有这两个java.io.File线程安全问题被回避？ [英] Have these two java.io.File thread safety issues been evaded?

问题描述

假设 Win32FileSystem 和 beginMultiThreading 在一个共享的MultiThreadingClass对象上多次同时运行，那么最可能的方式是什么这可能会导致数据竞争或其他线程问题？我知道这可能不是线程安全的，因为（1） setPath 的参数被重用。我还看到（2） path 不是 java.io.File 中的最终变量。但是，由于线程问题，我似乎无法找到代码可能自行错误的部分。

  public class MultiThreadingClass {
 private Holder h = new Holder（）; 
 private String path =c：\\somepath; 
 public void beginMultiThreading（）{
 h.setPath（new File（path））; 
 h.begin（）; 
} 
} 
 
公共类持有者{
私有文件路径; 
 public void setPath（File path）{
 this.path = path; 
 
 public void begin（）{
 System.out.println（path.getCanonicalPath（）+some string）; 
 
 
 $ / code $ 




解决方案

示例代码根本没有多线程。所以我假设多线程正在他们自己的 MultiThreadingClass 实例上运行，或者他们在它们之间共享一个公共实例。



无论如何，这段代码是线程安全的。唯一的共享状态是一个私有的字符串对象，不作为你的方法的一部分进行调整。


Assuming a Win32FileSystem and beginMultiThreading runs many times simultaneously on a shared MultiThreadingClass object, what is the most possible way that this can cause a data-race or some other threading issue? I know that this is probably not thread safe, because (1) the argument to setPath gets reused. I see also that (2) path is not a final variable in java.io.File. However, I can't seem to find a part where this code could error out on its own due to threading issue.

public class MultiThreadingClass {
    private Holder h = new Holder();
    private String path ="c:\\somepath"; 
    public void beginMultiThreading(){
        h.setPath(new File(path));
        h.begin();
    }
}

public class Holder {
    private File path;
    public void setPath(File path){
        this.path = path;
    }
    public void begin(){
        System.out.println(path.getCanonicalPath()+"some string");
    }
}

解决方案

Your example code has no multi-threading at all. So I'll assume that either multiple threads are operating on their own MultiThreadingClass instance, or that they are sharing a common instance between them.

Either way, this code is thread safe. The only shared state is a private string object, which is not adjusted as part of your methods.

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