Race Condition in Async State Updates
Application state becomes inconsistent under certain conditions. Two async operations complete in unexpected order, leaving the application in an invalid state. Clicking buttons rapidly, loading data concurrently, or quickly switching views exposes the race condition.
Works fine in normal usage but fails under concurrent load or rapid user actions.
Error Messages You Might See
Common Causes
- Multiple async requests start, last one completes first, overwrites state with stale data
- Conditional logic depends on operation A completing before B, but order varies
- No abort mechanism when new request starts while previous still pending
- UI state updates without waiting for all async operations to complete
- Callback functions referencing stale closure variables
How to Fix It
Use request IDs: only apply response if ID matches current request. Cancel previous requests when starting new one. Use async/await with proper error handling. Hold UI in loading state until all operations complete. In React: useEffect cleanup function to cancel when component unmounts. Consider promise race or Promise.all for coordinated async operations.
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Get HelpFrequently Asked Questions
How to prevent race conditions?
Track request ID. Ignore responses from outdated requests. Cancel pending requests when new one starts.
How to cancel async operations?
AbortController: const controller = new AbortController(); fetch(url, {signal: controller.signal}); controller.abort() cancels it.
Why do rapid clicks cause issues?
If click handler starts async operation but doesn't prevent previous one, both run. Disable button during async to prevent multiple starts.