TCP Server stops accepting after 10mins

TCP Server stops accepting after 10mins

[Steven Vacca]

Hi everyone.  I would very much appreciate help with the following problem:

The Unit Under Test (UUT) has Redhat's embedded Linux kernel (based on Linux
kernel 2.2.13), from the Redhat EDK 1.0, running on an embedded MPC860 uP
with 8M of RAM, and is connected to a LAN.

For my test, I have a TCP Client (Microsoft) on a PC, also connected to the
LAN, connect to the TCP Server (linux) on the UUT at the following intervals
(50/s = "50 connects per sec", 1/5s = "1 connect every 5 secs"):

       50/s, 1/5s, 1/20s, 1/30s, and 1/60s.

For 50/s, 1/5s, 1/20s, and 1/30s, approx. 10 minutes (+/- 1 connect period) is the
constant time when the TCP Client fails to connect to the Server.

But, whenever the connect frequency = 1/60s, or longer, then the problem goes
away and the TCP Client can connect forever at this rate.


Test Results:

50/s:	stopped connecting                 @  10:00		(over 29,500 connect()s.)

1/5s:	stopped connecting on next try @ 10:05

1/20s:	stopped connecting on next try @ 9:40

1/30s:	stopped connecting on next try @ 10:30

1/60s:   connects forever (several hours in test)


The fact that regardless of whether the connects occur at a very high frequency
(50/s) or low frequency (1/30s), the TCP Client fails to connect after 10 mins.
(I think 1min and 10 mins are key info). I would think that this would indicate
that the problem is not one of running out of allocated memory.
It appears that something happens once a minute, some type of cleanup, maybe?
And if that goes on for 10 times, then connects are denied.  As
long as at least 1 min is allowed to go by without accepting a connect from a
client, then there is no problem, and another 10 min period is allowed to occur.

This is very repeatable.  Note that if I pause the Client from connecting just before
the 10 minute time period connect() failure is to occur, and wait at least 1 minute
(can't be less), and then allow the Client to continue connecting, then the Client
is able to connect for another 10 minutes before the connect() failure occurs.

This problem occurs even when I have no threads running, and the TCP Server is
executing in the main() func.

Thanks a million for anybody's help or suggestions,

ShutEye Thinkin
Roanoke, Virginia  USA


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Re: TCP Server stops accepting after 10mins

[Steven Vacca]

Has anyone who is working with Redhat EDK 1.0, with its kernel
v2.2.13 and a TCP Server running on an MPC860, ever been able
to have a TCP Client (on another PC) connect at a rate of once every
30s, or more frequently (say, once every 5 secs) , to the TCP Server
for longer than 10 minutes?

Could someone who has this setup please try doing this?
Below are 2 good tests to try.  Both fail at 10 mins on my system.


Test scenario #1, connecting at once every 5s:

On another PC:
Client:   while (1)
               {
               socket()
               connect()
               close()
               5 sec delay        (120 connects in 10 mins)
               }

On Embedded EDK unit:
Server:   socket()
             bind()
             listen()

             while (1)
               {
               accept()
               close()
               }



Test scenario #2, connecting 50 times per sec:

On another PC:
Client:   while (1)
               {
               socket()
               connect()
               close()
               1/50 sec delay        (30,000 connects in 10 mins)
               }

On Embedded EDK unit:
Server:   socket()
             bind()
             listen()

             while (1)
               {
               accept()
               close()
               }


Thanks,

 ShutEye Thinkin


** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/

RE: TCP Server stops accepting after 10mins

[Steven Vacca]

I have also discovered that after the 10 mins, when the
TCP Server stops accepting, then if I wait 1 minute, the
TCP Client can once again start connecting for another
10 mins before connect failure.  Again, this is irregardless
of connect freqs of 50 times per sec or once every 30 secs.

-----Original Message-----
From:	Steven Vacca [SMTP:svacca@valcom.com]
Sent:	Monday, January 08, 2001 8:16 AM
To:	LinuxEmbeddedMailList (E-mail)
Subject:	Re: TCP Server stops accepting after 10mins


Has anyone who is working with Redhat EDK 1.0, with its kernel
v2.2.13 and a TCP Server running on an MPC860, ever been able
to have a TCP Client (on another PC) connect at a rate of once every
30s, or more frequently (say, once every 5 secs) , to the TCP Server
for longer than 10 minutes?

Could someone who has this setup please try doing this?
Below are 2 good tests to try.  Both fail at 10 mins on my system.


Test scenario #1, connecting at once every 5s:

On another PC:
Client:   while (1)
               {
               socket()
               connect()
               close()
               5 sec delay        (120 connects in 10 mins)
               }

On Embedded EDK unit:
Server:   socket()
             bind()
             listen()

             while (1)
               {
               accept()
               close()
               }



Test scenario #2, connecting 50 times per sec:

On another PC:
Client:   while (1)
               {
               socket()
               connect()
               close()
               1/50 sec delay        (30,000 connects in 10 mins)
               }

On Embedded EDK unit:
Server:   socket()
             bind()
             listen()

             while (1)
               {
               accept()
               close()
               }


Thanks,

 ShutEye Thinkin


** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/