CentralizedSamplingStrategy constructs a new recorder at each invocation when no service type in sampling request

[aapolait]

When an AWSXRayRecorder is built without plugins and without explicitly setting the origin, CentralizedSamplingStrategy#shouldTrace will be called with a sampling request that doesn't have a service type. It has the following fallback:

aws-xray-sdk-java/aws-xray-recorder-sdk-core/src/main/java/com/amazonaws/xray/strategy/sampling/CentralizedSamplingStrategy.java

Lines 63 to 65 in 9fb8e15

	if (!samplingRequest.getServiceType().isPresent()) {
	samplingRequest.setServiceType(AWSXRayRecorderBuilder.defaultRecorder().getOrigin());
	}

Not only does the fallback construct a new recorder at each invocation, but it also ends up being wasted work because the result of defaultRecorder() won't have any plugins either.

I'd be happy to submit a fix, but don't know what would be your preferred approach:

1. Just remove the fallback since it isn't working anyway?
2. Make CentralizedSamplingStrategy or AWSXRayRecorderBuilder have a list of default plugins that will be queried for origin when the recorder doesn't have an origin? (Though it looks like only EC2Plugin could be on the list since ECSPlugin always "matches" and ElasticBeanstalkPlugin is too noisy when it doesn't.)
3. Something else?

[chrisradek]

@aapolait
Thanks for bringing this up! I'll do some digging to see if this ever worked and what the expected behavior should be.

[chrisradek]

Closing since this was released in version 2.2.x.