On Saturday 11 August 2007 19:34, Dossy Shiobara wrote:
> Also, what if you need a pool/limit that does is shared across all
> servers in the entire process?  This is actually the truly useful use
> case of the pools/limits mechanism--e.g., ensuring that the entire nsd
> process doesn't attempt to use more than X number of threads, whatever
> that X is that the physical machine can support based on its
> size/capacity.

Here is the conceptual problem which needs to be addressed with this top down 
enforcement of limits:

Each threadpool or limit created is independent of all others. All it takes to 
add resources is to target them more directly (more url specific) when you 
create either. So this issue is there is no easy way to set an upper limit 
and then account for any takings from future threadpools.

default threadpool has 100 maxthreads.

 server1 default threadpool gets 75
 server2 default threadpool gets 75

maxthreads is the easiest to understand, other settings are more difficult.

The problem with ns_limits is worse: these are based purely upon url patterns. 
So how to apply limits from a top down enforcement seems difficult. 

These problems seem to exist because of the idea that you can enforce things 
top down and divy up resources on an overall basis. 

But there are are many use cases where you want the opposite effect: direct 
control over problem areas:

1. some DOS attack, just register a threadpool with 0 threads, problem solved.
2. admin access: needs to always have threads available.
3. one server needs to be locked down: register /* with zero threads.
3.1 POSTing needs to be shut down: register POST /* with zero threads.
4. some page becomes very popular: register a special threadpools to handle 
just that page. Rest of server is protected, even if the number of threads is 
high for that one page, even if that one page backs up with requests, all 
other servers are unaffected.

I'm just thinking of how to admin/control the system, it seems pretty 

tom jackson 

AOLserver - http://www.aolserver.com/

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