Shulou(Shulou.com)06/01 Report--

This article mainly explains "what are the advantages and disadvantages of shared memory in php". The content in the article is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn "what are the advantages and disadvantages of shared memory in php?"

In PHP, shared memory is an effective way to share and transfer data between two running processes on the same machine, which allows two unrelated processes to access the same logical memory and share the same physical memory between different processes.

Operating environment of this tutorial: windows10 system, PHP7.1 version, DELL G3 computer

What does shared memory mean in php

Shared memory is an effective way to share and transfer data between two running processes on the same machine. Shared memory between different processes is usually arranged into the same physical memory.

As the name implies, shared memory allows two unrelated processes to access the same logical memory.

A process can create a segment of memory that can be accessed by other processes, as long as it is assigned the correct permissions. Each memory segment has a unique ID (called shmid) that points to a physical memory area where other processes can manipulate it. Once the appropriate permissions are created and provided, other processes on the same machine can manipulate these memory segments: read, write, and delete, and if a process writes data to shared memory, the changes immediately affect any other process that can access the same shared memory.

This means that applications written in C can share information with applications written in other languages, such as Java or PHP. Shared memory is widely used in implementations for most languages, so access should not be a problem. To understand information, we can use a standard format, such as XML or JSON.

The use of shared memory is a fast way to exchange data between processes, mainly because the data is passed after the memory segment is created and does not involve the kernel. This method is often called interprocess communication (IPC). Other IPC methods include pipes, message queues, RPC, and sockets. This ability to exchange data quickly and reliably between applications is useful when using an ecosystem of applications that need to communicate with each other. Depending on the size of the ecosystem, common methods of exchanging information between applications using databases often result in slow queries or even Ihand O blocking. With shared memory, the absence of Ibank O slows the developer's progress.

Shared memory does not provide a synchronization mechanism, that is, there is no automatic mechanism to prevent the second process from reading it until the first process ends writing to the shared memory. So we usually need to use other mechanisms to synchronize access to shared memory.

The proposal in this article is simple: learn how to use PHP to create and manipulate shared memory segments and use them to store datasets that can be used by other applications. Even if there is no plan to use shared memory to exchange data, it has many benefits in itself, because it keeps applications away from Icano problems. There are many advantages to storing datasets directly in memory, from Web service data caching to session sharing. It is a very useful concept that every PHP developer should know.

Advantages and disadvantages of using shared memory

1. Advantages: we can see that it is very convenient to use shared memory for inter-process communication, and the interface of the function is also simple. Data sharing also makes the data between processes not to be transmitted, but directly accesses memory, which also speeds up the efficiency of the program. At the same time, it does not require the communication process to have a certain parent-son relationship like anonymous pipes.

2. Disadvantages: shared memory does not provide synchronization mechanism, which makes us often use other means to carry out inter-process synchronization when we use shared memory for inter-process communication.

We can use shared memory as a unique storage option, providing the advantages of fast read / write operations and process interoperability. For Web applications, this means:

Cache storage (database queries, Web service data, external data)

Session storage

Data exchange between applications

This storage technology is useful not only for caching, but also for data exchange between applications, as long as the data is stored in a format that can be read at both ends. Don't underestimate the power of shared memory in Web applications. There are many different ways to implement this storage cleverly, and the only limitation is the developer's creativity and skills.

Thank you for your reading, the above is the content of "what are the advantages and disadvantages of shared memory in php". After the study of this article, I believe you have a deeper understanding of what are the advantages and disadvantages of shared memory in php. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.