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Subject: Re: [boost] Any interest in a M:N green threading library?
From: Chen Xu (windoze.net_at_[hidden])
Date: 2015-08-12 12:58:06

These 2 libs look similiar, but there are some big differences.

boost-fiber uses M:1 scheduling, it uses a single threaded scheduler to
run multiple fibers within one thread.
        Most synchronizations between native threads can be avoided as it's
single threaded.
        You can use native TLS in fibers, which is more efficient than the
implementations in Boost.Thread and boost.green_thread.
        Although you can create multiple threads to run multiple sets of
fibers, each set of fibers are seperated, you need additional efforts
to migrate a fiber from a thread to another(work-stealing), also TLS
needs to be avoided in this case.
        Even with work stealing enabled, multiple fiber groups are often run
into imbalance, because work stealing is not automatic in boost-fiber.

boost.green_thread uses M:N scheduling, it schedules a group of green
threads across multiple native threads.
        boost.green_thread uses ASIO io_service for scheduling, seamlessly
cooperate with ASIO.
        Load is balanced across all native threads in a scheduler, server side
programs can utilize multi CPU cores more efficiently.
        Multiple native worker threads need synchronization to schedule green threads
        Scheduling is more complex than boost-fiber, makes a scheduler with
only one worker thread runs slightly slower than boost-fiber.
        Cannot use native TLS as green threads may migrate between native threads.

Both libraries have their own pros and cons, and fit in different
scenarios, my opinion, boost.green_thread is better for server side
programs as it can utilize multi cores easily.

Chen Xu

On 2015-08-12 15:08:23 +0000, Klaim - Joël Lamotte said:

> On 12 August 2015 at 16:20, Xu Chen <windoze.net_at_[hidden]> wrote:
>> Just cleanup some codes I wrote before, there is a M:N green threading
>> library built on top of Boost.Thread and Boost.Coroutine, conceptually it
>> works like goroutines in Go and (once existed) green threads in Rust.
>> With some refinements, it now supports all C++11/14 threading standard,
>> along with some extensions exist in Boost.Thread such as thread_group and
>> chainable futures.
>> It can be integrated with Boost.ASIO, all ASIO async functions can be used
>> as sync ones in green threads, similar to Boost.ASIO/Boost.Coroutine
>> integration.
>> Also it has some facilities to communicate with foreign threads, can by
>> used to integrate with external libs such as database drivers.
>> The code can be found at
>> I don't know much about boostbook tools so the documents are kind of
>> crippled, but I'll improve it if needed.
>> Regards,
>> Chen Xu
> I am not an expert in the domain but am I correct that you are proposing
> similar
> functionality to Boost.Fiber? ( )
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