AWS Documentation » AWS X-Ray » Developer Guide » AWS X-Ray SDK for Python » Generating Custom Subsegments with the X-Ray SDK for Python

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Generating Custom Subsegments with the X-Ray SDK for Python

Subsegments extend a trace's segment with details about work done in order to serve a request. Each time you make a call with an instrumented client, the X-Ray SDK records the information generated in a subsegment. You can create additional subsegments to group other subsegments, to measure the performance of a section of code, or to record annotations and metadata.

To manage subsegments, use the begin_subsegment and end_subsegment methods.

Example main.py – custom subsegment

from aws_xray_sdk.core import xray_recorder

subsegment = xray_recorder.begin_subsegment('annotations')
subsegment.put_annotation('id', 12345)
xray_recorder.end_subsegment()

To create a subsegment for a synchronous function, use the @xray_recorder.capture decorator. You can pass a name for the subsegment to the capture function or leave it out to use the function name.

Example main.py – function subsegment

from aws_xray_sdk.core import xray_recorder

@xray_recorder.capture('## create_user')
def create_user():
...

For an asynchronous function, use the @xray_recorder.capture_async decorator, and pass an async context to the recorder.

Example main.py – asynchronous function subsegment

from aws_xray_sdk.core.async_context import AsyncContext
from aws_xray_sdk.core import xray_recorder
xray_recorder.configure(service='my_service', context=AsyncContext())

@xray_recorder.capture_async('## create_user')
async def create_user():
    ...

async def main():
    await myfunc()

When you create a subsegment within a segment or another subsegment, the X-Ray SDK for Python generates an ID for it and records the start time and end time.

Example Subsegment with Metadata

"subsegments": [{
  "id": "6f1605cd8a07cb70",
  "start_time": 1.480305974194E9,
  "end_time": 1.4803059742E9,
  "name": "Custom subsegment for UserModel.saveUser function",
  "metadata": {
    "debug": {
      "test": "Metadata string from UserModel.saveUser"
    }
  },