Memory leaks suspected (gc objects increases)

[Badiboy]

I'm running Telegram bot and noticed the free memory degradation when running bot for a long time. Firstly, I suspect my code; then I suspect bot and finally I came to requests. :)
I used len(gc.get_objects()) to identify that problem exists. I located the communication routines, then cleared all bot code and comes to the example that raises the count of gc objects on every iteration.

Expected Result

len(gc.get_objects()) should give the same result on every loop iteration

Actual Result

The value of len(gc.get_objects()) increases on every loop iteration.

Test N2
GetObjects len: 27959
Test N3
GetObjects len: 27960
Test N4
GetObjects len: 27961
Test N5
GetObjects len: 27962
Test N6
GetObjects len: 27963
Test N7
GetObjects len: 27964

Reproduction Steps

token = "XXX:XXX"
chat_id = '111'
proxy = {'https':'socks5h://ZZZ'} #You may need proxy to run this in Russia

from time import sleep
import gc, requests

def garbage_info():
    res = ""
    res += "\nGetObjects len: " + str(len(gc.get_objects()))
    return res

def tester():
    count = 0
    while(True):
        sleep(1)
        count += 1
        msg = "\nTest N{0}".format(count) + garbage_info()
        print(msg)

        method_url = r'sendMessage'
        payload = {'chat_id': str(chat_id), 'text': msg}

        request_url = "https://api.telegram.org/bot{0}/{1}".format(token, method_url)
        method_name = 'get'

        session = requests.session()
        req = requests.Request(
            method=method_name.upper(),
            url=request_url,
            params=payload
        )
        prep = session.prepare_request(req)

        settings = session.merge_environment_settings(
            prep.url, None, None, None, None)
#            prep.url, proxy, None, None, None)  #Change the line to enable proxy
        send_kwargs = {
            'timeout': None,
            'allow_redirects': None,
        }
        send_kwargs.update(settings)
        resp = session.send(prep, **send_kwargs)

        # For more clean output
        gc.collect()

tester()

System Information

{
  "chardet": {
    "version": "3.0.4"
  },
  "cryptography": {
    "version": "2.3.1"
  },
  "idna": {
    "version": "2.7"
  },
  "implementation": {
    "name": "CPython",
    "version": "3.6.6"
  },
  "platform": {
    "release": "4.15.0-36-generic",
    "system": "Linux"
  },
  "pyOpenSSL": {
    "openssl_version": "1010009f",
    "version": "17.5.0"
  },
  "requests": {
    "version": "2.19.1"
  },
  "system_ssl": {
    "version": "1010007f"
  },
  "urllib3": {
    "version": "1.23"
  },
  "using_pyopenssl": true
}

[sigmavirus24]

In the future, please search closed and open issues before creating new ones that are duplicates.

Duplicate of #4601