LZHV: Accelerating LZ77 Compression Algorithm with Hash Verification

The longest match strategy in LZ77, a major bottleneck in the compression process, is accelerated in enhanced algorithms such as LZ4 and ZSTD by using a hash table. However, it may results in numerous random memory accesses, which modern CPUs handle inefficiently, thus reducing the compression speed. In this paper, we introduce the LZHV algorithm, which significantly reduces unnecessary memory accesses by over 99% through the implementation of hash verification within the hash table. By integrating LZHV into LZ4 at its default compression level and ZSTD at levels 3 and 4, we achieve a compression speed improvement of over 10% across various platforms.