As a senior AnQi CMS website operation personnel, I know that in daily management, process control is a key link in maintaining the stable operation of the website. When faced with the need to forcibly terminate the AnQiCMS process butkill -9When the command seems not to work, this is indeed a thorny problem.Below, I will draw on my experience to analyze the possible causes in detail and discuss the role of the process ID (PID) in this process.

Understandingkill -9the function

Firstly, we need to clarifykill -9the meaning of the command.killThe command is used to send a signal to a process, while-9then specifies the transmission.SIGKILLSignal.SIGKILLIt is a very special signal that forces the operating system to immediately terminate the target process without giving the process any opportunity to handle, clean up, or ignore the signal. This means that theoretically, any user-space process should terminate when receivingSIGKILLStop immediately after the signal. If the AnQiCMS process is runningkill -9Still "existing" or immediately "reviving" after that, then the reason is usually notkill -9It is not失效，but rather a deeper or more complex mechanism is at play.

Process ID (PID) plays a core role in termination operations.

The process ID (PID) is a unique identifier assigned by the operating system to each running process, it is the executionkillSpecify the key of the target process when issuing commands. You can consider it as the 'ID card number' of each process. When you executekill -9 PIDAt that time, the system will attempt to send a termination signal to the process with the specified PID. If the specified PID is incorrect, or if the target process you believe to be running is actually already dead and has been taken over by another new process (even if listening on the same port), thenkill -9Unable to terminate the process you expect. Therefore, the accuracy of the PID iskillthe basis of command validity.

kill -9Possible reasons why terminating the AnQiCMS process may be ineffective

Whenkill -9When unable to terminate the AnQiCMS process, there may be the following situations:

1. The process ID is inaccurate or has changed

This is the most common case. A process, especially like AnQiCMS, may be managed by a daemon script such asstart.sh）Application for monitoring and management, which may restart immediately with a new PID after termination. We saw it in the AnQiCMS installation document,start.shThe existence of a script, which usually includes checking if the AnQiCMS process is running and automatically restarting it.

For example,start.shThe script will checkps -ef | grep AnQiCMSfor the existence of the process with a command. If youkill -9terminated the current AnQiCMS process, andstart.shThe script detects the disappearance of a process within a few seconds, it will immediately start a new AnQiCMS instance, which will have a different PID. At this point, you will see a 'new' AnQiCMS process still running, mistakenly thinking that the previous one had disappeared.kill -9Failed.

To confirm this, you should execute.kill -9Run multiple times in a row.ps -ef | grep anqicmsTo observe the change in PID. If the PID changes, thenkill -9It was actually successful, but the guardian script quickly started a new process again.

2. The process is in an uninterruptible sleep state (D state).

Although it is not common, if the AnQiCMS process is runningkill -9At the moment, it is deeply engaged in kernel operations, such as waiting for network file system (NFS) I/O responses, accessing faulty hardware, or making certain hardware driver calls, it may enter a so-called "uninterruptible sleep" (D state). In this state, the process will completely ignore includingSIGKILLAll signals within.This is not a problem with the AnQiCMS application itself, but rather with the underlying operating system or hardware level.To solve this problem, it usually requires solving the root cause that causes the process to enter the D state, such as fixing hardware failures, unloading pending network shares, or even restarting the entire server.

Resource exhaustion leads to system hang

In extremely rare cases, if the entire system becomes extremely unstable due to exhaustion of memory, file descriptors, or other critical resources, the kernel may even fail to sendSIGKILLThe ability to signal or process its effects is limited.This usually comes with severe performance degradation of the entire system and a large number of error logs.In this case, the problem has exceeded the scope of a single AnQiCMS process, and an in-depth diagnosis of the entire server environment is required.

4. Insufficient privileges

When attempting to terminate a process that does not belong to your user or another user, if you do not have sufficient privileges (for example, notroota user),kill -9The command will not succeed. However, for system processes like AnQiCMS, they are usually run by a specific user, if you are running asroota user accountkill -9If, then permission issues are usually not a barrier.

How to effectively terminate the AnQiCMS process

If you encounterkill -9It seems invalid, please follow the steps below:

  • Check and confirm the PID multiple timesDuring executionkill -9Before usingps -ef | grep anqicmsConfirm the current PID. Executekill -9Run the command immediately again, observe whether the PID changes. If the PID has changed, it means the process has been terminated and quickly restarted.
  • Identify and stop the守护脚本If you find that the AnQiCMS process is always being restarted automatically, the problem lies with the daemon script responsible for monitoring and starting it (such as the one provided by AnQiCMS)start.shscript, or system-levelsystemdService, Docker container orchestration tools, etc.). You need to terminate this daemon script or service first, and then terminate the AnQiCMS process. The documentation mentioned.stop.shThe script exists for this purpose.
  • View system and application logsCheck the running log of AnQiCMS (such asrunning.log/check.log) as well as the system log (such asjournalctlor/var/log/syslog)，to obtain any clues about process termination or restart.
  • Check system health status：If you suspect a D state or other system-level issue, usetop/htop/iostat/dmesgCheck tools for CPU usage, memory usage, I/O wait, kernel error messages, etc., to diagnose the existence of deeper system problems.

Through the above analysis and diagnosis, you can usually find out why the AnQiCMS process cannot bekill -9completely terminated and take appropriate measures to solve the problem.

Frequently Asked Questions (FAQ)

1. I want to stop the AnQiCMS process for a while, but every timekill -9it restarts immediately afterwards. What should I do?

This is because of the AnQiCMS'sstart.shThe script (or a similar daemon) is monitoring and automatically restarting it. To stop AnQiCMS, you should use the one provided by it.stop.shScript. If AnQiCMS is running throughsystemdDocker or other service management tools, you need to use the corresponding commands of these tools to stop the service (for examplesystemctl stop anqicmsordocker stop anqicms-container)。Justkill -9Stopping the process without stopping its guardian will only cause it to restart infinitely.

2. Whyps -ef | grep anqicmsThe PID I seekill -9will change after?

This means yourkill -9The command was actually successful, it terminated the old AnQiCMS process. However, due to the presence of a daemon script (such asstart.sh) or the service manager is running in the background, it detects that the AnQiCMS process has stopped and immediately starts a new AnQiCMS instance.This new instance will receive a new, different PID.So, you see a new process rather than the 'resurrection' of the old one.

3. My server is very laggy,kill -9The command itself is also unresponsive, could this be the reason?

Ifkill -9The command itself cannot be executed quickly, which usually indicates that the entire operating system is experiencing a severe performance problem or resource bottleneck.Possible causes include: kernel-level issues (such as processes stuck in an uninterruptible D state waiting for hardware I/O), system memory or swap space exhaustion, disk subsystem failure, or extremely high CPU load causing the system to be unable to process commands in a timely manner.In this case, you need to check the health of the entire server, which may require restarting the server to resume normal operation.