Overlord throw exceptions on systems with 1 CPU

[maxd]

Hello All,

I can't run 'overlord' node on VirtualBox node with 1 CPU. It throw the exception:

013-11-28 11:40:22,507 ERROR [LeaderSelector-0] io.druid.indexing.overlord.TaskMaster - Failed to lead: {class=io.druid.indexing.overlord.TaskMaster, exceptionType=class java.lang.IllegalArgumentException, exceptionMessage=null}
java.lang.IllegalArgumentException
        at java.util.concurrent.ThreadPoolExecutor.<init>(ThreadPoolExecutor.java:1310)
        at java.util.concurrent.ThreadPoolExecutor.<init>(ThreadPoolExecutor.java:1198)
        at java.util.concurrent.Executors.newFixedThreadPool(Executors.java:89)
        at io.druid.indexing.overlord.ForkingTaskRunner.<init>(ForkingTaskRunner.java:101)
        at io.druid.indexing.overlord.ForkingTaskRunnerFactory.build(ForkingTaskRunnerFactory.java:63)
        at io.druid.indexing.overlord.TaskMaster$1.takeLeadership(TaskMaster.java:97)
        at org.apache.curator.framework.recipes.leader.LeaderSelector$3.run(LeaderSelector.java:328)
        at com.google.common.util.concurrent.MoreExecutors$SameThreadExecutorService.execute(MoreExecutors.java:293)
        at org.apache.curator.framework.recipes.leader.LeaderSelector.doWork(LeaderSelector.java:319)
        at org.apache.curator.framework.recipes.leader.LeaderSelector.doWorkLoop(LeaderSelector.java:376)
        at org.apache.curator.framework.recipes.leader.LeaderSelector.access$100(LeaderSelector.java:48)
        at org.apache.curator.framework.recipes.leader.LeaderSelector$2.call(LeaderSelector.java:197)
        at java.util.concurrent.FutureTask.run(FutureTask.java:262)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
        at java.lang.Thread.run(Thread.java:744)

As I understand the newFixedThreadPool method threw this exception because the nThreads argument was less than or equal 0.

I have increased number of CPU and this problem disappear. So, I think need to set nThreads argument to 1 as minimum in case when system has 1 CPU.

Thanks

[fjy]

This should be fixed in master now.