Possible memory leak when used with ASP.NET Core DI #148
Description
While investigating an issue with high CPU usage, a memory dump was taken of a long-running ASP.NET Core 6 server application (see below) that uses the PubNubPCL library.
The heap has a lot of retained instances of objects related to the PubNub API, particularly PNConfguration which, after about 3 days of continuous operation, occupies 107MB of heap space.
I suspect the issue lies with the lifetime of the PubNub client in the DI container. We have a thin wrapper around the PubNub API that we inject with a Transient lifetime. The constructor creates a new PubNub object and configures it every time it is injected.
Based on the large number of PubnubApi.ConcurrentDictionary objects also on the heap, I believe the PubNub client is supposed to have a Singleton lifetime, but I could not find any guidance in the documentation regarding DI containers.
Can you confirm the expected lifetime of the PubNub client? Is it expected to be a Singleton, or can it be constructed as needed in a long-running service?
Here is the relevant part of the heap analysis created with dotnet-dump. The command used was dumpheap -stat -live (statistical analysis of live objects only).
MT Count TotalSize Class Name
[snip]
00007f832b80f308 235225 7527200 PubnubApi.ConcurrentDictionary`2[[System.String, System.Private.CoreLib],[System.Net.HttpWebRequest, System.Net.Requests]]
00007f83294d3a10 235225 7527200 PubnubApi.NewtonsoftJsonDotNet
00007f832b827460 1 7786800 System.Collections.Generic.Dictionary`2+Entry[[System.String, System.Private.CoreLib],[PubnubApi.ConcurrentDictionary`2[[System.String, System.Private.CoreLib],[System.Net.HttpWebRequest, System.Net.Requests]], PubnubPCL]][]
00007f832b826520 1 7786800 System.Collections.Generic.Dictionary`2+Entry[[System.String, System.Private.CoreLib],[PubnubApi.EndPoint.TokenManager, PubnubPCL]][]
00007f832b8262a0 1 7786800 System.Collections.Generic.Dictionary`2+Entry[[System.String, System.Private.CoreLib],[PubnubApi.IPubnubLog, PubnubPCL]][]
00007f832b826020 1 7786800 System.Collections.Generic.Dictionary`2+Entry[[System.String, System.Private.CoreLib],[PubnubApi.PNConfiguration, PubnubPCL]][]
00007f83294d45b8 235225 13172600 PubnubApi.EndPoint.TokenManager
00007f8325678080 4495 13808408 System.Int32[]
00007f832b80b6a0 470451 15054432 PubnubApi.ConcurrentDictionary`2[[System.String, System.Private.CoreLib],[System.Boolean, System.Private.CoreLib]]
00007f832b8276e0 2 15573600 System.Collections.Generic.Dictionary`2+Entry[[System.String, System.Private.CoreLib],[PubnubApi.ConcurrentDictionary`2[[System.String, System.Private.CoreLib],[System.Boolean, System.Private.CoreLib]], PubnubPCL]][]
00007f8325e89150 708563 17005512 System.Threading.Timer
00007f8326aada58 708775 17010600 System.Threading.TimerHolder
00007f83255c5290 708988 17015712 System.Object
00007f832b826f38 235225 18818000 System.Collections.Generic.Dictionary`2[[System.String, System.Private.CoreLib],[System.Net.HttpWebRequest, System.Net.Requests]]
00007f8325ba2890 17 33503088 System.Collections.Generic.Dictionary`2+Entry[[System.String, System.Private.CoreLib],[System.String, System.Private.CoreLib]][]
00007f83294d4898 708502 34008096 PubnubApi.EndPoint.TelemetryManager
00007f832a8c9368 470451 37636080 System.Collections.Generic.Dictionary`2[[System.String, System.Private.CoreLib],[System.Boolean, System.Private.CoreLib]]
00007f8325abac58 38012 39857914 System.Byte[]
00007f83266827b8 708749 45359936 System.Threading.TimerCallback
00007f8326682678 708860 68050560 System.Threading.TimerQueueTimer
00007f832567d2e0 740815 68704692 System.String
00007f83294d2820 708502 107692304 PubnubApi.PNConfiguration
Total 7963348 objects