Hi Graham,
Thanks already for your pearls of wsgi-wisdom!
>> How much traffic does each site receive?
A lot of these will stay inactive for a long time. At a single time, only
at most 5 to 10 of the apps will have active users.
Ideally I'd like to launch the mod_wsgi daemon process only upon receiving
the first request in an app. I managed to avoid the preload but not the
daemon process itself.
>> What sort of traffic do they receive? Are they short lived requests less
than 500ms, or long lived requests that could last seconds?
On an active application, the request can last seconds indeed (due to
complex sql-queries, complex data validation, ...)
And an active user can easily generate a series of such requests. Hence the
>> What Apache MPM are you using (prefork/worker/event) and what are the
Apache MPM settings for that MPM?
We're using event MPM (which is the default on our ubuntu 18 server).
The settings are currently:
ServerLimit 90
StartServers 2
MinSpareThreads 30
MaxSpareThreads 60
ThreadLimit 30
ThreadsPerChild 30
MaxRequestWorkers 800
MaxConnectionsPerChild 0
We're using the mod_wsgi version 4.5 packaged with ubuntu 18. After
listening to your talk, I'll try out with the latest 4.9 version.
>>For 150 sites I would suggest you are adding too much capacity for each.
Even one process with 5 threads can handle a lot of concurrent requests if
requests are short lived. If you are trying to support sites which all have
long running requests for file uploads etc, you are asking for trouble. The
request timeout is ridiculously large, which suggests you might be trying
to handle long running file uploads, which as I said is a bad idea.
I hear you... and will reduce that request timeout.
>> WSGIRestrictEmbedded On
Already have that one indeed.
>> WSGIApplicationGroup %{GLOBAL}
>> This ensures the Python application runs in the main interpreter context
and not a sub interpreter. Various Python packages do not work properly in
sub interpreters. Ensuring main interpreter context is used will also save
a bit of memory as well since don't have the main interpreter context there
doing nothing when using a sub interpreter.
Don't have that one yet.
For security reasons, I'd like to keep the python processes for each tenant
100% separated. Does this option violate this?
Johan
Op zondag 16 januari 2022 om 22:42:42 UTC+1 schreef Graham Dumpleton:
> How much traffic does each site receive?
>
> What sort of traffic do they receive? Are they short lived requests less
> than 500ms, or long lived requests that could last seconds?
>
> What Apache MPM are you using (prefork/worker/event) and what are the
> Apache MPM settings for that MPM?
>
> For 150 sites I would suggest you are adding too much capacity for each.
> Even one process with 5 threads can handle a lot of concurrent requests if
> requests are short lived. If you are trying to support sites which all have
> long running requests for file uploads etc, you are asking for trouble. The
> request timeout is ridiculously large, which suggests you might be trying
> to handle long running file uploads, which as I said is a bad idea.
>
> Anyway, to get started I suggest you watch:
>
> https://www.youtube.com/watch?v=H6Q3l11fjU0
>
> Then do the following to at least cut down on CPU and memory.
>
> 1. Outside of all VirtualHosts add:
>
> WSGIRestrictEmbedded On
>
> This will ensure that the Python interpreter isn't setup in Apache child
> worker processes where not needed if only using mod_wsgi daemon mode.
>
> 2. In each VirtualHost add:
>
> WSGIApplicationGroup %{GLOBAL}
>
> This ensures the Python application runs in the main interpreter context
> and not a sub interpreter. Various Python packages do not work properly in
> sub interpreters. Ensuring main interpreter context is used will also save
> a bit of memory as well since don't have the main interpreter context there
> doing nothing when using a sub interpreter.
>
> Graham
>
> On 16 Jan 2022, at 7:42 pm, Johan De Taeye <[email protected]> wrote:
>
>
> HI All,
>
> I have a multi-tenant apache server where each tenant has its own wsgi
> application in its own virtual host.
> The apache configuration for a tenant roughly looks like:
> <VirtualHost *:443>
> ServerName domain-tenant-1 <http://env1.frepple.com/>
> WSGIDaemonProcess tenant1 user=www-data processes=4 threads=4
> inactivity-timeout=7200 request-timeout=3600 display-name=apache-tenant1
> WSGIProcessGroup tenant1
> WSGIScriptAlias / "/home/ubuntu/config/tenant1/wsgi.py"
> </VirtualHost>
>
> I am noticing detoriating response times when the number of tenants
> increases beyond a certain limit - say 150. Neither CPU, database and
> memory seem to be bottleneck.
> Are there any apache or mod_wsgi configurations/parameters that can be
> tuned/optimized for this type of deployment?
>
> All feedback & insight is highly appreciated!
>
> Johan
>
>
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