NullPointerException in CommandHandler when establishing connections

[zubchenok]

Bug Report

Current Behavior

NullPointerException happens when trying to establish large amount 1000000 of connections in 100 threads concurrently.

Stack trace

io.lettuce.core.RedisConnectionException: Unable to connect to 10.0.10.8/<unresolved>:6379
  at io.lettuce.core.RedisConnectionException.create(RedisConnectionException.java:78)
  at io.lettuce.core.RedisConnectionException.create(RedisConnectionException.java:56)
  at io.lettuce.core.cluster.PooledClusterConnectionProvider.lambda$getConnectionAsync$6(PooledClusterConnectionProvider.java:433)
  at java.base/java.util.concurrent.CompletableFuture.uniHandle(CompletableFuture.java:934)
  at java.base/java.util.concurrent.CompletableFuture$UniHandle.tryFire(CompletableFuture.java:911)
  at java.base/java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:510)
  at java.base/java.util.concurrent.CompletableFuture.completeExceptionally(CompletableFuture.java:2162)
  at io.lettuce.core.AbstractRedisClient.lambda$null$5(AbstractRedisClient.java:470)
  at java.base/java.util.concurrent.CompletableFuture.uniWhenComplete(CompletableFuture.java:863)
  at java.base/java.util.concurrent.CompletableFuture$UniWhenComplete.tryFire(CompletableFuture.java:841)
  at java.base/java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:510)
  at java.base/java.util.concurrent.CompletableFuture.completeExceptionally(CompletableFuture.java:2162)
  at io.lettuce.core.protocol.RedisHandshakeHandler.lambda$fail$4(RedisHandshakeHandler.java:139)
  at io.netty.util.concurrent.DefaultPromise.notifyListener0(DefaultPromise.java:578)
  at io.netty.util.concurrent.DefaultPromise.notifyListenersNow(DefaultPromise.java:552)
  at io.netty.util.concurrent.DefaultPromise.notifyListeners(DefaultPromise.java:491)
  at io.netty.util.concurrent.DefaultPromise.addListener(DefaultPromise.java:184)
  at io.netty.channel.DefaultChannelPromise.addListener(DefaultChannelPromise.java:95)
  at io.netty.channel.DefaultChannelPromise.addListener(DefaultChannelPromise.java:30)
  at io.lettuce.core.protocol.RedisHandshakeHandler.fail(RedisHandshakeHandler.java:138)
  at io.lettuce.core.protocol.RedisHandshakeHandler.lambda$channelActive$3(RedisHandshakeHandler.java:107)
  at java.base/java.util.concurrent.CompletableFuture.uniWhenComplete(CompletableFuture.java:863)
  at java.base/java.util.concurrent.CompletableFuture$UniWhenComplete.tryFire(CompletableFuture.java:841)
  at java.base/java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:510)
  at java.base/java.util.concurrent.CompletableFuture.completeExceptionally(CompletableFuture.java:2162)
  at io.lettuce.core.RedisHandshake.lambda$tryHandshakeResp3$1(RedisHandshake.java:105)
  at java.base/java.util.concurrent.CompletableFuture.uniWhenComplete(CompletableFuture.java:863)
  at java.base/java.util.concurrent.CompletableFuture$UniWhenComplete.tryFire(CompletableFuture.java:841)
  at java.base/java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:510)
  at java.base/java.util.concurrent.CompletableFuture.completeExceptionally(CompletableFuture.java:2162)
  at io.lettuce.core.protocol.AsyncCommand.doCompleteExceptionally(AsyncCommand.java:139)
  at io.lettuce.core.protocol.AsyncCommand.completeExceptionally(AsyncCommand.java:132)
  at io.lettuce.core.protocol.CommandHandler.exceptionCaught(CommandHandler.java:276)
  at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:302)
  at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:381)
  at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
  at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)
  at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1410)
  at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
  at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
  at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:919)
  at io.netty.channel.epoll.AbstractEpollStreamChannel$EpollStreamUnsafe.epollInReady(AbstractEpollStreamChannel.java:795)
  at io.netty.channel.epoll.EpollEventLoop.processReady(EpollEventLoop.java:480)
  at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:378)
  at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:997)
  at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
  at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
  at java.base/java.lang.Thread.run(Thread.java:833)
Caused by: java.lang.NullPointerException: Cannot invoke "io.netty.buffer.ByteBuf.refCnt()" because "this.buffer" is null
  at io.lettuce.core.protocol.CommandHandler.channelRead(CommandHandler.java:582)
  at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
  at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
  at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)
  at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1410)
  at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
  at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
  at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:919)
  at io.netty.channel.epoll.AbstractEpollStreamChannel$EpollStreamUnsafe.epollInReady(AbstractEpollStreamChannel.java:795)
  at io.netty.channel.epoll.EpollEventLoop.processReady(EpollEventLoop.java:480)
  at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:378)
  at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:997)
  at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
  at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
  at java.base/java.lang.Thread.run(Thread.java:833)

Input Code

Input Code

Scheduler scheduler = Schedulers.from(Executors.newCachedThreadPool());
Flowable
    .range(0, 1000000)
    .flatMapCompletable(x -> Completable
        .fromAction(() -> {
            for (int i = 0; i < 3; ++i) {
                long key = ThreadLocalRandom.current().nextLong();
                byte[] bytes = ByteBuffer.wrap(new byte[8]).putLong(key).array();
                lettuce.connect(ByteArrayCodec.INSTANCE).sync().objectIdletime(bytes);
            }
        })
        .subscribeOn(scheduler), false, 100
    )
    .blockingAwait();

Expected behavior/code

No NPE should happen in CommandHandler class even if it has no sense to create 1000000 connections.

Environment

• Lettuce version(s): 6.1.5.RELEASE and 6.2.0.RELEASE
• Redis version: 6.0.12
• Linux with netty EPOLL enabled

[mp911de]

For some reason, there's a read before/after a buffer was set to null. An earlier error must have happened. Please provide further details.

[zubchenok]

Just a useless update: I need more time to provide additional details.w

[github-actions[bot]]

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