Include an example Accumulo configuration file.

Make the batchwriter's number of threads configurable.

accumulo/src/main/conf/accumulo.properties

+# Copyright 2014 Cloudera, Inc. or its affiliates. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you
+# may not use this file except in compliance with the License. You
+# may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+# implied. See the License for the specific language governing
+# permissions and limitations under the License. See accompanying
+# LICENSE file.
+#
+# Sample Accumulo configuration properties
+#
+# You may either set properties here or via the command line.
+#
+
+# This will influence the keys we write
+accumulo.columnFamily=YCSB
+
+# This should be set based on your Accumulo cluster
+#accumulo.instanceName=ExampleInstance
+
+# Comma separated list of host:port tuples for the ZooKeeper quorum used
+# by your Accumulo cluster
+#accumulo.zooKeepers=zoo1.example.com:2181,zoo2.example.com:2181,zoo3.example.com:2181
+
+# This user will need permissions on the table YCSB works against
+#accumulo.username=ycsb
+#accumulo.password=protectyaneck
+
+# Controls how long our client writer will wait to buffer more data
+# measured in milliseconds
+accumulo.batchWriterMaxLatency=30000
+
+# Controls how much data our client will attempt to buffer before sending
+# measured in bytes
+accumulo.batchWriterSize=100000
+
+# Controls how many worker threads our client will use to parallelize writes
+accumulo.batchWriterThreads=1

accumulo/src/main/java/com/yahoo/ycsb/db/AccumuloClient.java

@@ -137,7 +137,8 @@ public class AccumuloClient extends DB {
 
 		long bwSize = Long.parseLong(getProperties().getProperty("accumulo.batchWriterSize", "100000"));
 		long bwMaxLatency = Long.parseLong(getProperties().getProperty("accumulo.batchWriterMaxLatency", "30000"));
-		_bw = _connector.createBatchWriter(table, bwSize, bwMaxLatency, 1);
+		int bwThreads = Integer.parseInt(getProperties().getProperty("accumulo.batchWriterThreads", "1"));
+		_bw = _connector.createBatchWriter(table, bwSize, bwMaxLatency, bwThreads);
 		// Create our scanners
 		_singleScanner = _connector.createScanner(table, Constants.NO_AUTHS);
 		_scanScanner = _connector.createScanner(table, Constants.NO_AUTHS);