YARN-9010. Fix the incorrect trailing slash deletion in constructor method of CGroupsHandlerImpl. (Zhankun Tang via wangda)

Change-Id: Iaecc66d57781cc10f19ead4647e47fc9556676da

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

@@ -87,9 +87,10 @@ class CGroupsHandlerImpl implements CGroupsHandler {
   CGroupsHandlerImpl(Configuration conf, PrivilegedOperationExecutor
       privilegedOperationExecutor, String mtab)
       throws ResourceHandlerException {
+    // Remove leading and trialing slash(es)
     this.cGroupPrefix = conf.get(YarnConfiguration.
         NM_LINUX_CONTAINER_CGROUPS_HIERARCHY, "/hadoop-yarn")
-        .replaceAll("^/", "").replaceAll("$/", "");
+        .replaceAll("^/+", "").replaceAll("/+$", "");
     this.enableCGroupMount = conf.getBoolean(YarnConfiguration.
         NM_LINUX_CONTAINER_CGROUPS_MOUNT, false);
     this.cGroupMountPath = conf.get(YarnConfiguration.

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/test/java/org/apache/hadoop/yarn/server/nodemanager/containermanager/linux/resources/TestCGroupsHandlerImpl.java

@@ -598,4 +598,42 @@ public class TestCGroupsHandlerImpl {
       FileUtils.deleteQuietly(cpu);
     }
   }
+
+  // Remove leading and trailing slashes
+  @Test
+  public void testCgroupsHierarchySetting() throws ResourceHandlerException {
+    YarnConfiguration conf = new YarnConfiguration();
+    conf.set(YarnConfiguration.NM_LINUX_CONTAINER_CGROUPS_MOUNT_PATH, tmpPath);
+    conf.set(YarnConfiguration.NM_LINUX_CONTAINER_CGROUPS_HIERARCHY,
+        "/hadoop-yarn");
+    CGroupsHandlerImpl cGroupsHandler = new CGroupsHandlerImpl(conf, null);
+    String expectedRelativePath = "hadoop-yarn/c1";
+    Assert.assertEquals(expectedRelativePath,
+        cGroupsHandler.getRelativePathForCGroup("c1"));
+
+    conf.set(YarnConfiguration.NM_LINUX_CONTAINER_CGROUPS_HIERARCHY,
+        "hadoop-yarn");
+    cGroupsHandler = new CGroupsHandlerImpl(conf, null);
+    Assert.assertEquals(expectedRelativePath,
+        cGroupsHandler.getRelativePathForCGroup("c1"));
+
+    conf.set(YarnConfiguration.NM_LINUX_CONTAINER_CGROUPS_HIERARCHY,
+        "hadoop-yarn/");
+    cGroupsHandler = new CGroupsHandlerImpl(conf, null);
+    Assert.assertEquals(expectedRelativePath,
+        cGroupsHandler.getRelativePathForCGroup("c1"));
+
+    conf.set(YarnConfiguration.NM_LINUX_CONTAINER_CGROUPS_HIERARCHY,
+        "//hadoop-yarn//");
+    cGroupsHandler = new CGroupsHandlerImpl(conf, null);
+    Assert.assertEquals(expectedRelativePath,
+        cGroupsHandler.getRelativePathForCGroup("c1"));
+
+    expectedRelativePath = "hadoop-yarn/root/c1";
+    conf.set(YarnConfiguration.NM_LINUX_CONTAINER_CGROUPS_HIERARCHY,
+        "//hadoop-yarn/root//");
+    cGroupsHandler = new CGroupsHandlerImpl(conf, null);
+    Assert.assertEquals(expectedRelativePath,
+        cGroupsHandler.getRelativePathForCGroup("c1"));
+  }
 }