CODEWITHSUNDEEP
linuxoracle-databasetomcatjdbcconnection-pooling
dmansfield
dmansfield

Reputation: 1128

oracle thin jdbc connection receiving "connection reset" after inactivity

I have a new tomcat application server running on tomcat 6, java 6 (openjdk), centos 6.2. The server is a virtual machine running under qemu-kvm on a centos 6.2 host. Both host and guest are 64-bit.

I have a case where a connection is opened, (from a connection pool) then a "long computation" occurs for about 4 hours, during which the connection is not used. Finally, a "commit" is issued, and the server gives a "connection reset" exception, specifically:

Caused by: java.net.SocketException: Connection reset
    at java.net.SocketInputStream.read(SocketInputStream.java:185)
    at oracle.net.ns.Packet.receive(Packet.java:282)
    at oracle.net.ns.DataPacket.receive(DataPacket.java:103)
    at oracle.net.ns.NetInputStream.getNextPacket(NetInputStream.java:230)
    at oracle.net.ns.NetInputStream.read(NetInputStream.java:175)
    at oracle.net.ns.NetInputStream.read(NetInputStream.java:100)
    at oracle.net.ns.NetInputStream.read(NetInputStream.java:85)
    at oracle.jdbc.driver.T4CSocketInputStreamWrapper.readNextPacket(T4CSocketInputStreamWrapper.java:122)
    at oracle.jdbc.driver.T4CSocketInputStreamWrapper.read(T4CSocketInputStreamWrapper.java:78)
    at oracle.jdbc.driver.T4CMAREngine.unmarshalUB1(T4CMAREngine.java:1179)
    at oracle.jdbc.driver.T4CMAREngine.unmarshalSB1(T4CMAREngine.java:1155)
    at oracle.jdbc.driver.T4CTTIfun.receive(T4CTTIfun.java:279)
    at oracle.jdbc.driver.T4CTTIfun.doRPC(T4CTTIfun.java:186)
    at oracle.jdbc.driver.T4C7Ocommoncall.doOCOMMIT(T4C7Ocommoncall.java:75)
    at oracle.jdbc.driver.T4CConnection.doCommit(T4CConnection.java:558)

The database server and the client are on the same subnet, except the server is a real physical host, and obviously the app-server is a guest running inside a physical machine on the same subnet.

The host used "bridged" networking.

This may not be a software problem at all but rather a linux os configuration (iptables?) issue, but I really don't know.

Upvotes: 1

Views: 10060

Answers (3)

SingCheong Chen
SingCheong Chen

Reputation: 11

@user is referring to a good workaround, by configuring "SQLNET.EXPIRE_TIME=10" in sqlnet.ora.

However, this workaround is only applicable if your application is using thick OCI (jdbc:oci), not thin (jdbc:thin) driver.

Linux has software firewall, i.e. iptables, which can drop idle network connection, so even you are in the same subnet, you have iptables software firewall. This is activated by default in all modern Linux, and up to Linux administrator to disable it.

By default, Linux iptables does not drop idle TCP/IP connections (jdbc belongs to TCP/IP protocol), so the Linux administrator must configured iptables to do so. Following is the detail explanation for any reader who are interested to know more:

http://www.digitage.co.uk/digitage/software/linux-security/cutter

Business users, security team, or architect often suggest network/OS admin to abort idle connection using firewall, as well as router. This is always a "recommendation" in the anti-hacking community, but it is not properly discussed, and causing application instability. Eventually, you should discuss with the team to find a balance

Upvotes: 1

souser
souser

Reputation: 6100

I have run into this a couple of times. Almost always caused by a network timeout (load balancer or firewall). But you have clearly mentioned that your servers are on the same subnet, so not really sure what is going on. Since you suspect iptables, can you turn it off, run the test and see if it works (too easy huh :)

Regardless, assuming you are connecting to an Oracle db, the following tweak helps

http://raibledesigns.com/rd/entry/tomcat_oracle_connectivity_problems

If you use a different db (say mysql) the setting might be different but the logic is the same. Setup a keepalive value to prevent the connection from being idle for too long. This way the firewal/load balancer/iptables software will not terminate it.

Upvotes: 1

user800014
user800014

Reputation:

As you can see in this post in Oracle Forums, this can have more than one problem / solution.

  • Check if your JDBC driver version is correct
  • Check your ORACLE_HOME environment variable
  • try add the argument -Djava.security.egd=file:///dev/urandom
  • Your logic use a singleton to get the connection? In the post this are mentioned too

Hope this helps you.

Upvotes: 1

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