最近把一些sql執行從hive改到spark，發現執行更慢，sql主要是一些insert overwrite操作，從執行計劃看到，用到InsertIntoHiveTable

spark-sql> explain insert overwrite table test2 select * from test1;
== Physical Plan ==
InsertIntoHiveTable MetastoreRelation temp, test2, true, false
+- HiveTableScan [buyer_id#20, member_reg_gender#21, reg_birthday#22, reg_birthday1#23, age#24, age_range#25], MetastoreRelation temp, test1
Time taken: 0.404 seconds, Fetched 1 row(s)

跟進程式碼
org.apache.spark.sql.hive.execution.InsertIntoHiveTable

  protected override def doExecute(): RDD[InternalRow] = {
    sqlContext.sparkContext.parallelize(sideEffectResult.asInstanceOf[Seq[InternalRow]], 1)
  }

  /**
   * Inserts all the rows in the table into Hive.  Row objects are properly serialized with the
   * `org.apache.hadoop.hive.serde2.SerDe` and the
   * `org.apache.hadoop.mapred.OutputFormat` provided by the table definition.
   *
   * Note: this is run once and then kept to avoid double insertions.
   
 
*/
  protected[sql] lazy val sideEffectResult: Seq[InternalRow] = {
    // Have to pass the TableDesc object to RDD.mapPartitions and then instantiate new serializer
    // instances within the closure, since Serializer is not serializable while TableDesc is.
    val tableDesc = table.tableDesc
    val tableLocation 
 
= table.hiveQlTable.getDataLocation
    val tmpLocation = getExternalTmpPath(tableLocation)
    val fileSinkConf = new FileSinkDesc(tmpLocation.toString, tableDesc, false)
    val isCompressed = hadoopConf.get("hive.exec.compress.output", "false").toBoolean

    if (isCompressed) {
      // Please note that isCompressed, "mapred.output.compress", "mapred.output.compression.codec",
      // and "mapred.output.compression.type" have no impact on ORC because it uses table properties
      // to store compression information.
      hadoopConf.set("mapred.output.compress", "true")
      fileSinkConf.setCompressed(true)
      fileSinkConf.setCompressCodec(hadoopConf.get("mapred.output.compression.codec"))
      fileSinkConf.setCompressType(hadoopConf.get("mapred.output.compression.type"))
    }

    val numDynamicPartitions = partition.values.count(_.isEmpty)
    val numStaticPartitions = partition.values.count(_.nonEmpty)
    val partitionSpec = partition.map {
      case (key, Some(value)) => key -> value
      case (key, None) => key -> ""
    }

    // All partition column names in the format of "<column name 1>/<column name 2>/..."
    val partitionColumns = fileSinkConf.getTableInfo.getProperties.getProperty("partition_columns")
    val partitionColumnNames = Option(partitionColumns).map(_.split("/")).getOrElse(Array.empty)

    // By this time, the partition map must match the table's partition columns
    if (partitionColumnNames.toSet != partition.keySet) {
      throw new SparkException(
        s"""Requested partitioning does not match the ${table.tableName} table:
           |Requested partitions: ${partition.keys.mkString(",")}
           |Table partitions: ${table.partitionKeys.map(_.name).mkString(",")}""".stripMargin)
    }

    // Validate partition spec if there exist any dynamic partitions
    if (numDynamicPartitions > 0) {
      // Report error if dynamic partitioning is not enabled
      if (!hadoopConf.get("hive.exec.dynamic.partition", "true").toBoolean) {
        throw new SparkException(ErrorMsg.DYNAMIC_PARTITION_DISABLED.getMsg)
      }

      // Report error if dynamic partition strict mode is on but no static partition is found
      if (numStaticPartitions == 0 &&
        hadoopConf.get("hive.exec.dynamic.partition.mode", "strict").equalsIgnoreCase("strict")) {
        throw new SparkException(ErrorMsg.DYNAMIC_PARTITION_STRICT_MODE.getMsg)
      }

      // Report error if any static partition appears after a dynamic partition
      val isDynamic = partitionColumnNames.map(partitionSpec(_).isEmpty)
      if (isDynamic.init.zip(isDynamic.tail).contains((true, false))) {
        throw new AnalysisException(ErrorMsg.PARTITION_DYN_STA_ORDER.getMsg)
      }
    }

    val jobConf = new JobConf(hadoopConf)
    val jobConfSer = new SerializableJobConf(jobConf)

    // When speculation is on and output committer class name contains "Direct", we should warn
    // users that they may loss data if they are using a direct output committer.
    val speculationEnabled = sqlContext.sparkContext.conf.getBoolean("spark.speculation", false)
    val outputCommitterClass = jobConf.get("mapred.output.committer.class", "")
    if (speculationEnabled && outputCommitterClass.contains("Direct")) {
      val warningMessage =
        s"$outputCommitterClass may be an output committer that writes data directly to " +
          "the final location. Because speculation is enabled, this output committer may " +
          "cause data loss (see the case in SPARK-10063). If possible, please use an output " +
          "committer that does not have this behavior (e.g. FileOutputCommitter)."
      logWarning(warningMessage)
    }

    val writerContainer = if (numDynamicPartitions > 0) {
      val dynamicPartColNames = partitionColumnNames.takeRight(numDynamicPartitions)
      new SparkHiveDynamicPartitionWriterContainer(
        jobConf,
        fileSinkConf,
        dynamicPartColNames,
        child.output)
    } else {
      new SparkHiveWriterContainer(
        jobConf,
        fileSinkConf,
        child.output)
    }

    @transient val outputClass = writerContainer.newSerializer(table.tableDesc).getSerializedClass
    saveAsHiveFile(child.execute(), outputClass, fileSinkConf, jobConfSer, writerContainer)

    val outputPath = FileOutputFormat.getOutputPath(jobConf)
    // TODO: Correctly set holdDDLTime.
    // In most of the time, we should have holdDDLTime = false.
    // holdDDLTime will be true when TOK_HOLD_DDLTIME presents in the query as a hint.
    val holdDDLTime = false
    if (partition.nonEmpty) {
      if (numDynamicPartitions > 0) {
        externalCatalog.loadDynamicPartitions(
          db = table.catalogTable.database,
          table = table.catalogTable.identifier.table,
          outputPath.toString,
          partitionSpec,
          overwrite,
          numDynamicPartitions,
          holdDDLTime = holdDDLTime)
      } else {
        // scalastyle:off
        // ifNotExists is only valid with static partition, refer to
        // https://cwiki.apache.org/confluence/display/Hive/LanguageManual+DML#LanguageManualDML-InsertingdataintoHiveTablesfromqueries
        // scalastyle:on
        val oldPart =
          externalCatalog.getPartitionOption(
            table.catalogTable.database,
            table.catalogTable.identifier.table,
            partitionSpec)

        var doHiveOverwrite = overwrite

        if (oldPart.isEmpty || !ifNotExists) {
          // SPARK-18107: Insert overwrite runs much slower than hive-client.
          // Newer Hive largely improves insert overwrite performance. As Spark uses older Hive
          // version and we may not want to catch up new Hive version every time. We delete the
          // Hive partition first and then load data file into the Hive partition.
          if (oldPart.nonEmpty && overwrite) {
            oldPart.get.storage.locationUri.foreach { uri =>
              val partitionPath = new Path(uri)
              val fs = partitionPath.getFileSystem(hadoopConf)
              if (fs.exists(partitionPath)) {
                if (!fs.delete(partitionPath, true)) {
                  throw new RuntimeException(
                    "Cannot remove partition directory '" + partitionPath.toString)
                }
                // Don't let Hive do overwrite operation since it is slower.
                doHiveOverwrite = false
              }
            }
          }

          // inheritTableSpecs is set to true. It should be set to false for an IMPORT query
          // which is currently considered as a Hive native command.
          val inheritTableSpecs = true
          externalCatalog.loadPartition(
            table.catalogTable.database,
            table.catalogTable.identifier.table,
            outputPath.toString,
            partitionSpec,
            isOverwrite = doHiveOverwrite,
            holdDDLTime = holdDDLTime,
            inheritTableSpecs = inheritTableSpecs)
        }
      }
    } else {
      externalCatalog.loadTable(
        table.catalogTable.database,
        table.catalogTable.identifier.table,
        outputPath.toString, // TODO: URI
        overwrite,
        holdDDLTime)
    }

    // Attempt to delete the staging directory and the inclusive files. If failed, the files are
    // expected to be dropped at the normal termination of VM since deleteOnExit is used.
    try {
      createdTempDir.foreach { path => path.getFileSystem(hadoopConf).delete(path, true) }
    } catch {
      case NonFatal(e) =>
        logWarning(s"Unable to delete staging directory: $stagingDir.\n" + e)
    }

    // un-cache this table.
    sqlContext.sparkSession.catalog.uncacheTable(table.catalogTable.identifier.quotedString)
    sqlContext.sessionState.catalog.refreshTable(table.catalogTable.identifier)

    // It would be nice to just return the childRdd unchanged so insert operations could be chained,
    // however for now we return an empty list to simplify compatibility checks with hive, which
    // does not return anything for insert operations.
    // TODO: implement hive compatibility as rules.
    Seq.empty[InternalRow]
  }

insert overwrite 執行分為三步，一個是select，一個是write，一個是load，前邊兩步沒什麼問題，主要是最後一步load，以loadPartition為例看下執行過程：

org.apache.spark.sql.hive.HiveExternalCatalog

  override def loadPartition(
      db: String,
      table: String,
      loadPath: String,
      partition: TablePartitionSpec,
      isOverwrite: Boolean,
      holdDDLTime: Boolean,
      inheritTableSpecs: Boolean): Unit = withClient {
    requireTableExists(db, table)

    val orderedPartitionSpec = new util.LinkedHashMap[String, String]()
    getTable(db, table).partitionColumnNames.foreach { colName =>
      // Hive metastore is not case preserving and keeps partition columns with lower cased names,
      // and Hive will validate the column names in partition spec to make sure they are partition
      // columns. Here we Lowercase the column names before passing the partition spec to Hive
      // client, to satisfy Hive.
      orderedPartitionSpec.put(colName.toLowerCase, partition(colName))
    }

    client.loadPartition(
      loadPath,
      db,
      table,
      orderedPartitionSpec,
      isOverwrite,
      holdDDLTime,
      inheritTableSpecs)
  }

這裡會呼叫HiveClientImpl.loadPartition

org.apache.spark.sql.hive.client.HiveClientImpl

  def loadPartition(
      loadPath: String,
      dbName: String,
      tableName: String,
      partSpec: java.util.LinkedHashMap[String, String],
      replace: Boolean,
      holdDDLTime: Boolean,
      inheritTableSpecs: Boolean): Unit = withHiveState {
    val hiveTable = client.getTable(dbName, tableName, true /* throw exception */)
    shim.loadPartition(
      client,
      new Path(loadPath), // TODO: Use URI
      s"$dbName.$tableName",
      partSpec,
      replace,
      holdDDLTime,
      inheritTableSpecs,
      isSkewedStoreAsSubdir = hiveTable.isStoredAsSubDirectories)
  }

這裡會呼叫Shim_v0_12.loadPartition

org.apache.spark.sql.hive.client.Shim_v0_12

  override def loadPartition(
      hive: Hive,
      loadPath: Path,
      tableName: String,
      partSpec: JMap[String, String],
      replace: Boolean,
      holdDDLTime: Boolean,
      inheritTableSpecs: Boolean,
      isSkewedStoreAsSubdir: Boolean): Unit = {
    loadPartitionMethod.invoke(hive, loadPath, tableName, partSpec, replace: JBoolean,
      holdDDLTime: JBoolean, inheritTableSpecs: JBoolean, isSkewedStoreAsSubdir: JBoolean)
  }

  private lazy val loadPartitionMethod =
    findMethod(
      classOf[Hive],
      "loadPartition",
      classOf[Path],
      classOf[String],
      classOf[JMap[String, String]],
      JBoolean.TYPE,
      JBoolean.TYPE,
      JBoolean.TYPE,
      JBoolean.TYPE)

這裡會反射呼叫hive的類Hive.loadPartition

org.apache.hadoop.hive.ql.metadata.Hive （1.2版本）

    public void loadPartition(Path loadPath, String tableName, Map<String, String> partSpec, boolean replace, boolean holdDDLTime, boolean inheritTableSpecs, boolean isSkewedStoreAsSubdir, boolean isSrcLocal, boolean isAcid) throws HiveException {
        Table tbl = this.getTable(tableName);
        this.loadPartition(loadPath, tbl, partSpec, replace, holdDDLTime, inheritTableSpecs, isSkewedStoreAsSubdir, isSrcLocal, isAcid);
    }

    public Partition loadPartition(Path loadPath, Table tbl, Map<String, String> partSpec, boolean replace, boolean holdDDLTime, boolean inheritTableSpecs, boolean isSkewedStoreAsSubdir, boolean isSrcLocal, boolean isAcid) throws HiveException {
        Path tblDataLocationPath = tbl.getDataLocation();
        Partition newTPart = null;

        try {
            Partition oldPart = this.getPartition(tbl, partSpec, false);
            Path oldPartPath = null;
            if (oldPart != null) {
                oldPartPath = oldPart.getDataLocation();
            }

            Path newPartPath = null;
            FileSystem oldPartPathFS;
            if (inheritTableSpecs) {
                Path partPath = new Path(tbl.getDataLocation(), Warehouse.makePartPath(partSpec));
                newPartPath = new Path(tblDataLocationPath.toUri().getScheme(), tblDataLocationPath.toUri().getAuthority(), partPath.toUri().getPath());
                if (oldPart != null) {
                    oldPartPathFS = oldPartPath.getFileSystem(this.getConf());
                    FileSystem loadPathFS = loadPath.getFileSystem(this.getConf());
                    if (FileUtils.equalsFileSystem(oldPartPathFS, loadPathFS)) {
                        newPartPath = oldPartPath;
                    }
                }
            } else {
                newPartPath = oldPartPath;
            }

            List<Path> newFiles = null;
            if (replace) {
                replaceFiles(tbl.getPath(), loadPath, newPartPath, oldPartPath, this.getConf(), isSrcLocal);
            } else {
                newFiles = new ArrayList();
                oldPartPathFS = tbl.getDataLocation().getFileSystem(this.conf);
                copyFiles(this.conf, loadPath, newPartPath, oldPartPathFS, isSrcLocal, isAcid, newFiles);
            }

            boolean forceCreate = !holdDDLTime;
            newTPart = this.getPartition(tbl, partSpec, forceCreate, newPartPath.toString(), inheritTableSpecs, newFiles);
            if (!holdDDLTime && isSkewedStoreAsSubdir) {
                org.apache.hadoop.hive.metastore.api.Partition newCreatedTpart = newTPart.getTPartition();
                SkewedInfo skewedInfo = newCreatedTpart.getSd().getSkewedInfo();
                Map<List<String>, String> skewedColValueLocationMaps = this.constructListBucketingLocationMap(newPartPath, skewedInfo);
                skewedInfo.setSkewedColValueLocationMaps(skewedColValueLocationMaps);
                newCreatedTpart.getSd().setSkewedInfo(skewedInfo);
                this.alterPartition(tbl.getDbName(), tbl.getTableName(), new Partition(tbl, newCreatedTpart));
                this.getPartition(tbl, partSpec, true, newPartPath.toString(), inheritTableSpecs, newFiles);
                return new Partition(tbl, newCreatedTpart);
            } else {
                return newTPart;
            }
        } catch (IOException var20) {
            LOG.error(StringUtils.stringifyException(var20));
            throw new HiveException(var20);
        } catch (MetaException var21) {
            LOG.error(StringUtils.stringifyException(var21));
            throw new HiveException(var21);
        } catch (InvalidOperationException var22) {
            LOG.error(StringUtils.stringifyException(var22));
            throw new HiveException(var22);
        }
    }

    protected static void replaceFiles(Path tablePath, Path srcf, Path destf, Path oldPath, HiveConf conf, boolean isSrcLocal) throws HiveException {
        try {
            FileSystem destFs = destf.getFileSystem(conf);
            boolean inheritPerms = HiveConf.getBoolVar(conf, ConfVars.HIVE_WAREHOUSE_SUBDIR_INHERIT_PERMS);

            FileSystem srcFs;
            FileStatus[] srcs;
            try {
                srcFs = srcf.getFileSystem(conf);
                srcs = srcFs.globStatus(srcf);
            } catch (IOException var20) {
                throw new HiveException("Getting globStatus " + srcf.toString(), var20);
            }

            if (srcs == null) {
                LOG.info("No sources specified to move: " + srcf);
            } else {
                List<List<Path[]>> result = checkPaths(conf, destFs, srcs, srcFs, destf, true);
                if (oldPath != null) {
                    try {
                        FileSystem fs2 = oldPath.getFileSystem(conf);
                        if (fs2.exists(oldPath)) {
                            if (FileUtils.isSubDir(oldPath, destf, fs2)) {
                                FileUtils.trashFilesUnderDir(fs2, oldPath, conf);
                            }

                            if (inheritPerms) {
                                inheritFromTable(tablePath, destf, conf, destFs);
                            }
                        }
                    } catch (Exception var19) {
                        LOG.warn("Directory " + oldPath.toString() + " cannot be removed: " + var19, var19);
                    }
                }

                if (srcs.length == 1 && srcs[0].isDir()) {
                    Path destfp = destf.getParent();
                    if (!destFs.exists(destfp)) {
                        boolean success = destFs.mkdirs(destfp);
                        if (!success) {
                            LOG.warn("Error creating directory " + destf.toString());
                        }

                        if (inheritPerms && success) {
                            inheritFromTable(tablePath, destfp, conf, destFs);
                        }
                    }

                    Iterator i$ = result.iterator();

                    while(i$.hasNext()) {
                        List<Path[]> sdpairs = (List)i$.next();
                        Iterator i$ = sdpairs.iterator();

                        while(i$.hasNext()) {
                            Path[] sdpair = (Path[])i$.next();
                            Path destParent = sdpair[1].getParent();
                            FileSystem destParentFs = destParent.getFileSystem(conf);
                            if (!destParentFs.isDirectory(destParent)) {
                                boolean success = destFs.mkdirs(destParent);
                                if (!success) {
                                    LOG.warn("Error creating directory " + destParent);
                                }

                                if (inheritPerms && success) {
                                    inheritFromTable(tablePath, destParent, conf, destFs);
                                }
                            }

                            if (!moveFile(conf, sdpair[0], sdpair[1], destFs, true, isSrcLocal)) {
                                throw new IOException("Unable to move file/directory from " + sdpair[0] + " to " + sdpair[1]);
                            }
                        }
                    }
                } else {
                    if (!destFs.exists(destf)) {
                        boolean success = destFs.mkdirs(destf);
                        if (!success) {
                            LOG.warn("Error creating directory " + destf.toString());
                        }

                        if (inheritPerms && success) {
                            inheritFromTable(tablePath, destf, conf, destFs);
                        }
                    }

                    Iterator i$ = result.iterator();

                    while(i$.hasNext()) {
                        List<Path[]> sdpairs = (List)i$.next();
                        Iterator i$ = sdpairs.iterator();

                        while(i$.hasNext()) {
                            Path[] sdpair = (Path[])i$.next();
                            if (!moveFile(conf, sdpair[0], sdpair[1], destFs, true, isSrcLocal)) {
                                throw new IOException("Error moving: " + sdpair[0] + " into: " + sdpair[1]);
                            }
                        }
                    }
                }

            }
        } catch (IOException var21) {
            throw new HiveException(var21.getMessage(), var21);
        }
    }

    public static boolean trashFilesUnderDir(FileSystem fs, Path f, Configuration conf) throws FileNotFoundException, IOException {
        FileStatus[] statuses = fs.listStatus(f, HIDDEN_FILES_PATH_FILTER);
        boolean result = true;
        FileStatus[] arr$ = statuses;
        int len$ = statuses.length;

        for(int i$ = 0; i$ < len$; ++i$) {
            FileStatus status = arr$[i$];
            result &= moveToTrash(fs, status.getPath(), conf);
        }

        return result;
    }

hive在執行loadPartition的時候，如果分割槽目錄已經存在，會呼叫replaceFiles，replaceFiles會呼叫trashFilesUnderDir，trashFilesUnderDir裡會逐個將檔案放到回收站；

spark執行loadPartition的時候，直接反射呼叫hive的邏輯，為什麼還會比hive執行慢很多呢？

這時注意到hive用的版本是2.1，spark2.1.1裡依賴的hive版本是1.2，對比hive1.2和hive2.1之間的程式碼發現，確實有差別，以下是hive2.1的程式碼：

org.apache.hadoop.hive.ql.metadata.Hive（2.1版本）

  /**
   * Trashes or deletes all files under a directory. Leaves the directory as is.
   * @param fs FileSystem to use
   * @param f path of directory
   * @param conf hive configuration
   * @param forceDelete whether to force delete files if trashing does not succeed
   * @return true if deletion successful
   * @throws IOException
   */
  private boolean trashFilesUnderDir(final FileSystem fs, Path f, final Configuration conf)
      throws IOException {
    FileStatus[] statuses = fs.listStatus(f, FileUtils.HIDDEN_FILES_PATH_FILTER);
    boolean result = true;
    final List<Future<Boolean>> futures = new LinkedList<>();
    final ExecutorService pool = conf.getInt(ConfVars.HIVE_MOVE_FILES_THREAD_COUNT.varname, 25) > 0 ?
        Executors.newFixedThreadPool(conf.getInt(ConfVars.HIVE_MOVE_FILES_THREAD_COUNT.varname, 25),
        new ThreadFactoryBuilder().setDaemon(true).setNameFormat("Delete-Thread-%d").build()) : null;
    final SessionState parentSession = SessionState.get();
    for (final FileStatus status : statuses) {
      if (null == pool) {
        result &= FileUtils.moveToTrash(fs, status.getPath(), conf);
      } else {
        futures.add(pool.submit(new Callable<Boolean>() {
          @Override
          public Boolean call() throws Exception {
            SessionState.setCurrentSessionState(parentSession);
            return FileUtils.moveToTrash(fs, status.getPath(), conf);
          }
        }));
      }
    }
    if (null != pool) {
      pool.shutdown();
      for (Future<Boolean> future : futures) {
        try {
          result &= future.get();
        } catch (InterruptedException | ExecutionException e) {
          LOG.error("Failed to delete: ",e);
          pool.shutdownNow();
          throw new IOException(e);
        }
      }
    }
    return result;
  }

可以看到在hive2.1裡刪除檔案用到了執行緒池，而在hive1.2裡是在for迴圈裡序列刪除，所以當檔案很多時，hive2.1比hive1.2（即spark2.1.1）就會快非常多；

spark依賴hive的方式是直接反射呼叫，由於hive1.2和hive2.1很多類的方法介面都有調整，很難升級，所以遇到這個問題只能通過修改spark裡Hive.trashFilesUnderDir程式碼，同樣改為執行緒池的方式來刪除檔案，問題解決；