Learning RxJava

Serializing Subjects

A critical gotcha to note with Subjects is this: the onSubscribe(), onNext(), onError(), and onComplete() calls are not threadsafe!  If you have multiple threads calling these four methods, emissions could start to overlap and break the Observable contract, which demands that emissions happen sequentially. If this happens, a good practice to adopt is to call toSerialized() on Subject to yield a  safely serialized Subject implementation (backed by the private SerializedSubject). This will safely sequentialize concurrent event calls so no train wrecks occur downstream:

Subject<String> subject =         PublishSubject.<String>create().toSerialized();

Unfortunately, due to limitations with the Java compiler (including Java 8), we ...