On Wed, Apr 21, 2010 at 8:57 AM, Paweł Stradomski <[email protected]> wrote:
> 2010/4/21 jazg <[email protected]>:
>>
>> Why would it prevent future requests if each request is a new thread?
>>
>> I could manually create another thread for the job, but it seems like that
>> should not be necessary. I still don't understand why setting content-length
>> didn't work, did pylons decide to override that for some reason?
>
> CherryPy definitely (and AFAIK paster too) uses a pool of worker
> threads. Starting a new thread for each request would be inefficient
> (both by having too many concurrent threads and by starting a new
> thread for each request, which is costly).
> This is similar to how Apache/mpm_prefork keeps a pool of processes.
>
> So, with a pool of eg 10 threads (default for CherryPy) ten requests
> that start those long-running tasks would deplete the pool completely.
> Further requests would be queued until one of the workers finishes.
PasteHTTPServer has a flexible number of threads, as many other
servers do. See paste/httpserver.py, ThreadPool and
WSGIThreadPoolServer docstrings and constructor args. The default is
10 threads ("workers").
"When there are no idle workers and a request comes in, another
worker *may* be spawned. If there are less than spawn_if_under
threads in the busy state, another thread will be spawned. So if
the limit is 5, and there are 4 hung threads and 6 busy threads,
no thread will be spawned."
"hung threads are threads that have been busy more than
hung_thread_limit seconds. Hung threads are killed when they live
longer than kill_thread_limit seconds. A thread is then
considered dying for dying_limit seconds, if it is still alive
after that it is considered a zombie."
You can set at least some of these variables directly in the [server]
section of the INI file.
There's also a ThreadPool.track_threads() method you can call to get a
summary of the server's state, although I don't know how you'd access
that method from a Pylons app.
--
Mike Orr <[email protected]>
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