we have developed an application using ASP.NET/C# MVC 4.0, SQL SERVER 2012 DB, Entity Framework, WCF Service. application website is hosted on IIS 10 and the operating system used is Windows Server 2016 and this is standalone WEB server dedicated for our project. application WCF web service is hosted using Windows Service and this is standalone APP server dedicated for our project. application database is hosted on SQL Farm and this is a common database server, where other projects databases (more than 60) are also hosted.
application is already running absolutely fine in PROD environment from couple of years. but suddenly from couple of months, we started facing as intermittent issue and i.e. application slow response
There are no errors, but the response time is too long, and sometimes it doesn't respond either, the browser keeps waiting for the web server. customer has complained that his web application gets slow sometimes. It happens at random times, the system just gets slow then after few hours (2-3) it gets back on track with normal response times. this slowness issue is affecting only to one specific MVC View, whereas other MVC views are rendering correctly at the same time when slowness issue occurs.
error handling is already in place in the .net code, but nothing gets logged in error log file. also DBA has confirmed that there are no issues on the SQL Farm and none of the other projects apart from us has reported slowness issue whose database is also hosted on the SQL Farm.
when tried to reproduce the same issue on UAT with the same PROD database copy & same user, was not able to reproduce it. UAT environment is exactly similar for WEB & APP server. only in case of UAT database server, we do not have SQL Farm here. we have standalone database server dedicated for our project.
here tried doing some R&D and verified few things, but still unable to resolve the issue. so could you please guide me here that what should i do/verify to resolve this issue.
thank you in advance for your inputs.