DnsNameResolver hangs for 5 seconds in InetAddress.getAllByName0 on Mac OSX

Expected behavior

DnsNameResolver constructor should be fast, anything slow offloaded until actually used. Or a warning given that environment in badly configured.

This is an environmental problem, but raising because its a regression from java DNS which doesn’t hang like this.

Feel free to close if you don’t want to worry about it in Netty.

Actual behavior

constructor hangs at program startup

Steps to reproduce

    System.out.println("started " + new Date());

    ThreadFactory threadFactory = new DefaultThreadFactory("netty", true);
    NioEventLoopGroup eventLoopGroup = new NioEventLoopGroup(1, threadFactory);

    DnsNameResolverBuilder builder = new DnsNameResolverBuilder(eventLoopGroup.next())
            .channelType(NioDatagramChannel.class)
            .optResourceEnabled(false)
            .maxQueriesPerResolve(3)
            .recursionDesired(true);

    DnsNameResolver re = builder.build();

    System.out.println("finished " + new Date());

started Sat Feb 25 13:17:16 GMT 2017 finished Sat Feb 25 13:17:21 GMT 2017

Fix

Fix is http://justthesam.com/2016/10/fixing-java-net-inet6addressimpl-lookupallhostaddr-slowdown/

Netty version

4.1.8.Final

JVM version (e.g. java -version)

$ java -version java version “9-ea” Java™ SE Runtime Environment (build 9-ea+157) Java HotSpot™ 64-Bit Server VM (build 9-ea+157, mixed mode)

OS version (e.g. uname -a)

Darwin xxx 16.4.0 Darwin Kernel Version 16.4.0: Thu Dec 22 22:53:21 PST 2016; root:xnu-3789.41.3~3/RELEASE_X86_64 x86_64

"main" #1 prio=5 os_prio=31 tid=0x00007f8c60809800 nid=0x1d03 runnable [0x00007000027a3000]
   java.lang.Thread.State: RUNNABLE
	at java.net.Inet6AddressImpl.lookupAllHostAddr(java.base@9-ea/Native Method)
	at java.net.InetAddress$PlatformNameService.lookupAllHostAddr(java.base@9-ea/InetAddress.java:921)
	at java.net.InetAddress.getAddressesFromNameService(java.base@9-ea/InetAddress.java:1501)
	at java.net.InetAddress$NameServiceAddresses.get(java.base@9-ea/InetAddress.java:840)
	- locked <0x00000006cfce83e8> (a java.net.InetAddress$NameServiceAddresses)
	at java.net.InetAddress.getAllByName0(java.base@9-ea/InetAddress.java:1491)
	at java.net.InetAddress.getLocalHost(java.base@9-ea/InetAddress.java:1623)
	at sun.management.VMManagementImpl.getVmId(java.management@9-ea/VMManagementImpl.java:144)
	at sun.management.RuntimeImpl.getName(java.management@9-ea/RuntimeImpl.java:59)
	at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(java.base@9-ea/Native Method)
	at jdk.internal.reflect.NativeMethodAccessorImpl.invoke(java.base@9-ea/NativeMethodAccessorImpl.java:62)
	at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(java.base@9-ea/DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(java.base@9-ea/Method.java:547)
	at io.netty.channel.DefaultChannelId.defaultProcessId(DefaultChannelId.java:121)
	at io.netty.channel.DefaultChannelId.<clinit>(DefaultChannelId.java:78)
	at io.netty.channel.AbstractChannel.newId(AbstractChannel.java:107)
	at io.netty.channel.AbstractChannel.<init>(AbstractChannel.java:79)
	at io.netty.channel.nio.AbstractNioChannel.<init>(AbstractNioChannel.java:84)
	at io.netty.channel.nio.AbstractNioMessageChannel.<init>(AbstractNioMessageChannel.java:42)
	at io.netty.channel.socket.nio.NioDatagramChannel.<init>(NioDatagramChannel.java:147)
	at io.netty.channel.socket.nio.NioDatagramChannel.<init>(NioDatagramChannel.java:115)
	at jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(java.base@9-ea/Native Method)
	at jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(java.base@9-ea/NativeConstructorAccessorImpl.java:62)
	at jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(java.base@9-ea/DelegatingConstructorAccessorImpl.java:45)
	at java.lang.reflect.Constructor.newInstance(java.base@9-ea/Constructor.java:473)
	at java.lang.Class.newInstance(java.base@9-ea/Class.java:558)
	at io.netty.channel.ReflectiveChannelFactory.newChannel(ReflectiveChannelFactory.java:38)
	at io.netty.bootstrap.AbstractBootstrap.initAndRegister(AbstractBootstrap.java:321)
	at io.netty.bootstrap.AbstractBootstrap.register(AbstractBootstrap.java:235)
	at io.netty.resolver.dns.DnsNameResolver.<init>(DnsNameResolver.java:249)
	at io.netty.resolver.dns.DnsNameResolverBuilder.build(DnsNameResolverBuilder.java:347)

[testn]

adding system property

-Djava.net.preferIPv4Stack=true

should help avoid the problem

[askiros]

It looks like an Mac OSX issue (resolution of the local host must happens inside java.lang.management.RuntimeMXBean#getName() causing the delay). The StackOverflow solution remove the delay.