Question

服务启动时，我想构建一个简单的管道。
我想隔离Flux接收器或处理器，以与之发射事件。
事件将来自多个线程，并应根据管道的subscribeOn()规范进行处理，但一切似乎都在main线程上运行。
什么是最好的方法？我在下面附上了我的尝试。
（我正在使用反应堆核心v3.2.8.RELEASE。）

import org.junit.jupiter.api.Test;

import reactor.core.publisher.DirectProcessor;
import reactor.core.publisher.Flux;
import reactor.core.publisher.FluxProcessor;
import reactor.core.publisher.FluxSink;
import reactor.core.scheduler.Schedulers;

/**
 * I want to construct my React pipelines during creation,
 * then emit events over the lifetime of my services.
 */
public class React1Test
{
    /**
     * Attempt 1 - use a DirectProcessor and send items to it.
     * Doesn't work though - seems to always run on the main thread.
     */
    @Test
    public void testReact1() throws InterruptedException
    {
        // Create the flux and sink.
        FluxProcessor<String, String> fluxProcessor = DirectProcessor.<String>create().serialize();
        FluxSink<String> sink = fluxProcessor.sink();

        // Create the pipeline.
        fluxProcessor
            .doOnNext(str -> showDebugMsg(str))   // What thread do ops work on?
            .subscribeOn(Schedulers.elastic())
            .subscribe(str -> showDebugMsg(str)); // What thread does subscribe run on?

        // Give the multi-thread pipeline a second.
        Thread.sleep(1000);

        // Time passes ... things happen ...
        // Pass a few messages to the sink, emulating events.
        sink.next("a");
        sink.next("b");
        sink.next("c");

        // It's multi-thread so wait a sec to receive.
        Thread.sleep(1000);
    }

    // Used down below during Flux.create().
    private FluxSink<String> sink2;

    /**
     * Attempt 2 - use Flux.create() and its FluxSink object.
     * Also seems to always run on the main thread.
     */
    @Test
    public void testReact2() throws InterruptedException
    {
        // Create the flux and sink.
        Flux.<String>create(sink -> sink2 = sink)
            .doOnNext(str -> showDebugMsg(str))   // What thread do ops work on?
            .subscribeOn(Schedulers.elastic())
            .subscribe(str -> showDebugMsg(str)); // What thread does subscribe run on?

        // Give the multi-thread pipeline a second.
        Thread.sleep(1000);

        // Pass a few messages to the sink.
        sink2.next("a");
        sink2.next("b");
        sink2.next("c");

        // It's multi-thread so wait a sec to receive.
        Thread.sleep(1000);
    }

    // Show us what thread we're on.
    private static void showDebugMsg(String msg)
    {
        System.out.println(String.format("%s [%s]", msg, Thread.currentThread().getName()));
    }
}

输出始终为：

a [main]
a [main]
b [main]
b [main]
c [main]
c [main]

但是我期望的是：

a [elastic-1]
a [elastic-1]
b [elastic-2]
b [elastic-2]
c [elastic-3]
c [elastic-3]

谢谢。

Answer 1

您看到[main]是因为您正在从主线程调用onNext。您使用的subscribeOn仅用于订阅（当create的lambda被触发时）。如果您使用elastic-*而不是publishOn，则会看到subscribeOn个线程已记录。

此外，考虑使用Processors，不鼓励将sink存储为字段。

Answer 2

您可以使用parallel()和runOn()而不是subscribeOn()来使sink.next()运行多线程。
bsideup也是正确的-您可以使用publishOn()强制下游运算符在一个不同的Scheduler线程上运行。

这是我更新的代码：

import org.junit.jupiter.api.Test;

import reactor.core.publisher.DirectProcessor;
import reactor.core.publisher.Flux;
import reactor.core.publisher.FluxProcessor;
import reactor.core.publisher.FluxSink;
import reactor.core.scheduler.Schedulers;

/**
 * I want to construct my React pipelines during creation,
 * then emit events over the lifetime of my services.
 */
public class React1Test
{
    /**
     * Version 1 - use a DirectProcessor to dynamically emit items.
     */
    @Test
    public void testReact1() throws InterruptedException
    {
        // Create the flux and sink.
        FluxProcessor<String, String> fluxProcessor = DirectProcessor.<String>create().serialize();
        FluxSink<String> sink = fluxProcessor.sink();

        // Create the pipeline.
        fluxProcessor
            .parallel()
            .runOn(Schedulers.elastic())
            .doOnNext(str -> showDebugMsg(str))   // What thread do ops work on?
            .subscribe(str -> showDebugMsg(str)); // What thread does subscribe run on?

        // Give the multi-thread pipeline a second.
        Thread.sleep(1000);

        // Time passes ... things happen ...
        // Pass a few messages to the sink, emulating events.
        sink.next("a");
        sink.next("b");
        sink.next("c");

        // It's multi-thread so wait a sec to receive.
        Thread.sleep(1000);
    }

    // Used down below during Flux.create().
    private FluxSink<String> sink2;

    /**
     * Version 2 - use Flux.create() and its FluxSink object.
     */
    @Test
    public void testReact2() throws InterruptedException
    {
        // Create the flux and sink.
        Flux.<String>create(sink -> sink2 = sink)
            .parallel()
            .runOn(Schedulers.elastic())
            .doOnNext(str -> showDebugMsg(str))   // What thread do ops work on?
            .subscribe(str -> showDebugMsg(str)); // What thread does subscribe run on?

        // Give the multi-thread pipeline a second.
        Thread.sleep(1000);

        // Pass a few messages to the sink.
        sink2.next("a");
        sink2.next("b");
        sink2.next("c");

        // It's multi-thread so wait a sec to receive.
        Thread.sleep(1000);
    }

    // Show us what thread we're on.
    private static void showDebugMsg(String msg)
    {
        System.out.println(String.format("%s [%s]", msg, Thread.currentThread().getName()));
    }
}

两个版本均产生所需的多线程输出：

a [elastic-2]
b [elastic-3]
c [elastic-4]
b [elastic-3]
a [elastic-2]
c [elastic-4]

Project Reactor，使用创建Lambda之外的Flux接收器

2 个答案: