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  1.  Home
  2. WEB400
  3. October 2015

Re: Hosting a Large Number of Node Apps on the IBM i

Earlier this year we had a discussion about whether Node.js is single or
multi-threaded. Kevin Turner replied that multiple threads appear in the
WRKJOB command. What more proof is needed that Node.js is multi-threaded?

Various sources indicate that the V8 engine is running in only 1 thread.
HTTP conversations, file stream I/O, database I/O, and similar I/O work are
dispatched to other Node threads.

The V8 engine registers callback routines with the thread which is running
the event loop. The event-loop thread alternates between evoking callback
routines in the V8 engine and responding to work placed in a queue by I/O
threads.




On Wed, Oct 14, 2015 at 9:36 AM, Henrik Rützou <hr@xxxxxxxxxxxx> wrote:

Aaron

I think Tim is the best to answer that question or I can write Lars Bak (a
fellow
Danish) that made the V8 and thereby the C code

On Wed, Oct 14, 2015 at 5:32 PM, Aaron Bartell <aaronbartell@xxxxxxxxx>
wrote:

So, if I'm understanding you correctly, cluster won't allow us to use
multiple cores on the IBM i because IBM i jobs run as single threads.

Cluster *will* allow multiple cores to be used, but multiple cores will
also be used without the cluster npm, though only when a Node.js API
calls
upon a C API to do the threading. This is what Henrik and I aren't yet
in
agreement about.


Aaron Bartell
litmis.com - Services for open source on IBM i


On Wed, Oct 14, 2015 at 10:26 AM, Kelly Cookson <KCookson@xxxxxxxxxxxx>
wrote:

Aaron,

He's talking about deliberate delegation of IBM i jobs (aka
processes)
so multiple Javascript statements can be run in true parallel, which
is not possible with a single process. But this doesn't address the
C threads where Node.js APIs deliberately offload known I/O blocking
to
C threads.
When Node.js does that offloading there is in fact multiple cores
being used that originated from a single Node.js process (again, as I
understand it).

I sent my last email before I received your response above.

So, if I'm understanding you correctly, cluster won't allow us to use
multiple cores on the IBM i because IBM i jobs run as single threads.
However, this is not such a big deal, since the node event loop hands
off
I/O blocking code to worker threads. The worker threads are executed
in C
and take advantage of IBM i's multiple cores.

I recognize your caveat that you are sharing your best understanding.
But
I want to make sure that I have the gist of what you are saying.

Thanks,

Kelly Cookson
IT Project Leader
Dot Foods, Inc.
1.217.773.4486 ext. 12676
kcookson@xxxxxxxxxxxx

-----Original Message-----
From: WEB400 [mailto:web400-bounces@xxxxxxxxxxxx] On Behalf Of Kelly
Cookson
Sent: Wednesday, October 14, 2015 9:46 AM
To: Web Enabling the IBM i (AS/400 and iSeries)
Subject: Re: [WEB400] Hosting a Large Number of Node Apps on the IBM i

Henrik,

Out of curiosity, why is it that the cluster module can't be used to
take
advantage of multiple cores on the IBM i?

Thanks,

Kelly Cookson
IT Project Leader
Dot Foods, Inc.
1.217.773.4486 ext. 12676
kcookson@xxxxxxxxxxxx

-----Original Message-----
From: WEB400 [mailto:web400-bounces@xxxxxxxxxxxx] On Behalf Of Henrik
Rützou
Sent: Wednesday, October 14, 2015 9:30 AM
To: Web Enabling the IBM i (AS/400 and iSeries)
Subject: Re: [WEB400] Hosting a Large Number of Node Apps on the IBM i

Aaron

here is a link ...

http://cjihrig.com/blog/scaling-node-js-applications/



On Wed, Oct 14, 2015 at 4:23 PM, Aaron Bartell <aaronbartell@xxxxxxxxx

wrote:

it cannot use several cores at the same time so one node.js
instance
is
limited to what processing power one core is able to deliever.

Are you sure this is correct and do you have a source for your
information that we can review? Yes, Node.js runs as a single
thread,
but the underlying C architecture of Node.js uses threads for
blocking
I/O calls (i.e. file system, networking, etc). So that means, as I
understand it, that a single Node.js server could make use of many
cores because of the underlying C threads.

Aaron Bartell
litmis.com - Services for open source on IBM i


On Wed, Oct 14, 2015 at 9:15 AM, Henrik Rützou <hr@xxxxxxxxxxxx>
wrote:

Tim

I was not saying that a single node.js instance was glued to a
specific core but it cannot use several cores at the same time so
one node.js instance
is
limited to what processing power one core is able to deliever.

This is not IBM Power specific, it is the same on all hw platforms.

On Wed, Oct 14, 2015 at 3:40 PM, Kelly Cookson
<KCookson@xxxxxxxxxxxx>
wrote:

Nathan,

Kelly is asking about a mix of both types of routing -
External
routing
within a reverse-proxy / load-balancer as well as internal
routing within Node's own HTTP service.

That's correct. I think my concerns have pretty well addressed in
people's
responses. I probably want to use a combination of strategies for
setting
up routes. For example:

* use a web server as a reverse proxy that routes to node apps
running
on
their own ports,

* use something like vhost or http-node-proxy within a node app
that routes to other node apps running on their own ports,

* use something like the ExpressJS router within a node app that
routes
to
modules or sub-apps that run within the same port.

* use something like the ExpressJS router within a node app that
routes
to
different pages of the app.

I don't need to worry so much about the number of ports used by
node
apps.
I didn't hear that any of the routing strategies above would be
better
or
worse when it comes to setting up a production environment for
fail-over
and load balancing--especially if I use a web server as a reverse
proxy.
And I didn't hear that any of the routing strategies above would
be
better
or worse for scaling up node apps (e.g., clustering).

Thanks,

Kelly Cookson
IT Project Leader
Dot Foods, Inc.
1.217.773.4486 ext. 12676
kcookson@xxxxxxxxxxxx

-----Original Message-----
From: WEB400 [mailto:web400-bounces@xxxxxxxxxxxx] On Behalf Of
Nathan Andelin
Sent: Wednesday, October 14, 2015 7:46 AM
To: Web Enabling the IBM i (AS/400 and iSeries)
Subject: Re: [WEB400] Hosting a Large Number of Node Apps on the
IBM i

I am sure Kelly is talking about the top level routing to the
app and how to handle that as opposed to the question of
internal routing to
"screens"
within the app.


Kelly is asking about a mix of both types of routing - External
routing within a reverse-proxy / load-balancer as well as
internal
routing
within
Node's own HTTP service.

How would one configure both so that a broadly-scoped system
performs well, scales well, you don't introduce too many HTTP
restarts?
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--
Regards,
Henrik Rützou

http://powerEXT.com <http://powerext.com/>
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--
Regards,
Henrik Rützou

http://powerEXT.com <http://powerext.com/>
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http://powerEXT.com <http://powerext.com/>
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