Rxjava: Multiple subscribers on observable

[nltran]

Hello,

Is it possible to have multiple subscriptions on a same observable? e.g:

Observable obs = <perform values computation>
Subscription sub1 = obs1.subscribe(...)
Subscription sub2 = obs2.subscribe(...)

From what I have understood, each time obs.subscribe(...) is called a new Observable is created. That leads to the fact the computation in obs is performed each time sub1 and sub2 subscribe.

The computations in obs are quite heavy and I would like compute them once and feed the results to both sub1 and sub2. Is this behaviour achievable?

Thank you,

Best regards,

[akarnokd]

Sure, use source.publish().refCount(). The computation runs once and everyone gets notified at the end.

[abersnaze]

If you don't like the sound of that we added obs = obs.share() to wrap the .publish().refCount(). This has one gotcha. If the source observable is asynchronous the first subscription could get a more values than the second subscription. A much safer way to do it is to the ConnectableObservable connObs = obs.publish() returned by publish method to connObs.connect() after all of the subscriptions have been completed.

Observable obs = <perform values computation>
ConnectableObservable connObs = obs.publish()
Subscription sub1 = connObs.subscribe(...)
Subscription sub2 = connObs.subscribe(...)
connObs.connect()

[benjchristensen]

Or the publish overload that takes a function so you do your logic within the function and it worries about connecting everything.

It is often far better than dealing with ConnectableObservable directly.

[akarnokd]

Closing due to inactivity. If you have further questions, don't hesitate to reopen this issue or create a new one.