Flutter应用批量上传MP4至Firebase Cloud Storage时内存溢出崩溃求助

问题背景 #

在Android设备的Flutter应用中，批量上传外部存储中的MP4文件至Firebase Cloud Storage时，上传15-19个文件后应用因OutOfMemoryError崩溃。测试环境为Android Pixel 3模拟器，使用54个约50MB的20秒MP4文件，连接Firebase Storage模拟器本地测试。同步、异步上传逻辑均触发该问题，实际项目使用队列结构（示例代码简化为Completer）。

复现代码 #

import 'dart:async';
import 'dart:io';

import 'package:firebase_storage/firebase_storage.dart';
import 'package:flutter/material.dart';
import 'package:firebase_core/firebase_core.dart';
import 'package:path_provider/path_provider.dart';
import 'firebase_options.dart';

Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp(
    options: DefaultFirebaseOptions.currentPlatform,
  );

  try {
    await FirebaseStorage.instance.useStorageEmulator('10.0.2.2', 9199);
  } catch (e) {
    print(e);
  }

  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('Firebase Upload Test'),
        ),
        body: Center(
          child: ElevatedButton(
            onPressed: () => uploadFromExternalDirectory(),
            child: const Text('Upload Assets'),
          ),
        ),
      ),
    );
  }


  void uploadFromExternalDirectory() async {
    try {
      final directory =
          await getExternalStorageDirectory();
      if (directory == null) {
        print('Error: Could not get external storage directory');
        return;
      }

      Directory videos = directory;

      final storage = FirebaseStorage.instance;

      // Iterate through files in the directory (synchronously)
      for (var entity in videos.listSync(recursive: false)) {
        print('Processing $entity');
        if (entity is File) {
          String fileName = entity.path;

          try {
            UploadTask task = storage.ref('test/$fileName').putFile(entity);

            // Use a Completer to create a Future that completes when the upload is done
            final Completer<void> completer = Completer<void>();

            final StreamSubscription<TaskSnapshot> streamSubscription =
                task.snapshotEvents.listen((TaskSnapshot snapshot) {
              double progress =
                  (snapshot.bytesTransferred / snapshot.totalBytes) * 100;
              print('Upload progress for $fileName: $progress%');
            }, onError: (error) {
              completer
                  .completeError(error); // Complete the future with an error
            }, onDone: () {
              completer.complete(); // Complete the future successfully
            });

            // Await the Completer's future to wait for the upload to finish
            await completer.future;

            // Cancel the stream subscription after the task is complete
            await streamSubscription.cancel();

            print('Upload of $fileName complete!');
          } on FirebaseException catch (e) {
            print('Error uploading $fileName: $e');
          }
        }
      }
    } catch (e) {
      // Handle any potential errors that might occur
      print('An error occurred: $e');
    }
  }
}

崩溃日志 #

I/pload_issue_app(24622): Alloc concurrent copying GC freed 273(182KB) AllocSpace objects, 0(0B) LOS objects, 0% free, 191MB/192MB, paused 28us,137us total 9.132ms
I/pload_issue_app(24622): WaitForGcToComplete blocked Alloc on Alloc for 9.821ms
I/pload_issue_app(24622): Starting a blocking GC Alloc
I/pload_issue_app(24622): WaitForGcToComplete blocked Alloc on Alloc for 9.805ms
I/pload_issue_app(24622): Starting a blocking GC Alloc
I/pload_issue_app(24622): Waiting for a blocking GC Alloc
I/pload_issue_app(24622): Clamp target GC heap from 215MB to 192MB
W/pload_issue_app(24622): Throwing OutOfMemoryError "Failed to allocate a 59 byte allocation with 88776 free bytes and 86KB until OOM, target footprint 201326592, growth limit 201326592; giving up on allocation because <1% of heap free after GC." (VmSize 19423944 kB)
I/pload_issue_app(24622): WaitForGcToComplete blocked Background on Alloc for 19.661ms
I/pload_issue_app(24622): Waiting for a blocking GC Alloc
I/pload_issue_app(24622): Forcing collection of SoftReferences for 16B allocation
I/pload_issue_app(24622): Waiting for a blocking GC Alloc
E/AndroidRuntime(24622): FATAL EXCEPTION: main
E/AndroidRuntime(24622): Process: com.example.upload_issue_app, PID: 24622
E/AndroidRuntime(24622): java.lang.OutOfMemoryError: Failed to allocate a 59 byte allocation with 88776 free bytes and 86KB until OOM, target footprint 201326592, growth limit 201326592; giving up on allocation because <1% of heap free after GC.
E/AndroidRuntime(24622):    at dalvik.system.VMRuntime.newNonMovableArray(Native Method)
E/AndroidRuntime(24622):    at java.nio.DirectByteBuffer$MemoryRef.<init>(DirectByteBuffer.java:71)
E/AndroidRuntime(24622):    at java.nio.ByteBuffer.allocateDirect(ByteBuffer.java:265)
E/AndroidRuntime(24622):    at io.flutter.plugin.common.StandardMessageCodec.encodeMessage(StandardMessageCodec.java:77)
E/AndroidRuntime(24622):    at io.flutter.plugin.common.BasicMessageChannel$IncomingMessageHandler$1.reply(BasicMessageChannel.java:266)
E/AndroidRuntime(24622):    at io.flutter.plugins.firebase.storage.GeneratedAndroidFirebaseStorage$FirebaseStorageHostApi$14.success(GeneratedAndroidFirebaseStorage.java:1312)
E/AndroidRuntime(24622):    at io.flutter.plugins.firebase.storage.GeneratedAndroidFirebaseStorage$FirebaseStorageHostApi$14.success(GeneratedAndroidFirebaseStorage.java:1309)
E/AndroidRuntime(24622):    at io.flutter.plugins.firebase.storage.FlutterFirebaseStoragePlugin.referencePutFile(FlutterFirebaseStoragePlugin.java:509)
E/AndroidRuntime(24622):    at io.flutter.plugins.firebase.storage.GeneratedAndroidFirebaseStorage$FirebaseStorageHostApi$-CC.lambda$setup$13(GeneratedAndroidFirebaseStorage.java:1321)
E/AndroidRuntime(24622):    at io.flutter.plugins.firebase.storage.GeneratedAndroidFirebaseStorage$FirebaseStorageHostApi$$ExternalSyntheticLambda13.onMessage(Unknown Source:2)
E/AndroidRuntime(24622):    at io.flutter.plugin.common.BasicMessageChannel$IncomingMessageHandler.onMessage(BasicMessageChannel.java:261)
E/AndroidRuntime(24622):    at io.flutter.embedding.engine.dart.DartMessenger.invokeHandler(DartMessenger.java:295)
E/AndroidRuntime(24622):    at io.flutter.embedding.engine.dart.DartMessenger.lambda$dispatchMessageToQueue$0$io-flutter-embedding-engine-dart-DartMessenger(DartMessenger.java:322)
E/AndroidRuntime(24622):    at io.flutter.embedding.engine.dart.DartMessenger$$ExternalSyntheticLambda0.run(Unknown Source:12)
E/AndroidRuntime(24622):    at android.os.Handler.handleCallback(Handler.java:958)
E/AndroidRuntime(24622):    at android.os.Handler.dispatchMessage(Handler.java:99)
E/AndroidRuntime(24622):    at android.os.Looper.loopOnce(Looper.java:205)
E/AndroidRuntime(24622):    at android.os.Looper.loop(Looper.java:294)
E/AndroidRuntime(24622):    at android.app.ActivityThread.main(ActivityThread.java:8177)
E/AndroidRuntime(24622):    at java.lang.reflect.Method.invoke(Native Method)
E/AndroidRuntime(24622):    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:552)
E/AndroidRuntime(24622):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:971)
I/pload_issue_app(24622): WaitForGcToComplete blocked Alloc on Background for 33.559ms
I/pload_issue_app(24622): Starting a blocking GC Alloc
I/pload_issue_app(24622): WaitForGcToComplete blocked Alloc on Background for 19.223ms
I/pload_issue_app(24622): Starting a blocking GC Alloc
I/pload_issue_app(24622): Clamp target GC heap from 215MB to 192MB
I/pload_issue_app(24622): Alloc concurrent copying GC freed 568(58KB) AllocSpace objects, 0(0B) LOS objects, 0% free, 191MB/192MB, paused 21us,11us total 10.624ms
I/pload_issue_app(24622): WaitForGcToComplete blocked Background on Alloc for 12.056ms
I/Process (24622): Sending signal. PID: 24622 SIG: 9
Lost connection to device.

Exited.

已尝试的方案 #

• 同步/异步上传逻辑，均触发OOM
• 改用putData方法，内存占用暴涨，崩溃更快；Flutter版无putStream方法
• 通过Flutter和Android内存分析工具发现：Flutter RSS持续增长，Android侧Java和Native内存周期性上升

解决方案建议 #

1. 优化上传任务的资源释放 #

• 上传完成后主动释放File对象引用，帮助GC回收内存：

  // 每个文件上传完成后
  entity = null;
  // 手动触发GC（可选，加速内存回收）
  System.runFinalization();
  

• 确保错误路径下也取消StreamSubscription，避免资源泄漏：

  StreamSubscription<TaskSnapshot>? streamSubscription;
  try {
    UploadTask task = storage.ref('test/$fileName').putFile(entity);
    streamSubscription = task.snapshotEvents.listen(...);
    await completer.future;
    await streamSubscription.cancel();
  } catch (e) {
    await streamSubscription?.cancel();
    print('Error uploading $fileName: $e');
  }
  

2. 限制并发上传数量 #

即使串行上传，底层Native侧资源可能未及时释放，通过Semaphore控制并发数（如最多2个）：

// 引入semaphore依赖或自行实现
final semaphore = Semaphore(2);
for (var entity in videos.listSync(recursive: false)) {
  if (entity is File) {
    await semaphore.acquire();
    try {
      // 上传逻辑
    } finally {
      semaphore.release();
      entity = null;
    }
  }
}

3. 通过Method Channel调用Android原生Firebase Storage API #

Flutter插件可能存在内存泄漏，直接调用原生putFile方法，原生侧资源管理更高效：

• 原生侧Kotlin代码：

  class FirebaseUploadHandler(private val context: Context) {
      private val storage = FirebaseStorage.getInstance()
  
      fun uploadFile(filePath: String, storagePath: String, result: MethodChannel.Result) {
          val file = File(filePath)
          val ref = storage.reference.child(storagePath)
          val uploadTask = ref.putFile(Uri.fromFile(file))
  
          uploadTask.addOnCompleteListener { task ->
              if (task.isSuccessful) {
                  result.success("Upload completed")
              } else {
                  result.error("UPLOAD_FAILED", task.exception?.message, null)
              }
          }
      }
  }
  

• Flutter侧调用代码：

  const platform = MethodChannel('com.example.firebase_upload');
  
  Future<void> uploadFileNative(String filePath, String storagePath) async {
    try {
      await platform.invokeMethod('uploadFile', {
        'filePath': filePath,
        'storagePath': storagePath,
      });
    } on PlatformException catch (e) {
      print("Native upload error: ${e.message}");
    }
  }
  

4. 调整Android应用内存配置 #

在android/app/build.gradle中增加堆内存，缓解内存压力：

android {
    defaultConfig {
        multiDexEnabled true
        javaMaxHeapSize "512m"
    }
}

5. 更新Firebase Storage插件版本 #

使用最新版firebase_storage，官方可能已修复内存泄漏问题：

dependencies:
  firebase_storage: ^latest_version

内容的提问来源于stack exchange，提问作者Dana Lambert