Recently we ran in to issues with regard to cache propagation. The use case is as follows:
1. Client does a get on a resource, and the server returns the resource and an Etag 2. Client modifies the resource and does a PUT with an If-Match header. 3. Repeat 1 and 2 several times Sometimes 2 succeeds, sometimes 2 fails with the origin service returning a 415 error (as per the HTTP spec). The reason for this is that when you do a PUT on a resource the ATS cache will purge any item under that URL. BUT, it takes time to propagate that change throughout the cluster. We have done gets against the cluster for an updated resource and seen stale data returned as much as 10 seconds after the PUT was completed. The question I have is does anybody know what the upper bound is for propagation delay on cache updates as a consequence of a PUT throughout the cluster such that all nodes are consistent with regard to the updated item?
