Our Learning on Publishing Sitecore Sublayouts

After we started using Web Deploy for publishing sublayouts on our multisite environment, we were getting random caching issues on our CD servers. We have multiple publishing target databases and load balanced multiple CD servers. So, as I mentioned in my previous blog, when a sublayout is published, it is published with help of Web Deploy to one server and then the sublayout is replicated to all other servers using DFS.

What kind of issues we found?

Sometimes we found that the published sublayout gets reflected on few servers, on few servers we still get older content. But surprisingly, the published sublayout was replicated on all servers and still we were getting different output from different servers. So, when this happens, we used to clear caches on servers where such issues occurred assuming this might be because of Sitecore caching issues, later on we found workaround to publishing those sublayouts again after 1 or 2 minutes.

Now you will understand how critical it would be to publish sublayouts and getting them reflected on live servers quickly to make go-lives, re-brandings, news releases or press releases successful in one go.

Note: We found this only for those Cacheable sublayouts.

Our learnings to fix such issues

1. Web Deploy publishing should be synchronous.

We analyzed below sequence happened rarely.
  1. First we started publishing, so as per my previous blog, Web Deploy will start deploying sublayout in async mode (By default Web Deploy is configured on Sitecore is asynchronous). So, sublayout item publishing and sublayout physical file deploying are done in parallel.
  2. So, chances that item gets published before sublayout file is copied.
  3. Now, item is published, so CD servers will invoke "publish:end:remote" event and clear HTML (sublayout) cache.
  4. Now, before the new published sublayout file gets deployed to CD server, end-user requested a page which uses the same sublayout. So, the HTML cache will be generated again for older Sublayout.
  5. Now, Web Deploy sent a new Sublayout. (So, we have HTML cache of older sublayout)

Learning: Sublayout publishing should always be synchronous, so publishing will get on hold till the sublayout is not deployed to the CD server, which can be configured in WebDeploy.config as below.
<event name="publish:begin">
 <handler type="SitecoreTactics.Publishing.BeginWebDeploy, SitecoreTactics" method="PublishSublayouts">
  <tasks hint="list:AddTask">

2. Target Database should be the first publishing target.

We have 3 publishing targets say, web, web-2, web-3. Means, any publishing will be done in this sequence itself. Earlier we found the target database inside the WebDeploy.config was set as last publishing target, means web-3. We might have done this in past to make sure the item is published before sublayout getting deployed.

But, as per our recent experiences and findings, we should keep it as first publishing target. So, in our case, it should be web. This will help us when there are multiple servers in DFS, so when DFS is taking some more time in replicating to other servers. So,  for reducing such chances of delayed Sublayout deploy, we should keep web as the publishing target in WebDeploy.config as below.
<tasks hint="list:AddTask">  
 <default type="Sitecore.Publishing.WebDeploy.Task">  
   <!-- It should be the first Publishing target database -->  

3. We can make few seconds delay in clearing HTML Cache.

If we have done above cases, there are no chances that the CD server where Web Deploy is sending Sublayout file will get any issues. But just consider a worst case where DFS is taking more time to replicate sublayouts to other servers. So, chances that HTML Cache will get cleared before the sublayout replication is done.

To avoid such cases, we can add a delay of few seconds, say 2 or 3 seconds before clearing HTML Cache (Only when the sublayouts are getting published)

Finally, we have hassle free one-time Sublayout publishing working without any caching issues very well! I'm sure this will be helpful to others who are facing same kind of issues.

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