There is active work on parallel JS with a range of approaches to shared
memory parallelism. I maintain a list of parallel JS projects
<https://github.com/SyntheticSemantics/List-of-Parallel-JS-Projects/> and
am interested in finding applications that use them. Are you working with
a particular application that lead to a requirement for shared-memory
parallel JS?
-J
On Monday, January 8, 2018 at 7:30:33 AM UTC-8, Bogdan wrote:
>
> I understand that updating object in shared memory need synchronization
> and even with in-memory database task in general there will be a global
> lock (not per-object because transaction will spread by different tables
> and object) and only one process will write to memory so I think just
> global lock will be enough for most tasks. But reading from shared memory
> is safe and there is no reason to not use all cpu cores to achieve more
> performance and that's why go and other languages will overcome js in this
> tasks. But I hope js will be able to compete and new features like
> SharedArrayBuffer and atomics seems like moving forward javascript to the
> right direction and I don't see why "JavaScript is not designed for such
> purposes.". Does SharedArrayBuffer supposed to do zero copy reading in
> different workers? How it implemented - by multiple threads or maybe it
> already using shared memory and different process?
>
> On Mon, Jan 8, 2018 at 6:04 PM, Jakob Kummerow <[email protected]
> <javascript:>> wrote:
>
>> No, you cannot simply share all memory to get multi-threading. For
>> safely/correctly working with shared memory, you need
>> locking/synchronization primitives as well as certain guarantees in the
>> language's memory model. JavaScript is not designed for such purposes.
>>
>>
>> On Mon, Jan 8, 2018 at 3:52 PM Bogdan <[email protected] <javascript:>>
>> wrote:
>>
>>> I don't know all details, I just a regular node developer who came up
>>> with idea of "threading" in js and hope anybody with deep knowledge will
>>> clarify some things. Javascript have old problem of lacking threading and
>>> all advices of using multiple processes doesn't help because there are
>>> important tasks (for example in-memory database or managing application
>>> cache) which needs shared memory to utilize all cpu cores and having full
>>> copy of that memory and synchronizing it by coping data over channels
>>> doesn't make sense. Recently I've found out an interesting linux feature
>>> like shader memory with shm_open and mmap which can allow zero-copy and
>>> zero-overhead access to shared memory from different processes. There are
>>> also some node modules which exposes this feature to javascript but seems
>>> like all they can do is exposing shared memory to javascript as an array
>>> which means all object managing, garbage collector, and other useful
>>> features we need to do all by ourselves. So I am wondering can v8 (if
>>> cannot now, maybe in it will with little hacking) allow to just map all
>>> heap into shared buffer so we can use the same objects from another process
>>> without copying?
>>>
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