Add support for connection pool monitoring #702

karpetrosyan · 2023-05-29T11:51:54Z

closes #508

httpcore/_async/connection_pool.py

karpetrosyan · 2023-05-30T08:16:31Z

These trace events were added.

connection_pool.reuse_connection when our request received the idle connection from the pool
connection_pool.set_connection when our request received the connection which was just created
connection_pool.unset_connection when the connection pool steals our request's connection

We can use an extension's trace to set a callback for these events because they are traced along with the request argument.

Additionally, some events do not support callbacks.

These are events that are unrelated to requests.

connection_pool.remove_idle_connection pool removes the idle connection
connection_pool.create_connection pool creates the connection
connection_pool.remove_expired_connection pool removes the expired connection

tomchristie · 2023-05-30T12:40:21Z

Could you demo some log output as part of the description here?

karpetrosyan · 2023-05-30T13:06:13Z

script

import asyncio
import logging

import httpcore

logging.basicConfig(
    format="%(levelname)s [%(asctime)s] %(name)s - %(message)s",
    datefmt="%Y-%m-%d %H:%M:%S",
)
logging.getLogger("httpcore.connection_pool").setLevel(logging.DEBUG)

async def main():
    async with httpcore.AsyncConnectionPool() as pool:
        tasks = []
        for i in range(5):
            tasks.append(pool.request('GET', 'http://encode.io'))
        await asyncio.gather(*tasks)

asyncio.run(main())

OUTPUT

DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - create_connection.started origin='http://encode.io:80'
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - create_connection.complete return_value=<AsyncHTTPConnection [CONNECTING]>
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - set_connection.started connection=<AsyncHTTPConnection [CONNECTING]>
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - set_connection.complete
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - Waiting for a connection.
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - The ConnectionPool currently has 1 request(s) awaiting connections.
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - Connection received.
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - The ConnectionPool currently has 0 request(s) awaiting connections.
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - create_connection.started origin='http://encode.io:80'
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - create_connection.complete return_value=<AsyncHTTPConnection [CONNECTING]>
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - set_connection.started connection=<AsyncHTTPConnection [CONNECTING]>
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - set_connection.complete
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - Waiting for a connection.
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - The ConnectionPool currently has 1 request(s) awaiting connections.
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - Connection received.
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - The ConnectionPool currently has 0 request(s) awaiting connections.
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - create_connection.started origin='http://encode.io:80'
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - create_connection.complete return_value=<AsyncHTTPConnection [CONNECTING]>
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - set_connection.started connection=<AsyncHTTPConnection [CONNECTING]>
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - set_connection.complete
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - Waiting for a connection.
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - The ConnectionPool currently has 1 request(s) awaiting connections.
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - Connection received.
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - The ConnectionPool currently has 0 request(s) awaiting connections.
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - create_connection.started origin='http://encode.io:80'
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - create_connection.complete return_value=<AsyncHTTPConnection [CONNECTING]>
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - set_connection.started connection=<AsyncHTTPConnection [CONNECTING]>
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - set_connection.complete
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - Waiting for a connection.
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - The ConnectionPool currently has 1 request(s) awaiting connections.
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - Connection received.
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - The ConnectionPool currently has 0 request(s) awaiting connections.
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - create_connection.started origin='http://encode.io:80'
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - create_connection.complete return_value=<AsyncHTTPConnection [CONNECTING]>
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - set_connection.started connection=<AsyncHTTPConnection [CONNECTING]>
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - set_connection.complete
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - Waiting for a connection.
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - The ConnectionPool currently has 1 request(s) awaiting connections.
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - Connection received.
DEBUG [2023-05-30 16:00:10] httpcore.connection_pool - The ConnectionPool currently has 0 request(s) awaiting connections.
DEBUG [2023-05-30 16:00:11] httpcore.connection_pool - Connection: <AsyncHTTPConnection ['http://encode.io:80', HTTP/1.1, IDLE, Request Count: 1]> was returned into the pool
DEBUG [2023-05-30 16:00:11] httpcore.connection_pool - Connection: <AsyncHTTPConnection ['http://encode.io:80', HTTP/1.1, IDLE, Request Count: 1]> was returned into the pool
DEBUG [2023-05-30 16:00:11] httpcore.connection_pool - Connection: <AsyncHTTPConnection ['http://encode.io:80', HTTP/1.1, IDLE, Request Count: 1]> was returned into the pool
DEBUG [2023-05-30 16:00:11] httpcore.connection_pool - Connection: <AsyncHTTPConnection ['http://encode.io:80', HTTP/1.1, IDLE, Request Count: 1]> was returned into the pool
DEBUG [2023-05-30 16:00:11] httpcore.connection_pool - Connection: <AsyncHTTPConnection ['http://encode.io:80', HTTP/1.1, IDLE, Request Count: 1]> was returned into the pool

karpetrosyan · 2023-05-30T13:16:10Z

With the trace extention enabled

import asyncio
import httpcore
async def log(a, b):
    if a.startswith('connection_pool'):
        print(a, b)
async def main():
    async with httpcore.AsyncConnectionPool(max_connections=1) as pool:
        tasks = []
        for i in range(5):
            tasks.append(pool.request('GET', 'http://encode.io', extensions={'trace': log}))
        await asyncio.gather(*tasks)
asyncio.run(main())

OUTPUT

connection_pool.set_connection.started {'connection': <AsyncHTTPConnection [CONNECTING]>}
connection_pool.set_connection.complete {'return_value': None}
connection_pool.reuse_connection.started {'connection': <AsyncHTTPConnection ['http://encode.io:80', HTTP/1.1, IDLE, Request Count: 1]>}
connection_pool.reuse_connection.complete {'return_value': None}
connection_pool.reuse_connection.started {'connection': <AsyncHTTPConnection ['http://encode.io:80', HTTP/1.1, IDLE, Request Count: 1]>}
connection_pool.reuse_connection.complete {'return_value': None}
connection_pool.reuse_connection.started {'connection': <AsyncHTTPConnection ['http://encode.io:80', HTTP/1.1, IDLE, Request Count: 1]>}
connection_pool.reuse_connection.complete {'return_value': None}
connection_pool.reuse_connection.started {'connection': <AsyncHTTPConnection ['http://encode.io:80', HTTP/1.1, IDLE, Request Count: 1]>}
connection_pool.reuse_connection.complete {'return_value': None}
connection_pool.unset_connection.started {'connection': <AsyncHTTPConnection ['http://encode.io:80', HTTP/1.1, ACTIVE, Request Count: 2]>}
connection_pool.unset_connection.complete {'return_value': None}
connection_pool.unset_connection.started {'connection': <AsyncHTTPConnection ['http://encode.io:80', HTTP/1.1, ACTIVE, Request Count: 2]>}
connection_pool.unset_connection.complete {'return_value': None}
connection_pool.unset_connection.started {'connection': <AsyncHTTPConnection ['http://encode.io:80', HTTP/1.1, ACTIVE, Request Count: 2]>}
connection_pool.unset_connection.complete {'return_value': None}
connection_pool.reuse_connection.started {'connection': <AsyncHTTPConnection ['http://encode.io:80', HTTP/1.1, IDLE, Request Count: 2]>}
connection_pool.reuse_connection.complete {'return_value': None}
connection_pool.reuse_connection.started {'connection': <AsyncHTTPConnection ['http://encode.io:80', HTTP/1.1, IDLE, Request Count: 2]>}
connection_pool.reuse_connection.complete {'return_value': None}
connection_pool.reuse_connection.started {'connection': <AsyncHTTPConnection ['http://encode.io:80', HTTP/1.1, IDLE, Request Count: 2]>}
connection_pool.reuse_connection.complete {'return_value': None}
connection_pool.unset_connection.started {'connection': <AsyncHTTPConnection ['http://encode.io:80', HTTP/1.1, ACTIVE, Request Count: 3]>}
connection_pool.unset_connection.complete {'return_value': None}
connection_pool.unset_connection.started {'connection': <AsyncHTTPConnection ['http://encode.io:80', HTTP/1.1, ACTIVE, Request Count: 3]>}
connection_pool.unset_connection.complete {'return_value': None}
connection_pool.reuse_connection.started {'connection': <AsyncHTTPConnection ['http://encode.io:80', HTTP/1.1, IDLE, Request Count: 3]>}
connection_pool.reuse_connection.complete {'return_value': None}
connection_pool.reuse_connection.started {'connection': <AsyncHTTPConnection ['http://encode.io:80', HTTP/1.1, IDLE, Request Count: 3]>}
connection_pool.reuse_connection.complete {'return_value': None}
connection_pool.unset_connection.started {'connection': <AsyncHTTPConnection ['http://encode.io:80', HTTP/1.1, ACTIVE, Request Count: 4]>}
connection_pool.unset_connection.complete {'return_value': None}
connection_pool.reuse_connection.started {'connection': <AsyncHTTPConnection ['http://encode.io:80', HTTP/1.1, IDLE, Request Count: 4]>}
connection_pool.reuse_connection.complete {'return_value': None}

tomchristie · 2023-06-09T13:15:14Z

Wonderful - thanks for working through this.

We should avoid adding extra state as part of this change, so I'd suggest we avoid the .self._requests_awaiting_connection.

It seems to me that the bits we'd like to trace don't fit in as well with the .started/.complete pairs that we're using elsewhere. Perhaps we want to trace these just as single events instead?

Maybe we'd implement that with a def trace() function for single event cases, instead of the Trace class?

The bits we want to monitor are state changes to ._pool and ._requests.

Suppose we started just with the following trace events/debug lines...

DEBUG [2023-06-09 10:55:09] httpcore.connection_pool - add_connection <HTTPConnection [...]>
DEBUG [2023-06-09 10:55:09] httpcore.connection_pool - add_request <Request [...]>
DEBUG [2023-06-09 10:55:09] httpcore.connection_pool - assign_request_to_connection <Request [...]> <HTTPConnection >
DEBUG [2023-06-09 10:55:09] httpcore.connection_pool - unassign_request_from_connection <Request [...]> <HTTPConnection [...]>
DEBUG [2023-06-09 10:55:09] httpcore.connection_pool - timeout_waiting_for_connection <Request [...]>
DEBUG [2023-06-09 10:55:09] httpcore.connection_pool - remove_request <Request [...]>
DEBUG [2023-06-09 10:55:09] httpcore.connection_pool - remove_connection <HTTPConnection [...]>

Would that be sufficiently comprehensive?

karpetrosyan · 2023-06-10T07:23:49Z

I've added all of the events you mentioned, as well as the "reuse_connection" event.

This is how it looks like now

connection_pool.add_request {'request': <Request [b'GET']>}
connection_pool.add_connection {'connection': <AsyncHTTPConnection [CONNECTING]>}
connection_pool.assign_request_to_connection {'request': <Request [b'GET']>, 'connection': <AsyncHTTPConnection [CONNECTING]>}
connection_pool.remove_request {'request': <Request [b'GET']>}
connection_pool.add_request {'request': <Request [b'GET']>}
connection_pool.reuse_connection {'connection': <AsyncHTTPConnection ['https://www.encode.io:443', HTTP/1.1, IDLE, Request Count: 1]>, 'request': <Request [b'GET']>}
connection_pool.assign_request_to_connection {'request': <Request [b'GET']>, 'connection': <AsyncHTTPConnection ['https://www.encode.io:443', HTTP/1.1, IDLE, Request Count: 1]>}
connection_pool.remove_request {'request': <Request [b'GET']>}
connection_pool.add_request {'request': <Request [b'GET']>}
connection_pool.reuse_connection {'connection': <AsyncHTTPConnection ['https://www.encode.io:443', HTTP/1.1, IDLE, Request Count: 2]>, 'request': <Request [b'GET']>}

karpetrosyan · 2023-06-10T07:35:47Z

Also timeout event

connection_pool.timeout_waiting_for_connection {'request': <Request [b'GET']>}

tomchristie

This is looking really promising...
Here's some initial suggestions.

docs/extensions.md

httpcore/_async/connection_pool.py

tests/_async/test_connection_pool.py

Co-authored-by: Tom Christie <tom@tomchristie.com>

…nto add-pool-monitoring

DoryZi · 2024-04-03T13:20:53Z

What's the status of this PR?

karpetrosyan changed the title ~~closes #508~~ Add support for connection pool monitoring May 29, 2023

karpetrosyan added the enhancement New feature or request label May 29, 2023

Pliner reviewed May 29, 2023

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karpetrosyan added 2 commits June 10, 2023 10:01

Add trace and atrace functions for single event traces

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Change trace events

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karpetrosyan force-pushed the add-pool-monitoring branch from 6888dbf to 8fa39ed Compare June 10, 2023 07:03

Add forgotten remove_connection log

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karpetrosyan added 2 commits June 10, 2023 11:44

update docs

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update changelog

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tomchristie requested changes Jun 12, 2023

View reviewed changes

karpetrosyan and others added 5 commits June 12, 2023 15:45

Update docs/extensions.md

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Co-authored-by: Tom Christie <tom@tomchristie.com>

Some refactoring

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Merge branch 'add-pool-monitoring' of github.com:karosis88/httpcore i…

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…nto add-pool-monitoring

Change 10 to logging.DEBUG

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Merge branch 'master' into add-pool-monitoring

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karpetrosyan and others added 7 commits July 2, 2023 07:12

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Add support for connection pool monitoring #702

Add support for connection pool monitoring #702

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Add support for connection pool monitoring #702

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