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Wednesday, 19 July 2017

ODI 12c Controlling Multiple Load Plans and Scenarios running multiple times together


ODI 12c Controlling Concurrent Execution of Scenarios and Load Plans


By default, nothing prevents two instances of the same scenario or load plan from running simultaneously.

This situation could occur in several ways. For example:

  • A load plan containing a Run Scenario Step is running in two or more instances, so the Run Scenario Step may be executed at the same time in more than one load plan instance.
  • A scenario is run from the command line, from ODI Studio, or as scheduled on an agent, while another instance of the same scenario is already running (on the same or a different agent or ODI Studio session.

Concurrent executions of the same scenario or load plan apply across all remote and internal agents.

Concurrent execution of multiple instances of a scenario or load plan may be undesirable, particularly if the job involves writing data. You can control concurrent execution using the Concurrent Execution Control options.

ODI identifies a specific scenario or load plan by its internal ID, and not by the name and version. Thus, a regenerated or modified scenario or load plan having the same internal ID is still treated as the same scenario or load plan. Conversely, deleting a scenario and generating a new one with the same name and version number would be creating a different scenario (because it will have a different internal ID).

While Concurrent Execution Control can be enabled or disabled for a scenario or load plan at any time, there are implications to existing running sessions and newly invoked sessions:

  • When switching Concurrent Execution Control from disabled to enabled, existing running and queued jobs are counted as executing jobs and new job submissions are processed with the Concurrent Execution Control settings at time of job submission.
  • When switching Concurrent Execution Control from enabled to disabled for a scenario or load plan, jobs that are already submitted and in waiting state (or those that are restarted later) will carry the original Concurrent Execution Control setting values to consider and wait for running and queued jobs as executing jobs.

However, if new jobs are submitted at that point with Concurrent Execution Control disabled, they could be run ahead of already waiting jobs. As a result, a waiting job may be delayed if, at the time of polling, the system finds executing jobs that were started without Concurrent Execution Control enabled. And, after a waiting job eventually starts executing, it may still be affected by uncontrolled jobs submitted later and executing concurrently.



To limit concurrent execution of a scenario or load plan, perform the following steps:
 
 
 
 
 
 
 

  1. Open the scenario or load plan by right-clicking it in the Designer or Operator Navigators and selecting Open.
  2. Select the Definition tab and modify the Concurrent Execution Controller options:

o   Enable the Limit Concurrent Executions check box if you do not want to allow multiple instances of this scenario or load plan to be run at the same time. If Limit Concurrent Executions is disabled (unchecked), no restriction is imposed and more than one instance of this scenario or load plan can be run simultaneously.

o   If Limit Concurrent Executions is enabled, set your desired Violation Behavior:

§  Raise Execution Error: if an instance of the scenario or load plan is already running, attempting to run another instance will result in a session being created but immediately ending with an execution error message identifying the session that is currently running which caused the Concurrent Execution Control error.

§  Wait to Execute: if an instance of the scenario or load plan is already running, additional executions will be placed in a wait status and the system will poll for its turn to run. The session's status is updated periodically to show the currently running session, as well as all concurrent sessions (if any) that are waiting in line to run after the running instance is complete.

If you select this option, the Wait Polling Interval sets how often the system will check to see if the running instance has completed. You can only enter a Wait Polling Interval if Wait to Execute is selected.

If you do not specify a wait polling interval, the default for the executing agent will be used: in ODI 12.1.3, the default agent value is 30 seconds.

  1. Click Save to save your changes.

 

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