# Quota limit
<subtitle>Understand access thresholds for platform APIs and sandbox operations to ensure your application runs smoothly. </subtitle>

In order to ensure the stability and fair sharing of services, the UCloud Sandbox platform sets frequency limits for various types of API calls and resource usage.

## Resource specifications and quotas

The following table lists detailed resource limits for the current platform:

| Category | Limit Item | Threshold/Description |
| :--- | :--- | :--- |
| **Computing Resources** | CPU/memory ratio | Support 1:1, 1:2, 1:4 |
| | CPU limit | 8 Core |
| | Memory limit | 8 GB |
| **Storage & Network** | Single user storage limit | 10 GB |
| | Public network bandwidth | 5 MB/s |
| | Disk I/O | 20 MB/s |
| **Sandbox Limit** | Number of concurrent runs | 20 |
| | Number of custom templates | 5 |
| **API** | API call current limit | Unlimited |

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## Behavior when limit is reached

When your calls exceed the set threshold, the platform will take the following protective measures:

* **HTTP Protocol**: When calling the REST API or sandbox port directly, `429 Too Many Requests` will be returned, indicating that the quota limit has been reached.
* **Python SDK**: Method call will throw `RateLimitException` exception.

> If you encounter frequency limitation issues, please contact our team for quota adjustment support.

## Best Practices

> **How ​​to deal with restrictions? **
1. **Exponential Backoff**: When `RateLimitException` is captured, it is recommended to use the exponential backoff algorithm (Exponential Backoff) to try again.
2. **Destroy in time**: For sandboxes that are no longer in use, be sure to explicitly call `.kill()` to release the concurrency quota.
3. **Batch merge**: Try to merge file reading and writing or related command execution to reduce frequent API round-trips in a short period of time.