Linux监控重要进程的实现方法

Linux监控重要进程的实现方法


人为干预情况下，能够自动重新启动，保证服务进程能够服务用户。这时就需要一个监控程序来实现能够让服务进程自动重新启动。查阅相关资料及尝试一些方法之后，总结linux系统监控重要进程的实现方法：脚本检测和子进程替换。

1、脚本检测 (1) 基本思路: 通过shell命令(ps -e | grep "$1" | grep -v "grep" | wc -l) 获取 $1 ($1 代表进程的名字)的进程数，脚本根据进程数来决定下一步的操作。通过一个死循环，每隔几秒检查一次系统中的指定程序的进程数，这里也可使用crontab来实现。 (2) 具体实现过程的代码如下: [ supervisor.sh ]

[plain] view plain copy print?

#! /bin/sh

# supervisor process

LOG_FILE=/var/log/supervisor_sh.log

# log function

function log() {

local t=$(date +"%F %X")

echo "[ $t ] $0 : $1 " >> ${LOG_FILE}

}

# check process number

# $1 : process name

function check_process() {

if [ -z $1 ]; then

log "Input parameter is empty."

return 0

fi

p_num=$(ps -e | grep "$1" | grep -v "grep" | wc -l)

log "p_num = $p_num"

echo $p_num

}

# supervisor process

while [ 1 ]

do

declare -i ch_num

p_name="apache2"

ch_num=$(check_process $p_name)

if [ $ch_num -eq 0 ]; then

killall $p_name

service $p_name start

fi

sleep 3

done

#! /bin/sh
# supervisor process

LOG_FILE=/var/log/supervisor_sh.log

# log function
function log() {
local t=$(date +"%F %X")
echo "[ $t ] $0 : $1 " >> ${LOG_FILE}
}

# check process number
# $1 : process name
function check_process() {
if [ -z $1 ]; then
log "Input parameter is empty."
return 0
fi

p_num=$(ps -e | grep "$1" | grep -v "grep" | wc -l)
log "p_num = $p_num"
echo $p_num
}

# supervisor process
while [ 1 ]
do
declare -i ch_num
p_name="apache2"
ch_num=$(check_process $p_name)
if [ $ch_num -eq 0 ]; then
killall $p_name
service $p_name start
fi
sleep 3
done

2、子进程替换 (1) 基本思路: a. 使用fork函数创建一个新的进程，在进程表中创建一个新的表项，而创建者(即父进程)按原来的流程继续执行，子进程执行自己的控制流程 b. 运用execv函数把当前进程替换为一个新的进程，新进程由path或file参数指定，可以使用execv函数将程序的执行从一个程序切换到另一个程序 c. 当fork启动一个子进程时，子进程就有了它自己的生命周期并将独立运行，此时可以在父进程中调用wait函数让父进程等待子进程的结束 (2) 基本的实现步骤: a. 首先使用fork系统调用，创建子进程 b. 在子进程中使用execv函数，执行需要自动重启的程序 c. 在父进程中执行wait函数等待子进程的结束，然后重新创建一个新的子进程 (3) 具体实现的代码如下: supervisor.c

[cpp] view plain copy print?

/**

*

* supervisor

*

* date: 2016-08-10

*

*/

#include <stdio.h>

#include <unistd.h>

#include <errno.h>

#include <string.h>

#include <sys/types.h>

#include <sys/wait.h>

#include <stdlib.h>

#include <time.h>

#define LOG_FILE "/var/log/supervisor.log"

void s_log(char *text) {

time_t t;

struct tm *tm;

char *log_file;

FILE *fp_log;

char date[128];

log_file = LOG_FILE;

fp_log = fopen(log_file, "a+");

if (NULL == fp_log) {

fprintf(stderr, "Could not open logfile '%s' for writing\n", log_file);

}

time(&t);

tm = localtime(&t);

strftime(date, 127, "%Y-%m-%d %H:%M:%S", tm);

/* write the message to stdout and/or logfile */

fprintf(fp_log, "[%s] %s\n", date, text);

fflush(fp_log);

fclose(fp_log);

}

int main(int argc, char **argv) {

int ret, i, status;

char *child_argv[100] = {0};

pid_t pid;

if (argc < 2) {

fprintf(stderr, "Usage:%s <exe_path> <args...>", argv[0]);

return -1;

}

for (i = 1; i < argc; ++i) {

child_argv[i-1] = (char *)malloc(strlen(argv[i])+1);

strncpy(child_argv[i-1], argv[i], strlen(argv[i]));

//child_argv[i-1][strlen(argv[i])] = '0';

}

while(1) {

pid = fork();

if (pid == -1) {

fprintf(stderr, "fork() error.errno:%d error:%s", errno, strerror(errno));

break;

}

if (pid == 0) {

s_log(child_argv[0]);

ret = execv(child_argv[0], (char **)child_argv);

s_log("execv return");

if (ret < 0) {

fprintf(stderr, "execv ret:%d errno:%d error:%s", ret, errno, strerror(errno));

continue;

}

s_log("exit child process");

exit(0);

}

if (pid > 0) {

pid = wait(&status);

fprintf(stdout, "Child process id: %d\n", pid);

//fprintf(stdout, "wait return");

s_log("Wait child process return");

}

}

return 0;

}

/**
*
* supervisor
*
* date: 2016-08-10
*
*/

#include <stdio.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <stdlib.h>
#include <time.h>

#define LOG_FILE "/var/log/supervisor.log"

void s_log(char *text) {
time_t      t;
struct tm  *tm;
char *log_file;
FILE *fp_log;
char date[128];

log_file = LOG_FILE;
fp_log = fopen(log_file, "a+");
if (NULL == fp_log) {
fprintf(stderr, "Could not open logfile '%s' for writing\n", log_file);
}

time(&t);
tm = localtime(&t);
strftime(date, 127, "%Y-%m-%d %H:%M:%S", tm);

/* write the message to stdout and/or logfile */
fprintf(fp_log, "[%s] %s\n", date, text);
fflush(fp_log);
fclose(fp_log);
}

int main(int argc, char **argv) {
int ret, i, status;
char *child_argv[100] = {0};
pid_t pid;
if (argc < 2) {
fprintf(stderr, "Usage:%s <exe_path> <args...>", argv[0]);
return -1;
}

for (i = 1; i < argc; ++i) {
child_argv[i-1] = (char *)malloc(strlen(argv[i])+1);
strncpy(child_argv[i-1], argv[i], strlen(argv[i]));
//child_argv[i-1][strlen(argv[i])] = '0';
}

while(1) {
pid = fork();
if (pid == -1) {
fprintf(stderr, "fork() error.errno:%d error:%s", errno, strerror(errno));
break;
}
if (pid == 0) {
s_log(child_argv[0]);
ret = execv(child_argv[0], (char **)child_argv);
s_log("execv return");
if (ret < 0) {
fprintf(stderr, "execv ret:%d errno:%d error:%s", ret, errno, strerror(errno));
continue;
}
s_log("exit child process");
exit(0);
}
if (pid > 0) {
pid = wait(&status);
fprintf(stdout, "Child process id: %d\n", pid);
//fprintf(stdout, "wait return");
s_log("Wait child process return");
}
}

return 0;
}

(4) 测试验证 a. 假设需要自动重启的程序为demo.c，其代码实现如下所示：

[cpp] view plain copy print?

/*

*

* demo

*

*/

#include <stdio.h>

#include <unistd.h>

#include <errno.h>

#include <string.h>

#include <sys/types.h>

#include <sys/wait.h>

#include <stdlib.h>

#include <time.h>

#define LOG_FILE "/var/log/demo.log"

void demo_log(int num) {

time_t t;

struct tm *tm;

char *log_file;

FILE *fp_log;

char date[128];

log_file = LOG_FILE;

fp_log = fopen(log_file, "a+");

if (NULL == fp_log) {

fprintf(stderr, "Could not open logfile '%s' for writing\n", log_file);

}

time(&t);

tm = localtime(&t);

strftime(date,127,"%Y-%m-%d %H:%M:%S",tm);

/* write the message to stdout and/or logfile */

fprintf(fp_log, "[%s] num = %d\n", date, num);

fflush(fp_log);

fclose(fp_log);

}

int main(int argc, char **argv[]) {

int num = 0;

while(1) {

sleep(10);

num++;

demo_log(num);

}

}

/*
*
* demo
*
*/

#include <stdio.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <stdlib.h>
#include <time.h>

#define LOG_FILE "/var/log/demo.log"

void demo_log(int num) {
time_t      t;
struct tm  *tm;
char *log_file;
FILE *fp_log;
char date[128];

log_file = LOG_FILE;
fp_log = fopen(log_file, "a+");
if (NULL == fp_log) {
fprintf(stderr, "Could not open logfile '%s' for writing\n", log_file);
}

time(&t);
tm = localtime(&t);
strftime(date,127,"%Y-%m-%d %H:%M:%S",tm);

/* write the message to stdout and/or logfile */
fprintf(fp_log, "[%s] num = %d\n", date, num);
fflush(fp_log);
fclose(fp_log);
}

int main(int argc, char **argv[]) {
int num = 0;

while(1) {
sleep(10);
num++;
demo_log(num);
}
}