wanghao f2dc050e4d Introduce Guru Meditation Reports into Cinder

This commit integrates functionality from the
`openstack.common.report` module into Cinder.
This enables Cinder services to receive SIGUSR1
and print a Guru Meditation Report to stderr.
The required modules were added to
'openstack-common.conf' as well.

It is essentially a copy from implementation of
nova side.

Change-Id: I5bbdc0f97db9b0ebd7b48e50ab7869e2ca33aead
Implements: blueprint guru-meditation-report

2015-06-16 12:01:28 +08:00

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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 USR1 signal to any Cinder process with support (see below). The GMR will then be outputted standard error for that particular process.

For example, suppose that cinder-api has process id 8675, and was run with 2>/var/log/cinder/cinder-api-err.log. Then, kill -USR1 8675 will trigger the Guru Meditation report to be printed to /var/log/cinder/cinder-api-err.log.

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:

Package: Shows information about the package to which this process belongs, including version information
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

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 cinder.openstack.common.report 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 (usually service.server(server) or something similar), register the GMR hook:

TextGuruMeditation.setup_autorun(version)

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 under cinder.openstack.common.report

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