Dart HttpRequest轮询 [英] Dart HttpRequest polling

问题描述

我有一个网络应用程序，它有一个定时器，触发轮询，每3秒获取数据。

我的请求Dart看起来像这样

）
.catchError（（e）=> _recentHistoryError（e））;

你能想到为什么会发生这种情况的任何原因吗？我认为这是一个内存泄漏...

编辑：
这是我的 _recentHistoryResponse / code>

  void _recentHistoryResponse（String data）
 {
 Map obj = JSON.decode（data）; 
 if（obj ['status'] =='success'）
 {
 list processes = obj ['data'] ['processes']; 
 List newItems = new List（）; 
 
列表oldIdsArray = new List（）; 
 
 int length = appDataDic.load_history_list.length; 
 for（HistoryDataVO oldVO in appDataDic.load_history_list）
 {
 oldIdsArray.add（oldVO.loadID）; 
} 
 
 for（进程中的映射进程）
 {
 HistoryDataVO dataVO = new HistoryDataVO（）; 
 dataVO.loadID = process ['loadID']; 
 dataVO.time = process ['time']; 
 dataVO.loadType = process ['loadType']; 
 dataVO.fileName = process ['fileName']; 
 dataVO.label = process ['label']; 
 dataVO.description = process ['description']; 
 dataVO.count = process ['count']; 
 dataVO.progress = process ['progress']; 
 dataVO.loadTask = process ['loadTask']; 
 
 //检查项目当前是否在列表中
 if（length> = 1）
 {
 if（！LoadHistoryHelper.exists（oldIdsArray，dataVO .loadID））
 {
 dataVO.isNew = true; 
} 
} 
 
 newItems.add（dataVO）; 
} 
 
 appDataDic.load_history_list.clear（）; 
 appDataDic.load_history_list.addAll（newItems）; 
 
} 
} 
  

我已注释掉exists检查！LoadHistoryHelper.exists（oldIdsArray，dataVO.loadID））（因为这似乎是显而易见的地方），但它的VM仍然崩溃。

此外，我已经采取了相同的代码，并把它放入一个孤立的应用程序，唯一的真正的区别是轮询检查是 appDataDic.load_history_list 只是一个 @observable列表，而不是 ObservableList 。

编辑2：
好​​吧，我发现 Map obj = JSON.decode（data）; 导致崩溃。我在一个Javascript论坛读取超时导致内存不被释放（我从来没有想过这个，但它是有道理的），这是真的吗？任何人都能想出一个更好的方法来做到这一点？我可以直接调用垃圾回收吗？

解决方案

还有另一个问题在这里，建议在HttpRequest中的内存泄漏;但我无法在Dart问题跟踪器中找到任何东西。如果您认为这可能是真正的内存泄漏，可能值得提出错误。

I have a web app that have a Timer that fires a poll to get data every 3 seconds. It works fine for about 2.5 minutes then Chromium crashes.

My request Dart looks like this

HttpRequest.getString('data/get_load_history_recent.json')
  .then((e) => _recentHistoryResponse(e))
  .catchError((e) => _recentHistoryError(e));

Can you think of any reasons why this would happen? I assume it's a memory leak...

Edit: Here is my _recentHistoryResponse()

void _recentHistoryResponse(String data)
{
  Map obj = JSON.decode(data);
  if(obj['status'] == 'success')
  {
    List processes = obj['data']['processes'];
    List newItems = new List();

    List oldIdsArray = new List();

    int length = appDataDic.load_history_list.length;
    for(HistoryDataVO oldVO in appDataDic.load_history_list)
    {
      oldIdsArray.add(oldVO.loadID);
    }

    for(Map process in processes)
    {
      HistoryDataVO dataVO = new HistoryDataVO(); 
      dataVO.loadID = process['loadID'];
      dataVO.time = process['time'];
      dataVO.loadType = process['loadType'];
      dataVO.fileName = process['fileName'];
      dataVO.label = process['label'];
      dataVO.description = process['description'];
      dataVO.count = process['count'];
      dataVO.progress = process['progress'];
      dataVO.loadTask = process['loadTask'];

      // Check if the item is currently in the list
      if(length >= 1)
      {
        if(!LoadHistoryHelper.exists(oldIdsArray, dataVO.loadID))
        {
          dataVO.isNew = true;
        }
      }

      newItems.add(dataVO);
    }

    appDataDic.load_history_list.clear();
    appDataDic.load_history_list.addAll(newItems);

  }
}

I have commented out the exists check !LoadHistoryHelper.exists(oldIdsArray, dataVO.loadID)) (because this seemed like the obvious place) but it the VM still crashes.

Also, I have taken this same code and put it into an isolated app with the only real difference in the poll check is appDataDic.load_history_list is just an @observable List, not an ObservableList.

Edit 2 : Ok, so I have discovered that Map obj = JSON.decode(data); causes the crash. I was reading in a Javascript forum that timeouts cause the memory to not be released (I had never thought of this but it makes sense), is this true? Can any one think of a better way to do this? Can I directly call the garbage collection? I'm running out of ideas.

解决方案

There's another question here, suggesting a memory leak in HttpRequest; however I'm not able to find anything in the Dart issue tracker. If you think this might be a real memory leak, it might be worth raising a bug.

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