Question

我有一个使用phonegap-plugin-barcodescanner（v 6.0.1）的cordova（目前为5.3.3）项目。最近我遇到了我认为在iOS 10中存在某种大内存泄漏的情况。当应用程序在iOS 10上运行时，它似乎永远不会释放与扫描程序相关的资源。但是在iOS 7或9上，一切正常。这可以在内存报告中看到。

iOS 10 ios10

iOS 7 ios7

我试图使用仪器中的泄漏检查器来追踪泄漏，但我似乎无法在测试中找到任何实质内容。我使用该工具找到的每个扫描大约有1KB的泄漏对象。

我想我的主要问题是，是否有更好的方法来追踪似乎与此扫描仪绑定的内存问题？在iOS 10中发生重新分配/引用计数的方式是否会发生某种变化会导致如此剧烈的变化？

我已经使用上面提到的插件创建了一个准系统cordova项目，并在此代码中显示了一个按钮的基本扫描程序调用，这应该提供可重现的测试。

<!DOCTYPE html>
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under the License.
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<html>
<head>
    <!--
    Customize this policy to fit your own app's needs. For more guidance, see:
        https://github.com/apache/cordova-plugin-whitelist/blob/master/README.md#content-security-policy
    Some notes:
        * gap: is required only on iOS (when using UIWebView) and is needed for JS->native communication
        * https://ssl.gstatic.com is required only on Android and is needed for TalkBack to function properly
        * Disables use of inline scripts in order to mitigate risk of XSS vulnerabilities. To change this:
            * Enable inline JS: add 'unsafe-inline' to default-src
    -->

    <meta name="format-detection" content="telephone=no">
    <meta name="msapplication-tap-highlight" content="no">
    <meta name="viewport" content="user-scalable=no, initial-scale=1, maximum-scale=1, minimum-scale=1, width=device-width">
    <link rel="stylesheet" type="text/css" href="css/index.css">
    <title>Hello World</title>
</head>
<body>
    <div class="app">
        <script type="text/javascript">
            function scanTest(field) {
                try {
                    debugger
                    var scanner = window.cordova.require("phonegap-plugin-barcodescanner.BarcodeScanner");
                    scanner.scan(
                                 function (result) {
                                 if (document.getElementById(field)) {
                                 document.getElementById(field).innerHTML = result.text;
                                 } else {
                                 alert("ScannerCouldntIdentifyMessage");
                                 }
                                 });
                } catch (e) {
                    alert("ErrorDescription: " + e);
                }
            }
        </script>
        <h1>Apache Cordova</h1>
        <div id="deviceready" class="blink">
            <p class="event listening">Connecting to Device</p>
            <p class="event received">Device is Ready</p>
            <p id="scan">Test scan</p>
            <a href="#" onclick="scanTest('scan')" id="scantest">Scan</a>
        </div>
    </div>
    <script type="text/javascript" src="cordova.js"></script>
    <script type="text/javascript" src="js/index.js"></script>
</body>
</html>

编辑：经过进一步调查后，我注意到VM中似乎有一个相当大的IOKit分配，我不知道它来自哪里。你可以在VM摘要中看到，iPad没有分配这100个MiB块，但是在iOS 10中这样做了。我还不确定它来自何处或是什么会强制这些额外的调用

iOS 10 ios10

iOS 7 ios7

Answer 1

我有同样的问题，但我现在解决了。只需用以下https://github.com/phonegap/phonegap-plugin-barcodescanner/blob/master/src/ios/CDVBarcodeScanner.mm

替换您的插件文件CDVBarcodeScanner.mm即可

Answer 2

在对github和进一步调查进行一些讨论后，我发现问题是由使用AVCaptureVideoDataOutputSampleBufferDelegate的插件引起的。看来视频输出设置导致IOKit级别的一些泄漏。

对此的解决方案是更新插件以使用AVCaptureMetadataOutputObjectsDelegate并更新输出以使用AVCaptureMetadataOutput类型。这需要实现方法(void)captureOutput:(AVCaptureOutput*)captureOutput didOutputMetadataObjects:(NSArray*)metadataObjects fromConnection:(AVCaptureConnection*)connection

这种方法与前一种方法非常相似，但不是使用zxing库进行解码，而是使用循环和AVMetadata类进行解码：

  for (AVMetadataObject *metaData in metadataObjects) {
    AVMetadataMachineReadableCodeObject* code = (AVMetadataMachineReadableCodeObject*)
[self.previewLayer transformedMetadataObjectForMetadataObject:
(AVMetadataMachineReadableCodeObject*)metaData];

  if ([self checkResult:code.stringValue]) {
    [self barcodeScanSucceeded:code.stringValue format:[self formatStringFromMetadata:code]];
  }

这些提到的更改是作为插件v 6.0.3的一部分发布的。

仅在iOS 10中扫描程序插件中的内存泄漏

2 个答案: