Analyzer nodejs-off-cpu

# Name

nodejs-off-cpu - Node JS-Land off-CPU Flame Graph

This analyzer profiles off-CPU time in JavaScript-land code execution within Node.js applications. It captures stack traces when JavaScript code is blocked or waiting, such as during asynchronous I/O operations, promise resolution, or event loop delays. The analyzer generates flame graphs with a blue color scheme that visualize time spent off-CPU across JavaScript function calls, helping identify blocking operations, inefficient async patterns, event loop starvation, and I/O bottlenecks that impact Node.js application responsiveness.

# Resource Category

off-CPU.

# Application Type & Technical Stack

• Node.js

# 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 nodejs-off-cpu -p PID

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

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

# trace any processes started from the specified executable path.
orxray analyzer run nodejs-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.