YARN-11692. Added a new config for cgroups v2 mount path

Change-Id: I1de48e26ce0f827be16a7c435f240c14487d2baa

Author: p-szucs

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-api/src/main/java/org/apache/hadoop/yarn/conf/YarnConfiguration.java

@@ -2733,6 +2733,10 @@ public static boolean isAclEnabled(Configuration conf) {
   public static final String NM_LINUX_CONTAINER_CGROUPS_MOUNT_PATH =
     NM_PREFIX + "linux-container-executor.cgroups.mount-path";
 
+  /** Where the linux container executor should mount cgroups v2 if not found */
+  public static final String NM_LINUX_CONTAINER_CGROUPS_V2_MOUNT_PATH =
+      NM_PREFIX + "linux-container-executor.cgroups.v2.mount-path";
+
   /**
    * Whether the apps should run in strict resource usage mode(not allowed to
    * use spare CPU)

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/resources/yarn-default.xml

@@ -2087,6 +2087,20 @@
     <name>yarn.nodemanager.linux-container-executor.cgroups.mount-path</name>
   </property>
 
+  <property>
+    <description>This property sets the mount path for CGroups v2.
+      This parameter is optional, and needed to be set only in mixed mode,
+      when CGroups v2 is mounted in a different path than Cgroups v1.
+      For example, in hybrid mode, CGroups v1 controllers can be mounted in
+      /sys/fs/cgroup, while v2 can be mounted in /sys/fs/cgroup/unified folder.
+      
+      If this value is not set, the value of
+      yarn.nodemanager.linux-container-executor.cgroups.mount-path
+      will be used for CGroups v2 as well.
+    </description>
+    <name>yarn.nodemanager.linux-container-executor.cgroups.v2.mount-path</name>
+  </property>
+
   <property>
     <description>Delay in ms between attempts to remove linux cgroup</description>
     <name>yarn.nodemanager.linux-container-executor.cgroups.delete-delay-ms</name>

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/main/java/org/apache/hadoop/yarn/server/nodemanager/containermanager/linux/resources/CGroupsMountConfig.java

@@ -25,12 +25,18 @@
 public class CGroupsMountConfig {
   private final boolean enableMount;
   private final String mountPath;
+  
+  // CGroups v2 mount path is only relevant in mixed CGroups v1/v2 mode,
+  // where v2 can be mounted in a different folder than v1.
+  private final String v2MountPath;
 
   public CGroupsMountConfig(Configuration conf) {
     this.enableMount = conf.getBoolean(YarnConfiguration.
         NM_LINUX_CONTAINER_CGROUPS_MOUNT, false);
     this.mountPath = conf.get(YarnConfiguration.
         NM_LINUX_CONTAINER_CGROUPS_MOUNT_PATH, null);
+    this.v2MountPath = conf.get(YarnConfiguration.
+        NM_LINUX_CONTAINER_CGROUPS_V2_MOUNT_PATH, mountPath);
   }
 
   public boolean ensureMountPathIsDefined() throws ResourceHandlerException {
@@ -62,11 +68,16 @@ public String getMountPath() {
     return mountPath;
   }
 
+  public String getV2MountPath() {
+    return v2MountPath;
+  }
+
   @Override
   public String toString() {
     return "CGroupsMountConfig{" +
         "enableMount=" + enableMount +
-        ", mountPath='" + mountPath + '\'' +
+        ", mountPath='" + mountPath +
+        ", v2MountPath='" + v2MountPath + '\'' +
         '}';
   }
 }

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/main/java/org/apache/hadoop/yarn/server/nodemanager/containermanager/linux/resources/CGroupsV2HandlerImpl.java

@@ -97,8 +97,8 @@ protected List<CGroupController> getCGroupControllers() {
   @Override
   protected Map<String, Set<String>> parsePreConfiguredMountPath() throws IOException {
     Map<String, Set<String>> controllerMappings = new HashMap<>();
-    controllerMappings.put(this.cGroupsMountConfig.getMountPath(),
-        readControllersFile(this.cGroupsMountConfig.getMountPath()));
+    controllerMappings.put(this.cGroupsMountConfig.getV2MountPath(),
+        readControllersFile(this.cGroupsMountConfig.getV2MountPath()));
     return controllerMappings;
   }