LTTng’s upcoming 2.11 release brings several exciting new features, including session rotation and user and kernel space call stack capture. This post takes a look at another new feature that's currently available in the 2.11 RC releases: dynamic user space tracing. This feature allows you to instrument functions in user space apps and shared libraries at run time by adding and removing user space probes.
Many LTTng users want to inspect traces while their tracing session continues to run in the background, but that's only possible with tools that support the "live" protocol. Historically, it has not been possible to process traces "offline". To be able to read, modify, or delete a trace file, you need to interrupt the tracing session. When you're investigating long-lived issues that can take days to track down, stopping the session to see whether the bug has triggered opens a window where you might miss it. And leaving the session running can result in huge traces that can take days to process.
Some of the world's largest and most critical applications are written in Python, a language used in everything from high-performance scientific programs to large-scale websites. Keeping that code running when issues arise often requires tracing on production systems where reliability and low-intrusiveness are vital.
Both the Windows and Linux ecosystems have a swath of battle-hardened performance analysis and investigation tools. But up until recently, developers and platform engineers could use none of these tools with .NET applications on Linux.
Getting them to work with .NET involved collaboration across many open source communities. The .NET team at Microsoft and the LTTng community worked together to bring .NET application performance analysis to Linux. Since one of this project's goals was to avoid reinventing the wheel—and to allow existing workflows to be used for .NET applications on Linux—the .NET team chose to enable usage of popular Linux tools such as LTTng and perf to enable performance analysis of .NET core applications.
Since we released the first public version of LTTng Scope, our new experimental graphical trace viewer, I thought it would be nice to do a quick tutorial on how to get started using it.
We'll go trough collecting a Linux kernel trace with LTTng, opening it in LTTng Scope, and then use a simple filter to pinpoint some events.