[Q&A] Memory leak countermeasures when dynamically generating RenderTexture in C#

Q. I am generating RenderTexture every frame from a C# script. However, if you keep playing, you will run out of memory and VRAM on your smartphone and the app will crash. Why isn't it automatically released?

A. Unity's RenderTexture is an "unmanaged resource" that internally holds a pointer to the GPU's native texture memory. Even if a C# variable goes out of scope, native memory is not automatically freed and remains, so you must free it manually in your code.

Code implementation patterns to prevent memory leaks

// Bad example: Generating and leaving it unattended (main cause of leaks)
void CaptureCamera() {
 RenderTexture rt = new RenderTexture(512, 512, 16);
 myCamera.targetTexture = rt;
 myCamera.Render();
 // rt goes out of scope, but the RenderTexture instance remains in VRAM! 
}

// Correct resolution code example:
private RenderTexture dynamicRT;

void CaptureCameraCorrect() {
 // Reuse or release if texture already exists
 if (dynamicRT != null) {
 dynamicRT.Release();
 Destroy(dynamicRT);
 }

 dynamicRT = new RenderTexture(512, 512, 16);
 myCamera.targetTexture = dynamicRT;
 myCamera.Render();
}

// Completely removes from VRAM memory when object is destroyed
void OnDestroy() {
 if (dynamicRT != null) {
 dynamicRT.Release();
 Destroy(dynamicRT);
 }
}