Github user frreiss commented on a diff in the pull request: https://github.com/apache/spark/pull/15005#discussion_r79765892 --- Diff: docs/building-spark.md --- @@ -16,24 +16,31 @@ Building Spark using Maven requires Maven 3.3.9 or newer and Java 7+. ### Setting up Maven's Memory Usage -You'll need to configure Maven to use more memory than usual by setting `MAVEN_OPTS`. We recommend the following settings: +If you are compiling with Java 7, you'll need to configure Maven to use more memory than usual by setting `MAVEN_OPTS`: export MAVEN_OPTS="-Xmx2g -XX:MaxPermSize=512M -XX:ReservedCodeCacheSize=512m" -If you don't run this, you may see errors like the following: +When compiling with Java 8, a similar but smaller set of memory parameters is necessary: + + export MAVEN_OPTS="-Xmx2g -XX:ReservedCodeCacheSize=512m" + +If you don't add these parameters to `MAVEN_OPTS`, you may see errors like the following: [INFO] Compiling 203 Scala sources and 9 Java sources to /Users/me/Development/spark/core/target/scala-{{site.SCALA_BINARY_VERSION}}/classes... [ERROR] PermGen space -> [Help 1] [INFO] Compiling 203 Scala sources and 9 Java sources to /Users/me/Development/spark/core/target/scala-{{site.SCALA_BINARY_VERSION}}/classes... [ERROR] Java heap space -> [Help 1] -You can fix this by setting the `MAVEN_OPTS` variable as discussed before. +You can fix these problems by setting the `MAVEN_OPTS` variable as discussed before. **Note:** -* For Java 8 and above this step is not required. -* If using `build/mvn` with no `MAVEN_OPTS` set, the script will automate this for you. +* This step is not needed for Java 8. +* If using `build/mvn` with no `MAVEN_OPTS` set, the script will automatically add the above options for Java 7 to the `MAVEN_OPTS` environment variable. +* The `test` phase of the Spark build will automatically add these options to `MAVEN_OPTS`, even when not using `build/mvn`. +* You may see warnings like "ignoring option MaxPermSize=1g; support was removed in 8.0" when building or running tests with Java 8. These warnings are harmless. --- End diff -- Developers will see the warning when compiling with `build/mvn`. Updating to clarify that.
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