"Failed to query property values" error on component in REDHAWK

Question

My waveform initializes well on startup, but after a few seconds into processing, it pops up a red flag on the symbol on the right in the IDE's SCA Explorer tab. The tool tip says "Failed to query property values".

I believe the issue is caused by the "process" method in the component taking too long, but I need to be able to obtain a certain element of a rather long list of chunks of data, so I can process each chunk. Therefore, I need to have a property of the component be a reference to this long list of data. Is there a better way of doing this? I had created a child process to do all of this, but that sort of defeats the purpose of using REDHAWK to manage the execution.

Thanks for your time!

Answer 1

Ben,

The first step will be to understand exactly what error occurred. This can be done by following the steps listed here. Basically:

1. Window > Show View > Other ...
2. Select General > Properties. The properties view should now be visible
3. In the SCA Explorer view, select the application with the red flag symbol
4. Now in the Properties view, you should see two tabs "Properties", and "Advanced". In the "Advanced" tab where will be a Status field that says "Failed to query property values...". When you select this field it will show a "Details..." button. Click that to receive the stack trace for the error.

Another alternative is to use the Python Sandbox (or unittest) capabilities to start your component and attempt a query. The equivalent error will be thrown as a Python exception. You can learn about the sandbox here.

As for the second part of your question, the REDHAWK process() method is already executing as a sub-thread, so it won't block query() operations unless you have created a thread lock (or used the propertySetAccess lock within your serviceFunction). If you are using a lock, then it is possible that the query() will block until the CORBA timeout is reached. You will know if this has occurred because the stack trace will be a CORBA Timeout error.

However, you said "I need to have a property of the component be a reference to this long list of data" so I think you may be getting an error related to the maximum CORBA transfer size. You can adjust the CORBA maximum transfer size by editing /etc/omniORB.cfg so the problem goes away, but your component will cause problems for others who use it. A better option is to reconsider the design of the component. You will probably want to use BULKIO ports to transfer the data in-to and out-of your component.

If you could provide more details about the algorithm you are using or source code examples, that could provide additional information that would help isolate the root problem.