Subject Re: Error reading data from the connection
Author Greg Kay
--- In, Helen Borrie <helebor@t...>
> At 12:42 AM 29/11/2005 +0000, you wrote:
> >Hi,
> >
> >We're using Delphi with FIBPlus components and a Linux Firebird 1.52
> >server with about 150 connections from Windows XP clients. Recently,
> >we've started getting intermittent "Error reading data from the
> >connection" exceptions in our client programs, usually from the same
> >place in the Delphi code. There are no corresponding problems in the
> >Firebird server log (there are lots of 104 errors but we seem to get
> >these most days with or without the "Error reading data from the
> >connection" on the clients.) Does anyone have any ideas on what might
> >be going on here?
> Well, it's due to a network error - the client has lost contact with
> server, one way or another. Either you have a dicey NIC; or, more
> in this case, the server crashed, given that it's consistently
happening at
> the same place in the Delphi code. HIghest on the suspect list
> would be a call to home-grown UDF that has a crash scenario
somewhere in
> some execution branch.
> That said, you don't say anything about the server, either which
model or
> what kind of configuration you are running it on. It might just be
> 150 concurrent connections saps the server resources anyway, and you
> one particularly humongous query that is habitually the last straw....
> ./heLen

We're using Classic 1.52 on a Linux 8 Gb dual CPU opteron 242. We have
no home-grown UDF's and the SQL that we get the "Error reading data
from the connection" problem is a simple short running SELECT. We have
also recently reduced the number of concurrent connections from about
300 to the 150 with a reduction in the average CPU load from about 30%
down to 20%. With the 300 connections we weren't getting these
connection errors. We get about 40 of these intermittent connection
errors in a day and on different client machines. Looking at our own
logs it seems that each connection problem occurs after a period of
inactivity on the client (anywhere from 5 minutes to an hour).

Given the above extra info is it still a possibility that the server
might have glitches due to a crash or overloading and that are not
reported in the server log?