Implementation Methods for Inter-Process Communication

Pipe

Pipe is one of the most fundamental mechanisms for inter-process communication (IPC). It enables data transmission through buffers managed by the kernel, and is divided into two types: anonymous pipe and named pipe.

• Anonymous Pipe is used only between parent and child processes, supporting unidirectional data transmission and suitable for simple process coordination.
• Named Pipe accesses data via file system paths, enabling cross-process and cross-session data exchange.
  Advantages：Simple to implement, high efficiency.
  Disadvantages：Supports only unidirectional communication, and cannot transmit data across networks.

Message Queue

Message Queue is a communication mechanism based on system calls, storing data in kernel-managed message queues.

• Characteristics：
  • Supports multiple processes for reading and writing, with data stored as message blocks.
  • Provides extended functionality such as message priority and type.
• Typical Use Cases：Scenarios requiring secure transmission of structured data, such as logging or task scheduling.
  Advantages：High security, supports multi-process access.
  Disadvantages：Creating and destroying message queues requires system resources, potentially leading to performance overhead.

Shared Memory

Shared Memory enables direct data exchange between processes by mapping physical memory regions. It is the most efficient IPC method.

• Implementation：
  • Uses shmget to create a shared memory segment, and shmat to map it into the process address space.
  • Requires semaphore synchronization to prevent data contention.
• Suitable Scenarios：High-performance real-time systems, such as video processing or large-scale data computation.
  Advantages：Data transmission speed is extremely fast, with no data copying required.
  Disadvantages：Complex synchronization mechanisms are required, which can lead to race conditions.

Semaphore

Semaphore is a synchronization tool for processes, controlling access to shared resources via a counter.

• Core Functionality：
  • P Operation (wait): Attempts to acquire the resource; fails and blocks if unavailable.
  • V Operation (signal): Releases the resource, notifying waiting processes.
• Extended Applications：Combined with shared memory, it enables complex synchronization logic.
  Advantages：Supports multi-process synchronization, suitable for distributed systems.
  Disadvantages：Cannot directly transmit data; used only for coordination operations.

Socket

Socket is a universal interface for cross-network communication, supporting both local and remote process communication.

• Classification：
  • Stream Socket (TCP): Connection-oriented, reliable transmission.
  • Datagram Socket (UDP): Connectionless, suitable for short message transmission.
• Typical Uses：Network services (e.g., HTTP, DNS) or distributed system communication.
  Advantages：Supports cross-network communication, flexible and standardized.
  Disadvantages：Requires handling of connection establishment, packet loss, etc.

File Sharing

Communication via File System is simple but inefficient, commonly used for logging or persistent data storage.

• Implementation：
  • Multiple processes open the same file in read-only or append mode.
  • Uses file locks to avoid conflicts.
• Limitations：Dependent on file system stability, may become a performance bottleneck.
  Advantages：Simple to implement, suitable for non-real-time scenarios.
  Disadvantages：Low efficiency, prone to data inconsistency issues.

Memory-Mapped File

Memory-Mapped File directly maps files to process address spaces, enabling efficient data sharing.

• Advantages：
  • Avoids explicit read/write operations, directly accessing files via memory.
  • Efficiently handles large files.
• Considerations：Requires managing file permissions and synchronization issues.
  Advantages：High performance, suitable for large data transmission.
  Disadvantages：High implementation complexity, requires careful memory management.