Guru Meditation Reports

Watcher contains a mechanism whereby developers and system administrators can generate a report about the state of a running Watcher service. This report is called a Guru Meditation Report (GMR for short).

Generating a GMR

A GMR can be generated by sending the USR2 signal to any Watcher process with support (see below). The GMR will then be outputted as standard error for that particular process.

For example, suppose that watcher-api has process id 8675, and was run with 2>/var/log/watcher/watcher-api-err.log. Then, kill -USR2 8675 will trigger the Guru Meditation report to be printed to /var/log/watcher/watcher-api-err.log.

Structure of a GMR

The GMR is designed to be extensible; any particular service may add its own sections. However, the base GMR consists of several sections:

Package

Shows information about the package to which this process belongs, including version informations.

Threads

Shows stack traces and thread ids for each of the threads within this process.

Green Threads

Shows stack traces for each of the green threads within this process (green threads don’t have thread ids).

Configuration

Lists all the configuration options currently accessible via the CONF object for the current process.

Plugins

Lists all the plugins currently accessible by the Watcher service.