为什么JVM不缓存JIT编译的代码？ [英] Why doesn't the JVM cache JIT compiled code?

问题描述

Sun的规范JVM实现将一些非常复杂的优化应用于字节码，以便在代码运行几次后获得接近本机的执行速度。问题是，为什么不将这个编译代码缓存到磁盘，以便在后续使用相同的函数/类时使用。因为它是，每次一个程序执行时，JIT编译器重新启动，而不是使用预编译版本的代码。

The canonical JVM implementation from Sun applies some pretty sophisticated optimization to bytecode to obtain near-native execution speeds after the code has been run a few times. The question is, why isn't this compiled code cached to disk for use during subsequent uses of the same function/class. As it stands, every time a program is executed, the JIT compiler kicks in afresh, rather than using a pre-compiled version of the code. Wouldn't adding this feature add a significant boost to the initial run time of the program, when the bytecode is essentially being interpreted?

推荐答案

因此，您需要一个机制来确定是否保存优化仍然是最佳的，在这一点，你可能只是重新优化在飞行。

So you'd need a mechanism to establish whether than saved optimisations were still optimal, at which point you might as well just re-optimise on the fly.

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