Function now executing properly after subscribe - reactive-programming

Question

I am having a Mono object, On which I have subscribed for doOnsuccess, In this method again I am saving the data in DB(CouchBase Using ReactiveCouchbaseRepository). after that, I am not getting any logs for Line1 and line2.
But this is working fine if I do not save this object, means I am getting logs for line 2.
Mono<User> result = context.getPayload(User.class);
result.doOnSuccess( user -> {
System.out.println("############I got the user"+user);
userRepository.save(user).doOnSuccess(user2->{
System.out.println("user saved"); // LINE 1
}).subscribe();
System.out.println("############"+user); // LINE2
}).subscribe();

Answer 1

Your code snippet is breaking a few rules you should follow closely:
You should not call subscribe from within a method/lambda that returns a reactive type such as Mono or Flux; this will decouple the execution from the main task while they'll both still operate on that shared state. This often ends up on issues because things are trying to read twice the same stream. It's a bit like you're trying to create two separate threads that try reading on the same outputstream.
you should not do I/O operations in doOnXYZ operators. Those are "side-effects" operators, meaning they are useful for logging, increment counters.
What you should try instead to chain Reactor operators to create a single reactive pipeline and return the reactive type for the final client to subscribe on it. In a Spring WebFlux application, the HTTP clients (through the WebFlux engine) are subscribing.
Your code snippet could look like this:
Mono<User> result = context.getPayload(User.class)
.doOnSuccess(user -> System.out.println("############Received user "+user))
.flatMap(user -> {return userRepository.save(user)})
.doOnSuccess(user -> System.out.println("############ Saved "+user));
return result;