写的 <%- is_home() %> 在首页(index) 返回 false ???

[zhwangart]

写 <%- is_home() %> 在 http://localhost:4000/ 返回 true ，然后生成（$ hexo g）文件中的 index.html 中，则显示 false ？？？
在 $ hexo g 之前已经多次执行 $ hexo clean

[zhwangart]

我找到问题原因了，是因为 <%- partial('_partial/header', null, {cache: !config.relative_link}) %>中的null, {cache: !config.relative_link}导致，如果删除 null就好了，请问这个 null 具体起什么作用？？？我是从默认主题中复制过来的！

[stevenjoezhang]

其实这并不是null的问题，正确的做法是删除{cache: !config.relative_link}。你可以看下文档，partial的cache选项是用于缓存的，遇到is_home这种在每个页面上不同的方法就出问题了。

[stevenjoezhang]

Duplicate of #3483

[zhwangart]

Duplicate of #3483

请问下为什么 is_home 会遇上 cache 就出问题呢？

[stevenjoezhang]

可以这样理解：执行hexo g，Hexo开始渲染第一个页面（可能并不是index），此页面中is_home()为false。然后，Hexo开始渲染第二个、第三个页面。由于开启了cache，Hexo不会重新执行is_home()方法，而是直接套用第一个页面的结果（即返回false，并没有重新渲染）。这就导致了问题。
hexo s的机制又与hexo g不同，因此更加令人感到困惑。

[zhwangart]

@stevenjoezhang 非常感谢！
让我这么笨的人都理解了这么难的关系...
那照理说，这算是 hexo 的一个 bug 吗？

[stevenjoezhang]

这个选项确实还不够智能（可能就是这么设计的？）毕竟如果能够根据页面类型进行缓存，就可以避免你说的这个问题。

[SukkaW]

@ppoffice has implement a smart _partial() helper with fragment cache automatically enabled: https://github.com/ppoffice/hexo-theme-icarus/blob/master/includes/helpers/override.js#L158-L187

The side-effect is huge memory usage since all partials will be cached in memory.

@zhwangart @stevenjoezhang

[stale]

This issue has been automatically marked as stale because lack of recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[ppoffice]

@ppoffice has implement a smart _partial() helper with fragment cache automatically enabled: https://github.com/ppoffice/hexo-theme-icarus/blob/master/includes/helpers/override.js#L158-L187

The side-effect is huge memory usage since all partials will be cached in memory.

@zhwangart @stevenjoezhang

@SukkaW
Actually, the memory size of the cache object is negligible, event with the _partial() helper I wrote. I took a snapshot of the heap when rendering https://github.com/jiangtj-lab/hexo-many-posts with hexo-theme-icarus:

The cache object in lib/plugins/helper/fragment_cache.js#L4 only takes up 3.0MB with 1418 HTML fragments. I also found out that most of the memory is consumed by the unreleased CacheStream in /lib/plugins/console/generate.js#L48. Thus, my suggestions to reduce the memory size of Hexo are

• Use the concurrency option when hexo g Solve "Out of memory" during generation by limiting the number of concurrent tasks #3665
• Simplify the HTML structure of your theme so that the rendered HTML fragments are small

[stale]

This issue has been automatically marked as stale because lack of recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[stevenjoezhang]

I'm closing this issue. Please join the discussion in #2451