Understand parallel jobs

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Parallel jobs represent the number of jobs your organization can run simultaneously. If you have one parallel job, only one pipeline job runs at a time. Additional jobs wait in a queue until the running job finishes.

Screenshot of Parallel job consumption.

How parallel jobs work

When you run a pipeline:

  • Each job consumes one parallel job slot
  • Jobs run on available agents (Microsoft-hosted or self-hosted)
  • If no parallel jobs are available, new jobs wait in queue
  • Jobs release their slot when they complete

Parallel job consumption example

Here's how parallel jobs work in practice:

  1. Build starts: FabrikamFiber CI Build 102 (main branch) begins - uses 1 parallel job
  2. Release triggered: FabrikamFiber Release 11 starts deployment - uses 1 parallel job
  3. Build queued: FabrikamFiber CI Build 101 (feature branch) waits because no parallel jobs available
  4. Waiting for approval: Release 11 pauses for approval - releases parallel job, Build 101 starts
  5. Release approved: Release 11 waits for Build 101 to finish before resuming

Key concepts

Pipeline jobs vs parallel jobs:

  • Pipeline jobs: Individual work units within your pipeline (build, test, deploy)
  • Parallel jobs: Capacity to run pipeline jobs simultaneously across your organization

Jobs that don't use parallel jobs:

  • Server jobs (jobs without agents)
  • Deployment group jobs
  • Jobs waiting for manual approval