Is Spring Framework HttpComponentsClientHttpRequestFactory thread safe?

Question

Could I have multiple threads use the same static instance of HttpComponentsClientHttpRequestFactory to safely create their respective ClientHttpRequest?

I am not able to find any manual that would tell me the answer.

I am presuming it is thread-safe simply because the all createRequest methods actually perform a new instantiation of a request object. For example,

public ClientHttpRequest createRequest(URI uri, HttpMethod httpMethod) throws IOException {
    HttpUriRequest httpRequest = createHttpUriRequest(httpMethod, uri);
    postProcessHttpRequest(httpRequest);
    return new HttpComponentsClientHttpRequest(getHttpClient(), httpRequest, createHttpContext(httpMethod, uri));
}

But then it calls a few other methods which may not be thread-safe.

In fact, if you do know the answer, where is the manual that would tell me the thread safety of anything in Spring?

Answer 1

Generally, any class within Spring infrastructure ending in Factory is thread-safe once it's initialized (i.e., once the constructor is called and the bean is initialized with its property values). Technically it's not thread-safe between constructor call and property injection, but all of the Spring ApplicationContext implementations I know of block requests for beans until context initialization is complete.

Bottom line is: don't create Factory objects outside of Spring manually and you should be fine.