Today I Learned: Memory Leak in Flutter
Is Memory Leak a Big Issue in Flutter?
I believe memory leaks are something to consider in Flutter, but they aren’t always critical, and app on iOS with Swift. Even the Flutter documentation doesn’t emphasize them as much compared to other topics like UI or widget design.
In today’s world, even low-tier Android devices have at least 4GB of RAM. Memory leaks become a serious issue in apps that consume a lot of resources, such as video editing apps or games that load large assets into memory.
However, most apps (80–90% on the market) use a ListView-DetailsView structure and primarily deal with text and images. For these apps, memory leaks are usually not a major concern.
📌 Let’s put it in perspective:
• If your app leaks 1KB of text 1,000 times, that’s only 1MB of RAM, which is equal to just 3–4 images.
• If you leak 100–200KB per image for 1000 images, that’s around 200MB — which isn’t significant compared to 1GB of available RAM (if the app can use 1GB out of 4GB).
• Games and video editing apps are different — they load hundreds of MBs of assets, music, and videos, making memory management much more critical.
Even though you may not always need to focus on memory leaks, it’s still useful to understand how to optimize memory usage when necessary.
🔗 Here’s the official Flutter documentation on memory management:
Flutter Memory Management Guide
🛠 What I Learned from My Research
Some widgets require disposal to free up memory properly, including (This part doesn’t mention in Flutter documentation):
✅ Widgets that need dispose(As far as i know)
• TextEditingController
• ScrollController
• AnimationController
• FocusNode / FocusScopeNode
• StreamSubscription / StreamController
• PageController
• TabController
• Any addListener function must have removeListener
🔹 More Tips:
💡 If a ScrollController has an addListener, simply disposing the ScrollController will automatically trigger removeListener.
💡 If you pass a controller to a child widget, the parent (where it was created) is responsible for disposing of it — not the child.
🚀 My Personal Findings
After disposing of all controllers, I didn’t see a significant drop in my app’s memory usage. It decreased slightly, but not enough to justify constant monitoring.
For now, I won’t worry too much about memory leaks in standard ListView-DetailsView apps. However, I’ll revisit this topic if memory issues become a real problem in the future.
