delphi – TCriticalSection TryEnter方法始终返回True

发布时间：2020-12-15 04:14:13 所属栏目：大数据来源：网络整理

导读：在TCriticalSection上调用TryEnter方法时,结果始终为true.当然,如果能够获得锁定,这应该只返回true？ var MyCritSect: TCriticalSection;begin MyCritSect := TCriticalSection.Create; try // MyCritSect.Enter; Writeln(BoolToStr(MyCritSect.TryEnter,Tru

在TCriticalSection上调用TryEnter方法时,结果始终为true.当然,如果能够获得锁定,这应该只返回true？

var
  MyCritSect: TCriticalSection;

begin
  MyCritSect := TCriticalSection.Create;
  try
    //    MyCritSect.Enter;
    Writeln(BoolToStr(MyCritSect.TryEnter,True)); // This should return True
    Writeln(BoolToStr(MyCritSect.TryEnter,True)); // This should return False?
    Readln;
  except
    on E: Exception do
      Writeln(E.ClassName,': ',E.Message);
  end;
end.

即使您取消注释MyCritSect.Enter;对于两次调用TryEnter,它仍然返回True.

我正在使用Delphi XE和Windows 10.

解决方法

关键部分是 re-entrant locks.从 documentation开始：

When a thread owns a critical section,it can make additional calls to EnterCriticalSection or TryEnterCriticalSection without blocking its execution. This prevents a thread from deadlocking itself while waiting for a critical section that it already owns.

如果使用不同的线程,您对TryEnter的调用将失败,并且第一个线程已经拥有该锁.

（编辑：李大同）

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