HDFS-3110. Use directRead API to reduce the number of buffer copies in libhdfs. Contributed by Henry Robinson.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1310185 13f79535-47bb-0310-9956-ffa450edef68

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -70,6 +70,9 @@ Trunk (unreleased changes)
     HDFS-2834. Add a ByteBuffer-based read API to DFSInputStream.
     (Henry Robinson via todd)
 
+    HDFS-3110. Use directRead API to reduce the number of buffer copies in
+    libhdfs (Henry Robinson via todd)
+
   BUG FIXES
 
     HDFS-2299. TestOfflineEditsViewer is failing on trunk. (Uma Maheswara Rao G

hadoop-hdfs-project/hadoop-hdfs/src/main/native/hdfs.c

@@ -123,6 +123,11 @@ static int errnoFromException(jthrowable exc, JNIEnv *env,
       goto done;
     }
 
+    if (!strcmp(excClass, "java.lang.UnsupportedOperationException")) {
+      errnum = ENOTSUP;
+      goto done;
+    }
+
     if (!strcmp(excClass, "org.apache.hadoop.security."
                 "AccessControlException")) {
         errnum = EACCES;
@@ -614,8 +619,29 @@ hdfsFile hdfsOpenFile(hdfsFS fs, const char* path, int flags,
     } else {
         file->file = (*env)->NewGlobalRef(env, jVal.l);
         file->type = (((flags & O_WRONLY) == 0) ? INPUT : OUTPUT);
+        file->flags = 0;
 
         destroyLocalReference(env, jVal.l);
+
+        if ((flags & O_WRONLY) == 0) {
+          // Try a test read to see if we can do direct reads
+          errno = 0;
+          char buf;
+          if (readDirect(fs, file, &buf, 0) == 0) {
+            // Success - 0-byte read should return 0
+            file->flags |= HDFS_FILE_SUPPORTS_DIRECT_READ;
+          } else {
+            if (errno != ENOTSUP) {
+              // Unexpected error. Clear it, don't set the direct flag.
+              fprintf(stderr,
+                      "WARN: Unexpected error %d when testing "
+                      "for direct read compatibility\n", errno);
+              errno = 0;
+              goto done;
+            }
+          }
+          errno = 0;
+        }
     }
 
     done:
@@ -706,10 +732,57 @@ int hdfsExists(hdfsFS fs, const char *path)
     return jVal.z ? 0 : -1;
 }
 
+// Checks input file for readiness for reading.
+static int readPrepare(JNIEnv* env, hdfsFS fs, hdfsFile f,
+                       jobject* jInputStream)
+{
+    *jInputStream = (jobject)(f ? f->file : NULL);
 
+    //Sanity check
+    if (!f || f->type == UNINITIALIZED) {
+      errno = EBADF;
+      return -1;
+    }
+
+    //Error checking... make sure that this file is 'readable'
+    if (f->type != INPUT) {
+      fprintf(stderr, "Cannot read from a non-InputStream object!\n");
+      errno = EINVAL;
+      return -1;
+    }
+
+    return 0;
+}
+
+// Common error-handling code between read paths.
+static int handleReadResult(int success, jvalue jVal, jthrowable jExc,
+                            JNIEnv* env)
+{
+  int noReadBytes;
+  if (success != 0) {
+    if ((*env)->ExceptionCheck(env)) {
+      errno = errnoFromException(jExc, env, "org.apache.hadoop.fs."
+                                 "FSDataInputStream::read");
+    }
+    noReadBytes = -1;
+  } else {
+    noReadBytes = jVal.i;
+    if (noReadBytes < 0) {
+      // -1 from Java is EOF, which is 0 here
+      noReadBytes = 0;
+    }
+    errno = 0;
+  }
+
+  return noReadBytes;
+}
 
 tSize hdfsRead(hdfsFS fs, hdfsFile f, void* buffer, tSize length)
 {
+    if (f->flags & HDFS_FILE_SUPPORTS_DIRECT_READ) {
+      return readDirect(fs, f, buffer, length);
+    }
+
     // JAVA EQUIVALENT:
     //  byte [] bR = new byte[length];
     //  fis.read(bR);
@@ -722,46 +795,26 @@ tSize hdfsRead(hdfsFS fs, hdfsFile f, void* buffer, tSize length)
     }
 
     //Parameters
-    jobject jInputStream = (jobject)(f ? f->file : NULL);
+    jobject jInputStream;
+    if (readPrepare(env, fs, f, &jInputStream) == -1) {
+      return -1;
+    }
 
     jbyteArray jbRarray;
     jint noReadBytes = 0;
     jvalue jVal;
     jthrowable jExc = NULL;
 
-    //Sanity check
-    if (!f || f->type == UNINITIALIZED) {
-        errno = EBADF;
-        return -1;
-    }
-
-    //Error checking... make sure that this file is 'readable'
-    if (f->type != INPUT) {
-        fprintf(stderr, "Cannot read from a non-InputStream object!\n");
-        errno = EINVAL;
-        return -1;
-    }
-
     //Read the requisite bytes
     jbRarray = (*env)->NewByteArray(env, length);
-    if (invokeMethod(env, &jVal, &jExc, INSTANCE, jInputStream, HADOOP_ISTRM,
+
-                     "read", "([B)I", jbRarray) != 0) {
+    int success = invokeMethod(env, &jVal, &jExc, INSTANCE, jInputStream, HADOOP_ISTRM,
-        errno = errnoFromException(jExc, env, "org.apache.hadoop.fs."
+                               "read", "([B)I", jbRarray);
-                                   "FSDataInputStream::read");
+
-        noReadBytes = -1;
+    noReadBytes = handleReadResult(success, jVal, jExc, env);;
-    }
+
-    else {
+    if (noReadBytes > 0) {
-        noReadBytes = jVal.i;
+      (*env)->GetByteArrayRegion(env, jbRarray, 0, noReadBytes, buffer);
-        if (noReadBytes > 0) {
-            (*env)->GetByteArrayRegion(env, jbRarray, 0, noReadBytes, buffer);
-        }  else {
-            //This is a valid case: there aren't any bytes left to read!
-          if (noReadBytes == 0 || noReadBytes < -1) {
-            fprintf(stderr, "WARN: FSDataInputStream.read returned invalid return code - libhdfs returning EOF, i.e., 0: %d\n", noReadBytes);
-          }
-            noReadBytes = 0;
-        }
-        errno = 0;
     }
 
     destroyLocalReference(env, jbRarray);
@@ -769,6 +822,52 @@ tSize hdfsRead(hdfsFS fs, hdfsFile f, void* buffer, tSize length)
     return noReadBytes;
 }
 
+// Reads using the read(ByteBuffer) API, which does fewer copies
+tSize readDirect(hdfsFS fs, hdfsFile f, void* buffer, tSize length)
+{
+    // JAVA EQUIVALENT:
+    //  ByteBuffer bbuffer = ByteBuffer.allocateDirect(length) // wraps C buffer
+    //  fis.read(bbuffer);
+
+    //Get the JNIEnv* corresponding to current thread
+    JNIEnv* env = getJNIEnv();
+    if (env == NULL) {
+      errno = EINTERNAL;
+      return -1;
+    }
+
+    jobject jInputStream;
+    if (readPrepare(env, fs, f, &jInputStream) == -1) {
+      return -1;
+    }
+
+    jint noReadBytes = 0;
+    jvalue jVal;
+    jthrowable jExc = NULL;
+
+    //Read the requisite bytes
+    jobject bb = (*env)->NewDirectByteBuffer(env, buffer, length);
+    if (bb == NULL) {
+      fprintf(stderr, "Could not allocate ByteBuffer");
+      if ((*env)->ExceptionCheck(env)) {
+        errno = errnoFromException(NULL, env, "JNIEnv::NewDirectByteBuffer");
+      } else {
+        errno = ENOMEM; // Best guess if there's no exception waiting
+      }
+      return -1;
+    }
+
+    int success = invokeMethod(env, &jVal, &jExc, INSTANCE, jInputStream,
+                               HADOOP_ISTRM, "read", "(Ljava/nio/ByteBuffer;)I",
+                               bb);
+
+    noReadBytes = handleReadResult(success, jVal, jExc, env);
+
+    destroyLocalReference(env, bb);
+
+    return noReadBytes;
+}
+
 
   
 tSize hdfsPread(hdfsFS fs, hdfsFile f, tOffset position,

hadoop-hdfs-project/hadoop-hdfs/src/main/native/hdfs.h

@@ -81,12 +81,16 @@ extern  "C" {
     };
 
     
+    // Bit fields for hdfsFile_internal flags
+    #define HDFS_FILE_SUPPORTS_DIRECT_READ (1<<0)
+
     /**
      * The 'file-handle' to a file in hdfs.
      */
     struct hdfsFile_internal {
         void* file;
         enum hdfsStreamType type;
+        uint32_t flags;
     };
     typedef struct hdfsFile_internal* hdfsFile;
       
@@ -203,7 +207,6 @@ extern  "C" {
      */
     tSize hdfsRead(hdfsFS fs, hdfsFile file, void* buffer, tSize length);
 
-
     /** 
      * hdfsPread - Positional read of data from an open file.
      * @param fs The configured filesystem handle.

hadoop-hdfs-project/hadoop-hdfs/src/main/native/hdfs_test.c

@@ -18,6 +18,8 @@
 
 #include "hdfs.h" 
 
+tSize readDirect(hdfsFS fs, hdfsFile f, void* buffer, tSize length);
+
 void permission_disp(short permissions, char *rtr) {
   rtr[9] = '\0';
   int i;
@@ -51,7 +53,6 @@ void permission_disp(short permissions, char *rtr) {
 } 
 
 int main(int argc, char **argv) {
-
     hdfsFS fs = hdfsConnectNewInstance("default", 0);
     if(!fs) {
         fprintf(stderr, "Oops! Failed to connect to hdfs!\n");
@@ -64,20 +65,25 @@ int main(int argc, char **argv) {
         exit(-1);
     } 
 
-        const char* writePath = "/tmp/testfile.txt";
+    const char* writePath = "/tmp/testfile.txt";
+    const char* fileContents = "Hello, World!";
+
     {
         //Write tests
         
-        
         hdfsFile writeFile = hdfsOpenFile(fs, writePath, O_WRONLY|O_CREAT, 0, 0, 0);
         if(!writeFile) {
             fprintf(stderr, "Failed to open %s for writing!\n", writePath);
             exit(-1);
         }
         fprintf(stderr, "Opened %s for writing successfully...\n", writePath);
-
+        tSize num_written_bytes =
-        char* buffer = "Hello, World!";
+          hdfsWrite(fs, writeFile, (void*)fileContents, strlen(fileContents)+1);
-        tSize num_written_bytes = hdfsWrite(fs, writeFile, (void*)buffer, strlen(buffer)+1);
+        if (num_written_bytes != strlen(fileContents) + 1) {
+          fprintf(stderr, "Failed to write correct number of bytes - expected %d, got %d\n",
+                  (int)(strlen(fileContents) + 1), (int)num_written_bytes);
+            exit(-1);
+        }
         fprintf(stderr, "Wrote %d bytes\n", num_written_bytes);
 
         tOffset currentPos = -1;
@@ -138,18 +144,86 @@ int main(int argc, char **argv) {
         }
         fprintf(stderr, "Current position: %ld\n", currentPos);
 
+        if ((readFile->flags & HDFS_FILE_SUPPORTS_DIRECT_READ) == 0) {
+          fprintf(stderr, "Direct read support incorrectly not detected "
+                  "for HDFS filesystem\n");
+          exit(-1);
+        }
+
+        fprintf(stderr, "Direct read support detected for HDFS\n");
+
+        // Clear flags so that we really go through slow read path
+        readFile->flags &= ~HDFS_FILE_SUPPORTS_DIRECT_READ;
+
         static char buffer[32];
         tSize num_read_bytes = hdfsRead(fs, readFile, (void*)buffer, 
                 sizeof(buffer));
         fprintf(stderr, "Read following %d bytes:\n%s\n", 
                 num_read_bytes, buffer);
 
+        memset(buffer, 0, strlen(fileContents + 1));
+
         num_read_bytes = hdfsPread(fs, readFile, 0, (void*)buffer, 
                 sizeof(buffer));
         fprintf(stderr, "Read following %d bytes:\n%s\n", 
                 num_read_bytes, buffer);
 
+        if (hdfsSeek(fs, readFile, 0L)) {
+            fprintf(stderr,
+                    "Failed to seek to file start for direct read test!\n");
+            exit(-1);
+        }
+
+        readFile->flags |= HDFS_FILE_SUPPORTS_DIRECT_READ;
+
+        memset(buffer, 0, strlen(fileContents + 1));
+        num_read_bytes = hdfsRead(fs, readFile, (void*)buffer,
+                sizeof(buffer));
+        if (strncmp(fileContents, buffer, strlen(fileContents)) != 0) {
+            fprintf(stderr, "Failed to read (direct). Expected %s but got %s (%d bytes)\n",
+                    fileContents, buffer, num_read_bytes);
+            exit(-1);
+        }
+        fprintf(stderr, "Read (direct) following %d bytes:\n%s\n",
+                num_read_bytes, buffer);
         hdfsCloseFile(fs, readFile);
+
+        // Test correct behaviour for unsupported filesystems
+        hdfsFile localFile = hdfsOpenFile(lfs, writePath, O_WRONLY|O_CREAT, 0, 0, 0);
+        if(!localFile) {
+            fprintf(stderr, "Failed to open %s for writing!\n", writePath);
+            exit(-1);
+        }
+
+        tSize num_written_bytes = hdfsWrite(lfs, localFile,
+                                            (void*)fileContents,
+                                            strlen(fileContents) + 1);
+
+        hdfsCloseFile(lfs, localFile);
+        localFile = hdfsOpenFile(lfs, writePath, O_RDONLY, 0, 0, 0);
+
+        if (localFile->flags & HDFS_FILE_SUPPORTS_DIRECT_READ) {
+          fprintf(stderr, "Direct read support incorrectly detected for local "
+                  "filesystem\n");
+          exit(-1);
+        }
+
+        memset(buffer, 0, strlen(fileContents + 1));
+        int result = readDirect(lfs, localFile, (void*)buffer, sizeof(buffer));
+        if (result != -1) {
+          fprintf(stderr, "Expected error from local direct read not seen!\n");
+          exit(-1);
+        }
+
+        if (errno != ENOTSUP) {
+          fprintf(stderr, "Error code not correctly set to ENOTSUP, was %d!\n",
+                  errno);
+          exit(-1);
+        }
+
+        fprintf(stderr, "Expected exception thrown for unsupported direct read\n");
+
+        hdfsCloseFile(lfs, localFile);
     }
 
     int totalResult = 0;
@@ -446,4 +520,3 @@ int main(int argc, char **argv) {
 /**
  * vim: ts=4: sw=4: et:
  */
-

hadoop-hdfs-project/hadoop-hdfs/src/main/native/tests/test-libhdfs.sh

@@ -17,126 +17,64 @@
 #
 
 #
-# Note: This script depends on 8 environment variables to function correctly:
+# Note: This script depends on 5 environment variables to function correctly:
-# a) CLASSPATH
+# a) HADOOP_HOME - must be set
-# b) HADOOP_PREFIX
+# b) HDFS_TEST_CONF_DIR - optional; the directory to read and write
-# c) HADOOP_CONF_DIR 
+# core-site.xml to. Defaults to /tmp
-# d) HADOOP_LOG_DIR 
+# c) LIBHDFS_BUILD_DIR - optional; the location of the hdfs_test
-# e) LIBHDFS_BUILD_DIR
+# executable. Defaults to the parent directory.
-# f) LIBHDFS_INSTALL_DIR
+# d) OS_NAME - used to choose how to locate libjvm.so
-# g) OS_NAME
+# e) CLOVER_JAR - optional; the location of the Clover code coverage tool's jar.
-# h) CLOVER_JAR
-# i} HADOOP_VERSION
-# j) HADOOP_HDFS_HOME
-# All these are passed by build.xml.
 #
 
+if [ "x$HADOOP_HOME" == "x" ]; then
+  echo "HADOOP_HOME is unset!"
+  exit 1
+fi
+
+if [ "x$LIBHDFS_BUILD_DIR" == "x" ]; then
+  LIBHDFS_BUILD_DIR=`pwd`/../
+fi
+
+if [ "x$HDFS_TEST_CONF_DIR" == "x" ]; then
+  HDFS_TEST_CONF_DIR=/tmp
+fi
+
+# LIBHDFS_INSTALL_DIR is the directory containing libhdfs.so
+LIBHDFS_INSTALL_DIR=$HADOOP_HOME/lib/native/
 HDFS_TEST=hdfs_test
-HADOOP_LIB_DIR=$HADOOP_PREFIX/lib
-HADOOP_BIN_DIR=$HADOOP_PREFIX/bin
 
-COMMON_BUILD_DIR=$HADOOP_PREFIX/build/ivy/lib/hadoop-hdfs/common
+HDFS_TEST_JAR=`find $HADOOP_HOME/share/hadoop/hdfs/ \
-COMMON_JAR=$COMMON_BUILD_DIR/hadoop-common-$HADOOP_VERSION.jar
+-name "hadoop-hdfs-*-tests.jar" | head -n 1`
 
-cat > $HADOOP_CONF_DIR/core-site.xml <<EOF
+if [ "x$HDFS_TEST_JAR" == "x" ]; then
-<?xml version="1.0"?>
+  echo "HDFS test jar not found! Tried looking in all subdirectories \
-<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>
+of $HADOOP_HOME/share/hadoop/hdfs/"
-<configuration>
+  exit 1
-<property>
-  <name>hadoop.tmp.dir</name>
-  <value>file:///$LIBHDFS_TEST_DIR</value>
-</property>
-<property>
-  <name>fs.default.name</name>
-  <value>hdfs://localhost:23000/</value>
-</property>
-</configuration>
-EOF
-
-cat > $HADOOP_CONF_DIR/hdfs-site.xml <<EOF
-<?xml version="1.0"?>
-<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>
-<configuration>
-<property>
-  <name>dfs.replication</name>
-  <value>1</value>
-</property>
-<property>
-  <name>dfs.support.append</name>
-  <value>true</value>
-</property>
-<property>
-  <name>dfs.namenode.logging.level</name>
-  <value>DEBUG</value>
-</property>
-</configuration>
-EOF
-
-cat > $HADOOP_CONF_DIR/slaves <<EOF
-localhost
-EOF
-
-# If we are running from the hdfs repo we need to make sure
-# HADOOP_BIN_DIR contains the common scripts.  
-# If the bin directory does not and we've got a common jar extract its
-# bin directory to HADOOP_PREFIX/bin. The bin scripts hdfs-config.sh and
-# hadoop-config.sh assume the bin directory is named "bin" and that it
-# is located in HADOOP_PREFIX.
-unpacked_common_bin_dir=0
-if [ ! -f $HADOOP_BIN_DIR/hadoop-config.sh ]; then
-  if [ -f $COMMON_JAR ]; then
-    jar xf $COMMON_JAR bin.tgz
-    tar xfz bin.tgz -C $HADOOP_BIN_DIR
-    unpacked_common_bin_dir=1
-  fi
 fi
 
-# Manipulate HADOOP_CONF_DIR too
+echo "Found HDFS test jar at $HDFS_TEST_JAR"
-# which is necessary to circumvent bin/hadoop
-HADOOP_CONF_DIR=$HADOOP_CONF_DIR:$HADOOP_PREFIX/conf
 
-# set pid file dir so they are not written to /tmp
+# CLASSPATH initially contains $HDFS_TEST_CONF_DIR
-export HADOOP_PID_DIR=$HADOOP_LOG_DIR
+CLASSPATH="${HDFS_TEST_CONF_DIR}"
-
-# CLASSPATH initially contains $HADOOP_CONF_DIR
-CLASSPATH="${HADOOP_CONF_DIR}"
 CLASSPATH=${CLASSPATH}:$JAVA_HOME/lib/tools.jar
 
-# for developers, add Hadoop classes to CLASSPATH
-if [ -d "$HADOOP_PREFIX/build/classes" ]; then
-  CLASSPATH=${CLASSPATH}:$HADOOP_PREFIX/build/classes
-fi
-if [ -d "$HADOOP_PREFIX/build/web/webapps" ]; then
-  CLASSPATH=${CLASSPATH}:$HADOOP_PREFIX/build/web
-fi
-if [ -d "$HADOOP_PREFIX/build/test/classes" ]; then
-  CLASSPATH=${CLASSPATH}:$HADOOP_PREFIX/build/test/classes
-fi
-
 # add Clover jar file needed for code coverage runs
 CLASSPATH=${CLASSPATH}:${CLOVER_JAR};
 
 # so that filenames w/ spaces are handled correctly in loops below
-IFS=
+IFS=$'\n'
 
-# add libs to CLASSPATH
+JAR_DIRS="$HADOOP_HOME/share/hadoop/common/lib/
-for f in $HADOOP_PREFIX/lib/*.jar; do
+$HADOOP_HOME/share/hadoop/common/
-  CLASSPATH=${CLASSPATH}:$f;
+$HADOOP_HOME/share/hadoop/hdfs
-done
+$HADOOP_HOME/share/hadoop/hdfs/lib/"
 
-for f in $HADOOP_PREFIX/*.jar; do 
+for d in $JAR_DIRS; do 
-  CLASSPATH=${CLASSPATH}:$f
+  for j in $d/*.jar; do
-done
+    CLASSPATH=${CLASSPATH}:$j
-for f in $HADOOP_PREFIX/lib/jsp-2.1/*.jar; do
+  done;
-  CLASSPATH=${CLASSPATH}:$f;
+done;
-done
-
-if [ -d "$COMMON_BUILD_DIR" ]; then
-  CLASSPATH=$CLASSPATH:$COMMON_JAR
-  for f in $COMMON_BUILD_DIR/*.jar; do
-    CLASSPATH=${CLASSPATH}:$f;
-  done
-fi
 
 # restore ordinary behaviour
 unset IFS
@@ -178,21 +116,37 @@ echo  LIB_JVM_DIR = $LIB_JVM_DIR
 echo  "++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++"
 # Put delays to ensure hdfs is up and running and also shuts down 
 # after the tests are complete
-cd $HADOOP_PREFIX
+rm $HDFS_TEST_CONF_DIR/core-site.xml
-echo Y | $HADOOP_BIN_DIR/hdfs namenode -format &&
-$HADOOP_BIN_DIR/hadoop-daemon.sh --script $HADOOP_BIN_DIR/hdfs start namenode && sleep 2
-$HADOOP_BIN_DIR/hadoop-daemon.sh --script $HADOOP_BIN_DIR/hdfs start datanode && sleep 2
-echo "Wait 30s for the datanode to start up..."
-sleep 30
-CLASSPATH=$CLASSPATH LD_PRELOAD="$LIB_JVM_DIR/libjvm.so:$LIBHDFS_INSTALL_DIR/libhdfs.so:" $LIBHDFS_BUILD_DIR/$HDFS_TEST
-BUILD_STATUS=$?
-sleep 3
-$HADOOP_BIN_DIR/hadoop-daemon.sh --script $HADOOP_BIN_DIR/hdfs stop datanode && sleep 2
-$HADOOP_BIN_DIR/hadoop-daemon.sh --script $HADOOP_BIN_DIR/hdfs stop namenode && sleep 2 
 
-if [ $unpacked_common_bin_dir -eq 1 ]; then
+$HADOOP_HOME/bin/hadoop jar $HDFS_TEST_JAR \
-  rm -rf bin.tgz
+    org.apache.hadoop.test.MiniDFSClusterManager \
+    -format -nnport 20300 -writeConfig $HDFS_TEST_CONF_DIR/core-site.xml \
+    > /tmp/libhdfs-test-cluster.out 2>&1 & 
+
+MINI_CLUSTER_PID=$!
+for i in {1..15}; do
+  echo "Waiting for DFS cluster, attempt $i of 15"
+  [ -f $HDFS_TEST_CONF_DIR/core-site.xml ] && break;
+  sleep 2
+done
+
+if [ ! -f $HDFS_TEST_CONF_DIR/core-site.xml ]; then
+  echo "Cluster did not come up in 30s"
+  kill -9 $MINI_CLUSTER_PID
+  exit 1
 fi
 
-echo exiting with $BUILD_STATUS
+echo "Cluster up, running tests"
+# Disable error checking to make sure we get to cluster cleanup
+set +e
+
+CLASSPATH=$CLASSPATH \
+LD_PRELOAD="$LIB_JVM_DIR/libjvm.so:$LIBHDFS_INSTALL_DIR/libhdfs.so:" \
+$LIBHDFS_BUILD_DIR/$HDFS_TEST
+
+BUILD_STATUS=$?
+
+echo "Tearing cluster down"
+kill -9 $MINI_CLUSTER_PID
+echo "Exiting with $BUILD_STATUS"
 exit $BUILD_STATUS