Server-connection channel limits

We can set server-connection channel limits to prevent client applications from exhausting queue manager channel resources, MAXINST, and to prevent a single client application from exhausting server-connection channel capacity, MAXINSTC.

A maximum total number of channels can be active at any time on an individual queue manager. The total number of server-connection channel instances are included in the maximum number of active channels.

If we do not specify the maximum number of simultaneous instances of a server-connection channel that can be started, then it is possible for a single client application, connecting to a single server-connection channel, to exhaust the maximum number of active channels that are available. When the maximum number of active channels is reached, it prevents any other channels from being started on the queue manager. To avoid this situation, we must limit the number of simultaneous instances of an individual server-connection channel that can be started, regardless of which client started them.

If the value of the limit is reduced to below the currently running number of instances of the server connection channel, even to zero, then the running channels are not affected. New instances cannot be started until sufficient existing instances have ceased to run so that the number of currently running instances is less than the value of the limit.

Also, many different client-connection channels can connect to an individual server-connection channel. The limit on the number of simultaneous instances of an individual server-connection channel that can be started, regardless of which client started them, prevents any client from exhausting the maximum active channel capacity of the queue manager. If we do not also limit the number of simultaneous instances of an individual server-connection channel that can be started from an individual client, then it is possible for a single, faulty client application to open so many connections that it exhausts the channel capacity allocated to an individual server-connection channel, and therefore prevents other clients that need to use the channel from connecting to it. To avoid this situation, we must limit the number of simultaneous instances of an individual server-connection channel that can be started from an individual client.

If the value of the individual client limit is reduced below the number of instances of the server-connection channel that are currently running from individual clients, even to zero, then the running channels are not affected. However, new instances of the server-connection channel cannot be started from an individual client that exceeds the new limit until sufficient existing instances from that client have ceased to run so that the number of currently running instances is less than the value of this parameter.

Parent topic: Channel control function