About OSProfiler

About OSProfiler

OSProfiler is an OpenStack cross-project profiling library. Its API provides different ways to add a new trace point. Trace points contain two messages (start and stop). Messages like below are sent to a collector:

{
    "name": <point_name>-(start|stop),
    "base_id": <uuid>,
    "parent_id": <uuid>,
    "trace_id": <uuid>,
    "info": <dict>
}

The fields are defined as follows:

base_id - <uuid> that is same for all trace points that belong to one trace. This is used to simplify the process of retrieving all trace points (related to one trace) from the collector.

parent_id - <uuid> of parent trace point.

trace_id - <uuid> of current trace point.

info - the dictionary that contains user information passed when calling profiler start() & stop() methods.

The profiler uses ceilometer as a centralized collector. Two other alternatives for ceilometer are pure MongoDB driver and Elasticsearch.

A notifier is setup to send notifications to ceilometer using oslo.messaging and ceilometer API is used to retrieve all messages related to one trace.

OSProfiler has entry point that allows the user to retrieve information about traces and present it in HTML/JSON using CLI.

For more details see OSProfiler – Cross-project profiling library.

How to Use OSProfiler with Ironic in Devstack

To use or test OSProfiler in ironic, the user needs to setup Devstack with OSProfiler and ceilometer. In addition to the setup described at Deploying Ironic with DevStack, the user needs to do the following:

Add the following to localrc to enable OSProfiler and ceilometer:

enable_plugin panko https://git.openstack.org/openstack/panko
enable_plugin ceilometer https://git.openstack.org/openstack/ceilometer
enable_plugin osprofiler https://git.openstack.org/openstack/osprofiler

# Enable the following services
CEILOMETER_NOTIFICATION_TOPICS=notifications,profiler
ENABLED_SERVICES+=,ceilometer-acompute,ceilometer-acentral
ENABLED_SERVICES+=,ceilometer-anotification,ceilometer-collector
ENABLED_SERVICES+=,ceilometer-alarm-evaluator,ceilometer-alarm-notifier
ENABLED_SERVICES+=,ceilometer-api

Run stack.sh.

Once Devstack environment is setup, edit ironic.conf to set the following profiler options and restart ironic services:

[profiler]
enabled = True
hmac_keys = SECRET_KEY # default value used across several OpenStack projects
trace_sqlalchemy = True

In order to trace ironic using OSProfiler, use openstackclient to run baremetal commands with --os-profile SECRET_KEY.

For example, the following will cause a <trace-id> to be printed after node list:

$ openstack --os-profile SECRET_KEY baremetal node list

Output of the above command will include the following:

Trace ID: <trace-id>
Display trace with command:
osprofiler trace show --html <trace-id>

The trace results can be seen using this command:

$ osprofiler trace show --html <trace-id>

The trace results can be saved in a file with --out file-name option:

$ osprofiler trace show --html <trace-id> --out trace.html

The trace results show the time spent in ironic-api, ironic-conductor, and db calls. More detailed db tracing is enabled if trace_sqlalchemy is set to true.

Sample Trace:

Sample Trace

Each trace has embedded trace point details as shown below:

Sample Trace Details
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