Guru Meditation Reports¶
Cinder contains a mechanism whereby developers and system administrators can generate a report about the state of a running Cinder executable. 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 Cinder process with support (see below). The GMR will then output to standard error for that particular process.
For example, suppose that
cinder-api has process id
8675, and was run
kill -USR2 8675 will trigger the Guru Meditation report to be printed
There is other way to trigger a generation of report, user should add a configuration in Cinder’s conf file:
[oslo_reports] file_event_handler=['The path to a file to watch for changes to trigger ' 'the reports, instead of signals. Setting this option ' 'disables the signal trigger for the reports.'] file_event_handler_interval=['How many seconds to wait between polls when ' 'file_event_handler is set, default value ' 'is 1']
a GMR can be generated by “touch”ing the file which was specified in file_event_handler. The GMR will then output to standard error for that particular process.
For example, suppose that
cinder-api was run with
2>/var/log/cinder/cinder-api-err.log, and the file path is
touch /tmp/guru_report will trigger the Guru Meditation report to be
Structure of a GMR¶
The GMR is designed to be extensible; any particular executable may add its own sections. However, the base GMR consists of several sections:
Shows information about the package to which this process belongs, including version information
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)
Lists all the configuration options currently accessible via the CONF object for the current process
Adding Support for GMRs to New Executables¶
Adding support for a GMR to a given executable is fairly easy.
First import the module (currently residing in oslo-incubator), as well as the Cinder version module:
from oslo_reports import guru_meditation_report as gmr from cinder import version
Then, register any additional sections (optional):
TextGuruMeditation.register_section('Some Special Section', some_section_generator)
Finally (under main), before running the “main loop” of the executable
service.server(server) or something similar), register the GMR
Extending the GMR¶
As mentioned above, additional sections can be added to the GMR for a particular executable. For more information, see the inline documentation about oslo.reports: oslo.reports