我在 DLL 中实现了一个函数,封装了对 Out-OF-Proc COM 服务器的异步调用。它看起来像这样:
HRESULT hr = S_OK;
bool bCoInitialized = false;
IXXXXInterface* pServer = NULL;
ISynchronize* pISynchronize = NULL;
AsyncIXXXXInterface* pAsyncServer = NULL;
ICancelMethodCalls* pICancel = NULL;
hr = CoInitializeEx(NULL,COINIT_MULTITHREADED);
if (hr == S_OK || hr == S_FALSE) {
bCoInitialized = true;
}
else if(hr == RPC_E_CHANGED_MODE) {
bCoInitialized = false;
}
else{
bCoInitialized = false;
goto cleanup
}
hr = CoCreateInstance(CLSID_XXXXInterface, NULL,
CLSCTX_ALL|CLSCTX_ACTIVATE_64_BIT_SERVER, IID_IXXXXInterface, (void**)&pServer);
if (FAILED (hr)) {
goto cleanup
}
ICallFactory* pCallFactory;
hr = pServer->QueryInterface (IID_ICallFactory, (void**) &pCallFactory);
if (FAILED (hr)) {
goto cleanup
}
hr = pCallFactory->CreateCall (IID_AsyncIXXXXInterface, NULL, IID_AsyncIXXXXInterface,
(IUnknown**) &pAsyncServer);
pCallFactory->Release();
if (FAILED (hr)) {
goto cleanup
}
hr = pAsyncServer->QueryInterface(IID_ISynchronize, (void**) &pISynchronize);
if (FAILED (hr)) {
goto cleanup
}
hr = pAsyncServer->QueryInterface(IID_ICancelMethodCalls, (void**) &pICancel);
if (FAILED (hr)) {
goto cleanup
}
// Do something use the async interface.
cleanup:
if(pICancel)
pICancel->Release();
if(pISynchronize)
pISynchronize->Release();
if(pAsyncServer)
pAsyncServer->Release();
if(pServer)
pServer->Release();
if(bCoInitialized) // If I comment out these
CoUninitialize(); // 2 lines, it will be OK.
问题是当我在多线程中调用该函数时,有时它会在 COM 的工作线程中使用调用堆栈在 combase.dll 中抛出异常。如果我只是注释掉最后两行,就可以了。看起来 CoUnitialize() 将释放所有资源,而 COM 线程池中的工作线程在某些情况下仍在使用它们。我不确定我的想法是否正确,或者其他地方有问题。如果我是对的,如何通过使用哪个 API 等待工作线程释放所有资源来避免这个问题?