GUID is not absolutely unique: Simple counter-proof

The general idea that GUID is uniqueness has been questioned. This article provides a simple C# program to demonstrate the non-uniqueness of GUIDs and comes with an improved version to improve program stability and performance.

Initial Program

The initial program tried to iterate over a series of GUIDs, which was expected to take a long time. However, due to its simple implementation, it fails to produce the expected results.

Improved version

To solve this problem, the program was refactored:

• Storage large amounts of GUIDs (bigHeapOGuids) using HashSet.
• Create multiple threads to continuously generate new GUIDs and check whether they conflict with bigHeapOGuids.

Program Execution

The program first fills bigHeapOGuids with GUIDs as much as possible, effectively exhausting available memory. The thread then starts generating the GUID and searches for a match in bigHeapOGuids. This process continues indefinitely, assuming that the universe has not yet ended.

Potential Issues

The program relies on an OutOfMemoryException to indicate when the memory that generated the GUID was exhausted. This is considered inefficient and can lead to unpredictable behavior.

Memory Management

To improve memory management, the program has been updated to use the garbage collector more efficiently. GC automatically manages memory allocation and release, allowing programs to run indefinitely.

Subsequent

Despite these improvements, the program assumes that the universe is not over yet. If cosmic heat silence occurs, the program will be closed gracefully.