Today, let's delve into how to determine whether the shutdown operation of AnQiCMS is 'gracefully' exiting or 'forcefully' interrupting.

Understanding the core difference between 'graceful shutdown' and 'forced shutdown'

Before discussing the shutdown strategy of AnQiCMS, we must first clarify the essential difference between the concepts of 'Graceful Shutdown' and 'Forced Shutdown'.

Graceful shutdownAs the name implies, it is like a program that will perform a series of follow-up tasks after receiving an end command. It will:

  • Stop receiving new requestsEnsure no new user sessions or tasks enter.
  • Complete existing tasks: Allow the current ongoing tasks such as the request, database operations, file writing, etc. to end smoothly. This is crucial for avoiding data loss or damage.
  • Release system resources orderly close database connections, network ports, cache connections, etc., and return the occupied system resources to the operating system.
  • Save stateIf the program needs to persist temporary states, they will be saved before shutdown.
  • Send a signalBefore completely stopping, a signal such as 'I am going to stop' may be sent to the log system or other monitoring services.

The goal of graceful shutdown is to ensure system stability and data integrity, while minimizing the impact on users.

whileForced shutdownIt is a rough and immediate interruption of program execution. It does not give the program any buffer time to complete its current work, nor does it perform any cleanup. The consequences are often:

  • Data loss or corruptionThe ongoing data write operation may be interrupted, leading to inconsistent data.
  • User experience is compromisedThe user's ongoing request may suddenly interrupt, possibly displaying an error page.
  • Resources are not released.The database connection, file lock, and other resources may not be closed normally, leading to long-term occupation of system resources and even affecting the startup of subsequent programs.
  • Incomplete log records：Unable to record the final running state or error information of the program.

In short, graceful shutdown means 'I'm ready to go', while forced shutdown is 'stop immediately, no resistance allowed'.

The Practical Operation of AnQiCMS: Analyzing Its Essence

Now, let's focus on the shutdown operation of AnQiCMS.From its update log, we have seen descriptions such as 'New...elegant startup and restart of the blog', indicating that AnQiCMS has considered elegant operations from the very beginning of its design.However, in the actual deployment and operation scripts, we may encounter some different situations.

Taking the deployment of AnQiCMS on a Linux server as an example, the official provides:stop.shThe script content is as follows:

#!/bin/bash
### stop anqicms
# author fesion
# the bin name is anqicms
BINNAME=anqicms
BINPATH="$( cd "$( dirname "$0"  )" && pwd  )"

# check the pid if exists
exists=`ps -ef | grep '\<anqicms\>' |grep -v grep |awk '{printf $2}'`
echo "$(date +'%Y%m%d %H:%M:%S') $BINNAME PID check: $exists" >> $BINPATH/check.log
echo "PID $BINNAME check: $exists"
if [ $exists -eq 0 ]; then
    echo "$BINNAME NOT running"
else
    echo "$BINNAME is running"
    kill -9 $exists # 核心在此！
    echo "$BINNAME is stop"
fi

Carefully observe this script, and you will find that its core instruction iskill -9 $exists. In the Linux system,killthe command is used to send signals to processes,-9the parameter represents the signal to be sentSIGKILL.SIGKILLis a special signal that forces the operating system to immediately terminate the target process without giving the process any opportunity to catch the signal, perform cleanup, or save the state. In other words, any process that iskill -9A terminated program cannot perform graceful cleanup.

Therefore, from this official providedstop.shscript, the default stop operation of AnQiCMS isForced shutdown.

For Windows users, if you found it through Task Manager,anqicms.exeProcess and click “End Task” to stop AnQiCMS, which is equivalent to under Linux.kill -9Being of the same nature, it also belongs toForced shutdownthe same category.

How to judge whether the shutdown of AnQiCMS is 'graceful' or 'forceful'?

To determine the shutdown method of AnQiCMS, we can observe and analyze from the following aspects:

  1. Check the stop command:

    • Forced shutdown: If the command used iskill -9(Linux) or Task Manager's 'End Task' (Windows), then there is no doubt, this is a forced shutdown.
    • Graceful shutdown[en]In an ideal case, the graceful shutdown command is usuallykill[en](without)-9[en]parameters, default to sending)SIGTERM[en]) orsystemctl stop(If AnQiCMS is running as a service and properly configured) etc. These instructions will send a signal that can be captured by the program, giving it a chance to handle it itself.

  2. Observe Log Output:

    • Graceful shutdownAnQiCMS program that implements graceful shutdown will print clear information such as 'Received shutdown signal, starting cleanup work', 'All active connections have been closed', and 'Service has been successfully stopped' in the log after receiving the shutdown signal.
    • Forced shutdownForced shutdown usually does not have these friendly log outputs.After a forced shutdown, you may only see the program suddenly terminate, or find some abnormal exit records in the crash log.

  3. Experience downtime:

    • Graceful shutdownIf AnQiCMS needs a period of time (a few seconds to several tens of seconds, depending on the number of active requests and cleaning tasks) to completely exit after receiving a shutdown command, this is usually a sign of graceful shutdown.It is waiting for the ongoing task to be completed.
    • Forced shutdown: Forced downtime is usually instantaneous, processes will disappear immediately, with almost no delay.

  4. Check system status:

    • Graceful shutdownAfter shutdown, system resources such as database connections and file locks should be cleanly released.
    • Forced shutdownSometimes, these resources may not be released for a long time, or some 'dirty data' files may be left.

According to the existing documents, although AnQiCMS has the vision of an elegant start-up/restart, its official stop script is based on forced shutdown. To achieve an elegant shutdown, the AnQiCMS program needs to have the ability to capture internally.SIGTERMThe ability to execute cleanup logic under (or the corresponding signal under Windows), and the operation and maintenance personnel need to modifystop.shscripts, and removekill -9replace it with a command without parameterskillcommand, or usesystemctl stopManage service tools to send the correct signals.

Summary and **Practice

It is crucial to understand the shutdown method for the operation of AnQiCMS.Although forced shutdown appears quick and effective in certain emergency situations, in the long run, the risks it poses to system stability should not be ignored.We should prioritize and try to use the graceful shutdown mechanism of the program to protect the data and user experience of the website.

If AnQiCMS itself has built-in graceful shutdown logic (the description in its update log suggests this), then it is recommended that you:

  1. Read the more detailed official documentation【en】Understand which signals AnQiCMS captures for graceful shutdown.
  2. Modify the shutdown script【en】Replace withkill -9SendSIGTERMofkill $PID, and leave enough response time for the program.
  3. Configure service managementRun AnQiCMS as a Systemd or Supervisor service and configure it correctlyKillSignalandTimeoutStopSecParameter, so that it can be gracefully stopped when the system shuts down or restarts.

Common Questions (FAQ)

Q1: What is AnQiCMS?stop.shDid the script execute a graceful shutdown? A1:No, according to the providedstop.shScript content that useskill -9Command. This is a way to forcefully terminate a process, which does not give AnQiCMS program any time to complete the current task or perform cleanup operations, therefore it is not an elegant shutdown.

**Q2