Why doesn't AsyncHttpClient close the thread after throwing an exception?

Question

I'm using the Zendesk Java Client . When I supply the correct credentials, it works as expected. However, I stumbled on a scenario where if the wrong credentials are passed in, the thread just hangs and it throws an error. Whether I run the code with or without the debugger, the code just stays running. It doesn't exit or return control to the debugger.

Is this an issue with the library, or am I misunderstanding how the AsyncHttpClient works?

My code is below:

fun zdtestWrongCredentials() {
    val client = asyncHttpClient(
        config()
            .setRequestTimeout(5000)
            .setReadTimeout(5000)
            .setShutdownTimeout(3000)
            .setPooledConnectionIdleTimeout(5000)
            .setKeepAlive(false)
    )

    var zd = Zendesk.Builder("https://website.zendesk.com")
        .setClient(client)
        .setUsername("john.doe@website.com")
        .setPassword("abcd")
        .build()

    var ticket = Ticket(123, "a", Comment("abc"))

    // The code hangs here. It's unclear why it exhibits this behavior.
    var test = zd.createTicket(ticket)

    // The code does not reach this line.
    client.close()

    return
}

Although I'm using Kotlin, I tried replicating this issue in a simple Java project and the issue persists.

The stack trace is below. There is an exception at the bottom, but even after this exception, the program does not exit/give control back to the debugger.

"C:\Program Files\Java\jdk-11.0.4\bin\java.exe"
09:47:01.463 [main] DEBUG io.netty.util.internal.logging.InternalLoggerFactory - Using SLF4J as the default logging framework
09:47:01.480 [main] DEBUG io.netty.util.ResourceLeakDetector - -Dio.netty.leakDetection.level: simple
09:47:01.480 [main] DEBUG io.netty.util.ResourceLeakDetector - -Dio.netty.leakDetection.targetRecords: 4
09:47:01.550 [main] DEBUG io.netty.util.internal.PlatformDependent - Platform: Windows
09:47:01.562 [main] DEBUG io.netty.util.internal.PlatformDependent0 - -Dio.netty.noUnsafe: false
09:47:01.562 [main] DEBUG io.netty.util.internal.PlatformDependent0 - Java version: 11
09:47:01.566 [main] DEBUG io.netty.util.internal.PlatformDependent0 - sun.misc.Unsafe.theUnsafe: available
09:47:01.567 [main] DEBUG io.netty.util.internal.PlatformDependent0 - sun.misc.Unsafe.copyMemory: available
09:47:01.568 [main] DEBUG io.netty.util.internal.PlatformDependent0 - java.nio.Buffer.address: available
09:47:01.575 [main] DEBUG io.netty.util.internal.PlatformDependent0 - direct buffer constructor: unavailable
java.lang.UnsupportedOperationException: Reflective setAccessible(true) disabled
    at io.netty.util.internal.ReflectionUtil.trySetAccessible(ReflectionUtil.java:31)
    at io.netty.util.internal.PlatformDependent0$4.run(PlatformDependent0.java:224)
    at java.base/java.security.AccessController.doPrivileged(Native Method)
    at io.netty.util.internal.PlatformDependent0.<clinit>(PlatformDependent0.java:218)
    at io.netty.util.internal.PlatformDependent.isAndroid(PlatformDependent.java:212)
    at io.netty.util.internal.PlatformDependent.<clinit>(PlatformDependent.java:80)
    at io.netty.util.ResourceLeakDetector.<init>(ResourceLeakDetector.java:171)
    at io.netty.util.ResourceLeakDetector.<init>(ResourceLeakDetector.java:213)
    at io.netty.util.ResourceLeakDetectorFactory$DefaultResourceLeakDetectorFactory.newResourceLeakDetector(ResourceLeakDetectorFactory.java:201)
    at io.netty.util.HashedWheelTimer.<clinit>(HashedWheelTimer.java:89)
    at org.asynchttpclient.DefaultAsyncHttpClient.newNettyTimer(DefaultAsyncHttpClient.java:96)
    at org.asynchttpclient.DefaultAsyncHttpClient.<init>(DefaultAsyncHttpClient.java:87)
    at org.asynchttpclient.Dsl.asyncHttpClient(Dsl.java:32)
    at com.website.MainKt.test123(Main.kt:321)
    at com.website.MainKt.main(Main.kt:288)
    at com.website.MainKt.main(Main.kt)
09:47:01.577 [main] DEBUG io.netty.util.internal.PlatformDependent0 - java.nio.Bits.unaligned: available, true
09:47:01.579 [main] DEBUG io.netty.util.internal.PlatformDependent0 - jdk.internal.misc.Unsafe.allocateUninitializedArray(int): unavailable
java.lang.IllegalAccessException: class io.netty.util.internal.PlatformDependent0$6 cannot access class jdk.internal.misc.Unsafe (in module java.base) because module java.base does not export jdk.internal.misc to unnamed module @4de5031f
    at java.base/jdk.internal.reflect.Reflection.newIllegalAccessException(Reflection.java:361)
    at java.base/java.lang.reflect.AccessibleObject.checkAccess(AccessibleObject.java:591)
    at java.base/java.lang.reflect.Method.invoke(Method.java:558)
    at io.netty.util.internal.PlatformDependent0$6.run(PlatformDependent0.java:334)
    at java.base/java.security.AccessController.doPrivileged(Native Method)
    at io.netty.util.internal.PlatformDependent0.<clinit>(PlatformDependent0.java:325)
    at io.netty.util.internal.PlatformDependent.isAndroid(PlatformDependent.java:212)
    at io.netty.util.internal.PlatformDependent.<clinit>(PlatformDependent.java:80)
    at io.netty.util.ResourceLeakDetector.<init>(ResourceLeakDetector.java:171)
    at io.netty.util.ResourceLeakDetector.<init>(ResourceLeakDetector.java:213)
    at io.netty.util.ResourceLeakDetectorFactory$DefaultResourceLeakDetectorFactory.newResourceLeakDetector(ResourceLeakDetectorFactory.java:201)
    at io.netty.util.HashedWheelTimer.<clinit>(HashedWheelTimer.java:89)
    at org.asynchttpclient.DefaultAsyncHttpClient.newNettyTimer(DefaultAsyncHttpClient.java:96)
    at org.asynchttpclient.DefaultAsyncHttpClient.<init>(DefaultAsyncHttpClient.java:87)
    at org.asynchttpclient.Dsl.asyncHttpClient(Dsl.java:32)
    at com.website.MainKt.test123(Main.kt:321)
    at com.website.MainKt.main(Main.kt:288)
    at com.website.MainKt.main(Main.kt)
09:47:01.579 [main] DEBUG io.netty.util.internal.PlatformDependent0 - java.nio.DirectByteBuffer.<init>(long, int): unavailable
09:47:01.579 [main] DEBUG io.netty.util.internal.PlatformDependent - sun.misc.Unsafe: available
09:47:01.634 [main] DEBUG io.netty.util.internal.PlatformDependent - maxDirectMemory: 6404702208 bytes (maybe)
09:47:01.635 [main] DEBUG io.netty.util.internal.PlatformDependent - -Dio.netty.tmpdir: C:\Users\john~1.doe\AppData\Local\Temp (java.io.tmpdir)
09:47:01.635 [main] DEBUG io.netty.util.internal.PlatformDependent - -Dio.netty.bitMode: 64 (sun.arch.data.model)
09:47:01.639 [main] DEBUG io.netty.util.internal.PlatformDependent - -Dio.netty.maxDirectMemory: -1 bytes
09:47:01.639 [main] DEBUG io.netty.util.internal.PlatformDependent - -Dio.netty.uninitializedArrayAllocationThreshold: -1
09:47:01.649 [main] DEBUG io.netty.util.internal.CleanerJava9 - java.nio.ByteBuffer.cleaner(): available
09:47:01.649 [main] DEBUG io.netty.util.internal.PlatformDependent - -Dio.netty.noPreferDirect: false
09:47:01.649 [main] DEBUG io.netty.util.ResourceLeakDetectorFactory - Loaded default ResourceLeakDetector: io.netty.util.ResourceLeakDetector@13acb0d1
09:47:01.705 [main] DEBUG io.netty.util.internal.PlatformDependent - org.jctools-core.MpscChunkedArrayQueue: available
09:47:02.621 [main] DEBUG io.netty.handler.ssl.JdkSslContext - Default protocols (JDK): [TLSv1.2, TLSv1.1, TLSv1] 
09:47:02.622 [main] DEBUG io.netty.handler.ssl.JdkSslContext - Default cipher suites (JDK): [TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384, TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256, TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA, TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA, TLS_RSA_WITH_AES_128_GCM_SHA256, TLS_RSA_WITH_AES_128_CBC_SHA, TLS_RSA_WITH_AES_256_CBC_SHA, TLS_AES_128_GCM_SHA256, TLS_AES_256_GCM_SHA384]
09:47:02.651 [main] DEBUG io.netty.channel.MultithreadEventLoopGroup - -Dio.netty.eventLoopThreads: 8
09:47:02.674 [main] DEBUG io.netty.channel.nio.NioEventLoop - -Dio.netty.noKeySetOptimization: false
09:47:02.675 [main] DEBUG io.netty.channel.nio.NioEventLoop - -Dio.netty.selectorAutoRebuildThreshold: 512
09:47:02.714 [main] DEBUG io.netty.util.internal.InternalThreadLocalMap - -Dio.netty.threadLocalMap.stringBuilder.initialSize: 1024
09:47:02.714 [main] DEBUG io.netty.util.internal.InternalThreadLocalMap - -Dio.netty.threadLocalMap.stringBuilder.maxSize: 4096
09:47:02.728 [main] DEBUG io.netty.buffer.PooledByteBufAllocator - -Dio.netty.allocator.numHeapArenas: 8
09:47:02.728 [main] DEBUG io.netty.buffer.PooledByteBufAllocator - -Dio.netty.allocator.numDirectArenas: 8
09:47:02.728 [main] DEBUG io.netty.buffer.PooledByteBufAllocator - -Dio.netty.allocator.pageSize: 8192
09:47:02.728 [main] DEBUG io.netty.buffer.PooledByteBufAllocator - -Dio.netty.allocator.maxOrder: 11
09:47:02.728 [main] DEBUG io.netty.buffer.PooledByteBufAllocator - -Dio.netty.allocator.chunkSize: 16777216
09:47:02.728 [main] DEBUG io.netty.buffer.PooledByteBufAllocator - -Dio.netty.allocator.tinyCacheSize: 512
09:47:02.728 [main] DEBUG io.netty.buffer.PooledByteBufAllocator - -Dio.netty.allocator.smallCacheSize: 256
09:47:02.728 [main] DEBUG io.netty.buffer.PooledByteBufAllocator - -Dio.netty.allocator.normalCacheSize: 64
09:47:02.728 [main] DEBUG io.netty.buffer.PooledByteBufAllocator - -Dio.netty.allocator.maxCachedBufferCapacity: 32768
09:47:02.728 [main] DEBUG io.netty.buffer.PooledByteBufAllocator - -Dio.netty.allocator.cacheTrimInterval: 8192
09:47:02.728 [main] DEBUG io.netty.buffer.PooledByteBufAllocator - -Dio.netty.allocator.useCacheForAllThreads: true
09:47:02.728 [main] DEBUG io.netty.buffer.PooledByteBufAllocator - -Dio.netty.allocator.maxCachedByteBuffersPerChunk: 1023
09:47:02.738 [main] DEBUG io.netty.buffer.ByteBufUtil - -Dio.netty.allocator.type: pooled
09:47:02.738 [main] DEBUG io.netty.buffer.ByteBufUtil - -Dio.netty.threadLocalDirectBufferSize: 0
09:47:02.738 [main] DEBUG io.netty.buffer.ByteBufUtil - -Dio.netty.maxThreadLocalCharBufferSize: 16384
09:47:03.522 [main] DEBUG org.zendesk.client.v2.Zendesk - Request POST https://website.zendesk.com/api/v2/tickets.json application/json; charset=UTF-8 92 bytes
09:47:03.568 [main] DEBUG io.netty.buffer.AbstractByteBuf - -Dio.netty.buffer.checkAccessible: true
09:47:03.568 [main] DEBUG io.netty.buffer.AbstractByteBuf - -Dio.netty.buffer.checkBounds: true
09:47:03.569 [main] DEBUG io.netty.util.ResourceLeakDetectorFactory - Loaded default ResourceLeakDetector: io.netty.util.ResourceLeakDetector@604c5de8
09:47:03.650 [main] DEBUG io.netty.channel.DefaultChannelId - -Dio.netty.processId: 12648 (auto-detected)
09:47:03.653 [main] DEBUG io.netty.util.NetUtil - -Djava.net.preferIPv4Stack: false
09:47:03.653 [main] DEBUG io.netty.util.NetUtil - -Djava.net.preferIPv6Addresses: false
09:47:04.352 [main] DEBUG io.netty.util.NetUtil - Loopback interface: [lo, Software Loopback Interface 1, 127.0.0.1] ([lo, Software Loopback Interface 1, 127.0.0.1], {})
09:47:04.353 [main] DEBUG io.netty.util.NetUtil - Failed to get SOMAXCONN from sysctl and file \proc\sys\net\core\somaxconn. Default: 200
09:47:05.043 [main] DEBUG io.netty.channel.DefaultChannelId - -Dio.netty.machineId: 00:50:b6:ff:fe:ae:6e:01 (auto-detected)
09:47:05.172 [AsyncHttpClient-3-1] DEBUG io.netty.util.Recycler - -Dio.netty.recycler.maxCapacityPerThread: 4096
09:47:05.172 [AsyncHttpClient-3-1] DEBUG io.netty.util.Recycler - -Dio.netty.recycler.maxSharedCapacityFactor: 2
09:47:05.173 [AsyncHttpClient-3-1] DEBUG io.netty.util.Recycler - -Dio.netty.recycler.linkCapacity: 16
09:47:05.173 [AsyncHttpClient-3-1] DEBUG io.netty.util.Recycler - -Dio.netty.recycler.ratio: 8
09:47:05.614 [AsyncHttpClient-3-1] DEBUG org.asynchttpclient.netty.channel.NettyConnectListener - Using new Channel '[id: 0xf398d3e1, L:/192.168.108.56:64305 - R:website.zendesk.com/104.16.54.111:443]' for 'POST' to '/api/v2/tickets.json'
09:47:05.630 [AsyncHttpClient-3-1] DEBUG io.netty.handler.ssl.SslHandler - [id: 0xf398d3e1, L:/192.168.108.56:64305 - R:website.zendesk.com/104.16.54.111:443] HANDSHAKEN: TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256
09:47:05.810 [AsyncHttpClient-3-1] DEBUG org.asynchttpclient.netty.handler.HttpHandler - 

Request DefaultFullHttpRequest(decodeResult: success, version: HTTP/1.1, content: UnpooledHeapByteBuf(freed))
POST /api/v2/tickets.json HTTP/1.1
Content-type: application/json; charset=UTF-8
content-length: 92
connection: close
host: website.zendesk.com
authorization: Basic RGVyZWsudG93cmlzc0BkZWxhd2FyZWxpZmUuY29tOlRlczE=
accept: */*
user-agent: AHC/2.1

Response DefaultHttpResponse(decodeResult: success, version: HTTP/1.1)
HTTP/1.1 401 Unauthorized
Date: Tue, 20 Aug 2019 13:47:06 GMT
Content-Type: application/json; charset=UTF-8
Content-Length: 37
Connection: close
Set-Cookie: __cfduid=d807076f1918856a9ecbded67e619ee901566308826; expires=Wed, 19-Aug-20 13:47:06 GMT; path=/; domain=.website.zendesk.com; HttpOnly
WWW-Authenticate: Basic realm="Web Password"
Strict-Transport-Security: max-age=31536000;
Cache-Control: no-cache
X-Zendesk-Origin-Server: app23.pod20.usw2.zdsys.com
X-Request-Id: 5094d137ce35e1fa-SEA
X-Runtime: 0.060433
X-Zendesk-Request-Id: 7d89cc0062f1b7e6f05c
Set-Cookie: __cfruid=b0a77a0d73109c7862b0ab39be944601c81b0353-1566308826; path=/; domain=.website.zendesk.com; HttpOnly
Expect-CT: max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
Server: cloudflare
CF-RAY: 5094d137ce35e1fa-ORD

09:47:05.829 [AsyncHttpClient-3-1] INFO org.asynchttpclient.netty.handler.intercept.Unauthorized401Interceptor - Can't handle 401 as auth was already performed
09:47:05.839 [AsyncHttpClient-3-1] DEBUG org.asynchttpclient.netty.channel.ChannelManager - Closing Channel [id: 0xf398d3e1, L:/192.168.108.56:64305 - R:website.zendesk.com/104.16.54.111:443] 
09:47:05.844 [AsyncHttpClient-3-1] DEBUG org.zendesk.client.v2.Zendesk - Response HTTP/401 Unauthorized
{"error":"Couldn't authenticate you"}
09:47:05.846 [AsyncHttpClient-3-1] DEBUG org.asynchttpclient.AsyncCompletionHandler - HTTP/401: Unauthorized - {"error":"Couldn't authenticate you"}
org.zendesk.client.v2.ZendeskResponseException: HTTP/401: Unauthorized - {"error":"Couldn't authenticate you"}
    at org.zendesk.client.v2.Zendesk$BasicAsyncCompletionHandler.onCompleted(Zendesk.java:1997)
    at org.asynchttpclient.AsyncCompletionHandler.onCompleted(AsyncCompletionHandler.java:66)
    at org.asynchttpclient.netty.NettyResponseFuture.loadContent(NettyResponseFuture.java:223)
    at org.asynchttpclient.netty.NettyResponseFuture.done(NettyResponseFuture.java:258)
    at org.asynchttpclient.netty.handler.AsyncHttpClientHandler.finishUpdate(AsyncHttpClientHandler.java:239)
    at org.asynchttpclient.netty.handler.HttpHandler.handleChunk(HttpHandler.java:113)
    at org.asynchttpclient.netty.handler.HttpHandler.handleRead(HttpHandler.java:142)
    at org.asynchttpclient.netty.handler.AsyncHttpClientHandler.channelRead(AsyncHttpClientHandler.java:76)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
    at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340)
    at io.netty.channel.ChannelInboundHandlerAdapter.channelRead(ChannelInboundHandlerAdapter.java:86)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
    at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340)
    at io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:102)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
    at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340)
    at io.netty.channel.CombinedChannelDuplexHandler$DelegatingChannelHandlerContext.fireChannelRead(CombinedChannelDuplexHandler.java:438)
    at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:323)
    at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:297)
    at io.netty.channel.CombinedChannelDuplexHandler.channelRead(CombinedChannelDuplexHandler.java:253)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
    at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340)
    at io.netty.handler.ssl.SslHandler.unwrap(SslHandler.java:1436)
    at io.netty.handler.ssl.SslHandler.decodeJdkCompatible(SslHandler.java:1203)
    at io.netty.handler.ssl.SslHandler.decode(SslHandler.java:1247)
    at io.netty.handler.codec.ByteToMessageDecoder.decodeRemovalReentryProtection(ByteToMessageDecoder.java:502)
    at io.netty.handler.codec.ByteToMessageDecoder.callDecode(ByteToMessageDecoder.java:441)
    at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:278)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
    at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340)
    at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1408)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
    at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:930)
    at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:163)
    at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:677)
    at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:612)
    at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:529)
    at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:491)
    at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:905)
    at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
    at java.base/java.lang.Thread.run(Thread.java:834)
Exception in thread "main" org.zendesk.client.v2.ZendeskResponseException: HTTP/401: Unauthorized - {"error":"Couldn't authenticate you"}
    at org.zendesk.client.v2.Zendesk.complete(Zendesk.java:2252)
    at org.zendesk.client.v2.Zendesk.createTicket(Zendesk.java:307)
    at com.website.MainKt.test123(Main.kt:349)
    at com.website.MainKt.main(Main.kt:288)09:47:05.849 [AsyncHttpClient-3-1] DEBUG org.asynchttpclient.netty.handler.HttpHandler - Channel Closed: [id: 0xf398d3e1, L:/192.168.108.56:64305 ! R:website.zendesk.com/104.16.54.111:443] with attribute DISCARD

    at com.website.MainKt.main(Main.kt)
Caused by: org.zendesk.client.v2.ZendeskResponseException: HTTP/401: Unauthorized - {"error":"Couldn't authenticate you"}
    at org.zendesk.client.v2.Zendesk$BasicAsyncCompletionHandler.onCompleted(Zendesk.java:1997)
    at org.asynchttpclient.AsyncCompletionHandler.onCompleted(AsyncCompletionHandler.java:66)
    at org.asynchttpclient.netty.NettyResponseFuture.loadContent(NettyResponseFuture.java:223)
    at org.asynchttpclient.netty.NettyResponseFuture.done(NettyResponseFuture.java:258)
    at org.asynchttpclient.netty.handler.AsyncHttpClientHandler.finishUpdate(AsyncHttpClientHandler.java:239)
    at org.asynchttpclient.netty.handler.HttpHandler.handleChunk(HttpHandler.java:113)
    at org.asynchttpclient.netty.handler.HttpHandler.handleRead(HttpHandler.java:142)
    at org.asynchttpclient.netty.handler.AsyncHttpClientHandler.channelRead(AsyncHttpClientHandler.java:76)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
    at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340)
    at io.netty.channel.ChannelInboundHandlerAdapter.channelRead(ChannelInboundHandlerAdapter.java:86)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
    at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340)
    at io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:102)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
    at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340)
    at io.netty.channel.CombinedChannelDuplexHandler$DelegatingChannelHandlerContext.fireChannelRead(CombinedChannelDuplexHandler.java:438)
    at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:323)
    at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:297)
    at io.netty.channel.CombinedChannelDuplexHandler.channelRead(CombinedChannelDuplexHandler.java:253)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
    at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340)
    at io.netty.handler.ssl.SslHandler.unwrap(SslHandler.java:1436)
    at io.netty.handler.ssl.SslHandler.decodeJdkCompatible(SslHandler.java:1203)
    at io.netty.handler.ssl.SslHandler.decode(SslHandler.java:1247)
    at io.netty.handler.codec.ByteToMessageDecoder.decodeRemovalReentryProtection(ByteToMessageDecoder.java:502)
    at io.netty.handler.codec.ByteToMessageDecoder.callDecode(ByteToMessageDecoder.java:441)
    at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:278)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
    at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340)
    at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1408)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
    at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:930)
    at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:163)
    at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:677)
    at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:612)
    at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:529)
    at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:491)
    at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:905)
    at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
    at java.base/java.lang.Thread.run(Thread.java:834)

Answer 1

Depending on how the async client is implemented it can throw an error in one thread/coroutine and then wait for a completion message or trigger in another part of its code.

Because the error was thrown, the trigger is never sent and thus the thread hangs in perpetuity.

I "built" a problem like this once, so yes it is possible.

Obviously, I don't know if this is actually the issue at hand.

Cheers and all the best!