Requests memory leak

Summary.

Expected Result

Program running normally

Actual Result

Program consuming all ram till stops working

Reproduction Steps

Pseudocode:

def function():
    proxies = {
        'https': proxy
    }
    session = requests.Session()
    session.headers.update({'User-Agent': 'user - agent'})
    try:                                           #
        login = session.get(url, proxies=proxies)  # HERE IS WHERE MEMORY LEAKS
    except:                                        #
        return -1                                  #
    return 0

System Information

$ python -m requests.help

{
  "chardet": {
    "version": "3.0.4"
  },
  "cryptography": {
    "version": ""
  },
  "idna": {
    "version": "2.6"
  },
  "implementation": {
    "name": "CPython",
    "version": "3.6.3"
  },
  "platform": {
    "release": "10",
    "system": "Windows"
  },
  "pyOpenSSL": {
    "openssl_version": "",
    "version": null
  },
  "requests": {
    "version": "2.18.4"
  },
  "system_ssl": {
    "version": "100020bf"
  },
  "urllib3": {
    "version": "1.22"
  },
  "using_pyopenssl": false
}

[guyskk]

Call Session.close() and Response.close() can avoid the memory leak. And ssl will consume more memory so the memory leak will more remarkable when request https urls.

First I make 4 test cases:

1. requests + ssl (https://)
2. requests + non-ssl (http://)
3. aiohttp + ssl (https://)
4. aiohttp + non-ssl (http://)

Pseudo code:

def run(url):
    session = requests.session()
    response = session.get(url)

while True:
    for url in urls:  # about 5k urls of public websites
        # execute in thread pool, size=10
        thread_pool.submit(run, url)

# in another thread, record memory usage every seconds

Memory usage graph(y-axis: MB, x-axis: time), requests use lots of memory and memory increase very fast, while aiohttp memory usage is stable:

Then I add Session.close() and test again:

def run(url):
    session = requests.session()
    response = session.get(url)
    session.close()  # close session !!

Memory usage significant decreased, but memory usage still increase over time:

Finally I add Response.close() and test again:

def run(url):
    session = requests.session()
    response = session.get(url)
    session.close()  # close session !!
    response.close()  # close response !!

Memory usage decreased again, and not increase over time:

Compare aiohttp and requests shows memory leak is not caused by ssl, it’s caused by connection resources not closed.

Useful scripts:

class MemoryReporter:
    def __init__(self, name):
        self.name = name
        self.file = open(f'memoryleak/memory_{name}.txt', 'w')
        self.thread = None

    def _get_memory(self):
        return psutil.Process().memory_info().rss

    def main(self):
        while True:
            t = time.time()
            v = self._get_memory()
            self.file.write(f'{t},{v}\n')
            self.file.flush()
            time.sleep(1)

    def start(self):
        self.thread = Thread(target=self.main, name=self.name, daemon=True)
        self.thread.start()


def plot_memory(name):
    filepath = 'memoryleak/memory_{}.txt'.format(name)
    df_mem = pd.read_csv(filepath, index_col=0, names=['t', 'v'])
    df_mem.index = pd.to_datetime(df_mem.index, unit='s')
    df_mem.v = df_mem.v / 1024 / 1024
    df_mem.plot(figsize=(16, 8))

System Information:

$ python -m requests.help
{
  "chardet": {
    "version": "3.0.4"
  },
  "cryptography": {
    "version": ""
  },
  "idna": {
    "version": "2.8"
  },
  "implementation": {
    "name": "CPython",
    "version": "3.7.4"
  },
  "platform": {
    "release": "18.0.0",
    "system": "Darwin"
  },
  "pyOpenSSL": {
    "openssl_version": "",
    "version": null
  },
  "requests": {
    "version": "2.22.0"
  },
  "system_ssl": {
    "version": "1010104f"
  },
  "urllib3": {
    "version": "1.25.6"
  },
  "using_pyopenssl": false
}

[jotunskij]

Similar issue. Requests eats memory when running in thread. Code to reproduce here:

import gc
from concurrent.futures import ThreadPoolExecutor, as_completed
import requests
from memory_profiler import profile

def run_thread_request(sess, run):
    response = sess.get('https://www.google.com')
    return

@profile
def main():
    sess = requests.session()
    with ThreadPoolExecutor(max_workers=1) as executor:
        print('Starting!')
        tasks = {executor.submit(run_thread_request, sess, run):
                    run for run in range(50)}
        for _ in as_completed(tasks):
            pass
    print('Done!')
    return

@profile
def calling():
    main()
    gc.collect()
    return

if __name__ == '__main__':
    calling()

In the code given above I pass a session object around, but if I replace it with just running requests.get nothing changes.

Output is:

➜  thread-test pipenv run python run.py
Starting!
Done!
Filename: run.py

Line #    Mem usage    Increment   Line Contents
================================================
    10     23.2 MiB     23.2 MiB   @profile
    11                             def main():
    12     23.2 MiB      0.0 MiB       sess = requests.session()
    13     23.2 MiB      0.0 MiB       with ThreadPoolExecutor(max_workers=1) as executor:
    14     23.2 MiB      0.0 MiB           print('Starting!')
    15     23.4 MiB      0.0 MiB           tasks = {executor.submit(run_thread_request, sess, run):
    16     23.4 MiB      0.0 MiB                       run for run in range(50)}
    17     25.8 MiB      2.4 MiB           for _ in as_completed(tasks):
    18     25.8 MiB      0.0 MiB               pass
    19     25.8 MiB      0.0 MiB       print('Done!')
    20     25.8 MiB      0.0 MiB       return


Filename: run.py

Line #    Mem usage    Increment   Line Contents
================================================
    22     23.2 MiB     23.2 MiB   @profile
    23                             def calling():
    24     25.8 MiB      2.6 MiB       main()
    25     25.8 MiB      0.0 MiB       gc.collect()
    26     25.8 MiB      0.0 MiB       return

And Pipfile looks like this:

[[source]]
url = "https://pypi.python.org/simple"
verify_ssl = true

[requires]
python_version = "3.6"

[packages]
requests = "==2.21.0"
memory-profiler = "==0.55.0"