Guru Meditation Reports (GMR) code in oslo.reports was recently updated to expect SIGUSR2 as opposed to SIGUSR1, because it is reserved by Apache 'mod_wsgi' for its own use. So, update the Nova doc, gmr.rst, to reflect this new reality. [1] https://review.openstack.org/#/c/223133/ -- guru_meditation_report: Use SIGUSR2 instead of SIGUSR1 Change-Id: Iac2d606103189b965581e0c6c20b55360a04e3a6
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Guru Meditation Reports
Nova contains a mechanism whereby developers and system administrators can generate a report about the state of a running Nova 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 Nova process with support (see below). The GMR will then be outputted standard error for that particular process.
For example, suppose that nova-api
has process id
8675
, and was run with
2>/var/log/nova/nova-api-err.log
. Then,
kill -USR2 8675
will trigger the Guru Meditation report to
be printed to /var/log/nova/nova-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 Nova version module:
from oslo_reports import guru_meditation_report as gmr
from nova import version
Then, register any additional sections (optional):
'Some Special Section',
TextGuruMeditation.register_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 oslo.reports