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| michal |
 Posted: Thu Sep 06, 2007 2:32 pm |
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User
Joined: 20 Jul 2006
Posts: 44
Location: London
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Hi,
I have the latest 1.68 Yaws running and receiving 5 requests per
second with peaks of 40 requests per second. Some of the Yaws
processes have very long message queues with peak up to 1500. All
messages are exit signals like this: {'EXIT',#Port<0.23517>,normal}.
The initail call of those processes is the yaws_server:acceptor0/2
function and they are waiting in prim_inet:recv0/3 most of the time.
It might be that some of the request that we are getting are not
proper HTTP reqests or that client on the other end does some magic
with opening and closing sockets. I need to investigate that more. But
my question is has anyone seen such long queues with exit signals
before?
Thanks
--
Michal Slaski
http://www.erlang-consulting.com
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| Guest |
| Posted: Thu Sep 06, 2007 5:30 pm |
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Guest
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Michal Slaski wrote:
> Hi,
> I have the latest 1.68 Yaws running and receiving 5 requests per
> second with peaks of 40 requests per second. Some of the Yaws
> processes have very long message queues with peak up to 1500. All
> messages are exit signals like this: {'EXIT',#Port<0.23517>,normal}.
> The initail call of those processes is the yaws_server:acceptor0/2
> function and they are waiting in prim_inet:recv0/3 most of the time.
>
This basically means that there are a lot of sockets that are
being closed on the client side and Yaws hasn't yet picked up on the
fact that the client sockets are closed. The emulator should be running
at 100% when you see this ??
The code in prim_inet.erl recv0() is just aching to pick up
that EXIT signal and report the socket as closed.
/klacke
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| michal |
| Posted: Fri Sep 07, 2007 1:58 pm |
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User
Joined: 20 Jul 2006
Posts: 44
Location: London
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Claes Wikstrom wrote:
> This basically means that there are a lot of sockets that are
> being closed on the client side and Yaws hasn't yet picked up on the
> fact that the client sockets are closed. The emulator should be
> running
> at 100% when you see this ??
Actually no. The beam process has peaks of 10% CPU utilization and
the system is not overloaded at all. After couple of minutes the
acceptor process dies and is restarted so its mailbox is empty. I
don't see any error messages.
Michal
--
Michal Slaski
http://www.erlang-consulting.com
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| Guest |
| Posted: Fri Sep 07, 2007 3:53 pm |
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Guest
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Michal Slaski wrote:
> Claes Wikstrom wrote:
>> This basically means that there are a lot of sockets that are
>> being closed on the client side and Yaws hasn't yet picked up on the
>> fact that the client sockets are closed. The emulator should be running
>> at 100% when you see this ??
>
> Actually no. The beam process has peaks of 10% CPU utilization and the
> system is not overloaded at all. After couple of minutes the acceptor
> process dies and is restarted so its mailbox is empty. I don't see any
> error messages.
>
> Michal
>
Suspicious, as you might know, in yaws there is one process per socket,
that process will sit in a gen_tcp:recv() call, when the socket dies, it
will send an EXIT sugnal and the socket will be reported as down, e.g
gen_tcp:recv() returns {error, closed}
The process will the report back to its top process that it is done.
In order to go forth with this - some debugging is probably required.
What are the HTTP messages getting in ? are there really processes in
prim_inet:recv() that do have an EXIT msg in the queue and the load is
still 10 % - don't think so .......
To debug/inspect these kind of behaviours, I usually use the bt() function in
my user_default.erl
Attached .
/klacke
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| michal |
| Posted: Fri Sep 07, 2007 4:13 pm |
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User
Joined: 20 Jul 2006
Posts: 44
Location: London
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Claes Wikstrom wrote:
> To debug/inspect these kind of behaviours, I usually use the bt()
> function in
> my user_default.erl
Many thanks. Will trace the incoming traffic and the acceptor process
and see what happens.
Michal
--
Michal Slaski
http://www.erlang-consulting.com
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