从程序集创建实例会引发内存泄漏

Question

我有一个桌面应用程序，我需要在不同的AppDomain中使用反射加载一些dll，调用一个方法并卸载AppDomain。我已经正确开发了它，但是最近我需要加载和卸载的程序集数量有所增加，现在，在加载 3 个 dll 后，当我尝试加载第 4 个 dll 时，我收到此异常：

System.TypeInitializationException: An exception occurred on startup type '<Module>'. ---> System.AccessViolationException: Attempted to read or write protected memory. This often indicates that other memory is corrupt.
en .cctor()
--- End of monitoring the inner exception stack ---
en System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean& canBeCached, RuntimeMethodHandleInternal& ctor, Boolean& bNeedSecurityCheck)
en System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, StackCrawlMark& stackMark)
en System.RuntimeType.CreateInstanceDefaultCtor(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, StackCrawlMark& stackMark)
en System.Activator.CreateInstance(Type type, Boolean nonPublic)
en System.RuntimeType.CreateInstanceImpl(BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes, StackCrawlMark& stackMark)
en System.Activator.CreateInstance(Type type, BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes)
en System.Reflection.Assembly.CreateInstance(String typeName, Boolean ignoreCase, BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes)
en BankIntegration.ReflectionCaller.CallInternal(String dll, String typename, String method, Object[] parameters)
en BankIntegration.ReflectionCaller.CallInternal(String dll, String typename, String method, Object[] parameters)
en BankIntegration.ReflectionCaller.Call(String pathToDLL, String typename, String method, Object[] parameters)
en BankIntegration.DllManager.init_bank_conectors(Server service)
en BankIntegration.frmClient..ctor(Server service, String dllPath, Int64 idclient)
en AVISync.frmInit.Button_clicked(Object sender, ItemClickEventArgs e)

在网上搜索后，我什至无法弄清楚问题出在哪里。如果我在视觉工作室上调试应用程序，它可以正常工作。它仅显示在已发布的应用程序中。这是相关代码：

'DLLManager：

For Each bean As BankIntegration.AppUtil.bankBean In aux
        Dim dllPath As String = Path.Combine(DLL_FILES_DIR, bean.DllName)
        Dim download As Boolean = False
        If File.Exists(dllPath) Then
            Dim info As BankInterfaces.beans.DLLInfo = ReflectionCaller.Call(dllPath, bean.DllNameSpace & ".Connector", BankInterfaces.Util.BANKINTERFACE_NAMES.getDLLInfo, Nothing)
            'Irrelevant code here'
            info = Nothing
            'Irrelevant code here'
        End If
            'Irrelevant code here'
        GC.Collect()
    Next

'反射来电者

Public Shared Function [Call](ByVal pathToDLL As String, ByVal typename As String, ByVal method As String, ByVal ParamArray parameters As Object()) As Object
    Dim permissions As New Security.PermissionSet(Security.Permissions.PermissionState.Unrestricted)
    Dim adSetup As New AppDomainSetup()
    adSetup.ApplicationBase = AppDomain.CurrentDomain.BaseDirectory
    Dim dom As AppDomain = AppDomain.CreateDomain(Guid.NewGuid.ToString, AppDomain.CurrentDomain.Evidence, adSetup, permissions)
    Dim ld As ReflectionCaller = DirectCast(dom.CreateInstanceAndUnwrap(Reflection.Assembly.GetExecutingAssembly().FullName, GetType(ReflectionCaller).FullName), ReflectionCaller)
    Dim result As Object = ld.CallInternal(pathToDLL, typename, method, parameters)
    AppDomain.Unload(dom)
    dom = Nothing
    ld = Nothing
    GC.Collect()
    Return result
End Function
Private Function CallInternal(dll As String, typename As String, method As String, parameters As Object()) As Object
    Dim a As Reflection.Assembly = Reflection.Assembly.LoadFile(dll)
    Dim o As Object = a.CreateInstance(typename) '<-- This line throws the exception after a few iterations'
    Dim t As Type = o.[GetType]()
    Dim m As Reflection.MethodInfo = t.GetMethod(method)
    Dim result As Object = m.Invoke(o, parameters)
    a = Nothing
    o = Nothing
    t = Nothing
    m = Nothing
    GC.Collect()
    Return result
End Function

Answer 1

在网上搜索 2 天后，我已经能够解决错误。这是针对我情况的任何人的解决方案。

1. 要通过反射加载的类必须实现 IDisposable 接口。

2. 这些类必须重写 Dispose 方法。在此方法中，只需强制垃圾回收器：

   GC.Collect(3)
   GC.SuppressFinalize(Me)