Is there an easy way to unregister a plugin from HystrixPlugins?

[Matt Brown]

I have a unit test which relies on some code that needs for a custom properties strategy to be registered with HystrixPlugins.getInstance().registerPropertiesStrategy().

However, if I have a second unit test which also needs to register the properties strategy with the HystrixPlugins instance, then it fails because the field can only be set in the HystrixPlugins singleton once:

    public void registerPropertiesStrategy(HystrixPropertiesStrategy impl) {

        if (!propertiesFactory.compareAndSet(null, impl)) {

            throw new IllegalStateException("Another strategy was already registered.");

        }

    } 

Is there a way I am missing to reset the plugin's references? 

[Ben Christensen]

You can reset the state of Hystrix using Hystrix.reset() which is intended for testing and clean shutdown. 

Ben Christensen

310.782.5511

@benjchristensen

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[benjchr...@netflix.com]

Actually, correction, Hystrix.reset() does not unregister plugins.

[Andrew Blick]

I'm also stuck on a similar problem. I registered a ConcurrencyStrategy in a unity test, and need a way to clear it so that when integration tests run, it has a clean state. I'm currently getting "Another strategy was already registered". I tried using Hystrix.reset() and also found that it does not reset the plugins. I then tried copying the code in HystrixPlugins.UnitTest.reset() (I'm working in Groovy, so I can access the private class and fields), but that didn't work either.

[Andrew Blick]

Turns our the HystrixPlugins.UnitTest.reset() method just misses one of the plugins. The following seems to fully reset Hystrix state:

Hystrix.reset()

HystrixPlugins.getInstance().@concurrencyStrategy.set(null);

HystrixPlugins.getInstance().@metricsPublisher.set(null);

HystrixPlugins.getInstance().@notifier.set(null);

HystrixPlugins.getInstance().@propertiesFactory.set(null);

HystrixPlugins.getInstance().@commandExecutionHook.set(null);

In Java, I imagine that something similar can be achieved via the reflection API.

[徐金铎]

however, i think the key about the registered strategy is probably HystrixConcurrencyStrategyDefault.class. In HystrixPlugins.class, when we want to get one strategy.

/**
 * Retrieve instance of {@link HystrixConcurrencyStrategy} to use based on order of precedence as defined in {@link HystrixPlugins} class header.
 * <p>
 * Override default by using {@link #registerConcurrencyStrategy(HystrixConcurrencyStrategy)} or setting property (via Archaius): <code>hystrix.plugin.HystrixConcurrencyStrategy.implementation</code> with the
 * full classname to load.
 * 
 * @return {@link HystrixConcurrencyStrategy} implementation to use
 */
public HystrixConcurrencyStrategy getConcurrencyStrategy() {
    if (concurrencyStrategy.get() == null) {
        // check for an implementation from Archaius first
        Object impl = getPluginImplementation(HystrixConcurrencyStrategy.class);
        if (impl == null) {
            // nothing set via Archaius so initialize with default
            concurrencyStrategy.compareAndSet(null, HystrixConcurrencyStrategyDefault.getInstance());
            // we don't return from here but call get() again in case of thread-race so the winner will always get returned
        } else {
            // we received an implementation from Archaius so use it
            concurrencyStrategy.compareAndSet(null, (HystrixConcurrencyStrategy) impl);
        }
    }
    return concurrencyStrategy.get();
}

.

It will get you a HystrixConcurrencyStrategyDefault.

在 2013年7月26日星期五 UTC+8上午4:26:52，Matt Brown写道：