Custom Instrumentation
To capture transactions customized to your organization's needs, you must first set up performance monitoring.
To instrument certain regions of your code, you can create transactions to capture them.
The following example creates a transaction for a scope that contains an expensive operation (for example, process_item
), and sends the result to Sentry:
from sentry_sdk import start_transaction
while True:
item = get_from_queue()
with start_transaction(op="task", name=item.get_transaction_name()):
# process_item may create more spans internally (see next examples)
process_item(item)
Add More Spans to the Transaction
The next example contains the implementation of the hypothetical process_item
function called from the code snippet in the previous section. Our SDK can determine if there is currently an open transaction and add all newly created spans as child operations to that transaction. Keep in mind that each individual span also needs to be manually finished; otherwise, spans will not show up in the transaction. When using spans and transactions as context managers, they are automatically finished at the end of the with
block.
You can choose the value of op
and description
.
import sentry_sdk
def process_item(item):
# omitted code...
with sentry_sdk.start_span(op="http", description="GET /") as span:
response = my_custom_http_library.request("GET", "/")
span.set_tag("http.status_code", response.status_code)
span.set_data("http.foobarsessionid", get_foobar_sessionid())
Retrieve a Transaction
In cases where you want to attach Spans to an already ongoing Transaction you can use Hub.current.scope.transaction
. This property will return a Transaction
in case there is a running Transaction otherwise it returns None
.
import sentry_sdk
transaction = sentry_sdk.Hub.current.scope.transaction
if transaction is None:
with sentry_sdk.start_transaction(name="task"):
do_task()
else:
transaction.name = "new name"
with transaction.start_child(op="task"): # equivalent to `sentry_sdk.start_span`
do_task()
Retrieve the Current Span
Started spans are stored in the scope, and can be fetched off the scope:
import sentry_sdk
span = sentry_sdk.Hub.current.scope.span
if span is None:
# no span in progress, create new transaction
with sentry_sdk.start_transaction(name="task"):
do_task()
else:
# new task span as child of current span
with span.start_child(op="task"):
do_task()