I'm going to try and hijack this thread if I may (!) because, as you say...Welcome! ;-)
[...] The other Tomcat server runs on a Red Hat 9 machine at my home. It connects to the above Oracle DB box - far away - using the same static IP address.
[...] The problem is with the the DB connections on my own RH9 server - they just *die* after a period of inactivity :-(
That period of inactivity can be as little as half and hour.
[...]
Very typical behaviour... at least in our scenario.
BTW - the 'first' login attempt (which reactivates the connection pooling)
never gets a response - it just times out.
Very true.
Do you think you can shed any light on this?
I'll try.
I have read just about every
single forum discussion - from Tomcat-User to Commons DBCP to you-name-it,
and I just cannot find the answer.
I have a very strict firewall policy on my Linux box - using iptables. Only port 80 packets get through. Nothing else.
Does that have something to do with my problem? Is there an ICMP port that I
need to open up?
Nope. No ICMP is needed for keepalives.
The reason of your headaches may be in /proc/sys/net/ipv4/netfilter
There, you have several timeout values. Check ip_conntrack_tcp_timeout_established.
Anyway, however high you set the values in there, there will be an upper limit. So, I think you need to avoid your connection being idle, so that your firewall does not drop it, even with low timeout values. To do that, I suggest to use the mechanism provided by DBCP to test idle connections every now and then.
testWhileIdle --> true
validationQuery --> select 'x' from dual
timeBetweenEvictionRunsMillis --> 300000 (five minutes. Or longer, as far as it works...)
On Monday, I may send you out production values. Now I don't have them, so I worked out some ;-)
I am not sure whether you will need to set some more parameters. The authoritative source of information is:
http://jakarta.apache.org/commons/dbcp/configuration.html
Other sources (link below) say that you also have to set numTestsPerEvictionRun. I'd suggest a value equal to maxIdle.
http://www.mail-archive.com/[EMAIL PROTECTED]/msg05339.html
And he also proposes another solution (which I have not tested):
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You can prevent that your firewall from dropping the connection using a oracle technique.
SQL*Net has a parameter which defines time interval to send a probe message to identify if the client process is still alive
- SQLNET.EXPIRE_TIME, sqlnet.ora file on the server side. SQLNET.EXPIRE_TIME = <your_value>
Set it to something like 30 when your firewall drops connection after 60 minutes.
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I hope that helped.
Antonio Fiol
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