Analyzer c-off-cpu

# Name

c-off-cpu - C-Land off-CPU Flame Graph

This analyzer profiles off-CPU time in C-land code execution across various native C/C++ applications including Envoy, NGINX, and other programs. It captures stack traces when native C code is blocked or waiting, such as during system calls, I/O operations, or synchronization primitives. The analyzer generates flame graphs that visualize time spent in blocking operations across C-level function calls, helping identify performance bottlenecks caused by waiting rather than active CPU usage in native code.

# Resource Category

off-CPU.

# Application Type & Technical Stack

• All
• Envoy

# Command Line Syntax

The analyzer can be invoked directly on the command-line via the orxray utility from the openresty-xray-cli software package.

Alternatively, the analyzer can also be invoked manually or automatically on the web console UI of OpenResty XRay (like on the Advanced web page).

# PID is the target process PID.
orxray analyzer run c-off-cpu -p PID

# trace a shell command directly
orxray analyzer run c-off-cpu -c SHELL_CMD

# PGID is the process group ID or any process's PID within the target process
# group.
orxray analyzer run c-off-cpu -p -PGID

# trace any processes started from the specified executable path.
orxray analyzer run c-off-cpu --exe /path/to/exe/file

# Tracing Multiple Processes

Supported.

# Output Formats

• Flame Graphs

# Author

The OpenResty Inc. Team.

# Copyright

Copyright (C) by OpenResty Inc. All rights reserved.