When java.util.concurrent.CancellationException happens?

[mykev...@gmail.com]

Hello,

I've posted a question https://groups.google.com/forum/#!topic/lettuce-redis-client-users/yks37yodyeE and I got another question.  I also get the following error some times.  What would that mean?  Redis commands fails when I get this error.

java.util.concurrent.CancellationException

at java.util.concurrent.CompletableFuture.cancel(CompletableFuture.java:2263)

at com.lambdaworks.redis.protocol.AsyncCommand.cancel(AsyncCommand.java:121)

at com.lambdaworks.redis.protocol.AsyncCommand.cancel(AsyncCommand.java:155)

at com.lambdaworks.redis.protocol.CommandWrapper.cancel(CommandWrapper.java:60)

at com.lambdaworks.redis.protocol.CommandHandler.cancelCommands(CommandHandler.java:826)

at com.lambdaworks.redis.protocol.CommandHandler.channelUnregistered(CommandHandler.java:155)

at io.netty.channel.AbstractChannelHandlerContext.invokeChannelUnregistered(AbstractChannelHandlerContext.java:191)

at io.netty.channel.AbstractChannelHandlerContext.invokeChannelUnregistered(AbstractChannelHandlerContext.java:177)

at io.netty.channel.AbstractChannelHandlerContext.fireChannelUnregistered(AbstractChannelHandlerContext.java:170)

at io.netty.channel.ChannelInboundHandlerAdapter.channelUnregistered(ChannelInboundHandlerAdapter.java:53)

at io.netty.channel.AbstractChannelHandlerContext.invokeChannelUnregistered(AbstractChannelHandlerContext.java:191)

at io.netty.channel.AbstractChannelHandlerContext.invokeChannelUnregistered(AbstractChannelHandlerContext.java:177)

at io.netty.channel.AbstractChannelHandlerContext.fireChannelUnregistered(AbstractChannelHandlerContext.java:170)

at io.netty.channel.ChannelInboundHandlerAdapter.channelUnregistered(ChannelInboundHandlerAdapter.java:53)

at io.netty.channel.AbstractChannelHandlerContext.invokeChannelUnregistered(AbstractChannelHandlerContext.java:191)

at io.netty.channel.AbstractChannelHandlerContext.invokeChannelUnregistered(AbstractChannelHandlerContext.java:177)

at io.netty.channel.AbstractChannelHandlerContext.fireChannelUnregistered(AbstractChannelHandlerContext.java:170)

at io.netty.channel.DefaultChannelPipeline$HeadContext.channelUnregistered(DefaultChannelPipeline.java:1312)

at io.netty.channel.AbstractChannelHandlerContext.invokeChannelUnregistered(AbstractChannelHandlerContext.java:191)

at io.netty.channel.AbstractChannelHandlerContext.invokeChannelUnregistered(AbstractChannelHandlerContext.java:177)

at io.netty.channel.DefaultChannelPipeline.fireChannelUnregistered(DefaultChannelPipeline.java:826)

at io.netty.channel.AbstractChannel$AbstractUnsafe$7.run(AbstractChannel.java:752)

at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:163)

at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:418)

at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:454)

at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:873)

at io.netty.util.concurrent.DefaultThreadFactory$DefaultRunnableDecorator.run(DefaultThreadFactory.java:144)

at java.lang.Thread.run(Thread.java:745)

Thanks in advance!

Kevin

[Mark Paluch]

This specific cancellation means that there were commands queued (not yet sent to Redis) and the connection was closed.

[mykev...@gmail.com]

Thank you for the explanation.

[fredtt...@gmail.com]

 io.netty.util.concurrent.SingleThreadEventExecutor$5.run

[vkc12uec]

Hi MarkP,

So what is the solution to this problem? I am seeing many error logs in my application using lettuce with same stacktrace. Do i need to increase threads or look why connection was closed? any hints?

[mpa...@pivotal.io]

The cause is that a connection is closed. So an apparent solution can be: Do not close your connection while you run commands.

Cheers, 

Mark