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Managing the Worker Queue
Phabricator User Documentation (Field Manuals)

Advanced guide to managing the background worker task queue.


Phabricator uses daemonized worker processes to execute some tasks (like importing repositories and sending mail) in the background.

In most cases, this queue will automatically execute tasks in an appropriate order. However, in some cases you may want to exercise greater control over which tasks execute, when, and at what priority.

Reference: Priority Levels

Tasks queued by Phabricator use these default priority levels:

1000ALERTSTime-sensitive notifications and email.
2000DEFAULTNormal publishing and processing.
2500COMMITImport of commits in existing repositories.
3000BULKEdits applied via "Bulk Edit" interface.
3500INDEXSearch engine index updates.
4000IMPORTImport of commits in new repositories.

Tasks with smaller priority numbers execute before tasks with larger priority numbers (for example, a task with priority 1000 will execute before a task with priority 2000).

Any positive integer is a valid priority level, and if you adjust the priority of tasks with bin/worker priority you may select any level even if Phabricator would never naturally queue tasks at that level. For example, you may adjust tasks to priority 5678, which will make them execute after all other types of natural tasks.

Although tasks usually execute in priority order, task execution order is not strictly a function of priority, and task priority does not guarantee execution order.

Large Repository Imports

The most common case where you may want to make an adjustment to the default behavior of the worker queue is when importing a very large repository like the Linux kernel.

Although Phabricator will automatically process imports of new repositories at a lower priority level than all other non-import tasks, you may still run into issues like these:

  • You may also want to import one or more other new repositories, and would prefer they import at a higher priority.
  • You may find overall repository performance is impacted by the large repository import.

You can manually change the priority of tasks with bin/worker priority. For example, if your copy of the Linux repository is R123 and you'd like it to import at a lower priority than all other tasks (including other imports of new repositories), you can run a command like this:

phabricator/ $ ./bin/worker priority --priority 5000 --container R123

This means: set all tasks associated with container R123 (in this example, the Linux repository) to priority 5000 (which is lower than any natural priority).

You can delay tasks until later with bin/worker delay, which allows you to schedule tasks to execute at night or over the weekend. For example, to pause an import for 6 hours, run a command like this:

phabricator/ $ ./bin/worker delay --until "6 hours" --container R123

The selected tasks will not execute until 6 hours from the time this command is issued. You can also provide an explicit date, or "now" to let tasks begin execution immediately.