Queue (QUEUE)

Executable objects are always processed within a Queue object. Queues are virtual spaces in which processes are submitted for execution. They allow you to sort out, separate and break out these processes in different lanes. They determine the maximum number tasks that can run in parallel and their priorities. For this reason, Queues are basic load balancing tools. Although they are active objects, Queues cannot be executed.

Object class: Active object

Object type/Short form: QUEUE

This page includes the following:

Assigning Queues to Objects

You have two possibilities to assign a Queue to an executable object:

On the object's Attributes page, see Attributes Page
At runtime using the :PUT_ATT script element for attribute QUEUE

When you modify object attributes dynamically and assign them new values, these values apply to only that particular generation. They are not stored in the object.

If an object has no specific Queue, the system automatically uses the Client Queue to process it. For more information, see CLIENT Queue.

Queues can be assigned to the following objects:

Workflow
Notification
Event
File Transfer
Group
Job
Remote Task Manager
Schedule
Script

There is no limit to the number of objects that you can assign to a Queue object.

Queue Status

Queues can have the following status:

Active
Inactive
Queue with 0 slots (it is not possible to start tasks), see Maximum Slots

Right-click a Queue to display the following options:

Set Filter to filter the list of Tasks using this Queue as criterion
Stop Queue/Start Queue
Modify its settings, including its maximum slots

Defining Queues

A Queue object definition is made up of the following pages:

Standard pages that are always available, no matter what type of object you are defining:

The object-specific page described here

Note: All the Queues in a Client are visible both in the Administration perspective and in the Process Monitoring perspective. In Client 0, the list of queues shows all Queue objects in all Clients in the system.

To Define the Queue-Specific Settings

Click Add Object on the toolbar.
On the Add Object dialog, select Queue. For more information, see Adding Objects.
The object opens to the Queue page on the left navigation pane. Here you define many of its most relevant properties.
In the Default Settings section, you specify the standard behavior of the Queue.
- Maximum Slots
  
  Maximum number of tasks that can run simultaneously in this Queue.
  
  When an object starts, the Queue slot is reserved before any other settings are checked. Sync objects, available resources, maximum number of parallel tasks allowed, Agent, and so on are considered afterward.
  - Default value: unlimited
  - Allowed values: 1 to 100000
  Important! Entering 0 is not allowed, it can only set by modifying the Queue.
- Priority
  
  Objects are processed based on their priority.
  - Default value: 200
  - Allowed values: 0 to 255, where:
    - 0 = highest priority
    - 255 = lowest priority
  Notes:
  - The priority that is defined in the Queue object is checked before the priority defined in the task. If two tasks have the same Queue priority, the priority that is specified in the task applies.
  - The settings in the Exception section might affect the priority of a task and overrule this definition.
- Time Zone
  
  You can assign a Time Zone (TZ) to this Queue. Time Zone objects affect the time calculation. You can select one or use a variable here. For more information, see Inserting Variables/VARA Objects in Objects and Scripts.
In the Exceptions section, you specify periods of time in which the default Queue settings do not apply. You can also define specific parameters for those periods.

Important! If you set the Maximum Slots value to unlimited, the exceptions that you define here have NO effect.
1. In From/To specify the period in hours and minutes you do not want the default settings to apply.
2. Optionally, select a Calendar to determine the days on which the default settings do not apply.
3. Optionally, select the Calendar Event (if available) that further restricts the days on which the default settings do not apply.
4. Enter the settings that should apply instead of the default ones, namely the maximum slots, and priority.
  
  You can also add a Description that helps users recognize this description later on. You can enter up to 255 characters.
  
  Important! The order of the exceptions in the table is relevant. The list is processed from top to bottom, that is, the first applicable exception is selected. You can arrange their order using the arrow up/down buttons.
Tip: After defining the Maximum Slots and at least one Exception you also have the option to use Consider ERT. For more information, see Considering ERT in Queue Objects.
Save your changes.

Priority Management

Queues provide priority management; this process assigns a default priority to a task. This priority can increase over time, altering priorities over processes in other queues. Operators can manually change the priority of a process on the fly.

Capping Parallel Executions

A Queue has a certain number of available slots. You can cap the number of parallel executions. If a Queue has 10 slots and you submit 15 tasks, 10 will execute while 5 will wait. If necessary, you can bypass Queue restrictions later, when objects have been executed but are in a waiting status (Waiting for Queue Slot). In these cases, right-click the task in the Process Monitoring perspective and select Ignore Queue Limit. The task starts immediately.