rejected execution exception

AbstractModelAdapter.java

    @Override
    public void persist(Map<String, Object> data) throws Exception {
        Map<String, List<Row>> databaseOperations = generateDatabaseOperations(data);

        for(String table: databaseOperations.keySet()) {
            List<Row> batch = databaseOperations.get(table);

            PutHelper.writeToTable(connectionPool, table, batch);
        }
    }

HBaseConnectionPool.java

package com.simplymeasured.models;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.client.HTableInterface;
import org.apache.hadoop.hbase.client.HTablePool;

/**
 * @author rob
 * @since 3/12/12
 */
public class HBaseConnectionPool implements ConnectionPool {
    public static final int TABLE_POOL_MAX_SIZE = 100;

    private HTablePool tablePool;

    public HBaseConnectionPool() {
        Configuration configuration = HBaseConfiguration.create();
        
        tablePool = new HTablePool(configuration, TABLE_POOL_MAX_SIZE);
    }

    @Override
    public HTableInterface getTable(String table) {
        HTableInterface tableInstance = tablePool.getTable(table);

        return tableInstance;
    }

    @Override
    public void putTable(HTableInterface table) {
        tablePool.putTable(table);
    }
}

norace.java

package com.simplymeasured.models;

import com.google.common.collect.Lists;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.client.HTableInterface;
import org.apache.hadoop.hbase.client.HTablePool;
import org.apache.hadoop.hbase.util.Bytes;

import javax.sound.midi.SysexMessage;
import java.util.LinkedList;
import java.util.List;

/**
* @author rob
* @since 3/12/12
*/
public class HBaseConnectionPool implements ConnectionPool {
    public static final int TABLE_POOL_MAX_SIZE = 100;

    private HTablePool tablePool;

    private static final List<HTableInterface> activeTableHandles = new LinkedList<HTableInterface>();

    public HBaseConnectionPool() {
        Configuration configuration = HBaseConfiguration.create();
        
        tablePool = new HTablePool(configuration, TABLE_POOL_MAX_SIZE);
    }

    @Override
    public HTableInterface getTable(String table) {
        HTableInterface tableInstance = tablePool.getTable(table);

        synchronized (activeTableHandles) {
            activeTableHandles.add(tableInstance);
        }

        return tableInstance;
    }

    @Override
    public void putTable(HTableInterface table) {
        synchronized (activeTableHandles) {
            if(!activeTableHandles.contains(table)) {
                try {
                    throw new Exception("Attempt to release a table handle that's not in use!");
                } catch(Exception ex) {
                    ex.printStackTrace();
                }
            }

            activeTableHandles.remove(table);
        }

        tablePool.putTable(table);
    }
}

PutHelper.java

    public static void writeToTable(ConnectionPool connectionPool, String tableName, List<Row> puts) throws Exception {
        HTableInterface table = connectionPool.getTable(tableName);

        try {
            table.batch(puts);
        } finally {
             connectionPool.putTable(table);
        }
    }

stack_trace.txt

java.util.concurrent.RejectedExecutionException: null
java/util/concurrent/ThreadPoolExecutor.java:1956:in `rejectedExecution'
java/util/concurrent/ThreadPoolExecutor.java:816:in `reject'
java/util/concurrent/ThreadPoolExecutor.java:1337:in `execute'
java/util/concurrent/AbstractExecutorService.java:120:in `submit'
org/apache/hadoop/hbase/client/HConnectionManager.java:1340:in `processBatch'
org/apache/hadoop/hbase/client/HTable.java:624:in `batch'
com/simplymeasured/models/PutHelper.java:157:in `writeToTable'
com/simplymeasured/models/adapters/AbstractModelAdapter.java:44:in `persist'
/home/deploy/hbase_worker/app/releases/20120822004505/lib/hbase_workers/rpc/tweets.rb:15:in `persist'
org/jruby/RubyArray.java:1615:in `each'
/home/deploy/hbase_worker/app/releases/20120822004505/lib/hbase_workers/rpc/tweets.rb:14:in `persist'
/home/deploy/hbase_worker/app/releases/20120822004505/lib/hbase_workers/rpc/rpc_base.rb:13:in 'safe_handler'
/home/deploy/hbase_worker/app/releases/20120822004505/lib/hbase_workers/rpc/tweets.rb:13:in `persist' org/jruby/RubyKernel.java:2080:in `send'
[GEM_ROOT]/bundler/gems/redisrpc-61352680ae0a/ruby/lib/redisrpc.rb:135:in `run_one'
[GEM_ROOT]/bundler/gems/redisrpc-61352680ae0a/ruby/lib/redisrpc.rb:104:in `run' 
org/jruby/RubyKernel.java:1410:in `loop'
[GEM_ROOT]/bundler/gems/redisrpc-61352680ae0a/ruby/lib/redisrpc.rb:104:in `run'
bin/rpc_server:40:in `(root)'
org/jruby/RubyKernel.java:1410:in `loop'
bin/rpc_server:27:in `__file__'
org/jruby/RubyProc.java:270:in `call'
org/jruby/RubyProc.java:224:in `call'