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Comment by sunnyps | Hacker News Reader

My understanding is that libdispatch is not a replacement for go's concurrency. With libdispatch each block (closure) that you dispatch runs on a given thread, if that block stalls for any reason then your thread is blocked. So even with a few blocked blocks (heh) your system could be stalled which is not the case with go where you can have millions of goroutines that are blocked.

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I've built systems with libdispatch and blocks. I found it much nicer than traditional C style non-blocking IO or typical pthreads, both of which I have also done.

• You don't need to use blocks, there are function callback versions of the calls available, but blocks are nicer.

• There are asynchronous IO routines, that covers most of your stalls.

• Go probably stalls threads on page faults, as does libdispatch.

You can read about the Linux port of libdispatch at https://github.com/nickhutchinson/libdispatch

It looks like the Linux port of libdispatch uses OS threads through pthreads, so it's not a candidate for the user space light-weight threads needed for efficient CSP.

I'm fairly certain that is just to get the worker pool. The blocks on the queue don't each get a thread.

libdispatch is more than just programs submitting blocks to queues – dispatch sources and event handlers can handle channels of asynchronous input as well.

I forgot about that part of libdispatch. You still can't do synchronous IO but you can use libdispatch semaphores, wait on a queue, etc. and that should not block the thread, right?

The docs offer different kinds of sources for automatically enqueueing blocks:

     #define DISPATCH_SOURCE_TYPE_DATA_ADD 
     #define DISPATCH_SOURCE_TYPE_DATA_OR 
     #define DISPATCH_SOURCE_TYPE_MACH_RECV 
     #define DISPATCH_SOURCE_TYPE_MACH_SEND 
     #define DISPATCH_SOURCE_TYPE_PROC 
     #define DISPATCH_SOURCE_TYPE_READ 
     #define DISPATCH_SOURCE_TYPE_SIGNAL 
     #define DISPATCH_SOURCE_TYPE_TIMER 
     #define DISPATCH_SOURCE_TYPE_VNODE 
     #define DISPATCH_SOURCE_TYPE_WRITE 
     #define DISPATCH_SOURCE_TYPE_MEMORYPRESSURE

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