Creating client without subscribing to a topic causes infinite loop

[ThorbenLindhauer]

This issue was imported from JIRA:

Field	Value
JIRA Link	CAM-11908
Reporter	@nevries
Has restricted visibility comments	false

---

What are the steps to reproduce your problem?

Just try that:

public static void main(String[] args) throws InterruptedException {
    ExternalTaskClient client = ExternalTaskClient.create()
        .baseUrl("http://localhost:8080/engine-rest")
        .asyncResponseTimeout(1000)
        .build();

    Thread.sleep(300_000);
}

What is the problem?

CPU usage goes to 100% (for one thread).

What would be the expected behavior:

Keep calm and wait for subscription.

Hints (optional):

This goes wild: camunda-external-task-client-java/client/src/main/java/org/camunda/bpm/client/topic/impl/TopicSubscriptionManager.java

Links:

• Another report of this problem: https://github.com/camunda/camunda-bpm-platform/issues/3392