Sitecore Core database index Update issue - indexing

Question

We are using a multi server environment with 1 CMS and 2 CD configuration. The CORE and WEB of CMS are being shared by CD 2 only and CD 1 as its own web and core.
The issue is- log files of CD2 are capturing the below mentioned error:
ManagedPoolThread #14 00:00:05 INFO Job started:Index_Update_IndexName=sitecore_core_index
ManagedPoolThread #14 00:00:05 ERROR Exception
Exception: System.Reflection.TargetInvocationException
Message: Exception has been thrown by the target of an invocation.
Source: mscorlib
at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor)
at System.Reflection.RuntimeMethodInfo.UnsafeInvokeInternal(Object obj, Object[] parameters, Object[] arguments)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
at System.Reflection.MethodBase.Invoke(Object obj, Object[] parameters)
at (Object , Object[] )
at Sitecore.Pipelines.CorePipeline.Run(PipelineArgs args)
at Sitecore.Jobs.Job.ThreadEntry(Object state)
Nested Exception
Exception: System.InvalidOperationException
Message: Configuration
Source: Sitecore.ContentSearch.LuceneProvider
at Sitecore.ContentSearch.LuceneProvider.LuceneIndex.EnsureInitialized()
at Sitecore.ContentSearch.LuceneProvider.LuceneIndex.CreateUpdateContext()
at Sitecore.ContentSearch.LuceneProvider.LuceneIndex.PerformUpdate(IEnumerable`1 indexableUniqueIds, IndexingOptions indexingOptions)
As we researched, we found that this type of error gets captured when issue with Core database index update. Further this was also confirmed by crawling log and checking the configuration within the \App_Config\Include\Sitecore.ContentSearch.Lucene.Index.Core which has this job defined for Index update.
Crawling log entries getting captured
INFO [Index=sitecore_core_index] IntervalAsynchronousUpdateStrategy executing.
INFO [Index=sitecore_core_index] Event Queue is forced
As a next step we took following steps but problem still exist:
Deleted old Core indexes and rebuilt for CMS and CD2 both.
My Questions:
If we have same core for CMS and CD2 then do we require index rebuilt for both environment because as per my info the index get saved in disk.
Secondly we are facing caching issue for CD2 only, is this related to index update.
Thirdly the config details Sitecore.ContentSearch.Lucene.Index.Core are present in CMS and CD2 also so is this responsible for these exception as two processs are updating indexes for the same Core indexes.
Lastly we have a separate core and web for CD1 with replication enabled but we still see these error being captured in CD1 as well. We are seeing this errors from past few months and recently the frequency of errors has increased due to which it is eating a huge chunk of physical memory in CD2 and causing application higher response time.

Answer 1

I figured out what the problem in my environment was. Look in your log file and before you seeing that exeption, do you see the following:
ManagedPoolThread #11 10:07:24 INFO Loading Dictionary from database. Domain: 'Dictionary'. Language: 'en'.
ManagedPoolThread #11 10:07:24 ERROR Error saving {sitecore file path}\Website\temp\dictionary.dat.
Exception: System.IO.IOException
Message: The file '{sitecore file path}\Website\temp\dictionary.dat' already exists.
Source: mscorlib
at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
at System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, Int32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions options, SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy, Boolean useLongPath, Boolean checkHost)
at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, FileOptions options, String msgPath, Boolean bFromProxy)
at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize)
at Sitecore.Globalization.Translate.Save()
If so, delete that and restart your site. This should fix the issue that you are seeing.