We have a n-tier (.net) web application where we have a Web tier -> App tier -> Database.
Everything worked fine until we went for load testing (using jmeter). When we simulated 100 concurrent users, after 3 -4 min. jmeter started logging SocketException, connection reset. When we checked application logs (we logs all the exceptions inside application) and system events, we could not find anything.
We have not taken any special measures for performance on web tier. But on App tier which is a wcf application, we have used per-call/multiple concurrency. We have used following configuration on app tier:
<serviceThrottling
maxConcurrentCalls = "200"
maxConcurrentSessions = "200"
maxConcurrentInstances = "200"/>
. . .
<binding name="defaultNetTcpBinding" closeTimeout="00:10:00" sendTimeout="00:10:00" receiveTimeout="00:10:00" openTimeout="00:10:00" maxReceivedMessageSize="2147483647" maxBufferPoolSize="2147483647"
maxConnections="200" listenBacklog="200">
Apart from this issue, our App tier usage is also on higher side (50-60%). Following are the configuration of our 3 VMs (one for each tier)
Web Server (Quantity = 1) Processor Intel Xeon CPU X5675 @3.07 GHz 2.19 GHz
Number of Cores (Virtual) 8
RAM 8GB
Operating System Windows Sever 2012 Standard
Processor Type 64 Bit
Softwares Installed NET Framework 4.5
App Server (Quantity = 1) Processor Intel Xeon CPU X5675 @3.07 GHz 3.07 GHz
Number of Cores (Virtual) 8
RAM 8GB
Operating System Windows Sever 2012 Standard
Processor Type 64 Bit
Softwares Installed NET Framework 4.5
DB Server (Quantity =1) Processor Intel Xeon CPU E7-4830v2 @ 2.20 GHz 2.19 GHz
Number of Cores (Virtual) 8
RAM 8GB
Operating System Windows Sever 2012 Standard
Processor Type 64 Bit
Softwares Installed Microsoft SQL Sever 2014