Docker Slowdown on MacOS: Causes and Solutions

Docker on MacOS presents performance challenges due to the underlying differences between Mac OS and a Linux kernel, which Docker requires to run efficiently. This abstraction layer between the kernel and Docker containers affects performance and limits the capabilities of Docker on MacOS compared to running it directly on Linux.

Reasons for Slow Performance:

• Abstraction Layer: Docker runs on MacOS using a client and an abstraction layer, causing performance overhead.
• Filesystem Differences: The Mac OS filesystem differs from that of Linux, leading to file access issues and bottlenecks.

Impact on Real-World Use Cases:

Using Symfony 4 on Docker v18 on MacOS Mojave, the execution time measurements for the following scenarios demonstrate the performance impact:

• First Time Rendering: 12000 ms
• With Symfony Cache: 344 ms
• With Docker Cache: 195 ms
• Without Docker (Symfony Cache): 82 ms

Improvements:

Although Docker performance cannot match that on Linux, some improvements can be made to mitigate the slowdown:

• Use Cached Volumes: By mounting local directories with the cached option, Docker can improve performance by caching frequently accessed files.
• Avoid Heavy Database Queries: Reducing the number and complexity of database queries can significantly improve overall performance.
• Optimize Symfony Configuration: Using Symfony performance optimization techniques, such as cache preloading, can also enhance the application's performance on Docker.