I’m encountering an issue where parallelizing Unity APK builds across multiple processes does not reduce total build time on an Apple M1 Pro Mac. Here are the details:
Environment
Hardware: MacBook Pro with M1 Pro chip (8-core CPU: 6 performance cores + 2 efficiency cores), 32GB RAM, 1TB SSD.
Software: Unity 2021.3.41f1; Python 3.9.6 for process orchestration.
Observation
Sequential builds: Building 3 Unity projects one after another takes ~4 minutes per project, totaling ~12 minutes.
Parallel builds: Using Python’s multiprocessing module to spawn 3 processes (one per project) also takes ~12 minutes total.
Process Implementation (Python snippet):**
import multiprocessing
import subprocess
def build_project(project_path):
"""
Builds a Unity project using command-line arguments.
Args:
project_path (str): Path to the Unity project directory.
"""
try:
# Define the Unity build command
command = [
"Unity", # Unity executable (ensure it's in your PATH)
"-quit", # Exit Unity after the build
"-batchmode", # Run in headless mode
"-projectPath", project_path, # Path to the Unity project
"-executeMethod", "BuildScript.BuildAndroid" # Custom build method
]
# Execute the command
print(f"Starting build for project: {project_path}")
os.system(command)
print(f"Build completed for project: {project_path}")
except subprocess.CalledProcessError as e:
print(f"Build failed for project {project_path}: {e}")
if __name__ == '__main__':
# List of Unity project paths
projects = [
"/path/to/Project1", # Replace with actual path
"/path/to/Project2", # Replace with actual path
"/path/to/Project3" # Replace with actual path
]
# Create a list to hold process objects
processes = []
# Start a process for each project
for project in projects:
process = multiprocessing.Process(target=build_project, args=(project,))
process.start()
processes.append(process)
# Wait for all processes to complete
for process in processes:
process.join()
print("All builds completed.")
Troubleshooting Attempts :
Verified no output path conflicts (each project writes to a separate directory).
Checked Unity Editor.log for errors – no apparent locks or failures.
Tested with 2 parallel processes instead of 3 – total time still ~8 minutes (close to 4x2).
SSD disk I/O appears healthy
Key Questions:
Why might parallel Unity builds on Apple Silicon not leverage multi-core efficiency as expected?