Single-author List <T> thread safety, no counters

Question

Looking through the database code , I looked for an error that was not related to this issue, I noticed that it was List<T>used incorrectly in some places . In particular:

• There were many threads simultaneously appealing to readers List, but using indexes in Listinstead enumerators.
• There Listwas one writer.
• There was synchronization , readers and writers accessed at the same time , but due to the structure of the code, the last element would never be available until the method that executed returned . ListAdd()
• Items Listhave never been deleted.

In the C # documentation, this should not be thread safe. But it never failed. I am wondering because of the specific implementation List(I assume this is an array, which redistributes when the space ends), is this 1-writer 0-enumerator n-reader add-only script randomly thread safe or is there some kind of unlikely script where it could explode in the current .NET4 implementation ?

edit: An important detail. I have not read some answers. Readers view Listits contents as read-only.

Answer 1

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http://msdn.microsoft.com/en-us/library/dd287108.aspx

Answer 2

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for (int index =0 ; index < list.Count; index++)
{
    MyClass myClass = list[index];//ok we are just reading the value from list
    myClass.SomeInteger++;//boom the same variable will be updated from another threads...
}

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Answer 3

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Answer 4

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Answer 5

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in (, .net) ++:

  List<Object^>^ objects = gcnew List<Object^>^();
  // in some reader thread:
  Monitor::Enter(objects);
  array<Object^>^ objs = gcnew array<Object^>(objects->Count);
  objects->CopyTo(objs);
  Monitor::Exit(objects);
  // use objs array

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