How to create docker goroutine, and memory heap, dumps

This document (000020101) is provided subject to the disclaimer at the end of this document.

Environment

Rancher 2.x

Situation

Task

It's important to observe Docker as it operates to help drive troubleshooting an issue. Here are some commands to generate memory heap and goroutine dumps without killing the Docker process.

Pre-requisites

Docker with an exposed socket (typically found at /var/run/docker.sock)

Resolution

Collecting dumps

Heap dump

Heap dumps report a sampling of memory allocations of live objects.

curl --unix-socket /var/run/docker.sock http://./debug/pprof/heap?debug=2

Goroutine dump

The goroutine dump reports stack traces of all current goroutines for the docker process.

curl --unix-socket /var/run/docker.sock http://./debug/pprof/goroutine?debug=2

The output normally is output to stdout, where it can be redirected to a file.

Depending on how Docker is configured, and where its configured to log to, the traces could end up in the docker.log file or with the system logs (syslog, journalctl, kern.log, messages, etc...).

Disclaimer

This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.