如何检测打开文件句柄的文件是否已在Windows上使用Perl删除？(How can I detect if the file for an open filehandle has been deleted on Windows using Perl?)

 这是因为共享payDayFormat ，它是一个SimpleDateFormat ： 
 
 
 
 日期格式未同步。 建议为每个线程创建单独的格式实例。 如果多个线程同时访问格式，则必须在外部进行同步。 
 
 
 它与Jodatime一起使用的原因是它的日期格式化程序没有共享的可变状态，因为它是明智的。 
 
 所以，您可以： 
 
 
 
 添加synchronized到方法签名; 
 
 
 在您使用payDayFormat地方添加一个synchronized块： 
Date billDate;
synchronized (payDayFormat) {
  billDate = payDayFormat.parse(repayDay);
}
 
 
 在方法内创建一个SimpleDateFormat的新实例; 
 
 
 使payDayFormat成为ThreadLocal<SimpleDateFormat> ，以便每个线程都有自己的副本。 
 

It's because of sharing payDayFormat, which is a SimpleDateFormat:
 
 
 
Date formats are not synchronized. It is recommended to create separate format instances for each thread. If multiple threads access a format concurrently, it must be synchronized externally.
 
 
The reason it works with Jodatime is that its date formatters don't have shared mutable state, because it's sensible.
 
So, you can either:
 
 
 
Add synchronized to the method signature;
 
 
Add a synchronized block just around where you use payDayFormat:
 
Date billDate;
synchronized (payDayFormat) {
  billDate = payDayFormat.parse(repayDay);
}
 
 
Create a new instance of SimpleDateFormat inside the method;
 
 
Make payDayFormat a ThreadLocal<SimpleDateFormat>, so that each thread has its own copy.