Posted on 2010-12-27 20:43
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Unix
#!/usr/bin/perl
use strict;
# 打印此脚本使用信息和输出说明。
################################################################
# Output the usage of this perl script
################################################################
sub usage
{
print "memmonitor: Monitor system memory usage\n";
print "1. if used memory is more than 75% of total memory, memmonitor\n";
print "will output one warning message per minites.\n";
print "2. if used memory is more than 90% of total momory, memmonitor\n";
print "will kill the processes that occupied the most memory untill\n";
print "used memory is less than 75% of total memory.\n\n";
return 0;
}
usage
my $total_mem;
my $used_mem;
my $next_line = 0;
my @rc;
my $rate;
# $total_mem 和 $used_mem 变量分别代表了总计实际内存大小和已经使用的内存大小
rc = `vmstat`;
foreach ( @rc ) {
if ( $next_line ) {
my @value = split /\s+/, $_;
$used_mem = @value[3] * 4;
$next_line = 0;
last;
} elsif ( /^.*mem=(\d+)MB$/ ) {
$total_mem = $1 * 1024;
} elsif ( /^.*avm.*$/ ) {
$next_line = 1;
}
}
# 这段代码使用了 vmstat 命令得到系统内存状态信息，并对结果进行逐行解析，得到各个字段的数据。
if ( $total_mem ) {
$rate = $used_mem / $total_mem;
}
# 计算得到了当前全局内存使用率
if ( $rate > 0.75 ) {
print "Warning: Memory is not enough\n";
}
# 如果内存使用率大于 0.75， 将打印出警告信息。
if ( $rate > 0.9 ) {
my $line_count = 0;
my @output = `ps aux | head -1;ps aux | sort -rn +5`;
foreach ( @output ) {
if ( $line_count ) {
my @killed_process = split /\s+/,$_;
print "Warning: Out of memory. Kill process: @killed_process[1]\n";
# 发送警告信息给 root 用户，保存程序运行记录。
`echo "Process @killed_process[1] has been killed because of unlimited memory \
allocation" | mail -s "Out of memory" root`
`kill -11 @killed_process[1]`;
last;
}
$line_count = $line_count + 1;
}
# 如果内存使用率大于 0.9，脚本将调用 ps 命令并且找出内存使用率最高的进程，打印出将要杀掉进程的警告信息，
#杀掉内存使用率最高的进程。 此过程将循环进行知道内存占用率低于 0.9
}