Looking for proxy settings will slow down the default http client

[myzhan]

Description of issue

I found this issue, and started to find out why. Althought many reasons have impacts on performance, I think I have found one.

The test script is simple.

from locust import HttpLocust, TaskSet, task

class UserBehavior(TaskSet):
    @task(2)
    def index(self):
        self.client.get("/")

class WebsiteUser(HttpLocust):
    host = "http://localhost:8080"
    task_set = UserBehavior

Starting with a single slave, and run dtruss on my macbook to have a look at the system calls. Then I found many not-so-related system calls.

stat64("/Users/myzhan/_netrc\0", 0x7FFEE8209FB0, 0x0)		 = -1 Err#2
stat64("/Users/myzhan/.netrc\0", 0x7FFEE8209FB0, 0x0)		 = -1 Err#2
stat64("/Users/myzhan/_netrc\0", 0x7FFEE8209FB0, 0x0)		 = -1 Err#2
stat64("/Users/myzhan/.netrc\0", 0x7FFEE8209FB0, 0x0)		 = -1 Err#2
stat64("/Users/myzhan/_netrc\0", 0x7FFEE8209FB0, 0x0)		 = -1 Err#2
stat64("/Users/myzhan/.netrc\0", 0x7FFEE8209FB0, 0x0)		 = -1 Err#2
stat64("/Users/myzhan/_netrc\0", 0x7FFEE8209FB0, 0x0)		 = -1 Err#2
stat64("/Users/myzhan/.netrc\0", 0x7FFEE8209FB0, 0x0)		 = -1 Err#2
stat64("/Users/myzhan/_netrc\0", 0x7FFEE8209FB0, 0x0)		 = -1 Err#2
stat64("/Users/myzhan/.netrc\0", 0x7FFEE8209FB0, 0x0)		 = -1 Err#2

By default, requests will looking for proxy settings, that's why these system calls show up.

By setting session.trust_env to False to disable the feature, the RPS increased from 400 to 700.

Expected behavior

Disable proxy by default, provide options to enable if needed.

Actual behavior

Environment settings

• OS: macOS Mojave
• Python version: 3.7.3
• Locust version: master branch

[cgoldberg]

cool.. can you create a PR for that?

[myzhan]

working on it.