Hi @muzammil_shahid ,
Welcome to SonarSource Community! 
In your sonar.log snippet, I see this:
Please check your es.log file. What appears in there?
Please also check https://docs.sonarqube.org/latest/requirements/requirements/ and Hardware recommendations as well.
Lastly, please try an Elasticsearch reindex as described in https://docs.sonarqube.org/latest/faq/:
How do I trigger a full ElasticSearch reindex?
Currently, the only way to force a reindex is to:
- Stop your server
- Remove the contents of the $SQ_HOME/data/es7 directory
- Start your server
Before doing this, you should be aware first that processes are in place on the SonarQube side that out-of-sync indices are detected and corrected, and second that a full re-index can be quite lengthy depending on the size of your instance.
Joe