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locustfile 是什么？ locustfile 是 Locust 性能测试工具的用户脚本，描述了单个用户的行为。
locustfile 是个普通的 Python 模块，如果写作locustfile.py，那么路径切换到文件所在目录，直接执行命令就能运行：
$ locust 如果换个名字，那么只能通过-f参数指定文件名运行：
$ locust -f locust_files/my_locust_file.py 与一般 Python 模块不同的是：locustfile 必须至少定义一个类，且继承自 User 类。
User 类 User 类表示性能测试的模拟用户，Locust 会在运行时创建 User 类的实例。
wait_time 属性 设置等待时间，默认值不等待，立即执行。
Locust 支持 4 种方式设置 wait_time 属性。
为了便于理解实际意义，我把源码贴在了下面。
constant函数，常量，任务执行完毕等待 X 秒开始下一任务。
def constant(wait_time): """ Returns a function that just returns the number specified by the wait_time argument Example:: class MyUser(User): wait_time = constant(3) """ return lambda instance: wait_time between函数，区间随机值，任务执行完毕等待 X-Y 秒（中间随机取值）开始下一任务。
def between(min_wait, max_wait): """ Returns a function that will return a random number between min_wait and max_wait. Example:: class MyUser(User): # wait between 3.0 and 10.5 seconds after each task wait_time = between(3.0, 10.5) """ return lambda instance: min_wait + random.random() * (max_wait - min_wait) constant_pacing函数，自适应，若任务耗时超过该时间，则任务结束后立即执行下一任务；若任务耗时不超过该时间，则等待达到该时间后执行下一任务。
def constant_pacing(wait_time): """ Returns a function that will track the run time of the tasks, and for each time it's called it will return a wait time that will try to make the total time between task execution equal to the time specified by the wait_time argument. In the following example the task will always be executed once every second, no matter the task execution time:: class MyUser(User): wait_time = constant_pacing(1) @task def my_task(self): time.sleep(random.random()) If a task execution exceeds the specified wait_time, the wait will be 0 before starting the next task. """ def wait_time_func(self): if not hasattr(self, "_cp_last_run"): self._cp_last_wait_time = wait_time self._cp_last_run = time() return wait_time else: run_time = time() - self._cp_last_run - self._cp_last_wait_time self._cp_last_wait_time = max(0, wait_time - run_time) self._cp_last_run = time() return self._cp_last_wait_time return wait_time_func 自定义wait_time方法，比如每次等待时间 1 秒 2 秒 3 秒递增：
class MyUser(User): last_wait_time = 0 def wait_time(self): self.last_wait_time += 1 return self.last_wait_time ... ...