As an experienced website operations expert, I know that fine-grained control of server resources is the key to ensuring the stable operation of the website.The occupation and release of network ports, especially a seemingly minor but potentially problematic link.Today, let's delve into the discussion of whether the port occupied by AnQiCMS service will be immediately released after its shutdown, as well as how we, as operators, should verify it.

Deeply explore: After the AnQiCMS service stops, whether the port is immediately released and its verification method

In the daily operation of the website, we often need to start, stop, or restart various services to cope with updates, maintenance, or troubleshooting.For AnQiCMS, an enterprise-level content management system developed based on the Go programming language, its high efficiency and concurrency features are widely praised.However, even the best systems require our special attention in resource management, especially the occupation of network ports.

Basic understanding of port occupation

In simple terms, a port is like a 'door number' on a server, and each running service communicates with the outside world through a specific port.AnQiCMS by default will use port 8001 for service listening, for example, we have seen the figure of the default port 8001 in the Baota panel or Docker deployment tutorial.If multiple AnQiCMS instances need to be run on the same server, or if AnQiCMS needs to be deployed with other services, proper port management becomes particularly important, because port conflicts can prevent services from starting.

Port release mechanism after the AnQiCMS service stops

When discussing whether the port is released 'immediately' after the service stops, this actually involves how the operating system handles process termination and the details of the network protocol.

Under ideal circumstances, when an application shuts down gracefully, it will actively close all network connections and notify the operating system to release the ports it is using.The operating system will then quickly mark these ports as available.However, the actual situation may not always be "immediate" as such.

Read the AnQiCMS deployment document, whether it is manual deployment under Linux environment or scheduled task in Baota panel, the script to stop the service (for examplestop.sh）usually adoptskill -9 {PID}This is a mandatory termination command. In the Windows environment, using Task Manager to 'End Task' also belongs to a similar mandatory shutdown operation.

The characteristic of this forced termination method is:)

  1. ImmediacyThe operating system will immediately kill the target process, not giving the application any opportunity to perform cleanup work.)
  2. Potential delay：Although the process is killed, the network connections associated with this process will not disappear completely from the system immediately. According to the TCP/IP protocol, after a connection is closed, it will enter a state namedTIME_WAITof the status.In this state, the operating system will retain the port and its connection information for a period of time (usually a few seconds to several minutes) to ensure that all packets have been transmitted or timed out, and to avoid interference from old connection packets with new connections.

Therefore, if the AnQiCMS service is stopped usingkill -9or a similar forced method, the port will not be released immediately in a strict sense. It may takeTIME_WAITStay in the state for a period of time, during which, trying to start another service that listens on the same port may fail, and you may receive an error message提示“Address already in use”or“Port already occupied”.

How to verify if the port has been released

After understanding the mechanism of port release, we can use some commands to verify the actual status of the port.

  1. How to verify in Linux environment:Linux system provideslsof（list open files）tool, can list all files opened by processes, including network connections.

    Verification command:

    lsof -i:{端口号}

    For example, to check port 8001:

    lsof -i:8001

    Output interpretation:

    • If the command produces no output, it means that the port is currently not being listened to or occupied by any process.
    • If you see something similaranqicms 12345 user TCP *:8001 (LISTEN)The output indicates that the AnQiCMS service is listening on this port.
    • If the service has stopped but you still see similar outputsTCP *:8001 (TIME_WAIT)The output means that the port is currently inTIME_WAITStatus, although there is no actual service listening, it may not be bound by other programs in a short period of time.
    • If another process occupies the port, it will display the information of the corresponding process.

  2. Verify under Windows environment:Windows system can be usednetstatcommand to view network connection status.

    Verification command:

    netstat -ano | findstr :{端口号}

    For example, to check port 8001:

    netstat -ano | findstr :8001

    Output interpretation:

    • This command lists all connections containing the specified port number and displays the process ID (PID).
    • LISTENINGThe status indicates that a service is listening on this port.
    • TIME_WAITThe status indicates that the port is waiting to close.
    • If there is no output, it means that the port is currently not occupied.
    • You can use任务管理器(or}tasklist | findstr {PID}）to find the process corresponding to the PID.

  3. Direct access verification：The most intuitive verification method is to try to access the AnQiCMS address via a browser (for examplehttp://yourdomain.com:8001).

    • If the display shows "Unable to access this website" or "Connection was refused", it means that the service has stopped and the port is not being listened on.
    • If the page displayed is AnQiCMS, it means the service is still running.
    • If the new service does not start after attempting to start a new service, and the browser access fails, it may be that the port is still in useTIME_WAITstatus.

Precautions for different deployment methods

  • Lan塔面板/Linux命令行部署：Due tostop.sh脚本通常使用kill -9，因此端口进入TIME_WAITThe possibility of status is relatively high. It is recommended to wait for about 30 seconds to 1 minute after stopping the service, and then try to start a new service or rebind the port, or throughlsofcommand to confirm the port status.
  • Docker deployment：Docker container processes stop, the Docker daemon will handle the container's resource release.Generally, stopping a Docker container will release the host's ports relatively quickly.TIME_WAIT. The verification method is still to check the ports on the host machine.
  • Windows manual operation：End the process through the Task Manager.anqicms.exeprocess, withkill -9similar, may also cause the port to enterTIME_WAITstatus. The verification method is the same as that under the Windows environmentnetstatthe same.

Conclusion and Recommendations

In summary, the AnQiCMS service is accessed through forced methods (such askill -9或Task Manager end) after stopping, the port it occupies will not be released "immediately" in a strict sense, but may beTIME_WAITStay in the state for a while. This means that if you try to restart AnQiCMS or bind other services to the same port within a short period of time, you may encounter port conflict issues.

As a senior website operator, I recommend that you:

  1. Always verify the port status:After each stop of AnQiCMS service, especially before immediately starting another service or restarting AnQiCMS, it is good practice to uselsofornetstatThe habit of verifying whether the command port is completely released.
  2. Reserved buffer time:If the verification finds that the port isTIME_WAITStatus, please wait for tens of seconds to a minute, allowing the operating system to complete the cleanup work.
  3. Plan port usage:For multi-site management scenarios, it is necessary to configure a separate port for each AnQiCMS instance to avoid inconvenience caused by port conflicts. You can modify the port by changing the directory under AnQiCMS root.config.jsonFile specifies different ports.

Through these meticulous operations, we can ensure the smooth operation of AnQiCMS service, avoiding various operational problems caused by improper port management.

Common Questions (FAQ)

  1. Why does the AnQiCMS service still prompt that the port is occupied after the new service starts, even though the previous service has stopped?This is usually because you used a forced method (such askill -9or Task Manager to end) stopped the AnQiCMS service. Although the process has been terminated, the operating system will keep the port open for the robustness of network communication.TIME_WAITStatus for a brief period of time (usually several seconds to a few minutes), during which other services cannot bind