在iOS上，内存管理，自动释放，永久堆的问题有时会超过250 kb [英] Problems with memory management, autorelease, permanent heap is sometimes 250+ kb on iOS

问题描述

我真的把头发拉到这个上面，似乎我在iOS应用程序上遇到了严重的内存管理问题。

I'm really pulling my hair out on this one, it seems that I'm having severe issues with memory management on an iOS app.

以下是这种情况：首先我加载表。当用户点击一个单元格时，它会呈现一个复杂的视图。关于视图的最大内存消耗是，它正在加载20+ UIImage 的500x500。该视图中还有另外两个选项卡，加载媒体列表（那些 UIImage s，但随后在表中）和另一个简单表格。

Here's the case: first I load table. When the user taps a cell, it presents a complicated view. The most memory consuming about the view is that it's loading 20+ UIImages of 500x500. There are two other tabs in that view, loading a list of media (those UIImages, but then in a table) and another simple table.

当我返回到第一个表视图时，仍然在堆上分配了超过250 kB。我知道这个观点很复杂，但是没有理由保持这么多记忆。好吧，猜猜看，当我切换到视图时，最终应用程序耗尽内存并被杀死。

When I return back to the first table view, apparently over 250 kB is still allocated on heap. I know the view is complicated, but there's no reason to keep so much memory alive. And well, guess what, when I do switch to the view a lot, eventually the app runs out of memory and gets killed.

我试图解决的问题：

• 修复所有分析问题，因此根据没有泄漏。


• 全部检查 init s再次发布，尽可能使用 autorelease 。


• 检查所有内存泄漏使用仪器 - >泄漏。在6的运行时间里，我得到的泄漏不超过2或3次。


• 最后，仪器 - >分配，检查堆。这让我感到困扰，在两个标记的快照之间我得到250+ kB的差异。我已经使用详细的视图调查了它。我无法理解它：当它指向我的一个方法/类时，我很确定那里的所有内容都已发布或自动释放。它也指向很多不是我的（比如 QuartzCore ）方法/类。

• Fix all Analyze issues, so according to that there are no leaks anymore.
• Check all inits again for releasing, making use of autorelease where possible.
• Checking all the memory leaks using Instruments -> Leaks. In a runtime of 6, I get not more than 2 or 3 leaks.
• Last, Instruments -> Allocation, checking the heap. This is what bothers me, between two marked heapshots I get a difference of 250+ kB. I've looked into it, using the detailed views. I can't get my head around it: when it's pointing to one of my methods/classes, I'm pretty sure everything in there is either released or autoreleased. It's also pointing to a lot of not-mine (say QuartzCore) methods/classes.

另外，我不明白为什么 autorelease 不会自动释放。我的意思是，它有时看起来像一个被标记为自动释放的对象，被释放的方式为时已晚。我自己没有创建任何 NSAutoreleasePool ，所以有可能只在运行时停止时才将池耗尽？如何定期排水池（即使它不是我的）。

Also, I don't understand why autorelease is not autoreleasing. I mean, it sometimes looks like an object that is marked for autoreleasing, is released way too late. I haven't created any NSAutoreleasePools myself, so is it possible that the pool is drained only when the runtime stops? How can I periodically drain the pool (even if it's not mine).

非常感谢任何帮助。

亲切的问候，

Reinder

用于堆检查： http://www.friday.com/bbum/2010/10/17/when-is-a-leak-not-a-leak-using-heapshot-analysis-to-find-undesirable-memory-growth/

推荐答案

我认为您可能希望首先尝试优化设计并阅读有效的内存管理指南。更好地理解组件和运行时不仅有助于跟踪内存分配，还可以更容易地找到泄漏。

I think you might want to try to optimize your design first and read guides for efficent memory management. A better understaning of the components and the runtime helps more than tracking memory allocations and will make it easier to find the leaks.

• 首先你应该始终使用发布。只在必要时才使用 autorelease 。


• 确保遵循UITableView实施指南和UITableViewCells的有效管理（延迟加载，重复使用单元格等）。


• 检查是否有保留周期（保留的视图控制器不会被释放）。


• 跟踪视图控制器和对象的重新分配


• 不要把东西留在你不再需要的内存中。


• 不要加载你现在不需要的东西。

• First you should always use release. Only use autorelease when necessary.
• Make sure you follow the guidelines for UITableView implementations and efficient management of UITableViewCells (lazy loading, cell reusing etc.).
• Check if you have retain-cycles (retained view controllers won't be deallocated).
• Track the deallocation of your view controllers and objects
• Don't keep stuff in memory you don't need anymore.
• Don't load stuff you don't need right now.

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