Question

If I have async logging turned on in nlog.config, where is the ThreadID captured?

Context: I’m starting a greenfield project using .NET, Rx, and TPL Dataflow (a.k.a. TDP). It will make heavy use of async operations and background work queues.

Goal: In my logging I’d like to capture the ManagedThreadId where the work is being performed, and when work is being done in parallel (easy to get wrong in Rx, where default scheduler isn’t ThreadPool). If I have async logging turned on in nlog.config, where is the ThreadID captured?

Concern: I don’t see ThreadID in the core LogEntry class for NLog. For example it isn’t sent to the browser in cbley/NLog.SignalR. If I have async logging turned on in nlog.config, where is the ThreadID captured? If it isn’t captured until the log entry is rendered (in an NLog background thread), then the ThreadId is useless to me and I need to find a more appropriate logging library.

Answer 1

NLog captures the threadid corrrectly.

NLog uses [ThreadAgnostic] on LayoutRender-derived classes that can be used/rendered outside the calling thread. Because ThreadIdLayoutRender doesn’t have that attribute it can’t be delayed until the after the async transition.