Explanation of block()/blockfirst()/blocklast() methods
The block() method is used to block the execution until the result from a reactive stream is available. This means that it pauses the current thread and waits for the stream to complete before proceeding any further. However, blocking is generally not recommended in reactive programming as it can lead to poor performance and defeat the purpose of asynchronous execution.
Similarly, the blockFirst() and blockLast() methods are used to block until the first or last element of a reactive stream is available, respectively. These methods can also result in blocking the thread and should be used with caution.
It seems that the code you are referring to is running in the thread reactor-http-nio-2. This specific thread is responsible for handling HTTP requests in a reactive web server. Blocking operations within this thread can have significant negative impact on the server’s performance, as it can lead to thread starvation and reduced concurrency.
Instead of using blocking techniques, it is recommended to embrace the reactive nature of the programming model. This can be achieved by utilizing asynchronous operations, such as chaining reactive operators or using non-blocking alternatives like Mono and Flux in Reactor.
Example:
Flux<String> names = Flux.just("John", "Jane", "Robert");
names.subscribe(name -> {
// Non-blocking logic to process each name
System.out.println("Processing: " + name);
});
In this example, the names Flux emits three elements: “John”, “Jane”, and “Robert”. The subscriber processes each element without blocking the main thread, allowing the application to efficiently handle multiple concurrent operations.