Configure application lazy start
By configuring application lazy start, we can release resources that are being consumed by inactive dynamic clusters so that other cluster instances in the cell can use these resources.
- Application lazy start requires that requests are routed through the on demand router. Application lazy start is not available if you use Intelligent Management for web servers.
- Internet Inter-ORB Protocol (IIOP) and Java Message Service (JMS) requests cannot be used because they are not routed through the ODR. Do not use application lazy start on dynamic clusters that run Session Initiation Protocol (SIP) applications.
- Do not enable lazy start if elasticity mode is enabled.
An application lazy start is the activation of the first application server instance of a deactivated dynamic cluster when an application request arrives. We decide which applications to deactivate and subsequently lazily start. Use application lazy start if you have an environment in which the ratio of the number of dynamic clusters to the number of nodes is high, and if many dynamic clusters are not accessed for a long period. By using application lazy start, we can increase the performance and efficiency of ythe environment.
- Create a dynamic cluster.
- Edit the dynamic cluster properties.
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Servers > Clusters > Dynamic clusters > dynamic_cluster_name
- Select option...
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If other dynamic clusters need resources, stop all instances of this cluster during periods of inactivity
- Set the Time to wait before stopping instances in minutes if the application placement controller determines that the resource is required by some other dynamic application cluster.
Results
The application placement controller tracks the amount of time that a dynamic cluster has been inactive. If another dynamic cluster needs resources, the application placement controller can stop the inactive dynamic cluster after the specified time period. The resources that were consumed by the inactive instance are released and made available for use by the dynamic cluster that requires additional resources. If a request arrives for the stopped dynamic cluster instance, the lazy start controller is activated and at least one server instance is started. In the meantime, HTTP error code 503 (server unavailable) is generated. The error page informs you that the requested application is starting and the request is resubmitted shortly.What to do next
- We can configure the application lazy start without the proactiveIdleStop custom property configured, once a application request arrives, the application server instance will start, but lazy start will never stop it in future.
- We can configure the application lazy start with the proactiveIdleStop custom property configured, the application server instance will stop after a specified time period.
- We can configure a custom error page for the ODR that can be used for the 503 error. The error page can include an HTTP meta refresh tag that causes the browser to automatically send the request again after a certain waiting period. For more information about configuring custom error pages, read about configuring ODRs.
Subtopics
- (dist)(zos) Application lazy start
- (dist)(zos) The lazy start controller
Related concepts