Re: [Ocamlnet-devel] Netplex issue with VServer PID namespace

[Gerd S. <in...@ge...>]

Am Montag, den 01.06.2015, 11:06 +0200 schrieb Thomas Calderon:
> Hi,
> 
> 
> We are observing an issue when using OCamlnet netplex in combination
> with VServer PID namespaces.
> We are using Netplex in the multi-process mode.
> 
> 
> Here is what we are doing:
>   - start our netplex controller
>     - use the post_add_hook to enter a new PID namespace
>   - use dynamic workload manager to spawn child workers
>     - configured with conn_limit=1
> 
> 
>   - launch a loop of client connections
>     - this spawns a new worker process for each connection
> 
> 
> After several successful connections of the loop, clients cannot
> connect anymore.
> We observe some worker processes in a defunct/zombie state.
> The controller and running worker processes seem deadlocked in some
> condition.
> 
> 
> When we do not use the post_add_hook to enter a new PID namespace, the
> problem cannot be triggered anymore.
> 
> 
> Do you have any hint on this?

The controller runs of course waitpid() on the terminated processes to
un-zombie these, and obviously this does not work. I guess you reach
then the maximum number of processes after some time.

You say "vServer" but there are several such technologies (Linux
containers, Virtuozzo, maybe some derived products). I also don't know
much about this corner of the OS.

What would definitely help is an strace -f of the server.

Gerd



> 
> 
> Many thanks.
> 
> 
> Thomas

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Gerd Stolpmann, Darmstadt, Germany    ge...@ge...
My OCaml site:          http://www.camlcity.org
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Company homepage:       http://www.gerd-stolpmann.de
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