[v8-users] Re: Can "threading" be implemented by mapping v8 heap to shared memory in linux?

[rahul sharma]

wrongly posted

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[v8-users] Re: Can "threading" be implemented by mapping v8 heap to shared memory in linux?

[rahul sharma]

Is it related to meltdown and spectre?

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Re: [v8-users] Can "threading" be implemented by mapping v8 heap to shared memory in linux?

[J Decker]

nwjs claims to support web worker with node, allowing true threading.  Each
thread gets its own javascript context and they don't share anything.  They
only communicate with messages.  The workers are entirely separate from
each other.

https://github.com/nwjs/nw.js/issues/494
https://groups.google.com/forum/#!msg/nwjs-general/jljGxjIyxK4/pVqyidTrBAAJ

pretty sure you'll need an addon if you want to share large chunks of data
using typed arrays... and/or provide other synchronization around the
buffers.


On Mon, Jan 8, 2018 at 7:30 AM, Bogdan Orlov  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 
> 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  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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>>> http://groups.google.com/group/v8-users
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Re: [v8-users] Can "threading" be implemented by mapping v8 heap to shared memory in linux?

[Bogdan Orlov]

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 
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  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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>> http://groups.google.com/group/v8-users
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Re: [v8-users] Can "threading" be implemented by mapping v8 heap to shared memory in linux?

[Jakob Kummerow]

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  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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> v8-users@googlegroups.com
> http://groups.google.com/group/v8-users
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[v8-users] Can "threading" be implemented by mapping v8 heap to shared memory in linux?

[Bogdan]

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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[v8-users] Re: Does V8 engine support multithreading programming?

[Sandeep kumar M]

I want to understand the reason behind acuire and release locks in j2v8 
library

On Friday, January 31, 2014 at 2:21:38 PM UTC+5:30, Sara Abdelhameed wrote:
>
> Hello all, 
> does v8 engine support multithreaded application ? and could I run two 
> different javascript code in two different threads at the same time ? 
>

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