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  4. Python SDK

Python SDK Python

Installation

The Blackfire Python SDK is available with the Blackfire Python Package.

Blackfire Python SDK

The Blackfire Python SDK allows you to generate profiles from your own code and eases the integration with third-party libraries.

The main entry point of the SDK is the blackfire module:

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from blackfire import probe

The probe allows you to profile any parts of your code:

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from blackfire import probe

probe.initialize()
probe.enable()

# some Python code you want to profile

probe.end()

Configuring the Blackfire Probe Manually

The Blackfire Probe is usually configured via environment variables, but you can customize the configuration when calling the initialize() method via optional parameters:

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from blackfire import probe

probe.initialize(
     # Client credentials. If None, they are read from environment variables, or config_file.
     client_id=None,
     client_token=None,
     # 1: error, 2: warning, 3: info, 4: debug
     log_level=None,
     # The destination of the log. i.e: /tmp/probe.log
     log_file=None,
     # Where to find the Blackfire CLI configuration file to retrieve the client_id and client_token values.
     config_file='~/.blackfire.ini',
     # The Blackfire Query, usually given by blackfire run or created on the fly by the SDK.
     query=None,
     # The network socket to use for contacting the agent
     agent_socket=None,
     # The connection timeout when connecting to the agent
     agent_timeout=None,
     # The Blackfire API endpoint
     endpoint=None,
 )

Instrumenting Code by Wrapping Execution

The SDK provides the run(call_end=True) method that simplifies the use of the enable() and disable() methods:

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from blackfire import probe

with probe.run():
    foo()
    bar()

is equivalent to:

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from blackfire import probe

probe.enable()
try:
    foo()
    bar()
finally:
    probe.disable()
    probe.end() # if call_end is True.

Instrumenting Code Using the Decorator

The SDK provides the @profile decorator, making it possible to profile functions separately:

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from blackfire import profile

@profile
def foo():
    import time
    time.sleep(1.0)

foo()

In the snippet above, function foo() is using the @profile decorator. A probe instance is created by the decorator, using the configuration defined by environment variables.

You may specify a pair of Client ID/Token in the decorator:

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from blackfire import profile

@profile(client_id = "my_client_id", client_token = "my_client_token")
def foo()
    import time
    time.sleep(1.0)

foo()

Controlling Automatic Instrumentation

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from blackfire import probe

probe.initialize()

Start profiling the code by calling enable():

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# Start the profiling
probe.enable()

Stop profiling the code by calling disable():

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# Stop the profiling
probe.disable()

You can call enable() and disable() as many times as needed in your code. You can also discard any collected data by calling clear_traces().

Calling end() instead of disable() stops the profiling and forces the collected data to be sent to Blackfire:

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# Stop the profiling
# Send the result to blackfire
probe.end()

Generating Sub-Profiles

Thanks to the Distributed Profiling feature, you can embed sub-profiles in a main profile.

For instance, when profiling command line programs that call sub-processes, you might want to trigger profiles for them as well. You can do so by generating a sub-profile request:

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import subprocess
import sys
import os
from blackfire import probe

probe.initialize(
    client_id='xxxx',
    client_token='xxxx'
)

with probe.run():
    env = os.environ.copy()
    env['BLACKFIRE_QUERY'] = probe.generate_subprofile_query()
    _ = subprocess.run([sys.executable, "my_subprocess.py"], env=env)

Sub-profiles also work for HTTP requests by adding a X-Blackfire-Query HTTP header.

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import requests
from blackfire import probe

with probe.run():
    url = 'https://mycustomapi.com'
    headers = {'X-Blackfire-Query:': probe.generate_subprofile_query()}
    r = requests.get(url, headers=headers)

Note

The target process or HTTP server being sub-profiled may be written in any language supported by Blackfire.

Adding a Marker to the Timeline View

With Markers, you can add cue-points to the Timeline View. This can be done by adding the following instruction in your code, where you want to add such a cue-point:

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from blackfire import probe
probe.add_marker('My Marker Label')