Analyzer sema-wait-fgraph

# Name

sema-wait-fgraph - Semaphore wait Calls

This analyzer profiles semaphore wait operations in OpenResty and Kong applications. It captures stack traces when threads block on semaphore waits, measuring wait durations and generating flame graphs that visualize the call paths and latency distributions. The analyzer helps identify synchronization bottlenecks and diagnose issues related to semaphore-based concurrency control.

# Resource Category

Latency.

# Application Type & Technical Stack

• OpenResty
• Kong
• APISIX

# 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 sema-wait-fgraph -p PID

# trace a shell command directly
orxray analyzer run sema-wait-fgraph -c SHELL_CMD

# PGID is the process group ID or any process's PID within the target process
# group.
orxray analyzer run sema-wait-fgraph -p -PGID

# trace any processes started from the specified executable path.
orxray analyzer run sema-wait-fgraph --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.