Dispatcher behavior during concurrent request of uncached or expired resources

[benjamin_mord]

Can Adobe please confirm the exact behavior of dispatcher during concurrent requests for the same page, when that page is either expired or not yet cached? Will Adobe CQ receive multiple concurrent requests for the same resource? Or will dispatcher only request a rerender once, have subsequent requests wait until that has completed, and then serve the same response to all requests which had accumulated up to the completion of the rerender? Or, for those resources which have expired, will dispatcher serve the previously cached version to concurrent incoming requests while it is waiting for CQ to complete rerendering it?

For example, mod_cache and varnish documentation are both very explicit about the mechanisms they offer to ensure that the origin server (CQ) never receives concurrent requests for the same resource, but I am unable to find this information in the current dispatcher documentation. Any clarification is greatly appreciated!

[aanchal-sikka · Accepted solution]

1. Serving Requests from Cache:

   • While the cache is being updated, the dispatcher might continue serving the previous (stale) version of the asset to incoming requests to avoid causing delays in responding to clients. For details, refer to https://experienceleague.adobe.com/docs/experience-manager-learn/dispatcher-tutorial/chapter-1.html?... 

2. Parallel Dispatchers:

   • If there are multiple dispatchers in a distributed environment, each dispatcher may independently handle the cache invalidation and update process.

[kautuk_sahni]

@benjamin_mord Did you find the suggestions from users helpful? Please let us know if more information is required. Otherwise, please mark the answer as correct for posterity. If you have found out solution yourself, please share it with the community.