load_test: update the Queue class provider to work well on MacOS

[kpouget]

see https://stackoverflow.com/questions/65609529/python-multiprocessing-queue-notimplementederror-macos

Summary by CodeRabbit

• Refactor
  • Improved internal handling of inter-process communication for more robust and reliable concurrent operations.

[coderabbitai]

Walkthrough

The changes modify load_test.py to use a new multiprocessing manager for queue creation. Instead of the previous context-based queues (using mp_ctx.Queue()), the code now instantiates logger_q, stop_q, and dataset_q with mp_mgr.Queue(). This change enhances inter-process communication by centralizing queue management with a multiprocessing manager while maintaining the original error handling and overall control flow.

Changes

File	Changes
load_test.py	Introduced mp_mgr via mp.Manager(). Updated queue declarations for logger_q, stop_q, and dataset_q from mp_ctx.Queue() to mp_mgr.Queue().

Sequence Diagram(s)

sequenceDiagram
    participant Main as Main Script
    participant Manager as MP Manager
    participant Worker as Worker Process

    Main->>Manager: Instantiate mp_mgr via mp.Manager()
    Main->>Manager: Create logger_q, stop_q, dataset_q using mp_mgr.Queue()
    Manager-->>Main: Return shared queues
    loop Inter-process communication
        Worker->>Manager: Request queue operations (log, stop, dataset tasks)
        Manager-->>Worker: Process queue actions
    end

Loading

Poem

In a code field so vast and new,
I hopped along with queues that flew.
mp_mgr led the way so bright,
Guiding messages day and night.
With hops and bytes in joyful cheer,
This rabbit sings: "Our queues are here!"
🐇✨

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📥 Commits

Reviewing files that changed from the base of the PR and between cc906c1 and ad177df.

📒 Files selected for processing (1)

• load_test.py (2 hunks)

🔇 Additional comments (5)

load_test.py (5)

1-2: Good addition of the shebang line.

The shebang line makes the script directly executable on Unix-like systems including MacOS, which aligns with the goal of improving MacOS compatibility.

---

122-123: Well-implemented manager for MacOS compatibility.

Using a manager object is a good approach to solve the NotImplementedError that can occur with Python multiprocessing Queue on MacOS. The Manager provides a server process that manages shared objects like queues across processes, ensuring better compatibility.

---

124-124: Appropriate change to manager-based queue.

Changing from mp_ctx.Queue() to mp_mgr.Queue() for the logger queue addresses the MacOS compatibility issue.

---

128-129: Consistent implementation of manager-based queues.

Good job consistently applying the manager-based queue approach to all queues in the code.

---

154-154: Consider using the manager for process creation.

Currently, processes are created using mp_ctx in the create_procs function, while queues use mp_mgr. For consistency, you might want to consider using the manager for process creation as well.

This comment aligns with a previous review suggestion that mentioned: "I think if we are using the manager class instead of context-based multi-processing, we should also use it to spin new processes (line #152). Have you tried using mp_mgr for the create_procs?"

Run the following to verify if this would work in your environment:

#!/bin/bash
# Verify if Manager can be used for process creation on MacOS
python3 -c "
import multiprocessing as mp
import platform

print(f'Testing on platform: {platform.system()}')

# Test if manager can create processes
mp_ctx = mp.get_context('spawn')
mp_mgr = mp_ctx.Manager()

try:
    # Try to create a process through the manager
    def test_func():
        print('Process created successfully')
    
    # See if Manager has a Process method like mp_ctx does
    if hasattr(mp_mgr, 'Process'):
        p = mp_mgr.Process(target=test_func)
        print('Manager has Process method')
    else:
        print('Manager does not have Process method, must continue using mp_ctx for process creation')
        # This is the current approach in the code
        p = mp_ctx.Process(target=test_func)
    
    p.start()
    p.join()
    
except Exception as e:
    print(f'Error: {e}')
"

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[coderabbitai]

Actionable comments posted: 0

🧹 Nitpick comments (1)

load_test.py (1)

126-127: LGTM! Consider documenting the MacOS compatibility fix.

The migration to manager-based queues is well-implemented. Consider adding a comment explaining why manager-based queues are used to help future maintainers understand the MacOS compatibility consideration.

+    # Use manager-based queues for better MacOS compatibility
     stop_q = mp_mgr.Queue(1)
     dataset_q = mp_mgr.Queue()

📜 Review details

Configuration used: CodeRabbit UI
Review profile: CHILL
Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 23db634 and cc906c1.

📒 Files selected for processing (1)

• load_test.py (1 hunks)

🔇 Additional comments (2)

load_test.py (2)

119-119: LGTM! Good solution for MacOS compatibility.

Using a multiprocessing Manager is a robust solution for handling shared queues across processes on MacOS, where the default Queue implementation can sometimes raise NotImplementedError.

---

122-122: LGTM! Consistent queue management.

The logger queue is correctly migrated to use the multiprocessing manager, maintaining consistent queue management across the application.

[sjmonson]

LGTM

[npalaska]

I think if we are using the manager class instead of context-based multi-processing, we should also use it to spin new processes (line #152). Have you tried using mp_mgr for the create_procs?

[kpouget]

good catch Nikhil. I followed the other suggestion.

[kpouget]

I updated the code to follow @npalaska's suggestion, and I added a shebang header to make it easier to launch the load test manually.

Tested on MacOS.

[kpouget]

@npalaska @sjmonson @dagrayvid any other feedback? good to merge?

[dagrayvid]

lgtm!

[kpouget]

great, thanks 🎉