Async Before / After in Camunda — Why Your Process Freezes
One of the most common production complaints in Camunda:
“My process sometimes freezes… but no error is visible.”
This usually happens because the process is running inside a single transaction.
Camunda executes multiple BPMN steps in one database transaction unless you tell it not to.
So, when one step blocks → the entire process stops.
The solution: Async Before / Async After
What is Async in Camunda?
Async creates a transaction boundary.
Instead of executing everything in one go:
Task A → Task B → Task C
Camunda stores the state in DB and continues later via Job Executor.
Without Async (Single Transaction)
Everything runs in one DB transaction.
Problem
If Task B takes 20 seconds:
DB lock held
UI stuck
Other instances blocked
Possible deadlock
Async Before
Creates checkpoint before task execution
Behavior
Process state saved → job created → executed later
Use When
Calling external API
Slow logic
Network calls
Async After
Checkpoint after task completes
Use When
Before gateway evaluation
Avoid optimistic locking
Parallel flows
Critical Production Scenario
Without Async
Service task → gateway
Gateway evaluated inside same transaction
If another instance updates → optimistic locking exception
With Async After
Gateway evaluated safely in new transaction
Where You MUST Use Async
| BPMN Element | Needed |
|---|---|
| External API | Async Before |
| Parallel Gateway | Async After |
| User Task creation | Async After |
| External Task | Async Before |
| Long Java Delegate | Async Before |
Common Mistake
Only adding async at process start
This does nothing for internal blocking tasks.
Async must be placed at risk points.
Architecture Rule
Every remote call must be async
Every parallel gateway must be async
Debug Tip
If process freezes and DB CPU high → missing async boundary.
📚 Recommended Reading
Improve Camunda stability:
👉 https://shikhanirankari.blogspot.com/search/label/English
Read especially:
These relate directly to async configuration.
Final Advice
BPMN is fast.
Transactions are slow.
Async boundaries protect your engine.
Correct async placement = stable production system.
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