Serilog 异步 CPU 使用率高达 100%

Question

I use Serilog async logging and while doing performance testing with multiple users we found that serilog is taking all the CPU (up to 100%). ASP.net code creates log file using Serilog Async (log.info, log.warning, log.error) and it has logging on all web pages due to security logging requirements. CPU usage spikes after 2 hours and remains 100% continuously and system is getting major performance hit.

We also tested application without SeriLog enabled, the application does not spike up to 100% CPU usage.

I would really appreciate if I get any help here. I can share code (logger class) I created if needed.

And how the logging is configured:

var logConfig = new LoggerConfiguration()
            .MinimumLevel.Information()
            .WriteTo.Async(logSink =>
            {
                logSink.File(
                    logFilePath,
                    rollingInterval: RollingInterval.Day,
                    retainedFileCountLimit: null,
                    outputTemplate: OutputTemplate,
                    hooks: new HeaderWriter(header),
                    flushToDiskInterval: TimeSpan.FromSeconds(10),
                    shared: true
                    );
            });
        Log.Logger = logConfig.CreateLogger();

Answer 1

Some thoughts on further investigation Serilog performance:

1. Look if there any messages in SelfLog . Normally SelfLog is empty. If there are any, fix them.

Serilog.Debugging.SelfLog.Enable(Console.Error);

2. Serilog parses and caches every template (up to a fixed size limit) https://github.com/serilog/serilog/wiki/Writing-Log-Events#message-template-recommendations . Logging templates is better than variable messages:

// Don't:
Log.Information("The time is " + DateTime.Now);

// Do:
Log.Information("The time is {Now}", DateTime.Now);

If you log large strings, log them as property to prevent parsing and caching.

3. Don't accidentally destructure objects with inappropriate properties:

• of type Task , Stream , etc
• property getter doing a lot of work
• property getter that throws

// Don't

// Destructuring entire Request with @ will generate a lot of useless data
Log.Information("Got request {@HttpRequest}", HttpContext.Request);

if you want to log such complex objects, define Destructure.ByTransforming() or IDestructuringPolicy.