RE: Weird database hanging

  • From: "Vishal Gupta" <vishal@xxxxxxxxxxxxxxxxx>
  • To: <sunil.kanderi@xxxxxxxxx>, "'Nigel Thomas'" <nigel_cl_thomas@xxxxxxxxx>
  • Date: Wed, 19 Sep 2007 09:01:15 +0100

It could be that your database is having too many incoming connection. On
Solaris default for listener is to accept 5 concurrent connection request.
Try increasing QUEUE_SIZE in listener.ora and reload the listener. Verify
that changes have taken place by verifying in lsnrctl status.



Vishal Gupta



From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
On Behalf Of Sunil Kanderi
Sent: 18 September 2007 17:46
To: Nigel Thomas
Cc: oracle-l
Subject: Re: Weird database hanging


Thanks to all those who responded. Some web applications do use connection
pooling and some don't. I will need to find out the upper limits on the
session pool size and also the rate of session starts. Thanks for the


On 9/18/07, Nigel Thomas <nigel_cl_thomas@xxxxxxxxx> wrote:

----- Original Message ----
From: Sunil Kanderi sunil.kanderi@xxxxxxxxx

.... We have lots of web applications running from that database and once in
a while there is a sudden spike in the number of connections from a Oracle
user related to one of the web applications and the concurrent connections
for that particular web application user jumps from 10 or 15 concurrent
connections to 100s in less than a couple of minutes. The database and the
server hang until these connections are cleared. At times we cannot even get
a connection to the server when this happens. I usually don't see any alerts
in the alert log when this happens. 


From this, I can't say why you see the initial slowdown - but I can say it
is common for connection pools to behave suicidally when faced with a slow
down. Traffic piling into the connection pool causes an explosion in the
number of connections - and there's nothing like a flood of new connections
to make the traffic jam worse. See

Regards Nigel


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