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From "zhengchenyu (JIRA)" <j...@apache.org>
Subject [jira] [Created] (YARN-5936) when cpu strict mode is closed, yarn couldn't assure scheduling fairness between containers
Date Fri, 25 Nov 2016 06:55:58 GMT
zhengchenyu created YARN-5936:
---------------------------------

             Summary: when cpu strict mode is closed, yarn couldn't assure scheduling fairness
between containers
                 Key: YARN-5936
                 URL: https://issues.apache.org/jira/browse/YARN-5936
             Project: Hadoop YARN
          Issue Type: Bug
          Components: nodemanager
    Affects Versions: 2.7.1
         Environment: CentOS7.1
            Reporter: zhengchenyu
            Priority: Critical
             Fix For: 2.7.1


    When using LinuxContainer, the setting that "yarn.nodemanager.linux-container-executor.cgroups.strict-resource-usage"
is true could assure scheduling fairness with the cpu bandwith of cgroup. But the cpu bandwidth
of cgroup would lead to bad performance in our experience. 
    Without cpu bandwidth of cgroup, cpu.share of cgroup is our only way to assure scheduling
fairness, but it is not completely effective. For example, There are two container that have
same vcore(means same cpu.share), one container is single-threaded, the other container is
multi-thread. the multi-thread will have more CPU time, It's unreasonable!
    Here is my test case, I submit two distributedshell application. And two commmand are
below:
(code)
hadoop jar share/hadoop/yarn/hadoop-yarn-applications-distributedshell-2.7.1.jar org.apache.hadoop.yarn.applications.distributedshell.Client
-jar share/hadoop/yarn/hadoop-yarn-applications-distributedshell-2.7.1.jar -shell_script ./run.sh
 -shell_args 10 -num_containers 1 -container_memory 1024 -container_vcores 1 -master_memory
1024 -master_vcores 1 -priority 10
hadoop jar share/hadoop/yarn/hadoop-yarn-applications-distributedshell-2.7.1.jar org.apache.hadoop.yarn.applications.distributedshell.Client
-jar share/hadoop/yarn/hadoop-yarn-applications-distributedshell-2.7.1.jar -shell_script ./run.sh
 -shell_args 1  -num_containers 1 -container_memory 1024 -container_vcores 1 -master_memory
1024 -master_vcores 1 -priority 10

     here show the cpu time of the two container:
(code)
  PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND
15448 yarn      20   0 9059592  28336   9180 S 998.7  0.1  24:09.30 java
15026 yarn      20   0 9050340  27480   9188 S 100.0  0.1   3:33.97 java
13767 yarn      20   0 1799816 381208  18528 S   4.6  1.2   0:30.55 java
   77 root      rt   0       0      0      0 S   0.3  0.0   0:00.74 migration/1   
(code)
    We find the cpu time of Muliti-Thread are ten times than the cpu time of Single-Thread,
though the two container have same cpu.share.
notes:
run.sh
(code) 
	java -cp /home/yarn/loop.jar:$CLASSPATH loop.loop $1	
(code) 
loop.java
(code) 
package loop;
public class loop {
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		int loop = 1;
		if(args.length>=1) {
			System.out.println(args[0]);
			loop = Integer.parseInt(args[0]);
		}
		for(int i=0;i<loop;i++){
			System.out.println("start thread " + i);
			new Thread(new Runnable() {
				@Override
				public void run() {
					// TODO Auto-generated method stub
					int j=0;
					while(true){j++;}
				}
			}).start();
		}
	}
}
(code) 



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