Unity遊戲執行閃退問題定位與解決（標籤：Oops、crashed、System out of memory、UnityEngine.AssetBundle:LoadAsset_Internal）
阿新 • • 發佈：2021-02-19
技術標籤：Unity3DunityAssetBundleLoadFromFile閃退無效記憶體
文章目錄
一、閃退問題
最近Unity工程釋出PC平臺的包，運行遊戲，出現了一個閃退的問題，彈框如下。
根據提示，找到對應的crash日誌。
開啟output_log.txt，如下：
... ... The file 'archive:/CAB-350107fab3529178780193de85391267/CAB-350107fab3529178780193de85391267' is corrupted! Remove it and launch unity again! [Position out of bounds!] (Filename: Line: 220) Mismatched serialization in the builtin class 'MonoScript'. (Read 41 bytes but expected 81 bytes) (Filename: Line: 1831) DynamicHeapAllocator allocation probe 1 failed - Could not get memory for large allocation 4227858432. DynamicHeapAllocator allocation probe 2 failed - Could not get memory for large allocation 4227858432. DynamicHeapAllocator allocation probe 3 failed - Could not get memory for large allocation 4227858432. DynamicHeapAllocator allocation probe 4 failed - Could not get memory for large allocation 4227858432. DynamicHeapAllocator out of memory - Could not get memory for large allocation 4227858432! Could not allocate memory: System out of memory! Trying to allocate: 4227858432B with 16 alignment. MemoryLabel: BaseObject Allocation happend at: Line:463 in Memory overview [ ALLOC_DEFAULT ] used: 117172692B | peak: 0B | reserved: 128778716B [ ALLOC_TEMP_JOB ] used: 0B | peak: 0B | reserved: 2097152B [ ALLOC_GFX ] used: 39689080B | peak: 0B | reserved: 44995820B [ ALLOC_CACHEOBJECTS ] used: 1044176B | peak: 0B | reserved: 10485760B [ ALLOC_TYPETREE ] used: 1242064B | peak: 0B | reserved: 4194304B [ ALLOC_PROFILER ] used: 0B | peak: 0B | reserved: 0B [ ALLOC_TEMP_THREAD ] used: 34816B | peak: 0B | reserved: 3244032B Could not allocate memory: System out of memory! Trying to allocate: 4227858432B with 16 alignment. MemoryLabel: BaseObject Allocation happend at: Line:463 in Memory overview [ ALLOC_DEFAULT ] used: 117172692B | peak: 0B | reserved: 128778716B [ ALLOC_TEMP_JOB ] used: 0B | peak: 0B | reserved: 2097152B [ ALLOC_GFX ] used: 39689080B | peak: 0B | reserved: 44995820B [ ALLOC_CACHEOBJECTS ] used: 1044176B | peak: 0B | reserved: 10485760B [ ALLOC_TYPETREE ] used: 1242064B | peak: 0B | reserved: 4194304B [ ALLOC_PROFILER ] used: 0B | peak: 0B | reserved: 0B [ ALLOC_TEMP_THREAD ] used: 34816B | peak: 0B | reserved: 3244032B (Filename: Line: 999) Crash!!! ... ... ========== OUTPUTING STACK TRACE ================== ERROR: SymGetSymFromAddr64, GetLastError: '試圖訪問無效的地址。 ' (Address: 00F9DCD0) 0x00F9DCD0 (SFish) ERROR: SymGetSymFromAddr64, GetLastError: '試圖訪問無效的地址。 ' (Address: 00F9F88C) 0x00F9F88C (SFish) ERROR: SymGetSymFromAddr64, GetLastError: '試圖訪問無效的地址。 ' (Address: 00F9FFAC) 0x00F9FFAC (SFish) 0x0121A644 (SFish) physx::shdfnd::Foundation::getTempAllocFreeTable 0x012157E3 (SFish) physx::shdfnd::Foundation::getTempAllocFreeTable 0x0121666A (SFish) physx::shdfnd::Foundation::getTempAllocFreeTable ERROR: SymGetSymFromAddr64, GetLastError: '試圖訪問無效的地址。 ' (Address: 00F9AFDF) 0x00F9AFDF (SFish) ERROR: SymGetSymFromAddr64, GetLastError: '試圖訪問無效的地址。 ' (Address: 00F9A553) 0x00F9A553 (SFish) ERROR: SymGetSymFromAddr64, GetLastError: '試圖訪問無效的地址。 ' (Address: 00F9A7A9) 0x00F9A7A9 (SFish) 0x0123D395 (SFish) physx::shdfnd::Foundation::getTempAllocFreeTable 0x05F9875A (Mono JIT Code) (wrapper managed-to-native) UnityEngine.AssetBundle:LoadAsset_Internal (string,System.Type) 0x05F9867D (Mono JIT Code) UnityEngine.AssetBundle:LoadAsset (string,System.Type) 0x05F98571 (Mono JIT Code) QRes.AssetBundleMgr:LoadAsset (string,string,bool) 0x05F9834E (Mono JIT Code) QRes.AssetBundleMgr:LoadExternAsset (string) 0x05F9817B (Mono JIT Code) QRes.AssetBundleMgr:LoadAssetFromAssetBundle (string) 0x17746A0F (Mono JIT Code) RbResDestory:Instantiate<object> (string) 0x17746908 (Mono JIT Code) RbResDestory:InstantiateGameObject (int) 0x15C4BB46 (Mono JIT Code) CR_NeHeRunner:Instead (intptr) 0x177A95A5 (Mono JIT Code) (wrapper native-to-managed) CR_NeHeRunner:Instead (intptr) 0x6DF8334E (tolua) lua_lessthan ERROR: SymGetSymFromAddr64, GetLastError: '找不到指定的模組。 ' (Address: 1F293288) ERROR: SymGetModuleInfo64, GetLastError: '動態連結庫(DLL)初始化例程失敗。 ' (Address: 1F293288) 0x1F293288 ((<unknown>)) ========== END OF STACKTRACE =========== **** Crash! ****
二、問題定位與解決
1、結論
根據日誌，得出結論：是在呼叫AssetBundle的LoadAsset介面的時候閃退的，訪問了一個無效的記憶體地址。
但，為什麼呢？
2、問題分析
遊戲中做了資源下載的功能：把資源打成AssetBundle，放在雲端，客戶端運行遊戲時從雲端下載AssetBundle包到本地，然後從本地中載入資源。
這個流程會存在一個什麼問題呢？
假設我們有個資源包：test.ab，我們把它放到雲端，客戶端下載到了本地並載入了這個AssetBundle；接著我們工程中修改了資源，重新打了test.ab放到雲端，遊戲客戶端在不重啟的情況下又觸發了test.ab的下載，那麼本地磁碟中的test.ab
AssetBundle物件與磁碟的AssetBundle檔案不對應了，如果此時呼叫LoadAsset介面就會出現無效記憶體訪問，導致閃退。
這又引出了另一個疑問，我們載入AssetBundle的時候，程式碼如下：
AssetBundle ab = AssetBundle.LoadFromFile(ab_path);
我們已經通過AssetBundle.LoadFromFile載入了AssetBundle到記憶體中，為什麼此時刪除或者覆蓋磁碟中的AssetBundle會影響記憶體中的AssetBundle呢？
事實上，AssetBundle.LoadFromFile
LoadAsset接口才會真正把資源從磁碟中讀取到記憶體中，並且只讀取對應的Asset；如果想要讀取AssetBundle中所有的Asset，可以使用LoadAllAssets或LoadAllAssetsAsync載入所有Asset。當我們使用
LoadAsset讀取了某個資源到記憶體中後，即使磁碟中的AssetBundle刪除或者被覆蓋成其他檔案，都不會再影響記憶體中再次LoadAsset這個資源了，也就是說，記憶體中的AssetBundle物件自身是會有一層快取的，第一次呼叫LoadAsset時是從磁碟中的AssetBundle檔案中讀取資源，再次呼叫LoadAsset相同資源是，直接從記憶體中的AssetBundle物件快取中讀取了。
3、解決辦法
根據分析，解決辦法就是首次載入AssetBundle物件後就執行LoadAllAssetsAsync載入所有Asset，即可避免因為資源覆蓋下載導致LoadAsset出現無效記憶體訪問。