KAFKA-2613; Make maxParallelForks configurable via Gradle config so it can be turned down on shared build infrastructure.

Author: Ewen Cheslack-Postava <me@ewencp.org>

Reviewers: Ismael Juma, Sriharsha Chintalapani

Closes #293 from ewencp/kafka-2613-user-configurable-max-forks

README.md

@@ -105,6 +105,12 @@ Please note for this to work you should create/update `~/.gradle/gradle.properti
 ### Running checkstyle on the java code ###
     ./gradlew checkstyleMain checkstyleTest
 
+### Limit the number of processes for each task ###
+    ./gradlew -Dorg.gradle.project.maxParallelForks=1 test
+
+This will most commonly be useful for automated builds where the full resources of the host running the build and tests
+may not be dedicated to Kafka's build.
+
 ### Running in Vagrant ###
 
 See [vagrant/README.md](vagrant/README.md).

build.gradle

@@ -45,6 +45,8 @@ ext {
     gradleVersion = "2.4"
     buildVersionFileName = "kafka-version.properties"
 
+    userMaxForks = project.hasProperty('maxParallelForks') ? maxParallelForks.toInteger() : null
+
     skipSigning = project.hasProperty('skipSigning') && skipSigning.toBoolean()
     shouldSign = !skipSigning && !version.endsWith("SNAPSHOT")
 
@@ -124,7 +126,7 @@ subprojects {
   }
 
   tasks.withType(Test) {
-    maxParallelForks = Runtime.runtime.availableProcessors()
+    maxParallelForks = userMaxForks ?: Runtime.runtime.availableProcessors()
   }
 
   jar {