Disconnect interval (DISCINT)

This attribute is the length of time after which a channel closes down, if no message arrives during that period.

This attribute is a time-out attribute, specified in seconds, for the server, cluster-sender, sender, and cluster-receiver channels. The interval is measured from the point at which a batch ends, that is when the batch size is reached or when the batch interval expires and the transmission queue becomes empty. If no messages arrive on the transmission queue during the specified time interval, the channel closes down. (The time is approximate.)

The close-down exchange of control data between the two ends of the channel includes an indication of the reason for closing. This ensures that the corresponding end of the channel remains available to start again.

We can specify any number of seconds from zero through 999 999 where a value of zero means no disconnect; wait indefinitely.

For server-connection channels using the TCP protocol, the interval represents the client inactivity disconnect value, specified in seconds. If a server-connection has received no communication from its partner client for this duration, it terminates the connection. The server-connection inactivity interval applies under the following circumstances:

• between IBM MQ API calls from a client
• between an MQGET call, only if:
  • client application executes an MQGET with WaitInterval
  • the DISCINT parameter is set on the server-connection channel and is smaller than the MQGET WaitInterval
  • the SHARECNV parameter of the server-connection channel is greater than 0.

This attribute is valid for channel types of:

• Sender
• Server
• Server connection
• Cluster sender
• Cluster receiver

This attribute is not applicable for server-connection channels using protocols other than TCP.

Note: Performance is affected by the value specified for the disconnect interval.

A low value (for example a few seconds) can be detrimental to system performance by constantly starting the channel. A large value (more than an hour) might mean that system resources are needlessly held up. We can also specify a heartbeat interval, so that when there are no messages on the transmission queue, the sending MCA sends a heartbeat flow to the receiving MCA, thus giving the receiving MCA an opportunity to quiesce the channel without waiting for the disconnect interval to expire. For these two values to work together effectively, the heartbeat interval value must be significantly lower than the disconnect interval value.

The default DISCINT value is set to 100 minutes. However, a value of a few minutes is often a reasonable value to use without impacting performance or keeping channels running for unnecessarily long periods of time. If it is appropriate for your environment we can change this value, either on each individual channel or through changing the value in the default channel definitions, for example SYSTEM.DEF.SENDER.

For more information, see Stop and quiescing channels.