tracetools_analysis

Analysis tools for ROS 2 tracing.

Trace analysis

After generating a trace (see ros2_tracing), we can analyze it to extract useful execution data.

Commands

Then we can process a trace to create a data model which could be queried for analysis.

$ ros2 trace-analysis process /path/to/trace/directory

Note that this simply outputs lightly-processed ROS 2 trace data which is split into a number of pandas DataFrames. This can be used to quickly check the trace data. For real data processing/trace analysis, see Analysis.

Since CTF traces (the output format of the LTTng tracer) are very slow to read, the trace is first converted into a single file which can be read much faster and can be re-used to run many analyses. This is done automatically, but if the trace changed after the file was generated, it can be re-generated using the --force-conversion option. Run with --help to see all options.

Analysis

The command above will process and output raw data models. We need to actually analyze the data and display some results. We recommend doing this in a Jupyter Notebook, but you can do this in a normal Python file.

$ jupyter notebook

Navigate to the analysis/ directory, and select one of the provided notebooks, or create your own!

For example:

from tracetools_analysis.loading import load_file
from tracetools_analysis.processor import Processor
from tracetools_analysis.processor.cpu_time import CpuTimeHandler
from tracetools_analysis.processor.ros2 import Ros2Handler
from tracetools_analysis.utils.cpu_time import CpuTimeDataModelUtil
from tracetools_analysis.utils.ros2 import Ros2DataModelUtil

# Load trace directory or converted trace file
events = load_file('/path/to/trace/or/converted/file')

# Process
ros2_handler = Ros2Handler()
cpu_handler = CpuTimeHandler()

Processor(ros2_handler, cpu_handler).process(events)

# Use data model utils to extract information
ros2_util = Ros2DataModelUtil(ros2_handler.data)
cpu_util = CpuTimeDataModelUtil(cpu_handler.data)

callback_symbols = ros2_util.get_callback_symbols()
callback_object, callback_symbol = list(callback_symbols.items())[0]
callback_durations = ros2_util.get_callback_durations(callback_object)
time_per_thread = cpu_util.get_time_per_thread()
# ...

# Display, e.g., with bokeh, matplotlib, print, etc.
print(callback_symbol)
print(callback_durations)

print(time_per_thread)
# ...

Note: bokeh has to be installed manually, e.g., with pip:

$ pip3 install bokeh

Design

See the ros2_tracing design document, especially the Goals and requirements and Analysis sections.

Packages

ros2trace_analysis

Package containing a ros2cli extension to perform trace analysis.

tracetools_analysis

Package containing tools for analyzing trace data.

See the API documentation.