Bug Fixes: race conditions where the System.Threading.Time callbacks can be called before constructor returns. #1439
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…structor returns. Can cause exceptions that can't be caught and crash the running app.
Contributor
@moorecj, that line of code in the exception is not a timer dispose. Is it?My bad. Just noticed the version: 8.0.11 see https://github.com/sipsorcery-org/sipsorcery/blob/v8.0.11/src/net/ICE/RtpIceChannel.cs#L1184 |
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Author
Yeah I was on version 8.0.4 when I saw the error. |
Member
|
Thanks for the PR. I wasn't aware of that behaviour. Seems like a bit of a flaw in the Timer implementation. |
sipsorcery
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Jul 14, 2025
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Bug: Instances of System.Threading.Timer can start a callback before the constructor of the Timer has returned. Particularly when the dueTime parameter is set to 0. In certain cases the timer attempts to dispose itself via its callback. This can cause exceptions that will crash the running app.
This was witnessed in the RtpIceChannel.CheckIceServers
Application: App.exe CoreCLR Version: 8.0.1124.51707 .NET Version: 8.0.11 Description: The process was terminated due to an unhandled exception. Exception Info: System.NullReferenceException: Object reference not set to an instance of an object. at SIPSorcery.Net.RtpIceChannel.CheckIceServers(Object state) in C:\Git\App\Common\sipsorcery\src\net\ICE\RtpIceChannel.cs:line 1184 at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state) --- End of stack trace from previous location --- at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state) at System.Threading.TimerQueueTimer.Fire(Boolean isThreadPool) at System.Threading.ThreadPoolWorkQueue.Dispatch() at System.Threading.PortableThreadPool.WorkerThread.WorkerThreadStart()I created a simple app to illustrate the issue:
The instances of the System.Threading.Timer have been changed to use the pattern of starting the timer after the contructor has returned. This ensures that the race is avoided.