Guardian Core: AnQiCMSstart.shDeep considerations in script PID checking

As an expert in website operation for many years, I know that every detail of the stable operation of the system is crucial.For a content management system like AnQiCMS that pursues efficiency and simplicity, even though its underlying technology is based on Go language with excellent concurrent processing capabilities, we still need a rigorous mechanism in daily operations to ensure the robustness of its running environment.start.shDoes the script need to check PID to avoid repeated startup?

start.shThe role of the script and the challenges it faces

AnQiCMS providesstart.sh脚本，这是我们启动 AnQiCMS 服务的重要工具。在实际部署中，尤其是在 Linux 服务器环境下，为了确保 AnQiCMS 能够持续稳定地运行，并且在服务器重启或程序意外退出后能自动恢复，我们通常会将其配置到系统的计划任务（如 Englishcrontab）中，set to execute once a minute.

Imagine if thisstart.shWhat will happen every time the script is triggered by the scheduled task, and it starts a new AnQiCMS process without hesitation?The system will soon be filled with a large number of duplicate AnQiCMS instances.This will undoubtedly bring a series of serious stability and performance issues.

Therefore,start.shScript PID (Process ID, process identifier) check is to solve this core challenge.It plays the role of an 'intelligent guardian', ensuring that only one healthy and active instance of AnQiCMS is running at all times.

is the core reason to avoid repeated startup

What specific problems might repeated startup cause? This is the crystallization of various technical considerations and operational experience:

  1. Resource abuse and sharp performance declineAnQiCMS as a content management system requires system resources such as CPU, memory, network ports, etc.Each time the program restarts, it consumes a new set of resources.If dozens or even hundreds of AnQiCMS processes run simultaneously, the server's CPU will be overloaded, memory will be rapidly exhausted, and network bandwidth will be occupied by unnecessary connections.This will not only make AnQiCMS itself respond slowly and even crash, but it will also affect other services running on the same server, ultimately leading to a sharp decline in the performance of the entire system and a steep decline in user experience.

  2. Port conflict is the primary obstacleAccording to AnQiCMS's design, it usually listens on a specific port (for example, the default port mentioned in the document is8001To provide HTTP service. The operating system stipulates that the same port can only be bound and used by one process at a time. Ifstart.shAttempt to start the second AnQiCMS instance, while the first instance is still running, then the second instance will not be able to bind to8001Port, thus starting failure and throwing an error. Even if AnQiCMS can run in the background without crashing immediately, this error will fill the log and hide the real problem.faq.mdAlso, it is explicitly mentioned that running multiple AnQiCMS instances on the same server requires assigning them different ports to avoid such port conflicts.

  3. Data consistency and potential data corruptionAlthough AnQiCMS is developed based on Go language, fully utilizing Goroutine to achieve high-performance concurrent processing, which mainly refers tothe internal process of a single processThe concurrency.When multiple independent AnQiCMS processes attempt to read and write to the same database, file cache, or session data simultaneously, it is very likely to lead to data inconsistency or data corruption, unless there is a well-designed distributed lock or data synchronization mechanism (which is usually considered in more complex distributed systems).For example, if two processes modify the same article simultaneously, which modification will take effect?or even worse, leading to database deadlock or file content chaos.PID check avoids this risk from the source.

  4. The chaos and uncertainty in operations managementImagine, when your website has issues, you need to check logs, restart services.If there are multiple AnQiCMS processes running in the background, you will not be able to determine which is the 'correct' process and which is the 'ghost' process.The service may stop only one instance when stopping the service, and other instances are still running, causing the problem to be unresolved.When checking logs, multiple processes may write to different log files or interleave writing to the same file, making it extremely difficult to troubleshoot issues.This uncertainty will greatly increase the complexity and risk of operations.

The working principle of PID check

AnQiCMSstart.shScript throughps -ef | grep '\<anqicms\>' | grep -v grep | wc -lSuch a combination of commands accurately completes the PID check.

  • ps -ef：List all running processes with detailed information.
  • grep '\<anqicms\>'：Filter out processes from the process list that contain the word “anqicms” (\<and\>Ensure that the match is the complete word, not a partial match).
  • grep -v grepExclude it.grepProcess the command itself, becausegrepIt is also a process that includes the keyword 'grep'.
  • wc -l：Count the final number of filtered rows, that is, the number of AnQiCMS processes.

If the count result (existsVariable) is 0, indicating that there are no AnQiCMS processes running, and the script will execute.nohup $BINPATH/$BINNAME >> $BINPATH/running.log 2>&1 &to start the AnQiCMS service. Conversely, ifexistsgreater than 0 indicates that AnQiCMS is already running, the script will exit silently without performing any operations, thus avoiding duplicate startups.

This design is simple and effective, providing basic operational support for AnQiCMS in various deployment environments (especially in environments without complex process guardian tools such assystemdorsupervisord) under the circumstances.

Summary

AnQiCMSstart.shThe PID check in the script is a wise choice made by its designer after fully considering the actual operation and maintenance scenarios to ensure system stability and reasonable resource utilization.It avoids resource waste, port conflicts, data risks, and management chaos caused by repeated startups through simple and effective shell commands, making AnQiCMS provide services to users in a more reliable and predictable manner.This reflects AnQiCMS's pursuit of rich features and excellent performance while also attaching great importance to the robustness of the system's underlying structure and the convenience of system maintenance.

Common Questions (FAQ)

  1. 问：EnglishCMS 的start.sh脚本检查 PID 后发现进程数大于 0，但实际网站无法访问，应该如何处理？答：这通常意味着 AnQiCMS 进程虽然存在，但可能已经“僵死”或处于异常状态，无法正常提供服务。The most direct method at this time is to manually stop the process first, then restart it.kill -9 [PID]Command forces the process to terminate (PID can belsof -i:8001orps -ef | grep anqicmsfound), then run it again./start.shor waitcrontabto automatically detect and start a new process in the next minute.

  2. 问：如果我在同一台服务器上部署多个 AnQiCMS 站点，它们的 Englishstart.sh脚本会冲突吗？ English答：Yes, there will be a conflict by default.Each AnQiCMS instance needs to listen on a separate port (for example, one using 8001, and another using 8002).start.sh脚本时，除了更改 EnglishBINPATH，您还需要修改 EnglishBINNAMEandgrepMatch the name, making it correspond to the unique executable file name for each instance (such asanqicms-site1,anqicms-site2), and the configuration of each instance must also be different to avoid port conflicts.config.jsonin the fileport.

  3. Question: Besidesstart.shWhat are some more advanced tools that can manage AnQiCMS processes?Answer: For more complex production environments, you can usesystemd(Standard service manager on Linux systems) orsupervisordAn equivalent process guardian tool.These tools can provide more comprehensive process start, stop, restart, log management, and resource limitation features.crontabandstart.shcombination.