ClassNotFoundException when using ServiceLoader

Hey, while writing plugins for BungeeCord proxy I ran into a problem with ClassLoader. Plugins use the redisson library to create the network It works like this:

1. BungeeCord loads available plugins
2. One of the plugins contains the redisson library and connects to redis
3. Another plugin use the previously loaded plugin with the library to synchronize the objects

All plugins are loaded using the same ClassLoader, so the same ClassLoader also loads the redisson library, and knows about classes that we serialize and keep in redis. Unfortunately the plugin that is loaded in step 3 throws a error like:

Exception in thread "main" org.redisson.client.RedisException: Unexpected exception while processing command
	at org.redisson.command.CommandAsyncService.convertException(CommandAsyncService.java:351)
	at org.redisson.command.CommandAsyncService.get(CommandAsyncService.java:148)
	at org.redisson.RedissonObject.get(RedissonObject.java:81)
	at org.redisson.RedissonBucket.get(RedissonBucket.java:104)
	at org.hesterq.redis.plugin.ExternalDataListener.tryGet(ExternalDataListener.java:22)
	at org.hesterq.redis.plugin.ExternalPlugin.enable(ExternalPlugin.java:31)
	at org.hesterq.redis.Server.main(Server.java:74)
Caused by: java.io.IOException: java.lang.ClassNotFoundException: org.hesterq.redis.plugin.ExternalData
	at org.redisson.codec.MarshallingCodec$3.decode(MarshallingCodec.java:153)
	at org.redisson.client.handler.CommandDecoder.decode(CommandDecoder.java:358)
	at org.redisson.client.handler.CommandDecoder.decodeCommand(CommandDecoder.java:177)
	at org.redisson.client.handler.CommandDecoder.decode(CommandDecoder.java:116)
	at org.redisson.client.handler.CommandDecoder.decode(CommandDecoder.java:101)
	at io.netty.handler.codec.ByteToMessageDecoder.decodeRemovalReentryProtection(ByteToMessageDecoder.java:508)
	at io.netty.handler.codec.ReplayingDecoder.callDecode(ReplayingDecoder.java:366)
	at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:276)
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
	at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)
	at io.netty.channel.DefaultChannelPipeline$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.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:166)
	at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:719)
	at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:655)
	at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:581)
	at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:493)
	at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989)
	at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
	at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
	at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.ClassNotFoundException: org.hesterq.redis.plugin.ExternalData
	at java.net.URLClassLoader.findClass(URLClassLoader.java:382)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:418)
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:352)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:351)
	at java.lang.Class.forName0(Native Method)
	at java.lang.Class.forName(Class.java:348)
	at org.jboss.marshalling.AbstractClassResolver.loadClass(AbstractClassResolver.java:129)
	at org.jboss.marshalling.AbstractClassResolver.resolveClass(AbstractClassResolver.java:110)
	at org.jboss.marshalling.river.RiverUnmarshaller.doReadClassDescriptor(RiverUnmarshaller.java:1033)
	at org.jboss.marshalling.river.RiverUnmarshaller.doReadNewObject(RiverUnmarshaller.java:1366)
	at org.jboss.marshalling.river.RiverUnmarshaller.doReadObject(RiverUnmarshaller.java:283)
	at org.jboss.marshalling.river.RiverUnmarshaller.doReadObject(RiverUnmarshaller.java:216)
	at org.jboss.marshalling.AbstractObjectInput.readObject(AbstractObjectInput.java:41)
	at org.redisson.codec.MarshallingCodec$3.decode(MarshallingCodec.java:151)
	... 23 more

So I wrote small ServiceLoader application to reproduce that issue.

Steps to reproduce or test case https://github.com/HesterQ/RedisServer

1. clone repo: https://github.com/HesterQ/RedisServer.git
2. redis-cli config set notify-keyspace-events KEA
3. ./test.sh for auto-install

or manually

1. clone repo: https://github.com/HesterQ/RedisServer.git
2. mvn clean install
3. copy all generated plugin jars (RedisServer-WriterPlugin; RedisServer-RedisProviderPlugin; RedisServer-ReaderPlugin) to RedisServer-Server\target\plugins\
4. redis-cli config set notify-keyspace-events KEA
5. run RedisServer-Server-1.0.0-SNAPSHOT.jar

Redis version 6.0.10

Redisson version

<dependency>
	<groupId>org.redisson</groupId>
	<artifactId>redisson-all</artifactId>
	<version>3.15.1</version>
</dependency>

Redisson configuration

Config config = new Config();
config.useSingleServer().setAddress("redis://127.0.0.1:6379");

[Lorak-mmk]

set useThreadClassLoader = false in configuration.

Yep, that was the issue - we didn’t know about this option, thanks.

[mrniko]

set useThreadClassLoader = false in configuration.