EventLoopContext#executeFromIO fails when executed by Netty GlobalEventExecutor

[vietj]

When Netty uses its GlobalEventExecutor thread and propagates into Vertx, EventLoopContext#executeFromIO does not expect such thread and fails to execute the task:

for instance:

An exception was thrown by io.vertx.core.net.impl.ChannelProvider$$Lambda$62/807291119.operationComplete() 
java.lang.IllegalStateException: Uh oh! Event loop context executing with wrong thread! Expected null got Thread[globalEventExecutor-1-2,5,FailOnTimeoutGroup]
    at io.vertx.core.impl.ContextImpl.lambda$wrapTask$2(ContextImpl.java:303)
    at io.vertx.core.impl.ContextImpl.executeFromIO(ContextImpl.java:190)
    at io.vertx.core.net.impl.NetClientImpl.failed(NetClientImpl.java:250)
    at io.vertx.core.net.impl.NetClientImpl.lambda$connect$5(NetClientImpl.java:225)
    at io.vertx.core.net.impl.ChannelProvider.lambda$connect$0(ChannelProvider.java:42)
    at io.netty.util.concurrent.DefaultPromise.notifyListener0(DefaultPromise.java:514)
    at io.netty.util.concurrent.DefaultPromise.notifyListenersNow(DefaultPromise.java:488)
    at io.netty.util.concurrent.DefaultPromise.access$000(DefaultPromise.java:34)
    at io.netty.util.concurrent.DefaultPromise$1.run(DefaultPromise.java:438)
    at io.netty.util.concurrent.GlobalEventExecutor$TaskRunner.run(GlobalEventExecutor.java:233)
    at io.netty.util.concurrent.DefaultThreadFactory$DefaultRunnableDecorator.run(DefaultThreadFactory.java:144)
    at java.lang.Thread.run(Thread.java:745)

This can happen if the creation of a Bootstrap fails, in this case the promise is created with the GlobalEventExecutor (see AbstractBootstrap#initAndRegister())

[vietj]

Example of issue failing the creation of a channel:

io.netty.channel.ChannelException: Unable to create Channel from class class io.netty.channel.socket.nio.NioSocketChannel
    at io.netty.channel.ReflectiveChannelFactory.newChannel(ReflectiveChannelFactory.java:40)
    at io.netty.bootstrap.AbstractBootstrap.initAndRegister(AbstractBootstrap.java:319)
    at io.netty.bootstrap.Bootstrap.doResolveAndConnect(Bootstrap.java:163)
    at io.netty.bootstrap.Bootstrap.connect(Bootstrap.java:145)
    at io.netty.bootstrap.Bootstrap.connect(Bootstrap.java:126)
    at io.vertx.core.net.impl.ChannelProvider.connect(ChannelProvider.java:37)
    at io.vertx.core.net.impl.NetClientImpl.connect(NetClientImpl.java:230)
    at io.vertx.core.net.impl.NetClientImpl.connect(NetClientImpl.java:97)
    at io.vertx.redis.impl.RedisConnection.connect(RedisConnection.java:139)
    at io.vertx.redis.impl.RedisConnection.send(RedisConnection.java:237)
    at io.vertx.redis.impl.AbstractRedisClient.send(AbstractRedisClient.java:193)
    at io.vertx.redis.impl.AbstractRedisClient.sendString(AbstractRedisClient.java:86)
    at io.vertx.redis.impl.RedisClientImpl.ping(RedisClientImpl.java:2195)
    at io.vertx.test.redis.SomeTest.lambda$doTheTest$4(SomeTest.java:55)
    at io.vertx.core.impl.ContextImpl.lambda$wrapTask$2(ContextImpl.java:324)
    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:440)
    at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:873)
    at java.lang.Thread.run(Thread.java:745)
Caused by: io.netty.channel.ChannelException: Failed to open a socket.
    at io.netty.channel.socket.nio.NioSocketChannel.newSocket(NioSocketChannel.java:64)
    at io.netty.channel.socket.nio.NioSocketChannel.<init>(NioSocketChannel.java:81)
    at io.netty.channel.socket.nio.NioSocketChannel.<init>(NioSocketChannel.java:74)
    at sun.reflect.GeneratedConstructorAccessor8.newInstance(Unknown Source)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
    at java.lang.Class.newInstance(Class.java:442)
    at io.netty.channel.ReflectiveChannelFactory.newChannel(ReflectiveChannelFactory.java:38)
    ... 19 more
Caused by: java.net.SocketException: Too many open files in system
    at sun.nio.ch.Net.socket0(Native Method)
    at sun.nio.ch.Net.socket(Net.java:411)
    at sun.nio.ch.Net.socket(Net.java:404)
    at sun.nio.ch.SocketChannelImpl.<init>(SocketChannelImpl.java:105)
    at sun.nio.ch.SelectorProviderImpl.openSocketChannel(SelectorProviderImpl.java:60)
    at io.netty.channel.socket.nio.NioSocketChannel.newSocket(NioSocketChannel.java:62)
    ... 26 more