I am developing a Flink application and it will use Cassandra Driver to interact with Cassandra DB. The Cassandra Driver is implemented in Singleton fashion and multiple Flink process functions will interact with it to get data from Cassandra. I also add a future callback to each Session.executeAsync's ResultSetFuture. The app is run on Kubernetes through Docker containers.
The environment is:
Flink version is 1.10.0 and using shaded netty, hadoop, guava and jackson.
Using cassandra-driver-mapping: 3.9.0 and shaded cassandra-driver-core: 3.9.0.
All dependencies are packaged in a single jar using Bazel. Before starting the Flink app, I check all the required classes are in the jar and are correct and complete. And I use the shaded dependency in order to avoid class loading conflict in JVM. But, when I start and run the Flink app. I keep seeing the following ClassNotFoundException in the Taskmanager logs.
java.lang.NoClassDefFoundError: com/datastax/driver/core/SessionManager$State
at com.datastax.driver.core.SessionManager.getState(SessionManager.java:211)
at io.uhana.cassandra.CassandraDriver.sessionNeedsReconnect(CassandraDriver.java:508)
at io.uhana.cassandra.CassandraDriver.access$000(CassandraDriver.java:61)
at io.uhana.cassandra.CassandraDriver$1.onFailure(CassandraDriver.java:518)
at com.google.common.util.concurrent.Futures$CallbackListener.run(Futures.java:1387)
at com.google.common.util.concurrent.AbstractFuture.executeListener(AbstractFuture.java:1015)
at com.google.common.util.concurrent.AbstractFuture.complete(AbstractFuture.java:868)
at com.google.common.util.concurrent.AbstractFuture.setException(AbstractFuture.java:713)
at com.datastax.driver.core.DefaultResultSetFuture.onSet(DefaultResultSetFuture.java:230)
at com.datastax.driver.core.RequestHandler.setFinalResult(RequestHandler.java:235)
at com.datastax.driver.core.RequestHandler.access$2600(RequestHandler.java:61)
at com.datastax.driver.core.RequestHandler$SpeculativeExecution.setFinalResult(RequestHandler.java:1011)
at com.datastax.driver.core.RequestHandler$SpeculativeExecution.onSet(RequestHandler.java:647)
at com.datastax.driver.core.Connection$Dispatcher.channelRead0(Connection.java:1262)
at com.datastax.driver.core.Connection$Dispatcher.channelRead0(Connection.java:1180)
at com.datastax.shaded.netty.channel.SimpleChannelInboundHandler.channelRead(SimpleChannelInboundHandler.java:105)
at com.datastax.shaded.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:356)
at com.datastax.shaded.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:342)
at com.datastax.shaded.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:335)
at com.datastax.shaded.netty.handler.timeout.IdleStateHandler.channelRead(IdleStateHandler.java:286)
at com.datastax.shaded.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:356)
at com.datastax.shaded.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:342)
at com.datastax.shaded.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:335)
at com.datastax.shaded.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:102)
at com.datastax.shaded.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:356)
at com.datastax.shaded.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:342)
at com.datastax.shaded.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:335)
at com.datastax.shaded.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:312)
at com.datastax.shaded.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:286)
at com.datastax.shaded.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:356)
at com.datastax.shaded.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:342)
at com.datastax.shaded.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:335)
at com.datastax.shaded.netty.channel.ChannelInboundHandlerAdapter.channelRead(ChannelInboundHandlerAdapter.java:86)
at com.datastax.driver.core.InboundTrafficMeter.channelRead(InboundTrafficMeter.java:38)
at com.datastax.shaded.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:356)
at com.datastax.shaded.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:342)
at com.datastax.shaded.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:335)
at com.datastax.shaded.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1304)
at com.datastax.shaded.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:356)
at com.datastax.shaded.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:342)
at com.datastax.shaded.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:921)
at com.datastax.shaded.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:135)
at com.datastax.shaded.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:646)
at com.datastax.shaded.netty.channel.nio.NioEventLoop.processSelectedKeysPlain(NioEventLoop.java:546)
at com.datastax.shaded.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:500)
at com.datastax.shaded.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:460)
at com.datastax.shaded.netty.util.concurrent.SingleThreadEventExecutor$2.run(SingleThreadEventExecutor.java:131)
at com.datastax.shaded.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: java.lang.ClassNotFoundException: com.datastax.driver.core.SessionManager$State
at java.base/java.net.URLClassLoader.findClass(URLClassLoader.java:471)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:588)
at org.apache.flink.util.ChildFirstClassLoader.loadClass(ChildFirstClassLoader.java:69)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
... 49 more
and
ConstantReconnectionPolicy$ConstantSchedule' [enable DEBUG level for full stacktrace] was thrown by a user handler's exceptionCaught() method while handling the following exception:
java.lang.NoClassDefFoundError: com/datastax/shaded/netty/handler/timeout/IdleState
at com.datastax.shaded.netty.handler.timeout.IdleStateHandler$ReaderIdleTimeoutTask.run(IdleStateHandler.java:493)
at com.datastax.shaded.netty.handler.timeout.IdleStateHandler$AbstractIdleTask.run(IdleStateHandler.java:466)
at com.datastax.shaded.netty.util.concurrent.PromiseTask$RunnableAdapter.call(PromiseTask.java:38)
at com.datastax.shaded.netty.util.concurrent.ScheduledFutureTask.run(ScheduledFutureTask.java:120)
at com.datastax.shaded.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:399)
at com.datastax.shaded.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:464)
at com.datastax.shaded.netty.util.concurrent.SingleThreadEventExecutor$2.run(SingleThreadEventExecutor.java:131)
at com.datastax.shaded.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: java.lang.ClassNotFoundException: com.datastax.shaded.netty.handler.timeout.IdleState
at java.base/java.net.URLClassLoader.findClass(URLClassLoader.java:471)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:588)
at org.apache.flink.util.ChildFirstClassLoader.loadClass(ChildFirstClassLoader.java:69)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
... 9 more
I also notice that these issues are easier to reproduce when giving more resources and parallelism to the Flink app and the process functions. And the issues are most likely happen in the future callback.
Any help appreciated!