I see, Thank you for the detailed reply. Now, the problem I see is that the end-users application is crashing after a day whenever he uses synchronous calls. It looks like he is looking to transition to asynchronous calls, but he would like to offer Synchronous calls as well.

Now, I perhaps did not explain myself better in my earlier email or forgot to provide more context so I apologize if it was not clear enough, but the reason for us to look at memory consumption on a "detailed" basis was to identify what was triggering the memory growth. Now, you can leave the application running for a day or two and it will eventually crash as it did for the customer.

Now, would this be true for COM development as well, I am familiar with the garbage collector in .NET but to be honest I have not done to much development with COM. Now, forgive my ignorance, but even if I was going to develop a COM app, Does the toolkit uses .NET runtime in the background so the Garbage collector would still be in place?

Hello Z,

I wanted to run something by you and see if I can get your thought on this. I am currently working with a customer that is experiencing some memory growth when using the OPC UA client object. Now, I believe we figured out why the memory was experienced and just want to run it by you.

We were able to replicate this by adding a While(1) to the ReadValue.Main.cpp Example:

void ReadValue::Main()
{
// Initialize the COM library
CoInitializeEx(NULL, COINIT_MULTITHREADED);
while(1)
{
// Instantiate the client object
_EasyUAClientPtr ClientPtr(__uuidof(EasyUAClient));

// Perform the operation
_variant_t value = ClientPtr->ReadValue(
/*L"opcua.demo-this.com:51211/UA/SampleServer",
L"nsu=http://test.org/UA/Data/;i=10853");*/
L"opc.tcp://10.1.10.72:62541",
L"nsu=urn:inductiveautomation:ignition:opcua:tags ;ns=2;s=[default]/PROCESS/MANAGEMENT/INSTANCE/ADMIN/IsActive");

// Display results
_variant_t vString;
vString.ChangeType(VT_BSTR, &value);
_tprintf(_T("valuem: %s\n"), (LPCTSTR)CW2CT((_bstr_t)vString));
}
// Release all interface pointers BEFORE calling CoUninitialize()
CoUninitialize();
}


It looks like the resources are delay-released, so the memory will start to increase(we monitored the memory using task manager) whenever one reads over 100 values. However, once it pauses one can see the memory drop over several seconds. It looks to me that calling ReadValue() method that fast causes memory growth.

with that in mind I have a few questions:

• Have you experienced this in the past? If so is this expected? or in other words, are we correct on our assessment?
• Is there any Documentation talking about the limitation on how fast the ReasValue method can be called?

The customer is using the 5.61 Version of the toolkit. I will be testing with the new version as well so I will get back to you if I can replicate it with the new version as well.

-Rod