Micronaut's EmbeddedServer startup extremely slow

Question

I created a micronaut "Hello World!" application and a JUnit test according to the Micronaut user guide:

https://docs.micronaut.io/latest/guide/index.html#creatingClient

on macOS Mojave (10.14) with Java 1.8.0_25-b17.

Unit test:

package hello;

import io.micronaut.http.HttpStatus;
import io.micronaut.http.client.RxHttpClient;
import io.micronaut.runtime.server.EmbeddedServer;
import io.micronaut.test.annotation.MicronautTest;
import org.junit.jupiter.api.Test;
import javax.inject.Inject;

import static org.junit.jupiter.api.Assertions.assertEquals;

@MicronautTest
public class HelloControllerTest {

    @Inject
    EmbeddedServer embeddedServer;

    @Test
    public void testIndex() throws Exception {
        // or (instead of the @Inject): 
        // EmbeddedServer embeddedServer = ApplicationContext.run(EmbeddedServer.class);

        try(RxHttpClient client = embeddedServer.getApplicationContext().createBean(RxHttpClient.class, embeddedServer.getURL())) {
            assertEquals(HttpStatus.OK, client.toBlocking().exchange("/hello").status());
        }
    }
}

The "Hello World!" application starts up quickly (about a second). The JUnit test, however, takes more than 75 seconds to complete. It 'hangs' on the following line for 75 seconds:

server = ApplicationContext.run(EmbeddedServer.class);

Suggested fix in /etc/hosts doesn't work

I've tried this suggested fix (adding the hostname to /etc/hosts after the "127.0.0.1 localhost" and "::1 localhost" entries -- both with and without the '.local' suffix):

https://docs.micronaut.io/latest/guide/index.html#problems

Jvm takes a long time to resolve ip-address for localhost

with no luck. I restarted my machine after changes to /etc/hosts.

The hostname resolution does not seem to be the problem though; I tested it with the inetTester.jar mentioned in the above link (download here: https://github.com/thoeni/inetTester), it takes only 6ms. I guess it must be something else.

(On the other hand, everyone who had problems with micronaut application startup time (which I do not) on macOS, and fixed it by adding hostname to /etc/hosts, also mentions this same ~75 second delay -- this can't really be a coincidence?)

Log file

The two lines in the log file, before and after the 75 second pause:

22:55:06.834 [main] DEBUG i.m.context.DefaultBeanContext - Registering singleton bean io.micronaut.http.server.netty.NioEventLoopGroupFactory@4b1c0397 for type [io.micronaut.http.server.netty.EventLoopGroupFactory] using bean key io.micronaut.http.server.netty.NioEventLoopGroupFactory
22:56:22.040 [main] DEBUG io.micronaut.context.lifecycle - Created bean [io.micronaut.http.server.netty.NettyHttpServer@2fe88a09] from definition [Definition: io.micronaut.http.server.netty.NettyHttpServer] with qualifier [null]

And a bit of context:

22:55:06.833 [main] DEBUG i.m.context.DefaultBeanContext - Finding candidate beans for type: interface io.micronaut.http.server.netty.ssl.ServerSslBuilder
22:55:06.833 [main] DEBUG i.m.context.DefaultBeanContext - Resolved bean candidates [] for type: interface io.micronaut.http.server.netty.ssl.ServerSslBuilder
22:55:06.833 [main] DEBUG i.m.context.DefaultBeanContext - Resolving beans for type: io.netty.channel.ChannelOutboundHandler
22:55:06.833 [main] TRACE i.m.context.DefaultBeanContext - Looking up existing beans for key: io.netty.channel.ChannelOutboundHandler
22:55:06.833 [main] TRACE i.m.context.DefaultBeanContext - No beans found for key: io.netty.channel.ChannelOutboundHandler
22:55:06.833 [main] DEBUG i.m.context.DefaultBeanContext - Finding candidate beans for type: interface io.netty.channel.ChannelOutboundHandler
22:55:06.833 [main] DEBUG i.m.context.DefaultBeanContext - Resolved bean candidates [] for type: interface io.netty.channel.ChannelOutboundHandler
22:55:06.833 [main] DEBUG i.m.context.DefaultBeanContext - Found no possible candidate beans of type [io.netty.channel.ChannelOutboundHandler] for qualifier: null 
22:55:06.833 [main] TRACE i.m.context.DefaultBeanContext - Looking up existing bean for key: io.micronaut.http.server.netty.EventLoopGroupFactory
22:55:06.833 [main] TRACE i.m.context.DefaultBeanContext - No existing bean found for bean key: io.micronaut.http.server.netty.EventLoopGroupFactory
22:55:06.833 [main] DEBUG i.m.context.DefaultBeanContext - Finding candidate beans for type: interface io.micronaut.http.server.netty.EventLoopGroupFactory
22:55:06.834 [main] DEBUG i.m.context.DefaultBeanContext - Finding candidate beans for type: class io.micronaut.http.server.netty.EpollEventLoopGroupFactory
22:55:06.834 [main] DEBUG i.m.context.DefaultBeanContext - Resolved bean candidates [] for type: class io.micronaut.http.server.netty.EpollEventLoopGroupFactory
22:55:06.834 [main] DEBUG i.m.context.DefaultBeanContext - Finding candidate beans for type: class io.micronaut.http.server.netty.KQueueEventLoopGroupFactory
22:55:06.834 [main] DEBUG i.m.context.DefaultBeanContext - Resolved bean candidates [] for type: class io.micronaut.http.server.netty.KQueueEventLoopGroupFactory
22:55:06.834 [main] DEBUG i.m.context.DefaultBeanContext - Resolved bean candidates [Definition: io.micronaut.http.server.netty.NioEventLoopGroupFactory] for type: interface io.micronaut.http.server.netty.EventLoopGroupFactory
22:55:06.834 [main] DEBUG i.m.context.DefaultBeanContext - Finalized bean definitions candidates: [Definition: io.micronaut.http.server.netty.NioEventLoopGroupFactory]
22:55:06.834 [main] DEBUG i.m.context.DefaultBeanContext - Found concrete candidate [Definition: io.micronaut.http.server.netty.NioEventLoopGroupFactory] for type: io.micronaut.http.server.netty.EventLoopGroupFactory 
22:55:06.834 [main] DEBUG io.micronaut.context.lifecycle - Created bean [io.micronaut.http.server.netty.NioEventLoopGroupFactory@4b1c0397] from definition [Definition: io.micronaut.http.server.netty.NioEventLoopGroupFactory] with qualifier [null]
22:55:06.834 [main] DEBUG i.m.context.DefaultBeanContext - Registering singleton bean io.micronaut.http.server.netty.NioEventLoopGroupFactory@4b1c0397 for type [io.micronaut.http.server.netty.EventLoopGroupFactory] using bean key io.micronaut.http.server.netty.NioEventLoopGroupFactory
22:56:22.040 [main] DEBUG io.micronaut.context.lifecycle - Created bean [io.micronaut.http.server.netty.NettyHttpServer@2fe88a09] from definition [Definition: io.micronaut.http.server.netty.NettyHttpServer] with qualifier [null]
22:56:22.041 [main] DEBUG i.m.context.DefaultBeanContext - Registering singleton bean io.micronaut.http.server.netty.NettyHttpServer@2fe88a09 for type [io.micronaut.runtime.server.EmbeddedServer] using bean key io.micronaut.http.server.netty.NettyHttpServer
22:56:22.042 [main] DEBUG i.n.c.MultithreadEventLoopGroup - -Dio.netty.eventLoopThreads: 16
22:56:22.050 [main] DEBUG io.netty.channel.nio.NioEventLoop - -Dio.netty.noKeySetOptimization: false
22:56:22.050 [main] DEBUG io.netty.channel.nio.NioEventLoop - -Dio.netty.selectorAutoRebuildThreshold: 512
22:56:22.056 [main] DEBUG i.n.util.internal.PlatformDependent - org.jctools-core.MpscChunkedArrayQueue: available
22:56:22.063 [main] TRACE io.netty.channel.nio.NioEventLoop - instrumented a special java.util.Set into: sun.nio.ch.KQueueSelectorImpl@2ca6546f
22:56:22.063 [main] TRACE io.netty.channel.nio.NioEventLoop - instrumented a special java.util.Set into: sun.nio.ch.KQueueSelectorImpl@6b63d445
22:56:22.063 [main] TRACE io.netty.channel.nio.NioEventLoop - instrumented a special java.util.Set into: sun.nio.ch.KQueueSelectorImpl@7578e06a
22:56:22.064 [main] TRACE io.netty.channel.nio.NioEventLoop - instrumented a special java.util.Set into: sun.nio.ch.KQueueSelectorImpl@30b2b76f
22:56:22.064 [main] TRACE io.netty.channel.nio.NioEventLoop - instrumented a special java.util.Set into: sun.nio.ch.KQueueSelectorImpl@56da52a7
22:56:22.064 [main] TRACE io.netty.channel.nio.NioEventLoop - instrumented a special java.util.Set into: sun.nio.ch.KQueueSelectorImpl@23ee75c5

Answer 1

I had a similar issue where the compiled native image was taking over 40 seconds to start. The problem in my case was the environment detection, disabling it solved my problem. I did it in code, you can do it via properties as explained in their docs.

fun main(args: Array<String>) {
            Micronaut.build()
                .packages("com.example")
                .deduceEnvironment(false)  // this line did the trick
                .mainClass(Application.javaClass)
                .start()
        }