Troubleshooting ASP.NET and IIS Scalability Hotspots
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Running ASP.NET applications on IIS? Do you understand how requests are processed by every component involved: IIS Native, IIS Modules, and ASP.NET? Scaling any type of application requires you to understand the inner workings of IIS and ASP.NET so queues and pools don’t become a bottleneck in your end-to-end execution flow. Join us for this webcast that shows you how to identify performance and scalability hotspots under different load conditions. You'll learn: How communication flows between browser, IIS, ASP.NET and back-end services including database How to monitor and tweak IIS and ASP.NET queues and pools to achieve optimal performance How to troubleshoot performance hotspots in IIS, Native and Managed Modules and ASP.NET How to identify synchronization issues in multi-threaded applications You will leave with specific ideas of where to start optimizing your queues, pools, and code implementation.
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Troubleshooting ASP.NET and IIS Scalability Hotspots
- 1. Please Standby: Webcast to Begin Shortly Unable to listen via your speakers? Dial in: Toll Free: (877) 309-2074 Access Code: 119-063-034 International: Click “telephone” in audio section, then click “additional numbers” Troubleshooting ASP.NET and IIS Scalability Hotspots
- 2. Confidential, Dynatrace, LLC Asad Ali Director, Product Specialist Dynatrace Troubleshooting ASP.NET and IIS Scalability Hotspots
- 3. • Real Use Cases • IIS/ASP.net Metrics • High Latency Application Example • Synchronization Issues • Sharepoint Example Agenda
- 4. Real Use Cases Confidential, Dynatrace LLC
- 5. Online Room Service 22% spent in IIS
- 6. Online Room Service Tip: Elapsed Time tells us WHEN a Method was executed!
- 8. Online Banking: Slow Balance Check 1.69m (=101s!) To Check Balance! 87% spent in IIS
- 9. Time really spent in IIS Tip: Elapsed Time tells us WHEN a Method was executed! Finding: Thread 32 in IIS waited 87s to pass control to Thread 30 in ASP.NET Tip: Thread# gives us insight on Thread Queues / Switches
- 10. • Modules Installed • IIS/ASP.net Metrics Confidential, Dynatrace LLC What To Look
- 13. Arrival Rate • Rate at which requests are arriving in the queue • Perfmon Counter: Http Service Request QueuesArrivalRate • Should be >= W3WP_W3SVCRequests / sec Confidential, Dynatrace LLC IIS/ASP.net Metrics
- 14. MaxQueueItemAge • Incoming requests are waiting at this long to be processed • Perfmon Counter: Http Service Request QueuesMaxQueueItemAge Confidential, Dynatrace LLC IIS/ASP.net Metrics
- 15. CLR ThreadPool Queue • Requests are queued if all the CLR threads are busy • Perfmon Counter: ASP.NET v4.0.30319/Requests Queued • Symptom: ASP.net returns 503 Service Unavailable Confidential, Dynatrace LLC IIS/ASP.net Metrics
- 16. Number of Free DB Connections • Number of free ADO.net connections available • Perfmon Counter: .Net Data Provider for SqlServer/NumberOfFreeConnections • Alert: If value == 0 Confidential, Dynatrace LLC ADO.Net Metrics
- 17. Number of Active DB Connections •Number of Active ADO.net connections •Perfmon Counter: .Net Data Provider for SqlServer/NumberOfActiveConnections Confidential, Dynatrace LLC ADO.Net Metrics
- 18. High Latency Application Example Confidential, Dynatrace LLC
- 20. Too Many Queries crash Undersized Pools Confidential, Dynatrace LLC
- 21. Online Banking: Slow Balance Check 1.69m (=101s!) To Check Balance! 87% spent in IIS 600! SQL Executions
- 22. SQL Executions Finding: EVERY SQL statement is executed on ITS OWN Connection! Tip: Look at “GetConnection”
- 23. Lesson Learned ASP.NET Worker Thread Pool Sizing! DB Connection Pools More Efficient SQL
- 24. SQL Executions Finding: EVERY SQL statement is executed on ITS OWN Connection! Tip: Look at “GetConnection”
- 25. SQL Executions Confidential, Dynatrace LLC #1: Same SQL is executed 67! times #2: NO PREPARATION because everything executed on new Connection
- 26. • Idle vs. Busy Threads • # SQLs / Request • # GetConnection Confidential, Dynatrace LLC Tips To Apply
- 29. Load vs. Memory vs Response Time vs. Threads Confidential, Dynatrace LLC Increasing Memory Avg Response Time: Increases over Time Max Response Time correlates with # Threads Max Response Time correlates with # Threads Load: System can’t handle constant load over time # of Worker Threads increase with constant load Layer Breakdown: Performance Problem is in their own code (Sync Time)
- 30. 96% Synchronization Time Confidential, Dynatrace LLC Monitor.Enter: By far biggest performance contributor Called from GetStatus and _GetDebugStatus. Why also from Debug method? Bug?
- 31. Excessive file attribute access second hotspot Confidential, Dynatrace LLC Can FileExist check be cached to reduce File Access? File Access next hotspots
- 32. • # of Threads vs # Incoming Requests • Time Spent in Sync • Time Spent in I/O Confidential, Dynatrace LLC Tips To Apply
- 34. Frustrated user report bad response times Confidential, Dynatrace LLC Frustrated User Slow Page Load caused by Browser JS Time Slow Page Load caused by Server-Side Processi
- 35. Really slow page Confidential, Dynatrace LLC 6.8s to deliver Default.aspx page Involved Web Parts Most of the Time spent In waiting
- 36. WebPart uses multiple parallel threads Confidential, Dynatrace LLC Async Threads are busy with I/O
- 37. First remote call is very slow Confidential, Dynatrace LLC Web Service call by ContentEditorWebPart HttpWebRequests uses ServicePoint internally First Web Serivce Requests takes 5.8s to return
- 38. Thread limit lets all other threads wait! Confidential, Dynatrace LLC We have 10 parallel calls in our background threads The other background threads spend their time “waiting” in the ServicePoint
- 39. Solution: Change Defaults Confidential, Dynatrace LLC
- 40. • Review installed IIS modules • Pay attention to IIS/ASP.net metrics • Optimize thread synchronization • Reduce I/O • Analyze SQL statements • Use DB Connection Pool Optimally Confidential, Dynatrace LLC Tips To Apply
- 41. Confidential, Dynatrace LLC Free Trial: bit.ly/dttrial
- 42. Thank you! Time for Q&A
Editor's Notes
- Looking from left to right, we see …..
- Got lot of complaints. High risk of losing customers. Always a bank around the corner.
- Looking from left to right, we see …..
- Http Service Request Queues\ArrivalRate" counter exceeds the"W3WP_W3SVC\Requests / sec" counter for the application pool's worker process over a period of time. This basically implies that more requests are coming into the system than are being processed, and this always eventually results in queueing.
- "Http Service Request Queues\MaxQueueItemAge" performance counter increasing. This means IIS is falling behind in request processing, so all incoming requests are waiting at least this long to begin getting processed.
- ASP.NET queues all incoming requests to the CLR threadpool. Behavior: If all CLR threads are busy, requests can queue up here up to the configuredprocessModel/requestQueueLimit. When there are more than this many total requests (executing + queued), ASP.NET returns 503 Service Unavailable. NOTE: Any async modules also re-post requests to the CLR threadpool, so requests can become “re-queued” again later in the request processing.
- In Classic mode, ASP.NET will queue all incoming requests to the per-application queue when there are not enough threads. Behavior: The threads available for request processing are determined by available threads in the CLR thread pool, minus the reserved threads set by the httpRuntime/minFreeThreads andhttpRuntime/minFreeLocalThreads attributes. NOTE: This queue has poor performance, and does not guarantee FIFO in application pools with multiple applications (because threads are shared between multiple apps, so a single app can starve the other applications of available threads).
- Add title – Tips to apply
- http://apmblog.compuware.com/2013/03/12/net-and-sharepoint-performance-dont-let-default-settings-ruin-your-end-user-experience/
- Add title – Tips to apply