Lock contention in ChildRequestTrackingSuppressionModule.AddRequestToDictionary()

[paveliak]

We had an incident with our service and while analyzing Perfview I observed severe lock contention with ConcurrentDictionary.AcquireAllLocks() coming from ChildRequestTrackingSuppressionModule.AddRequestToDictionary

ConcurrentDictionary.Count property acquires all locks which might cause lock contention under heavy load. Given that amount of items in this dictionary does not have to be exact please consider having a separate counter that you increment when adding item to the dictionary and taking the decision to create new dictionary basing on that counter (instead of Count property)

Repro Steps

Actual Behavior

Expected Behavior

Version Info

SDK Version : Microsoft.AI.Web, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35
.NET Version : 4.7.2
How Application was onboarded with SDK(VisualStudio/StatusMonitor/Azure Extension) :
OS : Windows server 2016
Hosting Info (IIS/Azure WebApps/ etc) : Azure, VM running IIS, we use VM scale sets

[cijothomas]

@paveliak Thanks for reporting! Would you be willing to make a contribution to this?
cc: @TimothyMothra

[paveliak]

@cijothomas I'll take a stab fixing it.

[github-actions]

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