Robert Stupp created SPARK-2389: ----------------------------------- Summary: globally shared SparkContext / shared Spark "application" Key: SPARK-2389 URL: https://issues.apache.org/jira/browse/SPARK-2389 Project: Spark Issue Type: Improvement Components: Spark Core Reporter: Robert Stupp
The documentation (in Cluster Mode Overview) cites: bq. Each application gets its own executor processes, which *stay up for the duration of the whole application* and run tasks in multiple threads. This has the benefit of isolating applications from each other, on both the scheduling side (each driver schedules its own tasks) and executor side (tasks from different applications run in different JVMs). However, it also means that *data cannot be shared* across different Spark applications (instances of SparkContext) without writing it to an external storage system. IMO this is a limitation that should be lifted to support any number of --driver-- client processes to share executors and to share (persistent / cached) data. This is especially useful if you have a bunch of frontend servers (dump web app servers) that want to use Spark as a _big computing machine_. Most important is the fact that Spark is quite good in caching/persisting data in memory / on disk thus removing load from backend data stores. Means: it would be really great to let different --driver-- client JVMs operate on the same RDDs and benefit from Spark's caching/persistence. It would however introduce some administration mechanisms to * start a shared context * update the executor configuration (# of worker nodes, # of cpus, etc) on the fly * stop a shared context Even "conventional" batch MR applications would benefit if ran fequently against the same data set. As an implicit requirement, RDD persistence could get a TTL for its materialized state. With such a feature the overall performance of today's web applications could then be increased by adding more web app servers, more spark nodes, more nosql nodes etc -- This message was sent by Atlassian JIRA (v6.2#6252)