无法维持恒定的速度，而在与NSURLSession后台上传文件在与、上传文件、后台、速度

2023-09-11 08:22:04 作者：面具后的冷笑

我想上传一些100的图像S3与AFURLSessionManager在10小批量背景像正在做什么，这里 - Manage活动任务在后台数NSURLSession

I am trying to upload some 100 images to S3 in the background with AFURLSessionManager in small batches of 10 like what is being done here- Manage the number of active tasks in a background NSURLSession

我使用的是共享NSURLSession并添加按照这个更多的任务任务时，一些任务的完成。每个文件的平均大小为约1.6 MB的和被确保每一个任务队列运行的任务的数量为5

I am using a shared NSURLSession and adding tasks according more tasks to this when some tasks are completed. Average size of each file is about 1.6 MB and the number of tasks that are guaranteed to run per a task queue is 5

下面是我的方法添加的任务：（也可作为一个更容易阅读要点）

Here is my method for adding the tasks: (also available as an easier-to-read gist)

    - (void) addTasksToSessionWithTaskObject:(Task*)taskObject withSessionInitialisationNeeded:(BOOL) needed{

        NSString *filePath = [[NSBundle mainBundle] pathForResource:pathForResourceFile ofType:resourceFileType];
        S3PutObjectRequest *putObjectRequest = [[S3PutObjectRequest alloc] initWithKey:targetFileKey
                                                                              inBucket:_bucketname];
        putObjectRequest.cannedACL = [S3CannedACL publicReadWrite];
        putObjectRequest.filename = filePath;
        putObjectRequest.contentType = [resourceFileType isEqualToString:@"MOV"] ? @"movie/mov" : @"image/jpg";
        putObjectRequest.endpoint = @"http://s3.amazonaws.com";
        putObjectRequest.contentLength=[[[NSFileManager defaultManager]
                                         attributesOfItemAtPath:filePath error:nil] fileSize];
        putObjectRequest.delegate = self;
        [putObjectRequest configureURLRequest];
        NSMutableURLRequest *request = [s3Client signS3Request:putObjectRequest];
        NSMutableURLRequest *request2 = [[NSMutableURLRequest alloc]initWithURL:[NSURL URLWithString:[NSString stringWithFormat:@"http://s3.amazonaws.com/UploadTest/%@",taskObject.fileKey]]];

        [request2 setHTTPMethod:request.HTTPMethod];
        [request2 setAllHTTPHeaderFields:[request allHTTPHeaderFields]];

        if(needed) {

                sharedSession = [self backgroundSession];   
        }
   NSURLSessionUploadTask *task = [sharedSession uploadTaskWithRequest:request2           fromFile:forFileUrl];

    task.taskDescription = pathForResourceFile;
    [currentlyActiveTaskIdArray addObject:@([task taskIdentifier])];

    [task resume];
}

这是我的代表做了

And this what I've done with the delegate

- (void)URLSession:(NSURLSession *)sessionI task:(NSURLSessionTask *)task
didCompleteWithError:(NSError *)error{

    dispatch_async(dispatch_get_main_queue(), ^{

        __block UIBackgroundTaskIdentifier bgTaskI = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{
            [[UIApplication sharedApplication] endBackgroundTask:bgTaskI];
        }];

        if([currentlyActiveTaskIdArray containsObject:@([task taskIdentifier])]){
            [currentlyActiveTaskIdArray removeObject:@([task taskIdentifier])];
        }
        if(currentlyActiveTaskIdArray.count < LOWER_SLAB_FOR_TASKS + 1){   
            [self initiateS3UploadForSetOfTasksIsItBeginningOfUpload:NO];
        }
        [[UIApplication sharedApplication] endBackgroundTask:bgTaskI];
    }); 
}

下面是code，以增加更多的任务

Here is the Code to add more tasks

 - (void) initiateS3UploadForSetOfTasksIsItBeginningOfUpload:(BOOL)beginning{
        int i=0;
        for(Task *eachTaskObject in tasksArray){
            if(i < numberOfTasksTobeAdded){  
                [self addTasksToSessionWithTaskObject:eachTaskObject WithSessionInitialisationNeeded:NO];
                i++;
            }
        }
    }

我一直在运行在前台模式和后台模式100文件测试。在前景模式中，上载的文件在一个一致的，稳定的和恒定的速度，它完成在第3分钟90个文件，并在20秒内，其余10个文件。

I've been running tests with 100 files in Foreground mode and Background mode. In Foreground mode, it uploads the files at a consistant, steady and constant speed, it completes 90 files in the first 3 minutes, and the remaining 10 files in 20 seconds.

当我运行在后台模式下的应用程序，我希望它上传第一个90个文件一样快，因为它在3分钟前台窗口那样，并在那之后减慢......但事实并非如此。在后台模式下，它上传在第一分钟15个文件，然后开始放缓...很多。它开始上载在8文件分批慢间隔：1分钟，3分钟，5分钟，10分钟，现在17分钟。我们在65个文件46分钟研究。

When I run the app in Background mode, I would expect it to upload the first 90 files just as fast as it did in the 3 minute Foreground window, and then slow down after that... but that's not the case. In Background mode, it uploads 15 files in the first minute, then it starts slowing down... a lot. It starts uploading in 8 file batches in slower and slower intervals: 1 minute, 3 minutes, 5 minutes, 10 minutes, and now 17 minutes. We're at 65 files 46 minutes in.

有没有一种方法来保持快速，至少拳头3分钟，或保持速度一致的背景是什么？

Is there a way to either keep it fast for at least the fist 3 minutes, or keep consistent speed in the background?

更新：继克莱香港专业教育学院切换回NSURLSession从AFURLSessionManager的意见在这里，因为正如他所指出的使用基于块的回调是一个非常冒险的事与NSURLSession。而且我已经打了HTTPMaximumConnectionsPerHost，并将此大约10 - 这给了更好的结果，但远远不能满足我想要的。

UPDATE: Following the comments from Clay here Ive switched back to NSURLSession from AFURLSessionManager because as he points out using block based callbacks is an extremely risky business with NSURLSession. Further I've played with HTTPMaximumConnectionsPerHost and set this around 10-this has given better results but nowhere near what I would want to be.

无法维持恒定的速度，而在与NSURLSession后台上传文件在与、上传文件、后台、速度

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