Re: Effect of listener on existing connections?
- From: "gym dot scuba dot kennedy at gmail" <kennedyii@xxxxxxxxxxx>
- Date: Fri, 13 Jun 2008 14:06:00 GMT
<groups.broberg@xxxxxxxxx> wrote in message
news:a8f8b4b1-adbb-4916-9b23-8d72f6d221ba@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Hi all,When you try to make a connection the Listener spawns a server process
Oracle support is not giving us satisfactory results. Perhaps you can
give some answers?
We've recently upgraded our system to Oracle 10.2.0.3.0, running on
Solaris (sparc) 10 inside a ZFS zone (our previous system was Oracle
9.2.0.4.0 running on sparc Solaris 8, and was running on that for the
last 5 years). Since the upgrade 6 weeks ago, we've had two instances
where our applications (running in the same O/S environment on a
different node on the cluster) have locked up - existing connections
to Oracle become unresponsive when executing SQL (with no error
message - they just block), and attempts to create new connections are
met with the error:
"ORA-03135: connection lost contact".
The first time this happened, the outage lasted for about 5 minutes,
then it went away, and execution proceeded normally. The second time
it happened it lasted for 25 minutes until we were able to intervene
manually, and "fixed" the problem by restarting the instance &
listener. During the time of the outage, there were no error messages
in the alert.log, listener.log or /var/adm/messages. However, a few
minutes after normal operation was restored (the first time), and
right as we were restarting the instance (the second time), we saw
these messages appear in the alert.log:
"WARNING: inbound connection timed out (ORA-3136)".
We also see these messages appearing with regularity in our listener
log, during all times of operation (not just in proximity to the
outage):
"WARNING: Subscription for node down event still pending"
We opened an SR with Oracle Support, but so far, I'm unimpressed with
their response. They've told me nothing that I already found on
Google from searching for those error messages - namely that we need
to add some lines to our listener.ora & sqlnet.ora:
listener.ora:
INBOUND_CONNECT_TIMEOUT_LISTENER = 0
SUBSCRIBE_FOR_NODE_DOWN_EVENT_LISTENER=OFF
sqlnet.ora:
SQLNET.INBOUND_CONNECT_TIMEOUT = 0
We've made these changes, but I have low confidence that they will
actually solve the problem (and I've told Oracle as much) for the
following reasons:
1. The SUBSCRIBE_FOR_NODE_DOWN_EVENT_LISTENER value is to address the
issue of the listener locking up if you're not using ONS. However,
how does a blocked listener explain the fact that apps with existing
connections to the db become blocked? My understanding (and I could
be wrong here) is that once you're connected to the instance, there is
no further authentication that needs to be performed. Our in-house
experiments also show that we can "kill -STOP" the listener and apps
with existing connections continue to perform normally.
2. The INBOUND_CONNECT_TIMEOUT value is to address the issue with
clients that are "slow to authenticate", but the "WARNING: inbound
connection timed out (ORA-3136)" message appears AFTER the crisis
interval - in the recent
case, it appeared 20 minutes after our app became blocked. I would
expect to see it within 60 seconds of the block, as that's what the
value currently is.
3. All apps trying to establish new connections (including sqlplus,
running on the same node as the instance) received the login error,
not just "certain apps" as described in the Oracle tech note
274303.1. Why would an app like sqlplus, running on the same box as
the server (which was the case here) need more than 1 minute to
authenticate when logging in? Even our own apps shouldn't be taking
long to authenticate.
Should this event occur again, I don't see how Support will be able to
resolve it, as they haven't asked me for any additional info. I want
to know from them what steps I need to take to gather information so
that they can REALLY fix the problem, or give me an answer that
unambiguously addresses the issue, rather than just googling on error
numbers. So far my requests for a clear action plan from them have
been met with the email equivalent of a blank, slack-jawed stare.
=========
So, my basic questions are:
1. Can listener unavailability cause existing client connections to
become unresponsive?
2. If the answer to #1 is "no", Is there some way I can escalate this
issue within Support to get to a analyst who actually understands how
the Oracle server works, and is capable of doing something other than
typing search queries into metalink?
Thanks,
-S
connects you to that process and then gets out of the way. On a test system
you can confirm this by running sqlplus to the test system. After you have
sucessfully connected shut down the listener on the test system. Your
sqlplus session should continue to function normally. In another sqlplus
session if you try to connect you will see that the listener is unavailable.
So the answer to #1 is No. The asnwer to number 2 is to escalate the SR.
Ask to give it a higher priority. I am assuming this is a production
system. If this system is critical for your business then escalate it.
That will help you get someone more compotent. You can always back off the
priority and you should retain the same tech.
Good luck.
Jim
.
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