PHP操作码缓存的基础 [英] Basics of PHP opcode cache

问题描述

当前，在一个我不打算将其再次用于另一个站点的大型项目中，我已经将该站点的名称硬编码到了所有文件中.现在，如果我要更改站点名称，则需要花费很多精力才能在任何地方进行更改.我知道一个明显的解决方案是将名称存储为变量或常量，但是我想您可以将其称为我的微优化思维方式:我一直认为这将是PHP解析起来少一件事.我确实意识到这不会有太大的不同，但是我只是想知道使用像APC这样的操作码缓存是否意味着PHP甚至不必重新解析它?

Currently on a very large project that I do not plan to re-use for another site, I have the site's name hardcoded into the files everywhere. Now, if I were ever to change the site name it would take a lot of effort to change that everywhere. I know the obvious solution is to just store the name as a variable or a constant, but I guess you could call it my micro-optimizing way of thinking: I always figured it would be one less thing PHP has to parse. I do realize it won't make much difference, but I just wanted to know whether using an opcode cache like APC would mean that PHP wouldn't even have to re-parse that?

推荐答案

真的:您不应该在意这样的事情.

Really : you shouldn't care about anything like that.

任何配置上的差异都意味着很多上的差异(例如，对于APC，apc.stat选项可能会对服务器的负载-以及其他任何方面产生很大的影响像数据库查询一样，您将获得数百倍的影响)

Any difference in configuration will means much more difference (for instance, the apc.stat option, for APC, can have quite an impact on the load of your server -- and anything like DB queries you do will have hundreds of time more impact)

在这里，可能重要的是可维护性:

Here, what probably matters is maintenability :

• 使用非硬编码的站点名称是否对您有好处((纳米优化除外))?
• 对它进行硬编码(相同的例外) 是否对您有任何好处?

• does it get you any benefit (except from that nano-optimisation) to have the site name not hard-coded ?
• does it get you any benefit to have it hard-coded (same exception) ?

如果在两种情况下答案都是否"，并且您的应用程序正常工作……那很重要！

If the answer is "no" in either case, and your application works... well, that's what matters !

如果您有时间花在进行微优化上，而不是进行微优化，那最好是用探查器遍历您的应用程序代码，遍历数据库查询，您正在获取静态JS/CSS的HTTP请求数/images，升级PHP或修改您的代码，使其可以在PHP 5.3 上运行(因为PHP 5.3对5.2进行了一些优化)，...

If you have time to spend with that kind of less than micro optimisations, it would probably be better spent going through your application code with a profiler, going through your DB queries, the number of HTTP requests you are doing to fetch static JS/CSS/images, upgrading PHP or modifying your code so it can run on PHP 5.3 (as PHP 5.3 comes with some optimisations over 5.2), ...

所有这些最有可能为您带来更高的收益；-)

All those will most probably get you a higher gain ;-)

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基本上，在加载PHP文件时:

Basically, when a PHP file is loaded :

• 从磁盘读取文件
• 已被解析并编译为操作码
• 操作码已执行

具有操作码缓存:

• 如果RAM中有一个包含操作码的地方，则这些操作码是从RAM中加载的(即不读取文件，也不进行解析/编译)
  • 如果没有，请参见之前的步骤-对于下一个请求，只需在执行之前添加将操作码存储到RAM"
  • if there is a place in RAM containing the opcodes, those are loaded from RAM (is, no reading of a file, nor parsing/compiling)
    • if not, see the steps before -- just add a "store the opcodes to RAM" before execution, for the next request

    apc.stat选项定义APC是应该检查文件的最后修改日期/时间，以决定是使用RAM中的操作码，还是重新编译文件(如果RAM中的操作码是较新的文件).

    The apc.stat option defines whether APC should examine the last modification date/time of a file to decide between using the opcodes from RAM, or re-compiling the file if it is more recent that the opcodes in RAM.

    禁用此选项意味着:

    • 不检查磁盘上的文件=>更快，并且使用更少的资源
      • 例如，当在负载非常大的服务器上禁用此选项时，我发现CPU负载下降了10％至15％.
      • files are not checked on disk => faster, and uses less resources
        • For instance, I've seen a drop of CPU-load, between 10 and 15%, when disabling this option on a quite loaded server

        
        不过，我所说的是正确的:可能有很多可以优化的事情，比起简单的我应该使用硬编码的值"与我应该使用常量/变量"，这意味着更重要的收益.

        
        Still, what I said is true : there are probably lots of things you can optimise that will mean more important gain than a simple "should I use hard-coded values" versus "should I use constants/variables".

        这篇关于PHP操作码缓存的基础的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！