In my nlog configuration, I've set
<targets async="true">
with the understanding that all logging now happens asynchronously to my application workflow. (and I have noticed a performance improvement, especially on the Email target). This has me thinking about log sequence though. I understand that with async, one has no guarantee of the order in which the OS will execute the async work. So if, in my web app, multiple requests come in to the same method, each logging their occurrence to NLog, does this really mean that the sequence in which the events appear in my log target will not necessarily be the sequence in which the log method was called by the various requests?
If so, is this just a consequence of async that one has to live with? Or is there something I can do to keep have my logs reflect the correct sequence?
Unfortunately this is something you have to live with. If it is important to maintain the sequence you'll have to run it synchronously.
But if it is possible for you to manually maintain a sequence number in the log message, it could be a solution.
I know this is old and I'm just ramping up on NLog but if you see a performance increase for the email client, you may want to just assert ASYNC for the email target?
来源：https://stackoverflow.com/questions/15607930/nlog-async-and-log-sequence