>>>>>> Thanks!
>>>>>>>>>>
>>>>>>>>>> <
>>>>>>>>>> http://apache-spark-user-list.1001560.n3.nabble.com/file/n24450/Screen_Shot_2015-08-25_at_10.png
>>>>>>>>>> >
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> --
>>>>>>>>>> View this message in context:
>>>>>>>>>> http://apache-spark-user-list.1001560.n3.nabble.com/Spark-Streaming-Checkpointing-Restarts-with-0-Event-Batches-tp24450.html
>>>>>>>>>> Sent from the Apache Spark User List mailing list
archive at
>>>>>>>>>> Nabble.com.
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> ---------------------------------------------------------------------
>>>>>>>>>> To unsubscribe, e-mail: user-unsubscribe@spark.apache.org
>>>>>>>>>> For additional commands, e-mail: user-help@spark.apache.org
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>

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