What is the difference between Schedulers.io() and Schedulers.computation()

Question

I use Observables in couchbase.

What is the difference between Schedulers.io() and Schedulers.computation()?

Aleron

Answer 1

Brief introduction of RxJava schedulers.

• Schedulers.io() – This is used to perform non-CPU-intensive operations like making network calls, reading disc/files, database operations, etc., This maintains a pool of threads.

• Schedulers.newThread() – Using this, a new thread will be created each time a task is scheduled. It’s usually suggested not to use scheduler unless there is a very long-running operation. The threads created via newThread() won’t be reused.

• Schedulers.computation() – This schedular can be used to perform CPU-intensive operations like processing huge data, bitmap processing etc., The number of threads created using this scheduler completely depends on number CPU cores available.

• Schedulers.single() – This scheduler will execute all the tasks in sequential order they are added. This can be used when there is a necessity of sequential execution is required.

• Schedulers.immediate() – This scheduler executes the task immediately in a synchronous way by blocking the main thread.

• Schedulers.trampoline() – It executes the tasks in First In – First Out manner. All the scheduled tasks will be executed one by one by limiting the number of background threads to one.

• Schedulers.from() – This allows us to create a scheduler from an executor by limiting the number of threads to be created. When the thread pool is occupied, tasks will be queued.

Fountainhead

How would you know the size of Database operations before implementing Schedulers.io()? Database operations size can be huge too like you said in computation "operations like processing huge data" so how would you know which one to use and when? – Ivetteivetts

Answer 2

From the documentation of rx:

Schedulers.computation( ) - meant for computational work such as event-loops and callback processing; do not use this scheduler for I/O (use Schedulers.io( ) instead); the number of threads, by default, is equal to the number of processors

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Schedulers.io( ) - meant for I/O-bound work such as asynchronous performance of blocking I/O, this scheduler is backed by a thread-pool that will grow as needed; for ordinary computational work, switch to Schedulers.computation( ); Schedulers.io( ) by default is a CachedThreadScheduler, which is something like a new thread scheduler with thread caching

Plant

and what is different? – Escobedo

As mentioned: One is meant for IO work (IO-bound). One is meant for computational work (cpu-bound). These concepts are well understood in the context of distributed computing. It is not specific to rx. – Plant

@ReutSharabani He means, "What differs in their implementation besides the number of available threads?" – Utoaztecan