With synchronous invocations, Function Compute executes a function immediately and returns the result — including execution output, a summary, and logs — directly to the caller.
Use synchronous invocations when your application needs the function result before it can continue.
How it works
When you invoke a function synchronously, Function Compute runs the function and holds the connection open until execution completes. The response includes:
Execution result (function return value)
Execution summary
Logs
Quotas and limits
By default, each Alibaba Cloud account can run up to 100 concurrent instances per region. The actual limit shown in Quota Center takes precedence. To increase the limit, submit a quota increase request in Quota Center.
Monitor throttling behavior using the throttling metrics for your function in the CloudMonitor console.
Execution concurrency
Execution concurrency indicates the number of concurrent invocations of a function in a period of time. Use this formula to estimate it:
Execution concurrency = Request rate × Execution duration
Request rate: number of requests or events per second
Execution duration: time from when a request reaches the instance to when execution completes, in seconds
Example
| Scenario | Request rate | Execution duration | Concurrency |
|---|---|---|---|
| OSS event processor | 10 req/s | 3 s | 30 |
Use the formula before deployment to estimate whether your expected load stays within your quota.
Billing
Execution concurrency directly affects billing. For details, see Billing overview.