API profiling at Pinterest
- Common profiling measurements are CPU, memory, and frequency of function calls. There are two approaches to taking these measurements - event-based profiling & statistical profiling.
- In event-based profiling, you track all occurrences of certain events such as function calls, returns and thrown exceptions. Statistical profiling is about sampling data by probing the call stack periodically. And it is less accurate but faster, with lower overheads.
- Pinterest’s API gateway service is written in Python. So, for memory profiling, tracemalloc package was used to track memory blocks.
- To calculate operational costs, Pinterest needed to combine resource utilization data and request metrics that show the popularity of each endpoint. This helped them identify the most costly endpoints and they also identified the engineers/teams they belonged to. This encouraged ownership and proactive performance monitoring by the respective teams.
- Dead code - unused, unowned code such as old experiments, tests and files, even lines of code in a file never actually called on in practice - can clutter repositories. Pinterest used a standard Python test coverage tool to identify dead code and then got rid of it.
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