No such extension org.apache.dubbo.rpc.cluster.LoadBalance by name random

[winflex]

• [x] I have searched the issues of this repository and believe that this is not a duplicate.
• [x] I have checked the FAQ of this repository and believe that this is not a duplicate.

Environment

• Dubbo version: 2.7.3
• Operating System version: Linux version 3.10.0-957.27.2.el7.x86_64 ([email protected]) (gcc version 4.8.5 20150623 (Red Hat 4.8.5-36) (GCC) )
• Java version: openjdk 11.0.2

Steps to reproduce this issue

    @Reference
    private UserService userService;
    @GetMapping("/v1/user/relation/trace/test2")
    public CompletableFuture<String> dubbo2Test() {
        return CompletableFuture.supplyAsync(() -> {
            return userService.getUserInfo("sam");
        }).thenApply(userInfo -> "s");
    }

2. dubbo config: it's very simple:

dubbo.registry.address=xxx
dubbo.reference.check=false

3. visit /v1/user/relation/trace/test2

Expected Result

"s"

Actual Result

2020-03-05 11:28:30.196 [ForkJoinPool.commonPool-worker-3] ERROR esa.restlight.core.bootstrap.DefaultDispatcherHandler - Error occurred when doing request(url=/v1/user/relation/trace/test2, method =GET)
java.util.concurrent.CompletionException: java.lang.IllegalStateException: No such extension org.apache.dubbo.rpc.cluster.LoadBalance by name random
        at java.base/java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:314)
        at java.base/java.util.concurrent.CompletableFuture.completeThrowable(CompletableFuture.java:319)
        at java.base/java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1702)
        at java.base/java.util.concurrent.CompletableFuture$AsyncSupply.exec(CompletableFuture.java:1692)
        at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:290)
        at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1020)
        at java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1656)
        at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1594)
        at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:177)
Caused by: java.lang.IllegalStateException: No such extension org.apache.dubbo.rpc.cluster.LoadBalance by name random
        at org.apache.dubbo.common.extension.ExtensionLoader.findException(ExtensionLoader.java:520)
        at org.apache.dubbo.common.extension.ExtensionLoader.createExtension(ExtensionLoader.java:527)
        at org.apache.dubbo.common.extension.ExtensionLoader.getExtension(ExtensionLoader.java:351)
        at org.apache.dubbo.rpc.cluster.support.AbstractClusterInvoker.initLoadBalance(AbstractClusterInvoker.java:296)
        at org.apache.dubbo.rpc.cluster.support.AbstractClusterInvoker.invoke(AbstractClusterInvoker.java:246)
        at org.apache.dubbo.rpc.cluster.support.wrapper.MockClusterInvoker.invoke(MockClusterInvoker.java:78)
        at org.apache.dubbo.rpc.proxy.InvokerInvocationHandler.invoke(InvokerInvocationHandler.java:55)
        at org.apache.dubbo.common.bytecode.proxy0.getUserInfo(proxy0.java)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:566)
        at org.apache.dubbo.config.spring.beans.factory.annotation.ReferenceAnnotationBeanPostProcessor$ReferenceBeanInvocationHandler.invoke(ReferenceAnnotationBeanPostProcessor.java:260)
        at com.sun.proxy.$Proxy72.getUserInfo(Unknown Source)
        at com.heytap.ugc.user.relation.rest.controller.TestController.lambda$dubbo2Test$34(TestController.java:182)
        at java.base/java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1700)
        ... 6 common frames omitted

point: only when ForkJoinPool.commonPool thread call userService.getUserInfo can reproduce this issue