doRefer in RestProtocol may cause OOM

[HzjNeverStop]

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

Environment

• Dubbo version: 2.7.3-SNAPSHOT
• Operating System version: mac os 10.13.6
• Java version: 1.8.0_171

Steps to reproduce this issue

1. run the code in unit test:

   @Test
    public void testRestProtocol() {
        protocol = ExtensionLoader.getExtensionLoader(Protocol.class).getExtension("rest");
        URL url = URL.valueOf("rest://127.0.0.1:5342/rest/say?version=1.0.0&interface=org.apache.dubbo.rpc.protocol.rest.DemoService");
        while (true) {
            Invoker<DemoService> invoker = protocol.refer(DemoService.class, url);
            invoker.destroy();
        }
    }

Pls. provide [GitHub address] to reproduce this issue.

Actual Result

What actually happens?
the size of LinkedList [clients] will keep growing, the ResteasyClient hold by it will not release, which will cause OOM easily.

 ResteasyClient client = new ResteasyClientBuilder().httpEngine(engine).build();
clients.add(client);

the clients in the linkedList will not release when invoker destroyed, they will only be released when the rest protocol destroyed.
I think the protocol layer should not hold the object's such like client, it should be hold by the invoker and has the same lifecycle with invoker

[kaojunsong]

@chickenlj hello,we have met the same issues.Is this a bug of dubbo,and how to fixed it?

[beiwei30]

I believe this issue has been addressed by #4614. @kaojunsong @HzjNeverStop would you mind to verify?

[cvictory]

@HzjNeverStop should you check this issue now ?
If you don't reply , i will close this issue firstly.

[HzjNeverStop]

@HzjNeverStop should you check this issue now ?
If you don't reply , i will close this issue firstly.

it's ok, please close this issue, thanks