Discord Reduced WebSocket Traffic by 40%

Discord has successfully reduced its websocket traffic by 40% through the implementation of zstandard compression, which replaced the previously used zlib. The transition aimed to enhance performance and reduce bandwidth usage, particularly on mobile platforms. Initially, zstandard did not perform as expected compared to zlib, primarily due to the lack of streaming compression capabilities. However, after forking the ezstd library to add streaming support, zstandard's performance improved significantly, achieving better compression ratios and faster compression times. The team also experimented with various compression settings and explored the use of dictionaries to optimize compression further. While the dictionary approach showed mixed results, the overall enhancements from zstandard streaming led to a notable reduction in payload sizes. Additionally, Discord investigated upgrading zstandard buffers during off-peak hours to utilize excess memory, although this strategy yielded less impact than anticipated due to memory fragmentation issues. Ultimately, the combination of these strategies has led to a more efficient and responsive service for users.

- Discord reduced websocket traffic by 40% using zstandard compression.

- Initial tests showed zstandard underperformed compared to zlib until streaming support was added.

- Compression settings were fine-tuned to optimize performance.

- Dictionary support was explored but ultimately deemed too complex for significant gains.

- Upgrading zstandard buffers during off-peak hours was less effective than expected due to memory fragmentation.