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From Pranav Desai <>
Subject Re: errors and shutdown message in 2.1.2 under load
Date Thu, 16 Sep 2010 22:30:09 GMT
On Thu, Sep 16, 2010 at 2:03 PM, Leif Hedstrom <> wrote:
> On 09/16/2010 02:45 PM, Pranav Desai wrote:
> On Thu, Sep 16, 2010 at 12:33 PM, Leif Hedstrom <> wrote:
>  On 09/16/2010 01:26 PM, Pranav Desai wrote:
> Hi!
> I am running a load test with some video files to see . I am using
> curl-loader to generate the load. I have modified it to add a random
> number to the URLs before sending so I can test with a single URL and
> still stress the cache. The webserver is a lighttpd server with
> rewrite rules to translate the random strings back to a common URL.
> The URL is essentially a 15MB video file. I can provide more details
> on the setup if needed.
> Ok, I've created   with this
> information. If you can find a core file (or, run traffic_server under gdb),
> and get a stack trace, that would be very helpful. Also, when it crashes,
> you might get a stack trace in /var/log/messages and/or one of the log files
> in the .../var/log/trafficserver  directory.
> Will do that.
> Is there an architecture diagram or doc some where that briefly
> describes how the system works especially in terms of the roles of the
> processes like traffic_manager and traffic_server and how they
> interact, communicate. How the threads get the request, who runs the
> event loop etc. Even a general block diagram would work for me. It
> will of great help in understanding the system.
> Well, the admin guide (
> should give some ideas on how the system overall runs (processes etc.), and
> the developers guide ( will
> give some ideas how things works under the hood.
> That much said, I can tell you what the three processes does (big picture);
> traffic_cop - This process starts the traffic_manager process, and it's
> primary task is to verify that the traffic_server process is responding to a
> built-in health check. If it doesn't, traffic_cop will kill the
> traffic_server process.
> traffic_manager - This process is responsible for various "admin" tasks, and
> also implements the (defunct) WebUI. In addition, it binds the "listen"
> port(s) that the server will accept requests on, and start the
> traffic_server process. If this process dies (either crashes or killed by
> traffic_cop), traffic_manager still has the ports bound, and will
> immediately restart traffic_server.
> traffic_server - This is the primary proxy server process. It will run <n>
> number of worker threads (net-threads), where n is configurable but
> defaulted to something reasonable based on the number of CPUs. It also runs
> <m> I/O threads, by default 4 threads per disk spindle (but this is also
> configurable, and 4 is probably to small in many cases). In addition, there
> are a few "helper" threads for things like logging etc.

That helps, I am looking at strace so its giving me some more info
before I start looking into the code. I couldn't find the IO thread
option but I guess its proxy.config.cache.threads_per_disk


-- Pranav

> Cheers,
> -- leif

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