Fixing empty paths in FileIO events (ETW)

This month marks ten years since I started this blog 🥂🥂🥂. On this occasion, I would like to thank you for being my reader! Let’s celebrate with a new post on ETW 🙂

Empty paths issue in the wtrace output has been bugging me for quite some time. As I started working on a new wtrace release (coming soon!), there came the right moment to fix it. I’ve seen other people struggling with this problem too, so I thought that maybe it’s worth a blog post 🙂 Wtrace uses the TraceEvent library to interact with the ETW API, and in this post, I will use this library as well. Note that this issue affects only the real-time ETW sessions.

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Wtrace 2.2

On the occasion of releasing wtrace 2.2, I decided to write a short post about new functionalities I added to this tool in the recent months. I hope you will find them interesting. Wtrace is a command line application which collects ETW traces from the system and the selected processes and outputs them to the console. It is very simple to use and runs on Windows 7+. Currently, it supports the collection of File I/O, TCP, ALPC, RPC, ISR, DPC, and PowerShell events.

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Releasing wtrace 1.0 and procgov 2.0

In today’s short post I would like to present you a new tool in my diagnostics toolkit: wtrace, and an update to procgov (or Process Governor). Let’s start with wtrace.


On Linux, when I need to check what a given process is doing, I usually use strace. I was always missing such a tool for Windows. We have procmon (which is great), but it does not run in a console, and thus can’t be used in the command line scripts, or on a Nano server. This might change soon, as in one of the latest episodes of the Defrag Tools show, Mark Russinovich shared the plan of releasing the procmon version for Nano. Till then though we don’t have much choice when it comes to real-time tracing. You may think of xperf or wpr, but those tools only record ETW events for further analysis. However, we may use the same ETW events in a realtime session, and print information they provide to the console output. This is how the idea for wtrace was born in my head. Few weeks ago Sasha Goldshtein released another tool for ETW processing named etrace, which basically does something very similar and has many interesting options. I decided to publish wtrace nonetheless, as my point was to create a tool with an extremely simple interface. Wtrace is collecting only a small subset of events (FileIO, TcpIp, Process/Thread Start) from the kernel provider. It may either start a process, or trace one that is already running. At the end of the trace it also shows some statistics (unless you use the –nosummary switch). Trace session will end either when you press Ctrl+C, or when the traced process terminates. Events are printed in the console window. An example session might look as follows:

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