1) Yes, if I disable writing out to kafka and replace it with some very
light weight action is rdd.take(1), the app is stable.
2) The partitions I spoke of in the previous mail are the number of
partitions I create from each dStream. But yes, since I do processing and
writing out, per partition, each dStream partition ends up getting written
to a kafka partition. Flow is, broadly:
5 Spark/Kafka Receivers -> Split each dStream into 30 partitions (150
partitions) -> Apply some transformation logic to each partition -> write
out each partition to kafka (kafka has 23 partitions). Let me increase the
number of partitions on the kafka side and see if that helps.
Here's what the main block of code looks like (I added persistence back):
val kInStreams = (1 to otherConf("inStreamCount").toInt).map{_ =>
KafkaUtils.createStream(ssc,otherConf("kafkaConsumerZk").toString,otherConf("kafkaConsumerGroupId").toString,
Map(otherConf("kafkaConsumerTopic").toString -> 1),
StorageLevel.MEMORY_AND_DISK_SER) }
if (!configMap.keySet.isEmpty)
{
// Process stream from each receiver separately
// (do not attempt to merge all streams and then re-partition,
this causes un-necessary and high amount of shuffle in the job)
for (k <- kInStreams)
{
// Re-partition stream from each receiver across all
compute nodes to spread out processing load and allows per partition
processing
// and, set persistence level to spill to disk along with
serialization
val kInMsgParts =
k.repartition(otherConf("dStreamPartitions").toInt).persist(org.apache.spark.storage.StorageLevel.MEMORY_AND_DISK_SER)
val outdata =
kInMsgParts.map(x=>myfunc(x._2,configMap)).persist(org.apache.spark.storage.StorageLevel.MEMORY_AND_DISK_SER)
// Write each transformed partition to Kafka via the
"writer" object
outdata.foreachRDD( rdd => rdd.foreachPartition(rec => {
val writer = new
KafkaOutputService(otherConf("kafkaProducerTopic").toString, propsMap)
writer.output(rec)
}) )
}
}
Here's the life-cycle of a lost block:
15/02/12 16:26:12 INFO BlockManagerInfo: Added input-4-1423758372200 in
memory on nodedn1-23-acme.com:34526 (size: 164.7 KB, free: 379.5 MB)
15/02/12 16:26:12 INFO BlockManagerInfo: Added input-4-1423758372200 in
memory on nodedn1-22-acme.com:42084 (size: 164.7 KB, free: 366.5 MB)
15/02/12 16:31:21 INFO BlockManagerInfo: Added input-4-1423758372200 on
disk on nodedn1-22-acme.com:42084 (size: 164.7 KB)
15/02/12 16:31:23 INFO BlockManagerInfo: Added input-4-1423758372200 on
disk on nodedn1-23-acme.com:34526 (size: 164.7 KB)
15/02/12 16:32:27 WARN TaskSetManager: Lost task 54.0 in stage 16291.0 (TID
1042569, nodedn1-13-acme.com): java.lang.Exception: Could not compute
split, block input-4-1423758372200 not found
15/02/12 16:32:27 INFO TaskSetManager: Lost task 54.1 in stage 16291.0 (TID
1042575) on executor nodedn1-21-acme.com: java.lang.Exception (Could not
compute split, block input-4-1423758372200 not found) [duplicate 1]
15/02/12 16:32:27 INFO TaskSetManager: Lost task 54.2 in stage 16291.0 (TID
1042581) on executor nodedn1-21-acme.com: java.lang.Exception (Could not
compute split, block input-4-1423758372200 not found) [duplicate 2]
15/02/12 16:32:27 INFO TaskSetManager: Lost task 54.3 in stage 16291.0 (TID
1042584) on executor nodedn1-20-acme.com: java.lang.Exception (Could not
compute split, block input-4-1423758372200 not found) [duplicate 3]
15/02/12 16:32:27 INFO TaskSetManager: Lost task 54.4 in stage 16291.0 (TID
1042586) on executor nodedn1-11-acme.com: java.lang.Exception (Could not
compute split, block input-4-1423758372200 not found) [duplicate 4]
15/02/12 16:32:27 INFO TaskSetManager: Lost task 54.5 in stage 16291.0 (TID
1042589) on executor nodedn1-14-acme.com: java.lang.Exception (Could not
compute split, block input-4-1423758372200 not found) [duplicate 5]
15/02/12 16:32:27 INFO TaskSetManager: Lost task 54.6 in stage 16291.0 (TID
1042594) on executor nodedn1-15-acme.com: java.lang.Exception (Could not
compute split, block input-4-1423758372200 not found) [duplicate 6]
15/02/12 16:32:27 INFO TaskSetManager: Lost task 54.7 in stage 16291.0 (TID
1042597) on executor nodedn1-20-acme.com: java.lang.Exception (Could not
compute split, block input-4-1423758372200 not found) [duplicate 7]
15/02/12 16:32:27 INFO TaskSetManager: Lost task 54.8 in stage 16291.0 (TID
1042600) on executor nodedn1-17-acme.com: java.lang.Exception (Could not
compute split, block input-4-1423758372200 not found) [duplicate 8]
15/02/12 16:32:27 INFO TaskSetManager: Lost task 54.9 in stage 16291.0 (TID
1042606) on executor nodedn1-20-acme.com: java.lang.Exception (Could not
compute split, block input-4-1423758372200 not found) [duplicate 9]
15/02/12 16:32:27 INFO TaskSetManager: Lost task 54.10 in stage 16291.0
(TID 1042609) on executor nodedn1-19-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 10]
15/02/12 16:32:27 INFO TaskSetManager: Lost task 54.11 in stage 16291.0
(TID 1042611) on executor nodedn1-14-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 11]
15/02/12 16:32:27 INFO TaskSetManager: Lost task 54.12 in stage 16291.0
(TID 1042615) on executor nodedn1-22-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 12]
15/02/12 16:32:27 INFO TaskSetManager: Lost task 54.13 in stage 16291.0
(TID 1042618) on executor nodedn1-19-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 13]
15/02/12 16:32:27 INFO TaskSetManager: Lost task 54.14 in stage 16291.0
(TID 1042622) on executor nodedn1-21-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 14]
15/02/12 16:32:27 INFO TaskSetManager: Lost task 54.15 in stage 16291.0
(TID 1042625) on executor nodedn1-16-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 15]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.16 in stage 16291.0
(TID 1042628) on executor nodedn1-20-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 16]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.17 in stage 16291.0
(TID 1042633) on executor nodedn1-16-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 17]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.18 in stage 16291.0
(TID 1042636) on executor nodedn1-17-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 18]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.19 in stage 16291.0
(TID 1042640) on executor nodedn1-17-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 19]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.20 in stage 16291.0
(TID 1042642) on executor nodedn1-16-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 20]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.21 in stage 16291.0
(TID 1042645) on executor nodedn1-16-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 21]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.22 in stage 16291.0
(TID 1042648) on executor nodedn1-14-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 22]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.23 in stage 16291.0
(TID 1042654) on executor nodedn1-23-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 23]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.24 in stage 16291.0
(TID 1042660) on executor nodedn1-22-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 24]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.25 in stage 16291.0
(TID 1042662) on executor nodedn1-21-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 25]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.26 in stage 16291.0
(TID 1042663) on executor nodedn1-14-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 26]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.27 in stage 16291.0
(TID 1042665) on executor nodedn1-17-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 27]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.28 in stage 16291.0
(TID 1042667) on executor nodedn1-19-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 28]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.29 in stage 16291.0
(TID 1042671) on executor nodedn1-14-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 29]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.30 in stage 16291.0
(TID 1042672) on executor nodedn1-12-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 30]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.31 in stage 16291.0
(TID 1042674) on executor nodedn1-14-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 31]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.32 in stage 16291.0
(TID 1042677) on executor nodedn1-19-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 32]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.33 in stage 16291.0
(TID 1042680) on executor nodedn1-22-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 33]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.34 in stage 16291.0
(TID 1042681) on executor nodedn1-20-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 34]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.35 in stage 16291.0
(TID 1042682) on executor nodedn1-17-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 35]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.36 in stage 16291.0
(TID 1042687) on executor nodedn1-20-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 36]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.37 in stage 16291.0
(TID 1042689) on executor nodedn1-17-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 37]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.38 in stage 16291.0
(TID 1042690) on executor nodedn1-17-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 38]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.39 in stage 16291.0
(TID 1042693) on executor nodedn1-22-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 39]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.40 in stage 16291.0
(TID 1042697) on executor nodedn1-22-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 40]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.41 in stage 16291.0
(TID 1042700) on executor nodedn1-13-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 41]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.42 in stage 16291.0
(TID 1042706) on executor nodedn1-15-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 42]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.43 in stage 16291.0
(TID 1042710) on executor nodedn1-14-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 43]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.44 in stage 16291.0
(TID 1042713) on executor nodedn1-17-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 44]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.45 in stage 16291.0
(TID 1042716) on executor nodedn1-19-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 45]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.46 in stage 16291.0
(TID 1042718) on executor nodedn1-15-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 46]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.47 in stage 16291.0
(TID 1042720) on executor nodedn1-12-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 47]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.48 in stage 16291.0
(TID 1042724) on executor nodedn1-12-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 48]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.49 in stage 16291.0
(TID 1042729) on executor nodedn1-16-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 49]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.50 in stage 16291.0
(TID 1042730) on executor nodedn1-21-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 50]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.51 in stage 16291.0
(TID 1042733) on executor nodedn1-21-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 51]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.52 in stage 16291.0
(TID 1042736) on executor nodedn1-19-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 52]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.53 in stage 16291.0
(TID 1042740) on executor nodedn1-20-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 53]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.54 in stage 16291.0
(TID 1042743) on executor nodedn1-22-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 54]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.55 in stage 16291.0
(TID 1042745) on executor nodedn1-18-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 55]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.56 in stage 16291.0
(TID 1042754) on executor nodedn1-17-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 56]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.57 in stage 16291.0
(TID 1042758) on executor nodedn1-17-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 57]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.58 in stage 16291.0
(TID 1042762) on executor nodedn1-12-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 58]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.59 in stage 16291.0
(TID 1042766) on executor nodedn1-23-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 59]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.60 in stage 16291.0
(TID 1042774) on executor nodedn1-20-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 60]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.61 in stage 16291.0
(TID 1042779) on executor nodedn1-13-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 61]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.62 in stage 16291.0
(TID 1042789) on executor nodedn1-20-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 62]
15/02/12 16:32:28 INFO TaskSetManager: Lost task 54.63 in stage 16291.0
(TID 1042793) on executor nodedn1-15-acme.com: java.lang.Exception (Could
not compute split, block input-4-1423758372200 not found) [duplicate 63]
org.apache.spark.SparkException: Job aborted due to stage failure: Task 54
in stage 16291.0 failed 64 times, most recent failure: Lost task 54.63 in
stage 16291.0 (TID 1042793, nodedn1-15-acme.com): java.lang.Exception:
Could not compute split, block input-4-1423758372200 not found
Exception in thread "main" org.apache.spark.SparkException: Job aborted due
to stage failure: Task 54 in stage 16291.0 failed 64 times, most recent
failure: Lost task 54.63 in stage 16291.0 (TID 1042793, nodedn1-15-acme.com):
java.lang.Exception: Could not compute split, block input-4-1423758372200
not found
Thanks for looking into it.
On Thu, Feb 12, 2015 at 8:10 PM, Tathagata Das <t...@databricks.com> wrote:
> Hey Tim,
>
> Let me get the key points.
> 1. If you are not writing back to Kafka, the delay is stable? That is,
> instead of "foreachRDD { // write to kafka }" if you do "dstream.count",
> then the delay is stable. Right?
> 2. If so, then Kafka is the bottleneck. Is the number of partitions, that
> you spoke of the in the second mail, that determines the parallelism in
> writes? Is it stable with 30 partitions?
>
> Regarding the block exception, could you give me a trace of info level
> logging that leads to this error? Basically I want trace the lifecycle of
> the block.
>
> TD
>
>
>
> On Thu, Feb 12, 2015 at 6:29 PM, Tim Smith <secs...@gmail.com> wrote:
>
>> Hi Gerard,
>>
>> Great write-up and really good guidance in there.
>>
>> I have to be honest, I don't know why but setting # of partitions for
>> each dStream to a low number (5-10) just causes the app to choke/crash.
>> Setting it to 20 gets the app going but with not so great delays. Bump it
>> up to 30 and I start winning the war where processing time is consistently
>> below batch time window (20 seconds) except for a batch every few batches
>> where the compute time spikes 10x the usual.
>>
>> Following your guide, I took out some "logInfo" statements I had in the
>> app but didn't seem to make much difference :(
>>
>> With a higher time window (20 seconds), I got the app to run stably for a
>> few hours but then ran into the dreaded "java.lang.Exception: Could not
>> compute split, block input-0-1423761240800 not found". Wonder if I need to
>> add RDD persistence back?
>>
>> Also, I am reaching out to Virdata with some ProServ inquiries.
>>
>> Thanks
>>
>>
>>
>>
>>
>> On Thu, Feb 12, 2015 at 4:30 AM, Gerard Maas <gerard.m...@gmail.com>
>> wrote:
>>
>>> Hi Tim,
>>>
>>> From this: " There are 5 kafka receivers and each incoming stream is
>>> split into 40 partitions" I suspect that you're creating too many
>>> tasks for Spark to process on time.
>>> Could you try some of the 'knobs' I describe here to see if that would
>>> help?
>>>
>>> http://www.virdata.com/tuning-spark/
>>>
>>> -kr, Gerard.
>>>
>>> On Thu, Feb 12, 2015 at 8:44 AM, Tim Smith <secs...@gmail.com> wrote:
>>>
>>>> Just read the thread "Are these numbers abnormal for spark streaming?"
>>>> and I think I am seeing similar results - that is - increasing the window
>>>> seems to be the trick here. I will have to monitor for a few hours/days
>>>> before I can conclude (there are so many knobs/dials).
>>>>
>>>>
>>>>
>>>> On Wed, Feb 11, 2015 at 11:16 PM, Tim Smith <secs...@gmail.com> wrote:
>>>>
>>>>> On Spark 1.2 (have been seeing this behaviour since 1.0), I have a
>>>>> streaming app that consumes data from Kafka and writes it back to Kafka
>>>>> (different topic). My big problem has been Total Delay. While execution
>>>>> time is usually <window size (in seconds), the total delay ranges from a
>>>>> minutes to hours(s) (keeps going up).
>>>>>
>>>>> For a little while, I thought I had solved the issue by bumping up the
>>>>> driver memory. Then I expanded my Kafka cluster to add more nodes and the
>>>>> issue came up again. I tried a few things to smoke out the issue and
>>>>> something tells me the driver is the bottleneck again:
>>>>>
>>>>> 1) From my app, I took out the entire write-out-to-kafka piece. Sure
>>>>> enough, execution, scheduling delay and hence total delay fell to sub
>>>>> second. This assured me that whatever processing I do before writing back
>>>>> to kafka isn't the bottleneck.
>>>>>
>>>>> 2) In my app, I had RDD persistence set at different points but my
>>>>> code wasn't really re-using any RDDs so I took out all explicit persist()
>>>>> statements. And added, "spar...unpersist" to "true" in the context. After
>>>>> this, it doesn't seem to matter how much memory I give my executor, the
>>>>> total delay seems to be in the same range. I tried per executor memory
>>>>> from
>>>>> 2G to 12G with no change in total delay so executors aren't memory
>>>>> starved.
>>>>> Also, in the SparkUI, under the Executors tab, all executors show 0/1060MB
>>>>> used when per executor memory is set to 2GB, for example.
>>>>>
>>>>> 3) Input rate in the kafka consumer restricts spikes in incoming data.
>>>>>
>>>>> 4) Tried FIFO and FAIR but didn't make any difference.
>>>>>
>>>>> 5) Adding executors beyond a certain points seems useless (I guess
>>>>> excess ones just sit idle).
>>>>>
>>>>> At any given point in time, the SparkUI shows only one batch pending
>>>>> processing. So with just one batch pending processing, why would the
>>>>> scheduling delay run into minutes/hours if execution time is within the
>>>>> batch window duration? There aren't any failed stages or jobs.
>>>>>
>>>>> Right now, I have 100 executors ( i have tried setting executors from
>>>>> 50-150), each with 2GB and 4 cores and the driver running with 16GB. There
>>>>> are 5 kafka receivers and each incoming stream is split into 40
>>>>> partitions.
>>>>> Per receiver, input rate is restricted to 20000 messages per second.
>>>>>
>>>>> Can anyone help me with clues or areas to look into, for
>>>>> troubleshooting the issue?
>>>>>
>>>>> One nugget I found buried in the code says:
>>>>> "The scheduler delay includes the network delay to send the task to
>>>>> the worker machine and to send back the result (but not the time to fetch
>>>>> the task result, if it needed to be fetched from the block manager on the
>>>>> worker)."
>>>>>
>>>>> https://github.com/apache/spark/blob/master/core/src/main/scala/org/apache/spark/ui/jobs/StagePage.scala
>>>>>
>>>>> Could this be an issue with the driver being a bottlneck? All the
>>>>> executors posting their logs/stats to the driver?
>>>>>
>>>>> Thanks,
>>>>>
>>>>> Tim
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>
>>
>
