I sped up serde_json strings by 20%

In a recent blog post, the author discusses optimizing the performance of the Rust serialization framework, serde_json, which is widely used for JSON parsing. The author identified that the error handling path in serde_json was significantly slower than the success path, prompting a performance review. By profiling the code, they pinpointed a function responsible for converting string indices to line/column positions as a bottleneck. The author replaced this function with a more efficient implementation using the memchr crate, which utilizes SIMD (Single Instruction, Multiple Data) for faster string searching and counting. This change resulted in a notable improvement in error path performance. Following this, the author explored further optimizations, particularly in string parsing, and learned that a two-pass algorithm was less efficient than a single-pass approach. They ultimately devised a method to check for escape characters and control codes in one pass using bitwise operations, which could simulate SIMD behavior. This approach aimed to maintain code simplicity while enhancing performance. The author’s contributions were well-received, with their pull request being quickly merged into the serde_json codebase, marking a successful first contribution to the project.

- The author optimized serde_json's error handling, improving performance by over 20%.

- Profiling revealed significant slowdowns in error path processing compared to success path.

- The memchr crate was utilized to enhance string searching efficiency.

- A single-pass algorithm was found to be more effective than a two-pass approach for string parsing.

- The author's pull request for optimizations was accepted, highlighting the collaborative nature of open-source development.