Tips and Tricks #130: Leverage ArrayPool for Temporary Buffer Reuse

Rent and return arrays from a shared pool to avoid repeated allocations in buffer-heavy code.

Code Snippet

using System.Buffers;

public byte[] ProcessData(Stream stream)
{
    // Rent a buffer from the shared pool
    byte[] buffer = ArrayPool.Shared.Rent(4096);
    try
    {
        int bytesRead = stream.Read(buffer, 0, buffer.Length);
        // Process buffer...
        return ProcessBuffer(buffer, bytesRead);
    }
    finally
    {
        // Always return the buffer
        ArrayPool.Shared.Return(buffer);
    }
}

Why This Helps

• Reuses memory instead of allocating new arrays
• Dramatically reduces GC collections in I/O-heavy code
• Thread-safe by design

How to Test

• Compare Gen0/Gen1 collections before and after
• Benchmark throughput under load

When to Use

File I/O, network operations, image processing, any scenario with frequent temporary buffers.

Performance/Security Notes

Always return buffers in a finally block. Rented arrays may be larger than requested.

References

• https://docs.microsoft.com/en-us/dotnet/api/system.buffers.arraypool-1

Try this tip in your next project and share your results in the comments!