Karsten McMinn wrote:

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> On 5/9/07, Daniel Ouellet  wrote:

>> I can now have two clients using 1000 parallel connections to one i386

>> 850MHz server, my old one that I was testing with and I get all that no

>> problem now. No delay and I can even push it more, but I figure at 2000

>> parallel connections I should be able to get some breathing time now.

>

> I've spent considerable time with tuning apache on openbsd to

> consume all available resources in OpenBSD. Here's the

> relevant httpd.conf sections:

Thanks. My configuration is more aggressive them yours and I can tell

you for a fact that the problem and limitations where not in the httpd

configuration, but in the OS part in my case anyway.
Some of your value I think would/could crash your system. Specially the:
MaxKeepAliveRequests 5000

MaxClients 5000
I don't think you could reach that high. Why, simply on a memory usage

stand point. That was my next exploration, but it's possible that one

apache process could take as much as 11MB
  6035 www        2    0   11M 9392K sleep    netcon   0:56  0.00% httpd
Obviously not all process would use that much. The question is really

depending on content. If small images and lots of them, then each

process use less memory. But if it is to serve all big files, then it's

possible to use a good amount of memory per process. Now I don't have

that answer here and I am not sure how to come with some logic on that,

but even if each process was using only 1MB, then 5000 would give you

5GB or RAM with is more then what OpenBSD was supporting until not so

long ago, so you will start to swap and god knows what will happen then.
So, I think the these two value are not realistic and safe to us.
> Timeout 300

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> KeepAlive On

> MaxKeepAliveRequests 5000

> KeepAliveTimeout 15

I use KeepAliveTimeout 5 and I am considering to reduce it.
If you think aboiut your suggestion here, you have KeepAliveTimeout 15

and then MaxKeepAliveRequests 5000, don't you see the paradox here?
If your server is really busy, and lots of images on one page for

example, then you would have a lots of process stuck in KeepAliveTimeout

time out stage, so that's why you most likely increase your MaxClients

5000 to compensate for that, but that's wrong I believe. It makes your

server use more resources and be slower to react.
I use a logic here for the value on how to fix it.
MaxKeepAliveRequests I think should be set based on how many possible

additional requests a URL from a browser that support keep alive and

multiple requests at once could have. How many, well I think it's based

on how many elements your web page can have. That's the idea here isn't

it? Many browsers will call the URL and when images for example are on

that page they will fire up an additional request to the web server. So,

in theory the maximum number of requests you should allow should be the

maximum possible of elements one page could have on it no? Assuming a

users can click a few pages in a few seconds may be, I think anything

above 1000 is not good. I could be wrong, but that's how I see it. I use

250 and it serve me well and allow to protect the server from abuse from

one source. I have some setup that allow 100 max here for the

MaxKeepAliveRequests. But I would think that 1000 should be plenty and

more then that may not be good. Unless my thinking above is wrong?
I can do more tests on that to know more obviously.
For testing reason in my lab I put MaxKeepAliveRequests 0, but I

wouldn't use that in production for sure.
Your value may be good, I just think not, but that's open to discussion.
One thing for sure having the same number for MaxKeepAliveRequests and

for MaxClients, I think is wrong as you open yourself to have one

attacker from one source to bring your server down and huge it all for

himself. I believe that MaxKeepAliveRequests should definitely be lower

then your MaxClients, not the same for sure.
> MinSpareServers 20

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> MaxSpareServers 30

> StartServers 50

I also thing that if you want to run a so busy server, that you should

have more StartServers and for sure have a bigger margin between the min

and max as it will always kill process and start new one where as you

fork a lots and that's a pretty slow process and costly as well.Again

here I use some logic and based that on what the traffic is like. If you

allow multiple requests per connection, wouldn't it make sense for you

to be sure that you could serve that connection and all it's requests

without having to fork new process? Meaning if you have 50 elements on

your page, then it's possible that some browser will send you 50

requests, so why not make sure you have 50 minimum process to serve

them? Again, that's logical to me. I have some setup that I keep a

minimum of 50 spare and maximum of 100 spare. Not always, but some cases

yes. But it's better then the defautl one for sure. (;>
> MaxClients 5000
To high I think based on the above explications. The risk of taking down

the server are to high to me, but I could be wrong. I think with a

properly setup server, 1000 is able to support a truck load of requests.

Most limitations were not find in the httpd setup in my tests and

regular operations. But again, I am open to discussion and exchange on

the subject.
> MaxRequestsPerChild 0
I haven't seen any memory leak in httpd in a long time, so not have any

limits here is find. On Solaris however, you would want that, or use to

want that for sure.
> I had staticlly compiled php into my httpd binary and obviously

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> raised HARD_LIMIT to 5000, using OpenBSD's apache.

I could have done that, but still run stock OpenBSD so module for now.

Yes there is definitely advantage to run static, but I try as much as

possible to run stock OS when possible for many reasons.
> This netted me an ability to serve about a max of 3000

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> requests per second on a 1.6ghz athlon with 256MB of memory.

Your amount of memory really puzzle me here specially based on your

configuration and on what you say your traffic is like. How could you

possibly allow 5000 MaxClients with 256MB of memory??? Doesn't compute

to me really.
Best,
Daniel