File prefetch refers to proactively fetching content from the origin server to CDN servers. It is especially useful when the CDN does not yet have the content cached, or when the cached content has expired, and you do not want end-user access speed to be affected.

For example:

• When there is no cache on the CDN and a user request reaches a CDN edge server, the CDN must first request the content from the origin server. After the CDN retrieves the content, it returns it to the user. In this case, the user experiences slower access because they must wait for the CDN to fetch the file from the origin.
• If you use the file prefetch feature in advance, the CDN proactively fetches and caches the file from the origin server. Then, when a user request reaches the CDN edge server, the content can be returned immediately without waiting for an origin fetch, significantly improving access speed.
• From the origin server’s perspective, file prefetch can also reduce the number of CDN origin fetches, thereby reducing origin load.

File prefetch is particularly suitable for large-scale events, such as software package releases, game updates, and similar scenarios. By prefetching resources to the CDN before the event starts, a high volume of concurrent user requests after the event begins will not significantly affect user access speed or origin server load.

How to Create a File Prefetch Task

1. Before creating a task, make sure that you have purchased an Atomile CDN product, configured acceleration services for your domain, and contacted Atomile technical support to enable file prefetch permissions.
2. Log in to the Atomile Console, and in the left-side menu go to Products > Application > Content Management > Prefetch, then click Create Task.
3. Configure the file prefetch task as needed.

URL Text Box

Enter the URLs of the files you want to prefetch.

• The domain of each URL must be a domain that has acceleration service enabled on Atomile.
• Enter only one URL per line. Multiple URLs must be entered on separate lines. Up to 500 URLs are allowed per task.
• URLs must begin with http:// or https:// and must be complete, specific file URLs. Regular expressions and directory paths are not supported. For example: http://www.a.com/image/test.png
• The maximum length of each URL is 2000 characters.
• If a URL contains Chinese characters, submit the escaped URL using UTF-8 encoding.
• By default, the daily limit is 20,000 prefetched URLs, and the total file size limit (also called prefetched space) is 5000 MB. If the total number of URLs in submitted tasks reaches 20,000, or the total prefetched file size reaches 5000 MB, you cannot create additional file prefetch tasks on that day.
• You can view the current remaining URL quota and remaining prefetch space in the console.
• If you need a higher quota, contact Atomile technical support.

Prefetch Time

• Immediate: The prefetch task is dispatched immediately after submission.
• Reserve: You can set a scheduled prefetch time. The task is not dispatched immediately after submission, but waits until the scheduled time.

How to Query File Prefetch Tasks

Log in to the Atomile Console, and in the left-side menu go to Products > Application > Content Management > Prefetch, then click Task Query.

You can query file prefetch tasks by time, domain, and URL.

Task Status

• run: In progress
• success: Completed successfully
• wait: Queued
• failure: Failed
• cancel: Canceled