YARN-1395. Distributed shell application master launched with debug flag can hang waiting for external ls process. Contributed by Chris Nauroth.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1540839 13f79535-47bb-0310-9956-ffa450edef68

hadoop-yarn-project/CHANGES.txt

@@ -118,6 +118,9 @@ Release 2.3.0 - UNRELEASED
     YARN-1374. Changed ResourceManager to start the preemption policy monitors
     as active services. (Karthik Kambatla via vinodkv)
 
+    YARN-1395. Distributed shell application master launched with debug flag can
+    hang waiting for external ls process. (cnauroth)
+
 Release 2.2.1 - UNRELEASED
 
   INCOMPATIBLE CHANGES

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-applications-distributedshell/src/main/java/org/apache/hadoop/yarn/applications/distributedshell/ApplicationMaster.java

@@ -21,6 +21,7 @@ package org.apache.hadoop.yarn.applications.distributedshell;
 import java.io.BufferedReader;
 import java.io.IOException;
 import java.io.InputStreamReader;
+import java.io.StringReader;
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.nio.ByteBuffer;
@@ -46,10 +47,12 @@ import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.classification.InterfaceStability;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.io.DataOutputBuffer;
+import org.apache.hadoop.io.IOUtils;
 import org.apache.hadoop.net.NetUtils;
 import org.apache.hadoop.security.Credentials;
 import org.apache.hadoop.security.UserGroupInformation;
 import org.apache.hadoop.security.token.Token;
+import org.apache.hadoop.util.Shell;
 import org.apache.hadoop.yarn.api.ApplicationConstants;
 import org.apache.hadoop.yarn.api.ApplicationConstants.Environment;
 import org.apache.hadoop.yarn.api.ApplicationMasterProtocol;
@@ -262,25 +265,20 @@ public class ApplicationMaster {
           + env.getValue());
     }
 
-    String cmd = "ls -al";
-    Runtime run = Runtime.getRuntime();
-    Process pr = null;
+    BufferedReader buf = null;
     try {
-      pr = run.exec(cmd);
-      pr.waitFor();
-
-      BufferedReader buf = new BufferedReader(new InputStreamReader(
-          pr.getInputStream()));
+      String lines = Shell.WINDOWS ? Shell.execCommand("cmd", "/c", "dir") :
+        Shell.execCommand("ls", "-al");
+      buf = new BufferedReader(new StringReader(lines));
       String line = "";
       while ((line = buf.readLine()) != null) {
         LOG.info("System CWD content: " + line);
         System.out.println("System CWD content: " + line);
       }
-      buf.close();
     } catch (IOException e) {
       e.printStackTrace();
-    } catch (InterruptedException e) {
-      e.printStackTrace();
+    } finally {
+      IOUtils.cleanup(LOG, buf);
     }
   }
 

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-applications-distributedshell/src/test/java/org/apache/hadoop/yarn/applications/distributedshell/TestDistributedShell.java

@@ -306,5 +306,31 @@ public class TestDistributedShell {
 
   }
 
+  @Test(timeout=90000)
+  public void testDebugFlag() throws Exception {
+    String[] args = {
+        "--jar",
+        APPMASTER_JAR,
+        "--num_containers",
+        "2",
+        "--shell_command",
+        Shell.WINDOWS ? "dir" : "ls",
+        "--master_memory",
+        "512",
+        "--master_vcores",
+        "2",
+        "--container_memory",
+        "128",
+        "--container_vcores",
+        "1",
+        "--debug"
+    };
+
+    LOG.info("Initializing DS Client");
+    Client client = new Client(new Configuration(yarnCluster.getConfig()));
+    Assert.assertTrue(client.init(args));
+    LOG.info("Running DS Client");
+    Assert.assertTrue(client.run());
+  }
 }