Thanks TD & Francois for the explanation & documentation. I'm curious if we have any performance benchmark with & without WAL for spark-streaming-kafka.
Also In spark-streaming-kafka (as kafka provides a way to acknowledge logs) on top of WAL can we modify KafkaUtils to acknowledge the offsets only when the RRDs are fully processed and are getting evicted out of the Spark memory thus we can be cent percent sure that all the records are getting processed in the system. I was thinking if it's good to have the kafka offset information of each batch as part of RDDs metadata and commit the offsets once the RDDs lineage is complete. On Thu, Dec 11, 2014 at 6:26 PM, Tathagata Das <tathagata.das1...@gmail.com> wrote: > > I am updating the docs right now. Here is a staged copy that you can > have sneak peek of. This will be part of the Spark 1.2. > > > http://people.apache.org/~tdas/spark-1.2-temp/streaming-programming-guide.html > > The updated fault-tolerance section tries to simplify the explanation > of when and what data can be lost, and how to prevent that using the > new experimental feature of write ahead logs. > Any feedback will be much appreciated. > > TD > > On Wed, Dec 10, 2014 at 2:42 AM, <francois.garil...@typesafe.com> wrote: > > [sorry for the botched half-message] > > > > Hi Mukesh, > > > > There's been some great work on Spark Streaming reliability lately. > > https://www.youtube.com/watch?v=jcJq3ZalXD8 > > Look at the links from: > > https://issues.apache.org/jira/browse/SPARK-3129 > > > > I'm not aware of any doc yet (did I miss something ?) but you can look at > > the ReliableKafkaReceiver's test suite: > > > > > external/kafka/src/test/scala/org/apache/spark/streaming/kafka/ReliableKafkaStreamSuite.scala > > > > -- > > FG > > > > > > On Wed, Dec 10, 2014 at 11:17 AM, Mukesh Jha <me.mukesh....@gmail.com> > > wrote: > >> > >> Hello Guys, > >> > >> Any insights on this?? > >> If I'm not clear enough my question is how can I use kafka consumer and > >> not loose any data in cases of failures with spark-streaming. > >> > >> On Tue, Dec 9, 2014 at 2:53 PM, Mukesh Jha <me.mukesh....@gmail.com> > >> wrote: > >>> > >>> Hello Experts, > >>> > >>> I'm working on a spark app which reads data from kafka & persists it in > >>> hbase. > >>> > >>> Spark documentation states the below [1] that in case of worker failure > >>> we can loose some data. If not how can I make my kafka stream more > reliable? > >>> I have seen there is a simple consumer [2] but I'm not sure if it has > >>> been used/tested extensively. > >>> > >>> I was wondering if there is a way to explicitly acknowledge the kafka > >>> offsets once they are replicated in memory of other worker nodes (if > it's > >>> not already done) to tackle this issue. > >>> > >>> Any help is appreciated in advance. > >>> > >>> > >>> Using any input source that receives data through a network - For > >>> network-based data sources like Kafka and Flume, the received input > data is > >>> replicated in memory between nodes of the cluster (default replication > >>> factor is 2). So if a worker node fails, then the system can recompute > the > >>> lost from the the left over copy of the input data. However, if the > worker > >>> node where a network receiver was running fails, then a tiny bit of > data may > >>> be lost, that is, the data received by the system but not yet > replicated to > >>> other node(s). The receiver will be started on a different node and it > will > >>> continue to receive data. > >>> https://github.com/dibbhatt/kafka-spark-consumer > >>> > >>> Txz, > >>> > >>> Mukesh Jha > >> > >> > >> > >> > >> -- > >> > >> > >> Thanks & Regards, > >> > >> Mukesh Jha > > > > > -- Thanks & Regards, *Mukesh Jha <me.mukesh....@gmail.com>*
