Why the connection operation of Lettuce takes more time than Jedis? - redis

Question

Connecting to local redis, Lettuce takes nearly 5000ms, but Jedis only takes 30ms.
I refer to thie example ConnectToRedis
I use the default spring-boot-starter with lombok dependency:
My Code：
#Component
#Slf4j
class LettuceRunner implements CommandLineRunner {
#Override
public void run(String... args) throws Exception {
StopWatch watch = new StopWatch();
RedisClient redisClient = RedisClient.create("redis://localhost:6379");
watch.start();
StatefulRedisConnection<String, String> connection = redisClient.connect();
watch.stop();
log.info("lettuce : {} ms", watch.getLastTaskTimeMillis());
connection.close();
redisClient.shutdown();
}
}
#Component
#Slf4j
class JedisRunner implements CommandLineRunner {
#Override
public void run(String... args) throws Exception {
StopWatch watch = new StopWatch();
watch.start();
Jedis jedis = new Jedis("localhost");
jedis.get("redis_key");
watch.stop();
log.info("jedis : {} ms", watch.getLastTaskInfo().getTimeMillis());
}
}
and the result is：
2020-08-14 17:02:28.236 INFO 21760 --- [ main] com.example.demo.JedisRunner : jedis : 27 ms
2020-08-14 17:02:33.318 INFO 21760 --- [ main] com.example.demo.LettuceRunner : lettuce : 4815 ms

Answer 1

Because Lettuce uses Netty and it spends the bulk of time initiating things in Netty.
Check the logs, as you can see, the bulk of the time spent is inside io.netty package:
2020-08-15 00:54:06.030 DEBUG 728 --- [ main] i.l.c.r.DefaultEventLoopGroupProvider : Creating executor io.netty.util.concurrent.DefaultEventExecutorGroup
2020-08-15 00:54:06.031 DEBUG 728 --- [ main] io.lettuce.core.RedisClient : Trying to get a Redis connection for: RedisURI [host='localhost', port=6379]
2020-08-15 00:54:06.120 DEBUG 728 --- [ main] io.lettuce.core.EpollProvider : Starting without optional epoll library
2020-08-15 00:54:06.122 DEBUG 728 --- [ main] io.lettuce.core.KqueueProvider : Starting without optional kqueue library
2020-08-15 00:54:06.123 DEBUG 728 --- [ main] i.l.c.r.DefaultEventLoopGroupProvider : Allocating executor io.netty.channel.nio.NioEventLoopGroup
2020-08-15 00:54:06.123 DEBUG 728 --- [ main] i.l.c.r.DefaultEventLoopGroupProvider : Creating executor io.netty.channel.nio.NioEventLoopGroup
2020-08-15 00:54:06.124 DEBUG 728 --- [ main] i.n.channel.MultithreadEventLoopGroup : -Dio.netty.eventLoopThreads: 12
2020-08-15 00:54:06.129 DEBUG 728 --- [ main] io.netty.channel.nio.NioEventLoop : -Dio.netty.noKeySetOptimization: false
2020-08-15 00:54:06.129 DEBUG 728 --- [ main] io.netty.channel.nio.NioEventLoop : -Dio.netty.selectorAutoRebuildThreshold: 512
2020-08-15 00:54:06.421 DEBUG 728 --- [ main] i.l.c.r.DefaultEventLoopGroupProvider : Adding reference to io.netty.channel.nio.NioEventLoopGroup#7c59cf66, existing ref count 0
2020-08-15 00:54:06.431 DEBUG 728 --- [ main] io.lettuce.core.RedisClient : Resolved SocketAddress localhost:6379 using RedisURI [host='localhost', port=6379]
2020-08-15 00:54:06.432 DEBUG 728 --- [ main] io.lettuce.core.RedisClient : Connecting to Redis at localhost:6379
2020-08-15 00:54:06.435 DEBUG 728 --- [ main] io.netty.channel.DefaultChannelId : -Dio.netty.processId: 728 (auto-detected)
2020-08-15 00:54:06.437 DEBUG 728 --- [ main] io.netty.util.NetUtil : -Djava.net.preferIPv4Stack: false
2020-08-15 00:54:06.437 DEBUG 728 --- [ main] io.netty.util.NetUtil : -Djava.net.preferIPv6Addresses: false
2020-08-15 00:54:06.659 DEBUG 728 --- [ main] io.netty.util.NetUtil : Loopback interface: lo (Software Loopback Interface 1, 127.0.0.1)
2020-08-15 00:54:06.660 DEBUG 728 --- [ main] io.netty.util.NetUtil : Failed to get SOMAXCONN from sysctl and file \proc\sys\net\core\somaxconn. Default: 200
2020-08-15 00:54:06.898 DEBUG 728 --- [ main] io.netty.channel.DefaultChannelId : -Dio.netty.machineId: 00:50:56:ff:fe:c0:00:08 (auto-detected)
2020-08-15 00:54:06.911 DEBUG 728 --- [ main] io.netty.buffer.ByteBufUtil : -Dio.netty.allocator.type: pooled
2020-08-15 00:54:06.912 DEBUG 728 --- [ main] io.netty.buffer.ByteBufUtil : -Dio.netty.threadLocalDirectBufferSize: 0
2020-08-15 00:54:06.912 DEBUG 728 --- [ main] io.netty.buffer.ByteBufUtil : -Dio.netty.maxThreadLocalCharBufferSize: 16384
2020-08-15 00:54:06.928 DEBUG 728 --- [ioEventLoop-8-1] io.netty.util.Recycler : -Dio.netty.recycler.maxCapacityPerThread: 4096
2020-08-15 00:54:06.928 DEBUG 728 --- [ioEventLoop-8-1] io.netty.util.Recycler : -Dio.netty.recycler.maxSharedCapacityFactor: 2
2020-08-15 00:54:06.928 DEBUG 728 --- [ioEventLoop-8-1] io.netty.util.Recycler : -Dio.netty.recycler.linkCapacity: 16
2020-08-15 00:54:06.928 DEBUG 728 --- [ioEventLoop-8-1] io.netty.util.Recycler : -Dio.netty.recycler.ratio: 8
2020-08-15 00:54:06.928 DEBUG 728 --- [ioEventLoop-8-1] io.netty.util.Recycler : -Dio.netty.recycler.delayedQueue.ratio: 8
2020-08-15 00:54:06.933 DEBUG 728 --- [ioEventLoop-8-1] io.netty.buffer.AbstractByteBuf : -Dio.netty.buffer.checkAccessible: true
2020-08-15 00:54:06.933 DEBUG 728 --- [ioEventLoop-8-1] io.netty.buffer.AbstractByteBuf : -Dio.netty.buffer.checkBounds: true
2020-08-15 00:54:06.933 DEBUG 728 --- [ioEventLoop-8-1] i.n.util.ResourceLeakDetectorFactory : Loaded default ResourceLeakDetector: io.netty.util.ResourceLeakDetector#20e9fc6c
2020-08-15 00:54:06.950 DEBUG 728 --- [ioEventLoop-8-1] io.lettuce.core.protocol.CommandHandler : [channel=0x1ced470d, [id: 0x7bd077d9] (inactive), chid=0x1] channelRegistered()
2020-08-15 00:54:06.953 DEBUG 728 --- [ioEventLoop-8-1] io.lettuce.core.protocol.CommandHandler : [channel=0x1ced470d, /127.0.0.1:2106 -> localhost/127.0.0.1:6379, chid=0x1] channelActive()
2020-08-15 00:54:06.954 DEBUG 728 --- [ioEventLoop-8-1] i.lettuce.core.protocol.DefaultEndpoint : [channel=0x1ced470d, /127.0.0.1:2106 -> localhost/127.0.0.1:6379, epid=0x1] activateEndpointAndExecuteBufferedCommands 0 command(s) buffered
2020-08-15 00:54:06.954 DEBUG 728 --- [ioEventLoop-8-1] i.lettuce.core.protocol.DefaultEndpoint : [channel=0x1ced470d, /127.0.0.1:2106 -> localhost/127.0.0.1:6379, epid=0x1] activating endpoint
2020-08-15 00:54:06.954 DEBUG 728 --- [ioEventLoop-8-1] i.lettuce.core.protocol.DefaultEndpoint : [channel=0x1ced470d, /127.0.0.1:2106 -> localhost/127.0.0.1:6379, epid=0x1] flushCommands()
2020-08-15 00:54:06.954 DEBUG 728 --- [ioEventLoop-8-1] i.lettuce.core.protocol.DefaultEndpoint : [channel=0x1ced470d, /127.0.0.1:2106 -> localhost/127.0.0.1:6379, epid=0x1] flushCommands() Flushing 0 commands
2020-08-15 00:54:06.954 DEBUG 728 --- [ioEventLoop-8-1] i.l.core.protocol.ConnectionWatchdog : [channel=0x1ced470d, /127.0.0.1:2106 -> localhost/127.0.0.1:6379, last known addr=localhost/127.0.0.1:6379] channelActive()
2020-08-15 00:54:06.954 DEBUG 728 --- [ioEventLoop-8-1] io.lettuce.core.protocol.CommandHandler : [channel=0x1ced470d, /127.0.0.1:2106 -> localhost/127.0.0.1:6379, chid=0x1] channelActive() done
2020-08-15 00:54:06.955 DEBUG 728 --- [ioEventLoop-8-1] io.lettuce.core.RedisClient : Connecting to Redis at localhost:6379: Success
2020-08-15 00:54:06.956 INFO 728 --- [ main] c.h.s.c.c.CacheStudyApplicationTests : lettuce : 925 ms
2020-08-15 00:54:06.956 DEBUG 728 --- [ main] io.lettuce.core.RedisChannelHandler : close()
2020-08-15 00:54:06.956 DEBUG 728 --- [ main] io.lettuce.core.RedisChannelHandler : closeAsync()
2020-08-15 00:54:06.956 DEBUG 728 --- [ main] i.lettuce.core.protocol.DefaultEndpoint : [channel=0x1ced470d, /127.0.0.1:2106 -> localhost/127.0.0.1:6379, epid=0x1] closeAsync()
2020-08-15 00:54:06.957 DEBUG 728 --- [ioEventLoop-8-1] i.l.core.protocol.ConnectionWatchdog : [channel=0x1ced470d, /127.0.0.1:2106 -> localhost/127.0.0.1:6379, last known addr=localhost/127.0.0.1:6379] userEventTriggered(ctx, io.lettuce.core.ConnectionEvents$Activated#1cda757f)
2020-08-15 00:54:06.958 DEBUG 728 --- [ main] io.lettuce.core.RedisClient : Initiate shutdown (0, 2, SECONDS)
2020-08-15 00:54:06.959 DEBUG 728 --- [ioEventLoop-8-1] io.lettuce.core.protocol.CommandHandler : [channel=0x1ced470d, /127.0.0.1:2106 -> localhost/127.0.0.1:6379, chid=0x1] channelInactive()
2020-08-15 00:54:06.959 DEBUG 728 --- [ioEventLoop-8-1] i.lettuce.core.protocol.DefaultEndpoint : [channel=0x1ced470d, /127.0.0.1:2106 -> localhost/127.0.0.1:6379, epid=0x1] deactivating endpoint handler
2020-08-15 00:54:06.960 DEBUG 728 --- [ioEventLoop-8-1] io.lettuce.core.protocol.CommandHandler : [channel=0x1ced470d, /127.0.0.1:2106 -> localhost/127.0.0.1:6379, chid=0x1] channelInactive() done
2020-08-15 00:54:06.960 DEBUG 728 --- [ioEventLoop-8-1] i.l.core.protocol.ConnectionWatchdog : [channel=0x1ced470d, /127.0.0.1:2106 -> localhost/127.0.0.1:6379, last known addr=localhost/127.0.0.1:6379] channelInactive()
2020-08-15 00:54:06.960 DEBUG 728 --- [ioEventLoop-8-1] i.l.core.protocol.ConnectionWatchdog : [channel=0x1ced470d, /127.0.0.1:2106 -> localhost/127.0.0.1:6379, last known addr=localhost/127.0.0.1:6379] Reconnect scheduling disabled
2020-08-15 00:54:06.960 DEBUG 728 --- [ioEventLoop-8-1] io.lettuce.core.protocol.CommandHandler : [channel=0x1ced470d, /127.0.0.1:2106 -> localhost/127.0.0.1:6379, chid=0x1] channelUnregistered()
2020-08-15 00:54:06.961 DEBUG 728 --- [ main] i.l.c.resource.DefaultClientResources : Initiate shutdown (0, 2, SECONDS)
2020-08-15 00:54:06.963 DEBUG 728 --- [ main] i.l.c.r.DefaultEventLoopGroupProvider : Initiate shutdown (0, 2, SECONDS)
2020-08-15 00:54:06.963 DEBUG 728 --- [ main] i.l.c.r.DefaultEventLoopGroupProvider : Release executor io.netty.channel.nio.NioEventLoopGroup#7c59cf66
2020-08-15 00:54:06.965 DEBUG 728 --- [ioEventLoop-8-1] io.netty.buffer.PoolThreadCache : Freed 1 thread-local buffer(s) from thread: lettuce-nioEventLoop-8-1