Merge Agent hanging after a large request

• Banana-823045

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  August 29, 2015 at 3:14 pm

  #320149

  Using merge replication + web synchronization, I have a situation when there are large amount of data changes to upload to the publisher, Merge agent would create a large request and send it over. The publisher gets it and is able to work on it. After few minutes it has finished but (I assume) the connection has been dropped. At the subscriber's side, it appears that the merge agent is hung. The output would look like something like this:

  Upload request size is XXX bytes.

  Uploaded a total of 100 chunks.

  Uploaded a total of 200 chunks.

  Uploaded a total of 211 chunks.

  The request message was sent to 'https://myserver.com/Replisapi.dll'

  Normally, when the publisher finishes working, the merge agent then continues processing. But when it takes more than few minutes (it seems to break about at 2 or 3 minutes), merge agent will hang as long as the InternetTimeout setting is (currently 20 minutes) before finally failing and retrying.

  But that's not right. The publisher was done and can't communicate back to the merge agent (presumably because the connection was dropped). As a result, merge agent will try to re-enumerate changes on top of giving appearance that it's hung.

  I've already fiddled with settings such as MaxUploadChanges, UploadGenerationsPerBatch, UploadReadChangesPerBatch, and UploadWriteChangesPerBatch. However, none of those setting actually ensure that the request message is too large. It has helped in breaking up the changes into separate batches (e.g. processing a single table rather than all tables) which results in more frequent updates and thus avoid the problem.

  However, when a single table has several changes, it is still lumped into one large request which then takes more than 2-3 minutes to process on publisher's side and thus I still end up with the same symptom of merge agent hanging.

  Is there anything else I could try to get merge agent to keep its connection alive even during processing a large request?

  Thanks in advance.