In scenarios such as flash sales and ticket grabbing, a large number of client requests are redirected to origin servers. To prevent origin servers from being overwhelmed due to traffic spikes, you can use the Waiting Room feature of Dynamic Content Delivery Network (DCDN) to redirect requests to origin servers based on a specific proportion. Excess requests are added to a waiting room to protect origin servers and reduce loads on origin servers.
Overview
The Waiting Room feature of DCDN uses queues to manage a large number of concurrent requests. When users request a resource, the Waiting Room feature limits the number of concurrent requests to prevent backend servers from being overloaded and improve system stability and performance. The Waiting Room feature provides:
Request queuing: If your website is experiencing high concurrency, DCDN routes excess requests to a waiting room and queues the requests based on the first-in first-out (FIFO) rule.
Traffic control: The Waiting Room feature can limit the queuing duration of each request to ensure that the loads on backend servers are acceptable.
The Waiting Room feature enables DCDN to control the concurrency based on the system load, ensure server stability, and deliver better user experience. This feature is suitable for scenarios such as traffic spikes, high concurrency, and centralized resource access.
Prerequisites
This feature is in beta release. To use this feature, submit a ticket.
Clients must support cookies.
Procedure
Log on to the DCDN console.
In the left-side navigation pane, click Domain Names.
- On the Domain Names page, find the domain name whose acceleration region you want to change and click Configure.
In the left-side navigation tree of the domain name, click Access Control.
Click the Waiting Room tab.
Click Add. In the dialog box that appears, configure the parameters. The following table describes the parameters.
Parameter
Description
Matching URI
The Waiting Room feature takes effect on requests that match the value of this parameter. Regular expressions are supported. For example,
.*specifies that all requests are matched.Origin Fetch Ratio
The proportion of requests in the waiting room that can be redirected to the origin server. For example, the value 100 specifies that all requests in the waiting room can be redirected to the origin server. This setting is equivalent to disabling the Waiting Room feature.
Queuing Duration (Seconds)
The period of time during which a request stays in the waiting room before it is removed from the waiting room.
Leave Wait Time (Seconds)
The period of time during which subsequent requests from a user can be redirected to the origin server without queuing after a request from the user is removed from the waiting room.
Waiting Page
The URL of the page that is displayed when user requests are in the waiting room. The URL cannot be within the value of the Matching URI parameter. Otherwise, an infinite loop occurs.
Click OK.