在Java中内联 [英] Inlining in Java

问题描述

在C ++中，我可以声明一个方法内联，编译器可能会内联它。据我所知，Java中没有这样的关键字。

如果JVM决定这样做，内联是否完成？我可以以某种方式影响这个决定吗？

解决方案

其他几个答案表明只有最终方法可以内联 - 这是不正确，因为HotSpot非常聪明，能够内联非最终方法，只要它们没有被覆盖尚未。当加载一个覆盖该方法的类时，它可以撤消其优化。显然，使方法最终意味着永远不需要...

基本上让JVM完成它的工作 - 它可能会比你更好地计算内联的位置你是否确信JVM没有做好工作？假设您正在使用HotSpot，您是否尝试过使用服务器版本而不是客户端？这可能会产生巨大的差异。

In C++ I can declare a method "inline" and the compiler is likely to inline it. As far as I understand there is no such keyword in Java.

Inlining is done if the JVM decides to do so? Can I influence this decision somehow?

解决方案

A couple of the other answers have suggested that only final methods can be inlined - this is not true, as HotSpot is smart enough to be able to inline non-final methods so long as they haven't been overridden yet. When a class is loaded which overrides the method, it can undo its optimisation. Obviously making the method final mean that's never required...

Basically let the JVM do its job - it's likely to be a lot better at working out where to inline than you are.

Do you have a situation where you're convinced that the JVM isn't doing a good job? Assuming you're using HotSpot, have you tried using the server version instead of client? That can make a huge difference.

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