问题背景
Redisson做分布式锁是目前比较流行的方式，但是在使用的过程中遇到一些坑：
- Redisson的分布式锁只能通过创建锁的线程进行解锁，正所谓解铃还须系铃人，不是同一个线程解锁会报异常
- 因为Redisson是为锁而生，所以一开始设计的时候，为了防止死锁，默认锁的过期时间为30S
- 当时我居然傻到用单元测试来测试Redisson的分布式锁，我太傻了，单元测试之后马上就会结束项目运行，那么就没有线程持有锁了，更别说还需要同线程解锁了
报异常：
2022-05-07 10:10:36.005 INFO 67300 --- [ main] c.y.redisson.utils.DistributedRedisLock : lock:true
2022-05-07 10:10:36.011 INFO 67300 --- [ main] c.y.redisson.utils.DistributedRedisLock : lock.isHeldByCurrentThread: false
2022-05-07 10:10:36.039 ERROR 67300 --- [ main] c.y.redisson.utils.DistributedRedisLock : DistributedRedisLock unlock [yuange] Exception:
java.lang.IllegalMonitorStateException: attempt to unlock lock, not locked by current thread by node id: 51f450d1-f832-4950-8e78-aec9a7484b8e thread-id: 1
at org.redisson.RedissonBaseLock.lambda$unlockAsync(RedissonBaseLock.java:316) ~[redisson-3.16.8.jar:3.16.8]
at java.util.concurrent.CompletableFuture.uniHandle(CompletableFuture.java:822) ~[na:1.8.0_221]
at java.util.concurrent.CompletableFuture$UniHandle.tryFire(CompletableFuture.java:797) ~[na:1.8.0_221]
at java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:474) ~[na:1.8.0_221]
at java.util.concurrent.CompletableFuture.complete(CompletableFuture.java:1962) ~[na:1.8.0_221]
at org.redisson.misc.RedissonPromise.trySuccess(RedissonPromise.java:83) ~[redisson-3.16.8.jar:3.16.8]
at org.redisson.command.CommandBatchService.lambda$executeAsync(CommandBatchService.java:324) ~[redisson-3.16.8.jar:3.16.8]
at java.util.concurrent.CompletableFuture.uniWhenComplete(CompletableFuture.java:760) ~[na:1.8.0_221]
at java.util.concurrent.CompletableFuture$UniWhenComplete.tryFire(CompletableFuture.java:736) ~[na:1.8.0_221]
at java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:474) ~[na:1.8.0_221]
at java.util.concurrent.CompletableFuture.complete(CompletableFuture.java:1962) ~[na:1.8.0_221]
at org.redisson.command.RedisCommonBatchExecutor.handleResult(RedisCommonBatchExecutor.java:162) ~[redisson-3.16.8.jar:3.16.8]
at org.redisson.command.RedisExecutor.checkAttemptPromise(RedisExecutor.java:476) ~[redisson-3.16.8.jar:3.16.8]
at org.redisson.command.RedisExecutor.lambda$execute(RedisExecutor.java:172) ~[redisson-3.16.8.jar:3.16.8]
at java.util.concurrent.CompletableFuture.uniWhenComplete(CompletableFuture.java:760) ~[na:1.8.0_221]
at java.util.concurrent.CompletableFuture$UniWhenComplete.tryFire(CompletableFuture.java:736) ~[na:1.8.0_221]
at java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:474) ~[na:1.8.0_221]
at java.util.concurrent.CompletableFuture.complete(CompletableFuture.java:1962) ~[na:1.8.0_221]
at org.redisson.client.handler.CommandDecoder.decodeCommandBatch(CommandDecoder.java:318) ~[redisson-3.16.8.jar:3.16.8]
at org.redisson.client.handler.CommandDecoder.decodeCommand(CommandDecoder.java:210) ~[redisson-3.16.8.jar:3.16.8]
at org.redisson.client.handler.CommandDecoder.decode(CommandDecoder.java:137) ~[redisson-3.16.8.jar:3.16.8]
at org.redisson.client.handler.CommandDecoder.decode(CommandDecoder.java:113) ~[redisson-3.16.8.jar:3.16.8]
at io.netty.handler.codec.ByteToMessageDecoder.decodeRemovalReentryProtection(ByteToMessageDecoder.java:510) ~[netty-codec-4.1.76.Final.jar:4.1.76.Final]
at io.netty.handler.codec.ReplayingDecoder.callDecode(ReplayingDecoder.java:366) ~[netty-codec-4.1.76.Final.jar:4.1.76.Final]
at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:279) ~[netty-codec-4.1.76.Final.jar:4.1.76.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379) ~[netty-transport-4.1.76.Final.jar:4.1.76.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365) ~[netty-transport-4.1.76.Final.jar:4.1.76.Final]
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357) ~[netty-transport-4.1.76.Final.jar:4.1.76.Final]
at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1410) ~[netty-transport-4.1.76.Final.jar:4.1.76.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379) ~[netty-transport-4.1.76.Final.jar:4.1.76.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365) ~[netty-transport-4.1.76.Final.jar:4.1.76.Final]
at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:919) ~[netty-transport-4.1.76.Final.jar:4.1.76.Final]
at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:166) ~[netty-transport-4.1.76.Final.jar:4.1.76.Final]
at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:722) ~[netty-transport-4.1.76.Final.jar:4.1.76.Final]
at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:658) ~[netty-transport-4.1.76.Final.jar:4.1.76.Final]
at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:584) ~[netty-transport-4.1.76.Final.jar:4.1.76.Final]
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:496) ~[netty-transport-4.1.76.Final.jar:4.1.76.Final]
at io.netty.util.concurrent.SingleThreadEventExecutor.run(SingleThreadEventExecutor.java:986) ~[netty-common-4.1.76.Final.jar:4.1.76.Final]
at io.netty.util.internal.ThreadExecutorMap.run(ThreadExecutorMap.java:74) ~[netty-common-4.1.76.Final.jar:4.1.76.Final]
at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30) ~[netty-common-4.1.76.Final.jar:4.1.76.Final]
at java.lang.Thread.run(Thread.java:748) ~[na:1.8.0_221]
2022-05-07 10:10:36.039 ERROR 67300 --- [ main] com.yg.redisson.main.RedissonTest : unlock failed
解决方案
1 这个异常报错主要有两个原因，刚才的背景介绍中说过
- 解锁需要创建锁的线程进行解锁，否则就报这个异常
- 过期时间默认30S，超过30S秒，即使用同一个线程解锁也会报这个异常，因为锁已经不存在了
总结
- 如果想使用不同线程都可以解锁，那么可以使用redis自带的setnx，可以在我的另一篇文章中看测试源码
作为程序员第 123 篇文章，每次写一句歌词记录一下，看看人生有几首歌的时间，wahahaha ...
