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Binary Log
Starting with MSBuild 15.3 a new binary log format is introduced, to complement the existing file and console loggers.
Goals:
- completeness (more information than the most detailed file log)
- build speed (doesn't slow the build down nearly as much as the diagnostic-level file log)
- smaller disk size (10-20x more compact than a file log)
- structure (preserves the exact build event args that can later be replayed to reconstruct the exact events and information as if a real build was running). File logs erase structure and are harder to parse (especially for multicore /m builds). Build analyzer tools are conceivable that could benefit from the structure in a binary log.
Use the new /bl switch to enable the binary logger:
> msbuild.exe MySolution.sln /bl
By default the binary log file is named msbuild.binlog and it is written to the current directory. To specify a custom log file name and/or path, pass it after a colon:
> msbuild.exe MySolution.sln /bl:out.binlog
You can use the binary logger simultaneously with other loggers, such as text file (/fl) and console loggers. They are independent and having a binary log side-by-side with other logs may be beneficial (for sending a log to other people or running automatic build analysis tools that rely on the exact build event structure without having to parse text logs).
When using the binary logger all other log formats are technically redundant since you can later reconstruct all the other logs from the binary log. To turn off console logging, pass the /noconlog switch. Builds will usually be much faster if you don't pass the console and file loggers.
It is also possible to use the BinaryLogger with older MSBuild versions, such as MSBuild 14.0. For this you'll need the StructuredLogger.dll available here: https://github.com/KirillOsenkov/MSBuildStructuredLog/releases/download/v1.0.123/StructuredLogger.dll
Alternatively you can download/install the https://www.nuget.org/packages/Microsoft.Build.Logging.StructuredLogger NuGet package and use the StructuredLogger.dll provided by it.
Once you have the StructuredLogger.dll on disk you can pass it to MSBuild like this:
> msbuild.exe /logger:BinaryLogger,"path\to\StructuredLogger.dll";msbuild.binlog
Instead of passing the project/solution to MSBuild.exe you can now pass a binary log to "build". This will replay all events to all other loggers (just the console by default). Here's an example of replaying a .binlog file to the diagnostic verbosity text log:
> msbuild.exe msbuild.binlog /noconlog /flp:v=diag;logfile=diag.log
You can use the MSBuild Structured Log Viewer tool to view .binlog files:
https://github.com/KirillOsenkov/MSBuildStructuredLog
The implementation of the binary logger is here: https://source.dot.net/#Microsoft.Build/Logging/BinaryLogger/BinaryLogger.cs https://github.com/Microsoft/msbuild/blob/master/src/Build/Logging/BinaryLogger/BinaryLogger.cs
It is a GZipStream-compressed binary stream of serialized BuildEventArgs objects. The event args objects are serialized and deserialized using: