blocks|key|824694|text|我一直都很幸运地使用File::NFSLock获得了脚本本身的独占锁。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|824695|use+Fcntl+qw(LOCK_EX+LOCK_NB);
use+File::NFSLock;

#+Try+to+get+an+exclusive+lock+on+myself.
my+$lock+=+File::NFSLock->new($0,+LOCK_EX%7CLOCK_NB);
die+"$0+is+already+running!\n"+unless+$lock;|code-block|syntax|javascript|824696|这在某种程度上与其他锁文件建议相同，除了尝试获取锁之外，我不需要做任何事情。|824697|entityMap|0|LINK|mutability|MUTABLE|url|https://metacpan.org/pod/File::NFSLock^0|A|D|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@$A|T|B|U|1|V]]|C|$]]|$1|D|3|E|5|F|7|W|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|X|8|@]|9|@]|C|$]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|C|$]]]|L|$M|$5|N|O|P|C|$Q|R]]]]

I have always had good luck using <a href="https://metacpan.org/pod/File::NFSLock" rel="nofollow noreferrer">File::NFSLock</a> to get an exclusive lock on the script itself.

<pre><code>use Fcntl qw(LOCK_EX LOCK_NB);
use File::NFSLock;

# Try to get an exclusive lock on myself.
my $lock = File::NFSLock-&gt;new($0, LOCK_EX|LOCK_NB);
die "$0 is already running!\n" unless $lock;
</code></pre>

This is sort of the same as the other lock file suggestions, except I don't have to do anything except attempt to get the lock.

blocks|key|825981|text|使用File::Pid将脚本的pid存储在一个文件中，脚本应在开始时检查该文件，如果找到则中止。您可以在脚本完成时删除pidfile，但这并不是真正必要的，因为您可以稍后简单地检查该进程id是否仍然有效(这也将解释脚本意外中止的情况)：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|825982|use+strict;
use+warnings;
use+File::Pid;

my+$pidfile+=+File::Pid->new({file+=>+/var/run/myscript});
exit+if+$pidfile->running();

$pidfile->write();

#+...+rest+of+script...

#+end+of+script
$pidfile->remove();
exit;|code-block|syntax|javascript|825983|entityMap|0|LINK|mutability|MUTABLE|url|http://search.cpan.org/perldoc/File::Pid^0|2|9|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

Use <a href="http://search.cpan.org/perldoc/File::Pid" rel="noreferrer">File::Pid</a> to store the script's pid in a file, which the script should check for at the start, and abort if found. You can remove the pidfile when the script is done, but it's not truly necessary, as you can simply check later to see if that process id is still alive (which will also account for the cases when your script aborts unexpectedly):

<pre><code>use strict;
use warnings;
use File::Pid;

my $pidfile = File::Pid-&gt;new({file =&gt; /var/run/myscript});
exit if $pidfile-&gt;running();

$pidfile-&gt;write();

# ... rest of script...

# end of script
$pidfile-&gt;remove();
exit;
</code></pre>

blocks|key|2528362|text|Sys::RunAlone模块很好地完成了您想要的任务。只需添加|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|2528363|++use+Sys::RunAlone;|code-block|syntax|javascript|2528364|在代码的顶部附近。|2528365|entityMap|0|LINK|mutability|MUTABLE|url|https://metacpan.org/pod/Sys::RunAlone^0|0|D|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@$A|T|B|U|1|V]]|C|$]]|$1|D|3|E|5|F|7|W|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|X|8|@]|9|@]|C|$]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|C|$]]]|L|$M|$5|N|O|P|C|$Q|R]]]]

The <a href="https://metacpan.org/pod/Sys::RunAlone" rel="nofollow noreferrer">Sys::RunAlone</a> module does what you want very nicely. Just add

<pre><code> use Sys::RunAlone;
</code></pre>

near the top of your code.

blocks|key|1117986|text|一种典型的方法是让每个进程打开并锁定某个文件。然后，该进程读取文件中包含的进程ID。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1117987|如果具有该ID的进程正在运行，则后来者将静默退出。否则，新的获胜者将其进程ID+(Perl中的$$)写入pidfile，关闭句柄(释放锁)，然后继续它的工作。|offset|length|style|CODE|1117988|示例实现如下：|1117989|#!+/usr/bin/perl

use+warnings;
use+strict;

use+Fcntl+qw/+:DEFAULT+:flock+:seek+/;

my+$PIDFILE+=+"/tmp/my-program.pid";
sub+take_lock+{
++sysopen+my+$fh,+$PIDFILE,+O_RDWR+%7C+O_CREAT+or+die+"$0:+open+$PIDFILE:+$!";
++flock+$fh+=>+LOCK_EX+++++++++++++++++++++++or+die+"$0:+flock+$PIDFILE:+$!";

++my+$pid+=+<$fh>;
++if+(defined+$pid)+{
++++chomp+$pid;
++++if+(kill+0+=>+$pid)+{
++++++close+$fh;
++++++exit+1;
++++}
++}
++else+{
++++die+"$0:+readline+$PIDFILE:+$!"+if+$!;
++}

++sysseek++$fh,+0,+SEEK_SET+or+die+"$0:+sysseek+$PIDFILE:+$!";
++truncate+$fh,+0+++++++++++or+die+"$0:+truncate+$PIDFILE:+$!";
++print++++$fh+"$$\n"+++++++or+die+"$0:+print+$PIDFILE:+$!";
++close++++$fh++++++++++++++or+die+"$0:+close:+$!";
}

take_lock;
print+"$0:+[$$]+running...\n";
sleep+2;|code-block|syntax|javascript|1117990|entityMap^0|0|1B|2|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|R|8|@$D|S|E|T|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|U|8|@]|9|@]|A|$]]|$1|J|3|K|5|L|7|V|8|@]|9|@]|A|$M|N]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

A typical approach is for each process to open and lock a certain file. Then the process reads the process ID contained in the file.

If a process with that ID is running, the latecomer exits quietly. Otherwise, the new winner writes its process ID (<code>$$</code> in Perl) to the pidfile, closes the handle (which releases the lock), and goes about its business.

Example implementation below:

<pre><code>#! /usr/bin/perl

use warnings;
use strict;

use Fcntl qw/ :DEFAULT :flock :seek /;

my $PIDFILE = "/tmp/my-program.pid";
sub take_lock {
 sysopen my $fh, $PIDFILE, O_RDWR | O_CREAT or die "$0: open $PIDFILE: $!";
 flock $fh =&gt; LOCK_EX or die "$0: flock $PIDFILE: $!";

 my $pid = &lt;$fh&gt;;
 if (defined $pid) {
 chomp $pid;
 if (kill 0 =&gt; $pid) {
 close $fh;
 exit 1;
 }
 }
 else {
 die "$0: readline $PIDFILE: $!" if $!;
 }

 sysseek $fh, 0, SEEK_SET or die "$0: sysseek $PIDFILE: $!";
 truncate $fh, 0 or die "$0: truncate $PIDFILE: $!";
 print $fh "$$\n" or die "$0: print $PIDFILE: $!";
 close $fh or die "$0: close: $!";
}

take_lock;
print "$0: [$$] running...\n";
sleep 2;
</code></pre>

blocks|key|2528395|text|我一直在使用这个-小而简单-不依赖于任何模块，可以在Windows+%2B+Linux上运行。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2528396|use+Fcntl+':flock';++++++++++++++++++++

###+Check+to+make+sure+there+is+only+one+instance+###
open+SELF,+"<+$0"+or+die("Cannot+run+two+instances+of+this+program");
unless+(+flock+SELF,+LOCK_EX+%7C+LOCK_NB+)+{
++++print+"You+cannot+run+two+instances+of+this+program+,+a+process+is+still+running";
++++exit+1;
}|code-block|syntax|javascript|2528397|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

I have always used this - small and simple - no dependancy on any module and works both Windows + Linux.

<pre><code>use Fcntl ':flock'; 

### Check to make sure there is only one instance ###
open SELF, "&lt; $0" or die("Cannot run two instances of this program");
unless ( flock SELF, LOCK_EX | LOCK_NB ) {
 print "You cannot run two instances of this program , a process is still running";
 exit 1;
}
</code></pre>

blocks|key|2528087|text|AFAIK+perl没有内置这样的东西。您可以轻松地创建一个临时文件，当您启动您的应用程序，并删除它，当您的脚本完成。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2528088|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

AFAIK perl has no such thing buildin. You could easily create a temporar file, when you start your application and delete it, when your script is done.

blocks|key|824556|text|给定频率，我通常会编写一个守护进程(服务器)，在作业运行之间很好地等待(即sleep())，而不是尝试使用cron进行相当细粒度的访问。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|824557|如有必要，在Unix+/+Linux系统上，您可以从/etc/inittab+(或替换)运行它，以确保它始终运行，并在进程被终止或死亡时自动重启。|824558|添加了：(并删除了一些不相关的东西)|BOLD|824559|always+present+(正在运行，但大部分时间是空闲的)守护进程方法的好处是消除了脚本的并发实例由cron自动启动的可能性。|824560|然而，这确实意味着您有责任正确地管理计时，例如在存在重叠的情况下(即前一次运行仍在运行，而新的触发器正在发生)。这可能会帮助您决定是使用派生守护进程还是非派生设计。在这种情况下，线程没有提供任何优势，因此不需要考虑它们的用法。|824561|这并不能完全消除运行多个进程的可能性，但这是许多守护进程的常见问题。典型的解决方案是使用信号量，例如文件上的互斥锁，以防止运行第二个实例。当进程结束时，文件锁会自动被遗忘，因此在异常终止(例如，电源故障)的情况下，不需要清理锁本身。|824562|一种使用Fcntl模块并使用带有O_EXCL标志(或O_RDWR+%7C+O_CREAT+%7C+O_EXCL)的Perl+sysopen的方法是given+by+Greg+Bacon。我要做的唯一的区别是将排它锁组合到sysopen调用中(即使用我建议的标志)，并删除当时冗余的flock调用。哦，我会遵循/var/run/daemonname.pid的UNIX+(&+Linux+FHS)文件系统和命名约定。|824563|另一种方法是使用djb的daemontools或similar来“守护”任务。|824564|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/a/2232970/83348|1|http://cr.yp.to/daemontools.html|2|https://serverfault.com/questions/192302/alternative-to-daemontools-djbtools-to-supervise-unix-processes^0|11|7|0|Q|C|0|0|3|0|0|0|0|G|6|Q|P|1M|7|3S|5|46|N|1X|J|0|0|C|B|1|O|7|2|0^^$0|@$1|2|3|4|5|6|7|16|8|@$9|17|A|18|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|19|8|@$9|1A|A|1B|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|1C|8|@$9|1D|A|1E|B|J]]|D|@]|E|$]]|$1|K|3|L|5|6|7|1F|8|@]|D|@]|E|$]]|$1|M|3|N|5|6|7|1G|8|@]|D|@]|E|$]]|$1|O|3|P|5|6|7|1H|8|@]|D|@]|E|$]]|$1|Q|3|R|5|6|7|1I|8|@$9|1J|A|1K|B|C]|$9|1L|A|1M|B|C]|$9|1N|A|1O|B|C]|$9|1P|A|1Q|B|C]|$9|1R|A|1S|B|C]]|D|@$9|1T|A|1U|1|1V]]|E|$]]|$1|S|3|T|5|6|7|1W|8|@]|D|@$9|1X|A|1Y|1|1Z]|$9|20|A|21|1|22]]|E|$]]|$1|U|3|-4|5|6|7|23|8|@]|D|@]|E|$]]]|V|$W|$5|X|Y|Z|E|$10|11]]|12|$5|X|Y|Z|E|$10|13]]|14|$5|X|Y|Z|E|$10|15]]]]

Given the frequency I would normally write a daemon (server) that nicely waits idly between job runs (i.e. <code>sleep()</code>) rather than try to use cron for fairly fine-grained access. 

If necessary, on Unix / Linux systems you could run it from <code>/etc/inittab</code> (or replacement) to ensure that it always running, and is automatically restarted in the process is killed or dies.

Added: (and some irrelevant stuff removed)

The always present (running, but mostly idle) daemon approach has the benefit of eliminating the possibility of concurrent instances of the script being being started by cron automatically.

However it does mean you are responsible for managing the timing correctly, such as in the case of there is an overlap (i.e. a previous run is still running, while a new trigger occurs). This may help you decide whether to use a forking daemon or non-forking design. Threads don't provide any advantage in this scenario, so there is no need to consider their usage. 

This does not completely eliminate the possibility of multiple processes running, but that a common problem with many daemons. The typical solution is to use a semaphore such as a mutually-exclusive lock on a file, to prevent a second instance from being run. The file-lock is automatically forgotten when the process ends, so in the case of abnormal termination (e.g. power failure) there is no clean-up necessary of the lock itself.

An approach using Fcntl module, and using a Perl <code>sysopen</code> with a <code>O_EXCL</code> flag (or <code>O_RDWR | O_CREAT | O_EXCL</code>) was <a href="https://stackoverflow.com/a/2232970/83348">given by Greg Bacon</a>. The only differences I would make are combine exclusive locking into the sysopen call (i.e. use the flags I've suggested), and remove the then redundant <code>flock</code> call. Oh, and I would follow the UNIX (&amp; Linux FHS) file-system and naming conventions of <code>/var/run/daemonname.pid</code>.

Another approach would be to use djb's <a href="http://cr.yp.to/daemontools.html" rel="nofollow noreferrer">daemontools</a> or <a href="https://serverfault.com/questions/192302/alternative-to-daemontools-djbtools-to-supervise-unix-processes">similar</a> to "daemonize" the task.

I need to run Perl script by cron periodically (~every 3-5 minutes). I want to ensure that only one Perl script instance will be running in a time, so next cycle won't start until the previous one is finished. Could/Should that be achieved by some built-in functionality of cron, Perl or I need to handle it at script level? 

I am quite new to Perl and cron, so help and general recommendations are appreciated.

Running only one Perl script instance by cron

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

文章

问答

视频

学习中心

腾讯云实验室

直播

竞赛

腾讯云代码分析专区

腾讯iOA零信任安全管理系统专区

腾讯云架构师技术同盟交流圈

腾讯云数据库专区

腾讯云顾问专区

腾讯云原生专区

腾讯混元专区

腾讯云TCE专区

腾讯云Lighthouse专区

腾讯云HAI专区

腾讯云Edgeone专区

腾讯云存储专区

腾讯云智能专区

腾讯轻联专区 

腾讯云开发专区

TAPD专区

腾讯轻量云游戏服专区

腾讯云最具价值专家

腾讯云架构师技术同盟

腾讯云创作之星

腾讯云开发者先锋

腾讯云代码助手

云原生构建

TAPD 敏捷项目管理

Cloud Studio

SDK中心

API中心

命令行工具

涵盖代码开发、场景应用、自动测试全流程，助你从零构建专属AI助手

一站式MCP教程库，解锁AI应用新玩法

我需要定期(~每3-5分钟)运行cron的Perl脚本。我希望确保一段时间内只有一个Perl脚本实例在运行，这样直到上一个周期结束后，下一个周期才会开始。这可以/应该通过cron、Perl的一些内置功能来实现吗?或者我需要在脚本级别处理它？我是Perl和cron的新手，因此非常感谢您的帮助和一般建议。

问cron仅运行一个Perl脚本实例
EN

回答 7

Stack Overflow用户

Stack Overflow用户

Stack Overflow用户

社区

活动

圈层

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问cron仅运行一个Perl脚本实例EN

回答 7

Stack Overflow用户

Stack Overflow用户

Stack Overflow用户

社区

活动

圈层

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问cron仅运行一个Perl脚本实例
EN