Re: how to blend a DStream and a broadcast variable?
Excellent. Is there an example of this somewhere? Sent from my iPhone On Nov 6, 2014, at 1:43 AM, Sean Owen so...@cloudera.com wrote: Broadcast vars should work fine in Spark streaming. Broadcast vars are immutable however. If you have some info to cache which might change from batch to batch, you should be able to load it at the start of your 'foreachRDD' method or equivalent. That's simple and works assuming your batch interval isn't so short and data so big that loading it every time is a burden. On Wed, Nov 5, 2014 at 11:30 PM, spr s...@yarcdata.com wrote: My use case has one large data stream (DS1) that obviously maps to a DStream. The processing of DS1 involves filtering it for any of a set of known values, which will change over time, though slowly by streaming standards. If the filter data were static, it seems to obviously map to a broadcast variable, but it's dynamic. (And I don't think it works to implement it as a DStream, because the new values need to be copied redundantly to all executors, not partitioned among the executors.) Looking at the Spark and Spark Streaming documentation, I have two questions: 1) There's no mention in the Spark Streaming Programming Guide of broadcast variables. Do they coexist properly? 2) Once I have a broadcast variable in place in the periodic function that Spark Streaming executes, how can I update its value? Obviously I can't literally update the value of that broadcast variable, which is immutable, but how can I get a new version of the variable established in all the executors? (And the other ever-present implicit question...) 3) Is there a better way to implement this? -- View this message in context: http://apache-spark-user-list.1001560.n3.nabble.com/how-to-blend-a-DStream-and-a-broadcast-variable-tp18227.html Sent from the Apache Spark User List mailing list archive at Nabble.com. - To unsubscribe, e-mail: user-unsubscr...@spark.apache.org For additional commands, e-mail: user-h...@spark.apache.org - To unsubscribe, e-mail: user-unsubscr...@spark.apache.org For additional commands, e-mail: user-h...@spark.apache.org
how to blend a DStream and a broadcast variable?
My use case has one large data stream (DS1) that obviously maps to a DStream. The processing of DS1 involves filtering it for any of a set of known values, which will change over time, though slowly by streaming standards. If the filter data were static, it seems to obviously map to a broadcast variable, but it's dynamic. (And I don't think it works to implement it as a DStream, because the new values need to be copied redundantly to all executors, not partitioned among the executors.) Looking at the Spark and Spark Streaming documentation, I have two questions: 1) There's no mention in the Spark Streaming Programming Guide of broadcast variables. Do they coexist properly? 2) Once I have a broadcast variable in place in the periodic function that Spark Streaming executes, how can I update its value? Obviously I can't literally update the value of that broadcast variable, which is immutable, but how can I get a new version of the variable established in all the executors? (And the other ever-present implicit question...) 3) Is there a better way to implement this? -- View this message in context: http://apache-spark-user-list.1001560.n3.nabble.com/how-to-blend-a-DStream-and-a-broadcast-variable-tp18227.html Sent from the Apache Spark User List mailing list archive at Nabble.com. - To unsubscribe, e-mail: user-unsubscr...@spark.apache.org For additional commands, e-mail: user-h...@spark.apache.org
Re: how to blend a DStream and a broadcast variable?
Broadcast vars should work fine in Spark streaming. Broadcast vars are immutable however. If you have some info to cache which might change from batch to batch, you should be able to load it at the start of your 'foreachRDD' method or equivalent. That's simple and works assuming your batch interval isn't so short and data so big that loading it every time is a burden. On Wed, Nov 5, 2014 at 11:30 PM, spr s...@yarcdata.com wrote: My use case has one large data stream (DS1) that obviously maps to a DStream. The processing of DS1 involves filtering it for any of a set of known values, which will change over time, though slowly by streaming standards. If the filter data were static, it seems to obviously map to a broadcast variable, but it's dynamic. (And I don't think it works to implement it as a DStream, because the new values need to be copied redundantly to all executors, not partitioned among the executors.) Looking at the Spark and Spark Streaming documentation, I have two questions: 1) There's no mention in the Spark Streaming Programming Guide of broadcast variables. Do they coexist properly? 2) Once I have a broadcast variable in place in the periodic function that Spark Streaming executes, how can I update its value? Obviously I can't literally update the value of that broadcast variable, which is immutable, but how can I get a new version of the variable established in all the executors? (And the other ever-present implicit question...) 3) Is there a better way to implement this? -- View this message in context: http://apache-spark-user-list.1001560.n3.nabble.com/how-to-blend-a-DStream-and-a-broadcast-variable-tp18227.html Sent from the Apache Spark User List mailing list archive at Nabble.com. - To unsubscribe, e-mail: user-unsubscr...@spark.apache.org For additional commands, e-mail: user-h...@spark.apache.org - To unsubscribe, e-mail: user-unsubscr...@spark.apache.org For additional commands, e-mail: user-h...@spark.apache.org
