Tagged with "dynamic-tracing"

Ylang: Universal Language for eBPF, Stap+, GDB, and More (Part 4)

Dec 31, 2021 13 mins read Posted by Yichun Zhang (updated Mar 17, 2022)

Transparent Container Tracing
Efficient Stack Unwinding
Analyzing Dead Processes (Core Dumps)
Very Low Tracing Overhead
Standard Ylang Libraries & Tools
Network Filtering & Control
The Ylang Compiler’s Implementation
Operating System Support
Contributions to Open-Source Communities

Ylang: Universal Language for eBPF, Stap+, GDB, and More (Part 3)

Dec 28, 2021 10 mins read Posted by Yichun Zhang (updated Jan 1, 2022)

The Language Syntax (Continued)
- String Literals
- Built-in Regex Support
- Full Control-Flow Support
- Floating-Point Number Support
- Compared to Open-Source Toolchains
Transparent Debug Symbol Handling
- Debug Symbols: No Runtime Overhead
- Centralized Package Database
- Fuzzy Matching Debug Symbols

Ylang: Universal Language for eBPF, Stap+, GDB, and More (Part 2)

Nov 14, 2021 14 mins read Posted by Yichun Zhang (updated Jan 1, 2022)

The Language Syntax (Continued)
- Macros with Extensions
- Tracer and Tracee Spaces
- Probes
- Extended Variable Types

Ylang: Universal Language for eBPF, Stap+, GDB, and More (Part 1)

Nov 12, 2021 13 mins read Posted by Yichun Zhang (updated Jun 17, 2022)

What is Dynamic Tracing
Why the “Y” Name
Getting Started
Various Backends and Runtimes
Why a Unified Frontend Language
The Language Syntax

Introduction to Lua-Land CPU Flame Graphs

Aug 31, 2020 18 mins read Posted by Yichun Zhang (updated Mar 7, 2022)

What is a Flame Graph
Simple Lua samples
Complicated Lua applications
Sampling overhead
Safety
Compatibility
Other types of Lua-land Flame Graphs

Memory Fragmentation in OpenResty and Nginx's Shared Memory Zones

Aug 10, 2020 9 mins read Posted by Yichun Zhang (updated Mar 7, 2022)

An empty zone
Filling entries of similar sizes
Deleting odd-numbered keys
Deleting the keys in the first half
Mitigating Fragmentation

How OpenResty and Nginx Shared Memory Zones Consume RAM

Aug 4, 2020 13 mins read Posted by Yichun Zhang (updated Mar 7, 2022)

Slabs and pages
What is allocated is not what is paid for
Fake Memory Leaks
HUP reload

The Wonderland of Dynamic Tracing (Part 4 of 7)

Jun 27, 2020 7 mins read Posted by Yichun Zhang (updated Mar 7, 2022)

This is Part 4 of the series “The Wonderland of Dynamic Tracing” which consists of 7 parts. I will keep updating this series to reflect the state of art of the dynamic tracing world. Read more...

The Wonderland of Dynamic Tracing (Part 3 of 7)

Jun 26, 2020 11 mins read Posted by Yichun Zhang (updated Mar 7, 2022)

Applications of SystemTap in Production
- Case #1: Slow Debugging Code Left in Production
- Case #2: Long request latency outliers
- Case #3: From Network Issues to Disk Issues
- Case #4: File Handle Cache Tradeoffs
- Case #5: Compiled Regex Cache Tuning