I am hoping to understand the cause of this and hopefully find a solution - I have looked at every possible solution, but haven't been able to fix it.

Sitecore v8.2 update 3 using SOLR.

In my current set up, Core DB is not shared between CM and CD servers. Index update strategy for web db is onPublishEndAsync.

I created a new item and published it. Item was published to the web db, but the item didn't appear in the index. I thought perhaps core db might have a play in this. So, I changed the settings as follows.

1. Both CM and CD servers to share the core db.
2. Set up the InstanceName and Publishing.PublishingInstance instance name on CM and CD servers.
3. Updated the eventqueue polling interval to 1 minute.
4. Changed the crawling log to add debug information.

Index is still not updated and the message that I see in the logs is 'Event Queue is empty. Incremental update returns'

All the events are processed in the event queue according to EventQueueStats.aspx

What could be the cause of it?

Edit:

I kicked off index rebuild from 'developers' tab, but even that didn't update the web index. The core name and the ID is correct.

Job ended: Index Rebuild (sitecore_web_index) (units processed: )

Noticed the following error in the crawling logs

2160 14:36:31 INFO  Crawler [sitecore_web_index]: Processed 144000 items
6020 14:36:31 WARN  Crawler : AddRecursive DoItemAdd failed - {253432DD-6A2D-4908-A4C2-C3ABB46736DC}
Exception: SolrNet.Exceptions.SolrConnectionException
Message: The request was aborted: The request was canceled.
Source: SolrNet
   at SolrNet.Impl.SolrConnection.PostStream(String relativeUrl, String contentType, Stream content, IEnumerable`1 parameters)
   at SolrNet.Impl.SolrConnection.Post(String relativeUrl, String s)
   at SolrNet.Impl.SolrBasicServer`1.SendAndParseHeader(ISolrCommand cmd)
   at Sitecore.ContentSearch.SolrProvider.SolrBatchUpdateContext.AddRange(IEnumerable`1 group, Int32 groupSize)
   at Sitecore.ContentSearch.SolrProvider.SolrBatchUpdateContext.AddDocument(Object itemToAdd, IExecutionContext[] executionContexts)
   at Sitecore.ContentSearch.SitecoreItemCrawler.DoAdd(IProviderUpdateContext context, SitecoreIndexableItem indexable)
   at Sitecore.ContentSearch.HierarchicalDataCrawler`1.CrawlItem(T indexable, IProviderUpdateContext context, CrawlState`1 state)

Nested Exception

Exception: System.Net.WebException
Message: The request was aborted: The request was canceled.
Source: System
   at System.Net.ConnectStream.CloseInternal(Boolean internalCall, Boolean aborting)
   at System.Net.ConnectStream.System.Net.ICloseEx.CloseEx(CloseExState closeState)
   at System.Net.ConnectStream.Dispose(Boolean disposing)
   at System.IO.Stream.Close()
   at SolrNet.Impl.SolrConnection.PostStream(String relativeUrl, String contentType, Stream content, IEnumerable`1 parameters)

Nested Exception

Exception: System.IO.IOException
Message: Cannot close stream until all bytes are written.
Source: System
   at System.Net.ConnectStream.CloseInternal(Boolean internalCall, Boolean aborting)

Would that have interfered with index rebuild or optimization?