【发布时间】：2015-11-15 11:51:06
【问题描述】：
我在服务器模式下使用 Redis，而不是在集群模式下。我有 3 个 Redis Server 实例正在运行，3 个从属对应于这 3 个主控。我还有 3 个 Sentinel，每个 Sentinel 监视所有三个 master。
要连接到我的 Sentinel 并创建一个池，我使用的是 ShardedJedisSentinelPool。现在我从这个池中获取连接的类看起来像这样
public class RedisServerConnectionDAL
{
private RedisServerConnectionDAL()
{
}
private static ShardedJedisSentinelPool pool;
private static ShardedJedis jedis;
private static ShardedJedisPipeline pipeline;
private static Set<String> redissentinels;
private static List<String> redismasters;
private static int redistimeout;
private static RedisServerConnectionDAL redisdal;
private static Map<String,String> redisconfmap;
public static int WAIT_IF_FAIL;
public static int RETRIES;
public synchronized static RedisServerConnectionDAL getInstance()
{
if(redisdal==null)
{
Properties redisprops = new Properties();
redisprops = ConfigReader.ReadConfig(Constant.REDIS_CONNECTION_CONFIG_FILE);
GenericObjectPoolConfig config = new GenericObjectPoolConfig();
redisconfmap = new HashMap(redisprops);
redisdal = new RedisServerConnectionDAL();
String redisNodesString = redisconfmap.get(Constant.REDIS_SENTINELS);
redissentinels = new HashSet<String>(Arrays.asList(redisNodesString.split(Constant.CONFIGURATION_FILE_MULTIVALUE_SEPERATOR)));
String redisMastersString = redisconfmap.get(Constant.REDIS_MASTERS);
redismasters = new ArrayList<String>();
redismasters.addAll(Arrays.asList(redisMastersString.split(Constant.CONFIGURATION_FILE_MULTIVALUE_SEPERATOR)));
redistimeout = Integer.parseInt(redisconfmap.get(Constant.REDIS_TIMEOUT));
WAIT_IF_FAIL = Integer.parseInt(redisconfmap.get(Constant.REDIS_WAIT_IF_FAIL));
RETRIES = Integer.parseInt(redisconfmap.get(Constant.REDIS_RETRIES));
pool = new ShardedJedisSentinelPool(redismasters, redissentinels, config, redistimeout);
jedis = pool.getResource();
pipeline = jedis.pipelined();
}
return redisdal;
}
public ShardedJedis getJedisResource()
{
jedis = pool.getResource();
return jedis;
}
public ShardedJedisPipeline getPipelineResource()
{
pipeline = jedis.pipelined();
return pipeline;
}
public ShardedJedisPipeline getPipeline()
{
return pipeline;
}
public ShardedJedis getJedis()
{
return jedis;
}
public static void resetRedisServerConnectionDal()
{
pipeline = null;
jedis = null;
redisdal = null;
}
}
所以，现在无论我想在哪里与 Redis 交互，我都会做这样的事情
Jedis jedis = RedisServerConnectionDAL.getInstance.getJedis();
try
{
//code.....
}
catch(JedisConnectionException jce)
{
log.error(jce.getMessage());
StringWriter sw = new StringWriter();
PrintWriter pw = new PrintWriter(sw);
jce.printStackTrace(pw);
log.error("Error:" + sw.toString());
if(retrycount < RedisServerConnectionDAL.RETRIES)
{
retrycount++;
log.error("Waiting for " + RedisServerConnectionDAL.WAIT_IF_FAIL + ", after which it will reconnect to Redis.");
try
{
Thread.sleep(RedisServerConnectionDAL.WAIT_IF_FAIL);
}
catch (InterruptedException e)
{
log.error(e.getMessage());
e.printStackTrace(pw);
log.error("Error:" + sw.toString());
log.error("Error while Sleeing!!!");
}
RedisServerConnectionDAL.resetRedisServerConnectionDal();
jedis = RedisServerConnectionDAL.getInstance();.getJedisResource();
pipeline = redisserverconnectiondal.getPipelineResource();
}
else
{
log.error("Redis retries exhausted");
log.error(jce.getMessage());
StringWriter sw1 = new StringWriter();
PrintWriter pw1 = new PrintWriter(sw1);
jce.printStackTrace(pw1);
log.error("Error:" + sw1.toString());
log.error("Error while executing pipeline in Redis!");
retrycount = 0;;
}
}
catch(Exception e)
{
log.error(e.getMessage());
StringWriter sw = new StringWriter();
PrintWriter pw = new PrintWriter(sw);
e.printStackTrace(pw);
log.error("Error:" + sw.toString());
log.error("Error while executing pipeline in Redis!");
}
但我不断收到连接拒绝异常、连接关闭异常等异常。
有时我也会在一行的 catch 块中得到空指针异常
jedis = RedisServerConnectionDAL.getInstance();.getJedisResource();
典型的异常日志如下所示
ERROR com.cleartrail.entityprofiling.rediscachecomponent.InMemoryDataAccessLayer - Error:redis.clients.jedis.exceptions.JedisConnectionException: java.net.SocketException: Connection reset
at redis.clients.jedis.Protocol.sendCommand(Protocol.java:94)
at redis.clients.jedis.Protocol.sendCommand(Protocol.java:74)
at redis.clients.jedis.Connection.sendCommand(Connection.java:78)
at redis.clients.jedis.BinaryClient.hexists(BinaryClient.java:257)
at redis.clients.jedis.Client.hexists(Client.java:174)
at redis.clients.jedis.Jedis.hexists(Jedis.java:705)
at redis.clients.jedis.ShardedJedis.hexists(ShardedJedis.java:213)
at com.cleartrail.entityprofiling.rediscachecomponent.InMemoryDataAccessLayer.checkForNewEntity(InMemoryDataAccessLayer.java:339)
at com.cleartrail.entityprofiling.rediscachecomponent.InMemoryDataAccessLayer.writeInMemoryData(InMemoryDataAccessLayer.java:215)
at com.cleartrail.entityprofiling.rediscachecomponent.InMemoryDataAccessLayer.run(InMemoryDataAccessLayer.java:715)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.net.SocketException: Connection reset
at java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:113)
at java.net.SocketOutputStream.write(SocketOutputStream.java:153)
at redis.clients.util.RedisOutputStream.flushBuffer(RedisOutputStream.java:31)
at redis.clients.util.RedisOutputStream.writeIntCrLf(RedisOutputStream.java:186)
at redis.clients.jedis.Protocol.sendCommand(Protocol.java:81)
... 10 more
我知道我没有以正确的方式使用连接池。请建议正确的方法。另外，我使用的 jedis 是多线程环境，其中两个线程将调用 RedisServerConnectionDAL.getInstance().getJedisResource() 方法并与 Redis 交互。 Jedis 线程安全吗？
【问题讨论】：
标签： java multithreading redis jedis