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The scenario is: The situation is this:

  • i have sql based application client Keep a client "untouched" for 10minutes or more.
  • Come back
  • Do an operation that triggers a dbserver call (This means: write in a socket which is already open to a dbserver instance)

What happens now is the following:

  • The "write" to the socket gets stuck for 18 seconds.
  • Then we get an "error" (connection closed) in the client side (dcl error -209)
  • Then the client reconnects - and all works fine.

The strange thing is this "write" operation that gets "stuck".

Could a switch config or OS/application decide to close established connections that are not used after some delay? (Apparently set at 10 minutes). Why would this "intermediary" device cause a timeout of 18 seconds when we try to write in the "old connection"?

Please advice

asked 10 Jul '13, 06:35

tbaror's gravatar image

tbaror
10121215
accept rate: 0%

edited 10 Jul '13, 09:42

Jasper's gravatar image

Jasper ♦♦
23.8k551284


could a switch config or os/application can decide to close open connections that are not used after some delay?

sounds like there is a firewall between your client and server. After some time of inactivity in the TCP connection (no packet sent in either direction), it will drop the session in its internal tables.

Why would this "intermediary" device cause a timeout of 18 seconds when we try to write in the "old connection"?

If the client sends a new packet, the firewall will drop that packet, as there is no 'open' session any longer. The client may/will re-try to send the packet for a certain amount of time (18 seconds in your case) and then give up and show the error message.

So, if there is a firewall involved, please ask the firewall admin to increase the "IDLE timeout" for those sessions. The firewall could be on the SQL server as well!

Regards
Kurt

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answered 10 Jul '13, 07:09

Kurt%20Knochner's gravatar image

Kurt Knochner ♦
24.8k1039237
accept rate: 15%

edited 10 Jul '13, 07:23

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question asked: 10 Jul '13, 06:35

question was seen: 1,865 times

last updated: 10 Jul '13, 09:42

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