svn merge -c 1558883 FIXES: HADOOP-10146. Workaround JDK7 Process fd close bug (daryn)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1558885 13f79535-47bb-0310-9956-ffa450edef68

hadoop-common-project/hadoop-common/CHANGES.txt

@@ -227,6 +227,8 @@ Release 2.4.0 - UNRELEASED
     HADOOP-10236. Fix typo in o.a.h.ipc.Client#checkResponse. (Akira Ajisaka
     via suresh)
 
+    HADOOP-10146. Workaround JDK7 Process fd close bug (daryn)
+
 Release 2.3.0 - UNRELEASED
 
   INCOMPATIBLE CHANGES

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/Shell.java

@@ -21,6 +21,7 @@ import java.io.BufferedReader;
 import java.io.File;
 import java.io.IOException;
 import java.io.InputStreamReader;
+import java.io.InputStream;
 import java.util.Arrays;
 import java.util.Map;
 import java.util.Timer;
@@ -511,7 +512,17 @@ abstract public class Shell {
       }
       // close the input stream
       try {
-        inReader.close();
+        // JDK 7 tries to automatically drain the input streams for us
+        // when the process exits, but since close is not synchronized,
+        // it creates a race if we close the stream first and the same
+        // fd is recycled.  the stream draining thread will attempt to
+        // drain that fd!!  it may block, OOM, or cause bizarre behavior
+        // see: https://bugs.openjdk.java.net/browse/JDK-8024521
+        //      issue is fixed in build 7u60
+        InputStream stdout = process.getInputStream();
+        synchronized (stdout) {
+          inReader.close();
+        }
       } catch (IOException ioe) {
         LOG.warn("Error while closing the input stream", ioe);
       }
@@ -524,7 +535,10 @@ abstract public class Shell {
         LOG.warn("Interrupted while joining errThread");
       }
       try {
-        errReader.close();
+        InputStream stderr = process.getErrorStream();
+        synchronized (stderr) {
+          errReader.close();
+        }
       } catch (IOException ioe) {
         LOG.warn("Error while closing the error stream", ioe);
       }