From d96f8c997b9bb5c3d61f513d2c71d67ccf8e85d6 Mon Sep 17 00:00:00 2001 From: Andrew Or Date: Tue, 1 Dec 2015 19:51:12 -0800 Subject: [SPARK-12081] Make unified memory manager work with small heaps The existing `spark.memory.fraction` (default 0.75) gives the system 25% of the space to work with. For small heaps, this is not enough: e.g. default 1GB leaves only 250MB system memory. This is especially a problem in local mode, where the driver and executor are crammed in the same JVM. Members of the community have reported driver OOM's in such cases. **New proposal.** We now reserve 300MB before taking the 75%. For 1GB JVMs, this leaves `(1024 - 300) * 0.75 = 543MB` for execution and storage. This is proposal (1) listed in the [JIRA](https://issues.apache.org/jira/browse/SPARK-12081). Author: Andrew Or Closes #10081 from andrewor14/unified-memory-small-heaps. --- docs/configuration.md | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'docs/configuration.md') diff --git a/docs/configuration.md b/docs/configuration.md index 741d6b2b37..c39b489085 100644 --- a/docs/configuration.md +++ b/docs/configuration.md @@ -719,8 +719,8 @@ Apart from these, the following properties are also available, and may be useful spark.memory.fraction 0.75 - Fraction of the heap space used for execution and storage. The lower this is, the more - frequently spills and cached data eviction occur. The purpose of this config is to set + Fraction of (heap space - 300MB) used for execution and storage. The lower this is, the + more frequently spills and cached data eviction occur. The purpose of this config is to set aside memory for internal metadata, user data structures, and imprecise size estimation in the case of sparse, unusually large records. Leaving this at the default value is recommended. For more detail, see -- cgit v1.2.3