How to set transactions per minute in Locust - python-3.x

Question

I am writing a LoadTestShape Class. I want to be able to set number of transaction per minute. If I try to set it by specifying user_count it doesn't work because the RPS will vary cpu to cpu .
If say I want to set 1000 transaction per minute, how can we achieve that in locust?

Answer 1

The only way to "achieve" this in Locust is implementing Pacing, the logic is:
You know how much time one iteration takes for one user
If user manages to finish faster - you need to introduce some "think time" so your thread "sleeps" till the desired time
If iteration is slower - no sleep is required.
This answer shows how you can create a custom load shape
Alternatively you can consider switching to a load testing tool which provides such functionality, i.e. Apache JMeter with Constant Throughput Timer

Answer 2

for this timing that's enough to add a LoadTestShape class to locustfile.py like the below code which I use for one of my tests you can change the number of users or other parameters as you want(I write a full docstring that describes each parameter in that):
class StagesShape(LoadTestShape):
"""
A simply load test shape class that has different user and spawn_rate at
different stages.
Keyword arguments:
stages -- A list of dicts, each representing a stage with the following keys:
duration -- When this many seconds pass the test is advanced to the next stage
users -- Total user count
spawn_rate -- Number of users to start/stop per second
stop -- A boolean that can stop that test at a specific stage
stop_at_end -- Can be set to stop once all stages have run.
"""
stages = [
{"duration": 60, "users": 3, "spawn_rate": 0.05},
{"duration": 60, "users": 6, "spawn_rate": 0.05},
{"duration": 60, "users": 9, "spawn_rate": 0.05},
{"duration": 60, "users": 12, "spawn_rate": 0.05},
{"duration": 60, "users": 15, "spawn_rate": 0.05},
{"duration": 60, "users": 18, "spawn_rate": 0.05},
{"duration": 60, "users": 21, "spawn_rate": 0.05},
{"duration": 60, "users": 24, "spawn_rate": 0.05},
{"duration": 60, "users": 27, "spawn_rate": 0.05},
{"duration": 60, "users": 30, "spawn_rate": 0.05},
]
def tick(self):
run_time = self.get_run_time()
for stage in self.stages:
if run_time < stage["duration"]:
tick_data = (stage["users"], stage["spawn_rate"])
return tick_data
return None

Answer 3

I ended up using constant_throughput to control the number of requests per second.
For different time of the day I'd use a different throughput value.
Simply set the wait_time = constant_throughput(0.1). Based on RPS you want you can either set the value low for less number of requests and more for more RPS.