SharePoint Content Source Stuck on Starting or Completing status

Irrespective of SharePoint version like 2010 or 2013, if you experience issue with content source is stuck on "Starting" even after few hours you started the crawl or stuck on "Completing" hours after actually completing the crawl. 

Cause: your crawler queue is high and items are taking long time to process it causing repository latency on content sources:

In crawl logs, you might see below error:

Processing this item failed because of a XML parser error.

Processing this item failed because of a IFilter parser error.

Application Logs >>Event Viewer:

Log Name:      Application

Source:        Microsoft-SharePoint Products-SharePoint Server Search

Date:          XXX

Event ID:      1330

Task Category: Crawler:Gatherer Service

Level:         Warning

Keywords:     

User:          XXX

Computer:      XXX

Description:

The search service stopped the filter daemon because it was consuming too many resources. A new daemon will automatically be started, and no user action is required.

Solution:

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Step that could help you to overcome this situation:

Restart the Search service:

Start > Run > Services.msc
Restart service - "SharePoint Server Search14"

OR

Executing the following command (recommended one)
net stop Osearch14 && net start Osearch14