Memory-Mapped File

Definitions

1. A technique that maps a file directly into a process's virtual address space, allowing the program to read/write the file as if it were memory. The OS handles paging data in and out transparently. Enables zero-copy file access, shared memory between processes, and is used by databases (LMDB, MongoDB's old engine) and search engines.

   In plain English: Making a file appear as regular memory so your program can read it like an array instead of using file read operations.

   Example: "The search index uses mmap — the entire 20GB index is accessible as memory, and the OS handles caching the hot pages."

Related Terms

• Allocator
• Ring Buffer
• Memory Pool
• io_uring
• Lock-Free Data Structure
• ARM Architecture
• Array Buffer
• Batch Processing Detail
• Inline Assembly
• Runaway Process
• Buffer Size