HADOOP-19134. Use StringBuilder instead of StringBuffer. (apache#6692). Contributed by PJ Fanning

Author: pjfanning

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/crypto/key/KeyShell.java

@@ -169,7 +169,7 @@ protected int init(String[] args) throws IOException {
 
   @Override
   public String getCommandUsage() {
-    StringBuffer sbuf = new StringBuffer(USAGE_PREFIX + COMMANDS);
+    StringBuilder sbuf = new StringBuilder(USAGE_PREFIX + COMMANDS);
     String banner = StringUtils.repeat("=", 66);
     sbuf.append(banner + "\n");
     sbuf.append(CreateCommand.USAGE + ":\n\n" + CreateCommand.DESC + "\n");

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/DF.java

@@ -163,7 +163,7 @@ protected void parseExecResult(BufferedReader lines) throws IOException {
   @VisibleForTesting
   protected void parseOutput() throws IOException {
     if (output.size() < 2) {
-      StringBuffer sb = new StringBuffer("Fewer lines of output than expected");
+      StringBuilder sb = new StringBuilder("Fewer lines of output than expected");
       if (output.size() > 0) {
         sb.append(": " + output.get(0));
       }

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FileUtil.java

@@ -1052,7 +1052,7 @@ private static void unTarUsingTar(InputStream inputStream, File untarDir,
 
   private static void unTarUsingTar(File inFile, File untarDir,
       boolean gzipped) throws IOException {
-    StringBuffer untarCommand = new StringBuffer();
+    StringBuilder untarCommand = new StringBuilder();
     // not using canonical path here; this postpones relative path
     // resolution until bash is executed.
     final String source = "'" + FileUtil.makeSecureShellPath(inFile) + "'";

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/oncrpc/RpcDeniedReply.java

@@ -58,7 +58,7 @@ public RejectState getRejectState() {
 
   @Override
   public String toString() {
-    return new StringBuffer().append("xid:").append(xid)
+    return new StringBuilder().append("xid:").append(xid)
         .append(",messageType:").append(messageType).append("verifier_flavor:")
         .append(verifier.getFlavor()).append("rejectState:")
         .append(rejectState).toString();

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/ProviderUtils.java

@@ -148,7 +148,7 @@ public static Configuration excludeIncompatibleCredentialProviders(
     if (providerPath == null) {
       return config;
     }
-    StringBuffer newProviderPath = new StringBuffer();
+    StringBuilder newProviderPath = new StringBuilder();
     String[] providers = providerPath.split(",");
     Path path = null;
     for (String provider: providers) {

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/alias/CredentialShell.java

@@ -127,7 +127,7 @@ protected int init(String[] args) throws IOException {
 
   @Override
   public String getCommandUsage() {
-    StringBuffer sbuf = new StringBuffer(USAGE_PREFIX + COMMANDS);
+    StringBuilder sbuf = new StringBuilder(USAGE_PREFIX + COMMANDS);
     String banner = StringUtils.repeat("=", 66);
     sbuf.append(banner + "\n")
         .append(CreateCommand.USAGE + ":\n\n" + CreateCommand.DESC + "\n")

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/ssl/SSLHostnameVerifier.java

@@ -370,7 +370,7 @@ public void check(final String[] hosts, final String[] cns,
                     strictWithSubDomains);
             }
             // Build up lists of allowed hosts For logging/debugging purposes.
-            StringBuffer buf = new StringBuffer(32);
+            StringBuilder buf = new StringBuilder(32);
             buf.append('<');
             for (int i = 0; i < hosts.length; i++) {
                 String h = hosts[i];
@@ -408,15 +408,15 @@ public void check(final String[] hosts, final String[] cns,
                 throw new SSLException(msg);
             }
 
-            // StringBuffer for building the error message.
-            buf = new StringBuffer();
+            // StringBuilder for building the error message.
+            buf = new StringBuilder();
 
             boolean match = false;
             out:
             for (Iterator<String> it = names.iterator(); it.hasNext();) {
                 // Don't trim the CN, though!
                 final String cn = StringUtils.toLowerCase(it.next());
-                // Store CN in StringBuffer in case we need to report an error.
+                // Store CN in StringBuilder in case we need to report an error.
             buf.append(" <")
             .append(cn)
             .append('>');

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

@@ -1014,7 +1014,7 @@ private void runCommand() throws IOException {
     BufferedReader inReader =
             new BufferedReader(new InputStreamReader(process.getInputStream(),
                 StandardCharsets.UTF_8));
-    final StringBuffer errMsg = new StringBuffer();
+    final StringBuilder errMsg = new StringBuilder();
 
     // read error and input streams as this would free up the buffers
     // free the error stream buffer
@@ -1208,7 +1208,7 @@ public static class ShellCommandExecutor extends Shell
       implements CommandExecutor {
 
     private String[] command;
-    private StringBuffer output;
+    private StringBuilder output;
 
 
     public ShellCommandExecutor(String[] execString) {
@@ -1289,7 +1289,7 @@ public String[] getExecString() {
 
     @Override
     protected void parseExecResult(BufferedReader lines) throws IOException {
-      output = new StringBuffer();
+      output = new StringBuilder();
       char[] buf = new char[512];
       int nRead;
       while ( (nRead = lines.read(buf, 0, buf.length)) > 0 ) {

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

@@ -1334,7 +1334,7 @@ public static String wrap(String str, int wrapLength, String newLineStr,
 
       int inputLineLength = str.length();
       int offset = 0;
-      StringBuffer wrappedLine = new StringBuffer(inputLineLength + 32);
+      StringBuilder wrappedLine = new StringBuilder(inputLineLength + 32);
 
       while(inputLineLength - offset > wrapLength) {
         if(str.charAt(offset) == 32) {

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/fs/shell/TestCount.java

@@ -580,7 +580,7 @@ public MockQuotaUsage() {
     public String toString(boolean hOption,
         boolean tOption, List<StorageType> types) {
       if (tOption) {
-        StringBuffer result = new StringBuffer();
+        StringBuilder result = new StringBuilder();
         result.append(hOption ? HUMAN : BYTES);
 
         for (StorageType type : types) {

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/security/alias/TestCredentialProviderFactory.java

@@ -114,7 +114,7 @@ public void testUriErrors() throws Exception {
   }
 
   private static char[] generatePassword(int length) {
-    StringBuffer sb = new StringBuffer();
+    StringBuilder sb = new StringBuilder();
     Random r = new Random();
     for (int i = 0; i < length; i++) {
       sb.append(chars[r.nextInt(chars.length)]);

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestShell.java

@@ -480,7 +480,7 @@ public void testBashQuote() {
   @Test(timeout=120000)
   public void testDestroyAllShellProcesses() throws Throwable {
     Assume.assumeFalse(WINDOWS);
-    StringBuffer sleepCommand = new StringBuffer();
+    StringBuilder sleepCommand = new StringBuilder();
     sleepCommand.append("sleep 200");
     String[] shellCmd = {"bash", "-c", sleepCommand.toString()};
     final ShellCommandExecutor shexc1 = new ShellCommandExecutor(shellCmd);

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/functional/TestRemoteIterators.java

@@ -86,7 +86,7 @@ public void log(Object o) {
    */
   @Test
   public void testSingleton() throws Throwable {
-    StringBuffer result = new StringBuffer();
+    StringBuilder result = new StringBuilder();
     String name = "singleton";
     RemoteIterator<String> it = remoteIteratorFromSingleton(name);
     assertStringValueContains(it, "SingletonIterator");

hadoop-common-project/hadoop-kms/src/test/java/org/apache/hadoop/crypto/key/kms/server/TestKMS.java

@@ -167,7 +167,7 @@ protected String generateLoadBalancingKeyProviderUriString() {
       if (kmsUrl == null || kmsUrl.size() == 0) {
         return null;
       }
-      StringBuffer sb = new StringBuffer();
+      StringBuilder sb = new StringBuilder();
 
       for (int i = 0; i < kmsUrl.size(); i++) {
         sb.append(KMSClientProvider.SCHEME_NAME + "://" +

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/tools/DFSck.java

@@ -195,7 +195,7 @@ private Integer listCorruptFileBlocks(String dir, String baseUrl)
     final String cookiePrefix = "Cookie:";
     boolean allDone = false;
     while (!allDone) {
-      final StringBuffer url = new StringBuffer(baseUrl);
+      final StringBuilder url = new StringBuilder(baseUrl);
       if (cookie > 0) {
         url.append("&startblockafter=").append(String.valueOf(cookie));
       }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/tools/offlineEditsViewer/OfflineEditsXmlLoader.java

@@ -32,7 +32,6 @@
 import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp;
 import org.apache.hadoop.hdfs.server.namenode.FSEditLogOpCodes;
 import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.OpInstanceCache;
-import org.apache.hadoop.hdfs.tools.offlineEditsViewer.OfflineEditsViewer;
 import org.apache.hadoop.hdfs.util.XMLUtils.Stanza;
 import org.xml.sax.Attributes;
 import org.xml.sax.InputSource;
@@ -57,7 +56,7 @@ class OfflineEditsXmlLoader
   private Stanza stanza;
   private Stack<Stanza> stanzaStack;
   private FSEditLogOpCodes opCode;
-  private StringBuffer cbuf;
+  private StringBuilder cbuf;
   private long nextTxId;
   private final OpInstanceCache opCache = new OpInstanceCache();
 
@@ -119,7 +118,7 @@ public void startDocument() {
     stanza = null;
     stanzaStack = new Stack<Stanza>();
     opCode = null;
-    cbuf = new StringBuffer();
+    cbuf = new StringBuilder();
     nextTxId = -1;
   }
 
@@ -182,7 +181,7 @@ public void startElement (String uri, String name,
   @Override
   public void endElement (String uri, String name, String qName) {
     String str = XMLUtils.unmangleXmlString(cbuf.toString(), false).trim();
-    cbuf = new StringBuffer();
+    cbuf = new StringBuilder();
     switch (state) {
     case EXPECT_EDITS_TAG:
       throw new InvalidXmlException("expected <EDITS/>");

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/tools/offlineImageViewer/PBImageCorruption.java

@@ -85,7 +85,7 @@ long getId() {
   }
 
   String getType() {
-    StringBuffer s = new StringBuffer();
+    StringBuilder s = new StringBuilder();
     if (type.contains(PBImageCorruptionType.CORRUPT_NODE)) {
       s.append(PBImageCorruptionType.CORRUPT_NODE);
     }

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/DFSTestUtil.java

@@ -340,7 +340,7 @@ private class MyFile {
         for (int idx = 0; idx < nLevels; idx++) {
           levels[idx] = gen.nextInt(10);
         }
-        StringBuffer sb = new StringBuffer();
+        StringBuilder sb = new StringBuilder();
         for (int idx = 0; idx < nLevels; idx++) {
           sb.append(dirNames[levels[idx]]);
           sb.append("/");

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestHDFSTrash.java

@@ -180,7 +180,7 @@ private Trash getPerUserTrash(UserGroupInformation ugi,
       FileSystem fileSystem, Configuration config) throws IOException {
     // generate an unique path per instance
     UUID trashId = UUID.randomUUID();
-    StringBuffer sb = new StringBuffer()
+    StringBuilder sb = new StringBuilder()
         .append(ugi.getUserName())
         .append("-")
         .append(trashId.toString());

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestBlockManager.java

@@ -1833,7 +1833,7 @@ public void testMetaSavePostponedMisreplicatedBlocks() throws IOException {
     DataInputStream in = new DataInputStream(fstream);
 
     BufferedReader reader = new BufferedReader(new InputStreamReader(in));
-    StringBuffer buffer = new StringBuffer();
+    StringBuilder buffer = new StringBuilder();
     String line;
     try {
       while ((line = reader.readLine()) != null) {
@@ -1861,7 +1861,7 @@ public void testMetaSaveMissingReplicas() throws Exception {
     FileInputStream fstream = new FileInputStream(file);
     DataInputStream in = new DataInputStream(fstream);
     BufferedReader reader = new BufferedReader(new InputStreamReader(in));
-    StringBuffer buffer = new StringBuffer();
+    StringBuilder buffer = new StringBuilder();
     String line;
     try {
       while ((line = reader.readLine()) != null) {
@@ -1933,7 +1933,7 @@ public void testMetaSaveInMaintenanceReplicas() throws Exception {
     FileInputStream fstream = new FileInputStream(file);
     DataInputStream in = new DataInputStream(fstream);
     BufferedReader reader = new BufferedReader(new InputStreamReader(in));
-    StringBuffer buffer = new StringBuffer();
+    StringBuilder buffer = new StringBuilder();
     String line;
     try {
       while ((line = reader.readLine()) != null) {
@@ -1989,7 +1989,7 @@ public void testMetaSaveDecommissioningReplicas() throws Exception {
     FileInputStream fstream = new FileInputStream(file);
     DataInputStream in = new DataInputStream(fstream);
     BufferedReader reader = new BufferedReader(new InputStreamReader(in));
-    StringBuffer buffer = new StringBuffer();
+    StringBuilder buffer = new StringBuilder();
     String line;
     try {
       while ((line = reader.readLine()) != null) {

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/web/resources/TestWebHdfsDataLocality.java

@@ -196,7 +196,7 @@ public void testExcludeDataNodes() throws Exception {
       //For GETFILECHECKSUM, OPEN and APPEND,
       //the chosen datanode must be different with exclude nodes.
 
-      StringBuffer sb = new StringBuffer();
+      StringBuilder sb = new StringBuilder();
       for (int i = 0; i < 2; i++) {
         sb.append(locations[i].getXferAddr());
         { // test GETFILECHECKSUM

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/webapp/ConfBlock.java

@@ -83,7 +83,7 @@ public class ConfBlock extends HtmlBlock {
               __().
       tbody();
       for (ConfEntryInfo entry : info.getProperties()) {
-        StringBuffer buffer = new StringBuffer();
+        StringBuilder buffer = new StringBuilder();
         String[] sources = entry.getSource();
         //Skip the last entry, because it is always the same HDFS file, and
         // output them in reverse order so most recent is output first

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/test/java/org/apache/hadoop/mapreduce/v2/app/TestRecovery.java

@@ -2080,7 +2080,7 @@ private void writeOutput(TaskAttempt attempt, Configuration conf)
 
   private void validateOutput() throws IOException {
     File expectedFile = new File(new Path(outputDir, partFile).toString());
-    StringBuffer expectedOutput = new StringBuffer();
+    StringBuilder expectedOutput = new StringBuilder();
     expectedOutput.append(key1).append('\t').append(val1).append("\n");
     expectedOutput.append(val1).append("\n");
     expectedOutput.append(val2).append("\n");

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/test/java/org/apache/hadoop/mapreduce/v2/app/webapp/TestAMWebServicesAttempts.java

@@ -516,7 +516,7 @@ public void verifyTaskAttemptGeneric(TaskAttempt ta, TaskType ttype,
     String expectDiag = "";
     List<String> diagnosticsList = ta.getDiagnostics();
     if (diagnosticsList != null && !diagnostics.isEmpty()) {
-      StringBuffer b = new StringBuffer();
+      StringBuilder b = new StringBuilder();
       for (String diag : diagnosticsList) {
         b.append(diag);
       }

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/test/java/org/apache/hadoop/mapreduce/v2/app/webapp/TestAMWebServicesJobs.java

@@ -600,7 +600,7 @@ public void verifyAMJobGenericSecure(Job job, int mapsPending,
     String diagString = "";
     List<String> diagList = job.getDiagnostics();
     if (diagList != null && !diagList.isEmpty()) {
-      StringBuffer b = new StringBuffer();
+      StringBuilder b = new StringBuilder();
       for (String diag : diagList) {
         b.append(diag);
       }

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-common/src/main/java/org/apache/hadoop/mapred/LocalJobRunner.java

@@ -1027,8 +1027,8 @@ static void setupChildMapredLocalDirs(Task t, JobConf conf) {
     String taskId = t.getTaskID().toString();
     boolean isCleanup = t.isTaskCleanupTask();
     String user = t.getUser();
-    StringBuffer childMapredLocalDir =
-        new StringBuffer(localDirs[0] + Path.SEPARATOR
+    StringBuilder childMapredLocalDir =
+        new StringBuilder(localDirs[0] + Path.SEPARATOR
             + getLocalTaskDir(user, jobId, taskId, isCleanup));
     for (int i = 1; i < localDirs.length; i++) {
       childMapredLocalDir.append("," + localDirs[i] + Path.SEPARATOR

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-common/src/main/java/org/apache/hadoop/mapreduce/v2/util/MRWebAppUtil.java

@@ -145,7 +145,7 @@ public static String getApplicationWebURLOnJHSWithoutScheme(Configuration conf,
     InetSocketAddress address = NetUtils.createSocketAddr(
       hsAddress, getDefaultJHSWebappPort(),
       getDefaultJHSWebappURLWithoutScheme());
-    StringBuffer sb = new StringBuffer();
+    StringBuilder sb = new StringBuilder();
     if (address.getAddress() != null &&
         (address.getAddress().isAnyLocalAddress() ||
          address.getAddress().isLoopbackAddress())) {

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-common/src/test/java/org/apache/hadoop/mapred/TestLocalModeWithNewApis.java

@@ -102,7 +102,7 @@ public void testNewApis() throws Exception {
   static String readOutput(Path outDir, Configuration conf) 
       throws IOException {
     FileSystem fs = outDir.getFileSystem(conf);
-    StringBuffer result = new StringBuffer();
+    StringBuilder result = new StringBuilder();
 
     Path[] fileList = FileUtil.stat2Paths(fs.listStatus(outDir,
            new Utils.OutputFileUtils.OutputFilesFilter()));

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/FileInputFormat.java

@@ -470,7 +470,7 @@ public static void addInputPaths(JobConf conf, String commaSeparatedPaths) {
    */ 
   public static void setInputPaths(JobConf conf, Path... inputPaths) {
     Path path = new Path(conf.getWorkingDirectory(), inputPaths[0]);
-    StringBuffer str = new StringBuffer(StringUtils.escapeString(path.toString()));
+    StringBuilder str = new StringBuilder(StringUtils.escapeString(path.toString()));
     for(int i = 1; i < inputPaths.length;i++) {
       str.append(StringUtils.COMMA_STR);
       path = new Path(conf.getWorkingDirectory(), inputPaths[i]);

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/InvalidInputException.java

@@ -61,7 +61,7 @@ public List<IOException> getProblems() {
    * @return the concatenated messages from all of the problems.
    */
   public String getMessage() {
-    StringBuffer result = new StringBuffer();
+    StringBuilder result = new StringBuilder();
     Iterator<IOException> itr = problems.iterator();
     while(itr.hasNext()) {
       result.append(itr.next().getMessage());

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/MultiFileSplit.java

@@ -70,7 +70,7 @@ private void addToSet(Set<String> set, String[] array) {
 
   @Override
   public String toString() {
-    StringBuffer sb = new StringBuffer();
+    StringBuilder sb = new StringBuilder();
     for(int i=0; i < getPaths().length; i++) {
       sb.append(getPath(i).toUri().getPath() + ":0+" + getLength(i));
       if (i < getPaths().length -1) {

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/SortedRanges.java

@@ -207,7 +207,7 @@ public synchronized void write(DataOutput out) throws IOException {
   }
 
   public String toString() {
-    StringBuffer sb = new StringBuffer();
+    StringBuilder sb = new StringBuilder();
     Iterator<Range> it = ranges.iterator();
     while(it.hasNext()) {
       Range range = it.next();

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/TaskLog.java

@@ -518,8 +518,8 @@ static String buildCommandLine(List<String> setup, List<String> cmd,
                                 throws IOException {
 
     String stdout = FileUtil.makeShellPath(stdoutFilename);
-    String stderr = FileUtil.makeShellPath(stderrFilename);    
-    StringBuffer mergedCmd = new StringBuffer();
+    String stderr = FileUtil.makeShellPath(stderrFilename);
+    StringBuilder mergedCmd = new StringBuilder();
 
     // Export the pid of taskJvm to env variable JVM_PID.
     // Currently pid is not used on Windows
@@ -606,7 +606,7 @@ static String buildDebugScriptCommandLine(List<String> cmd, String debugout)
    */
   public static String addCommand(List<String> cmd, boolean isExecutable) 
   throws IOException {
-    StringBuffer command = new StringBuffer();
+    StringBuilder command = new StringBuilder();
     for(String s: cmd) {
     	command.append('\'');
       if (isExecutable) {