如何判断另一个进程何时停止写入Perl中的文件？

# 打开文件
open(my $fh, '>>', 'file.txt') or die "Can't open file: $!";

# 锁定文件
flock($fh, LOCK_EX) or die "Can't lock file: $!";

# 写入文件
print $fh "Hello, world!\n";

# 解锁文件
flock($fh, LOCK_UN) or die "Can't unlock file: $!";

# 关闭文件
close($fh);

use strict;
use warnings;
use Inotify;

# 创建inotify对象
my $inotify = Inotify->new;

# 添加监视
my $watch_descriptor = $inotify->add_watch('file.txt', IN_MODIFY);

# 循环处理事件
while (my @events = $inotify->read) {
    foreach my $event (@events) {
        if ($event->IN_MODIFY) {
            print "File modified\n";
        }
    }
}

use strict;
use warnings;
use Time::HiRes qw(sleep);

my $file = 'file.txt';
my $last_size = -s $file;

while (1) {
    sleep 1;
    my $current_size = -s $file;
    if ($current_size != $last_size) {
        print "File is being written\n";
        $last_size = $current_size;
    } else {
        print "File is not being written\n";
    }
}