I am honestly confused about what dispatchers to u...

# coroutines

[Riku]

I am honestly confused about what dispatchers to use server-side. Everything I have read so far has been focused on Android. Any recommendations for a general guide to when to use what dispatcher?

[tseisel]

As a rule of thumb :
• Dispatchers.Main may not exist on the server-side.
• Dispatchers.Default should be used for computational tasks that requires CPU power such as reducing, transforming, etc. It has a pool of thread equal to the number of CPU cores to avoid overloading the CPU when scheduling too much work.
• <http://Dispatchers.IO|Dispatchers.IO> , as its name suggests, should be used for blocking IO such as database access, file read/write and network communication. It has a larger pool of threads than Default because IO tasks don't need much CPU time, it just waits and blocks a thread.

[Riku]

Thanks. what about long or continuously running coroutines, that stream values on a schedule?

[Riku]

For example, let’s say every 10 minutes my server will send a status update to the UI. I am guessing this should run on its own thread?

[tseisel]

I think you can run that on <http://Dispatchers.IO|Dispatchers.IO> since it has the largest thread pool and your task requires some network connectivity.
You could write it this way:

launch(<http://Dispatchers.IO|Dispatchers.IO>) {
    while(true) {
        postStatusUpate(...)
        delay(10 * 60 * 1000) // 10 minutes in milliseconds
    }
}

Note that while the coroutine is suspended in delay it is not actively using a thread.

[Riku]

👍