Java如何处理除零？ [英] How does Java handle division by zero?

问题描述

它是否只是在每次完成除法时检查除数是否与零不同（即使在JIT编码中）？

Does it simply check if divisor is different from zero every time there is division done (even in JIT-ed code)?

我的意思是VM如何设法抛出以前没有被操作系统杀死的异常？

I mean how VM manages to throw an exception without being previously killed by the OS?

推荐答案

在Unix环境中，除零是 signal 通过 SIGFPE 引导，JVM将安装一个信号处理程序，用于捕获 SIGFPE 反过来抛出 s ArithmeticException 。如果您对内部感兴趣，请参阅例如男子信号

In an Unix environment, in which division-by-zero is signalled via SIGFPE, the JVM will have installed a signal handler which traps the SIGFPE and in turn throws an ArithmeticException. If you're interested in the internals, see e.g. man signal

我认为OP所要求的是基于以下事实：直到/除非 SIGFPE 处理程序到位，大多数进程将在接收此信号时采取默认操作，即终止。因此，例如，一个C程序

What I believe the OP is asking is based on the fact that, until/unless a SIGFPE handler is in place, most processes will take the default action on receiving this signal, which is to terminate. Thus, e.g. a C program

 int main (int argc, char** argv) { int n = 5 / 0; } 

...如果它甚至编译，将被默认 SIGFPE <杀死/ code>→ SIG_DFL 操作。相反，JVM的处理程序发出（ catch able） RuntimeException ，以便可以以本机看似的方式处理这些异常。

… if it even compiles, will be killed by the default SIGFPE → SIG_DFL action. The JVM's handler instead issues the (catchable) RuntimeException so that these exceptions can be handled in a native-seeming way.

正如其他几个人指出的那样，只是为了完整性，事实上从内核生成的 SIGFPE 通常从处理器本身的特殊中断映射;因此，管道类似于

As several others pointed out, and just for completeness, in point of fact the SIGFPE generated from the kernel is generally mapped from a special interrupt from the processor itself; thus, the "pipeline" is something like

• CPU错误陷阱中断→内核中断处理程序→ SIGFPE SIG_DFL →处理死亡

• CPU error trap interrupt → kernel interrupt handler → SIGFPE SIG_DFL → process death

或

• CPU错误陷阱中断→内核中断处理程序→ JVM中的SIGFPE 处理程序→用户代码中的RuntimeException ArithmeticException

• CPU error trap interrupt → kernel interrupt handler → SIGFPE handler in JVM → RuntimeException ArithmeticException in user code

非-Unix平台的处理类似。

On non-Unix platforms the handling is analogous.

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