I have the following code in Codename One:
Log.p("getPageMap,pre addToQueueAndWait");
NetworkManager.getInstance().addToQueueAndWait(connectionRequest);
Log.p("getPageMap,post addToQueueAndWait");
It executes mutiple times and retrieves data from the internet (https://api.beta.tab.com.au...).
When I run in the simulator, all is ok.
When I run on a physical phone, and monitor via logcat, two executions work ok, a third execution results in the first Log.p statement appearing, but the second Log.p statement does not appear. i.e. execution appears to "freeze" within addToQueueAndWait.
Is there further logging / debugging I can include to determine the cause of the problem?
Things I've tried: I did have a call to addNetworkErrorListener (but it did not appear to be triggered). I have overridden GZConnectionRequest's handleErrorResponseCode, handleException, postResponse and buildRequestBody with basic Log.p statements, but they don't seem to provide any useful information. Things that may impact: the website has recently changed to return gzipped json, but I think I've adjusted to this change accordingly. Cookies may be a factor - are they handled differently in the simulator vs device? Changing the priority of the CZConnectionRequest to PRIORITY_CRITICAL appears to have had a posivite impact. Should I move away from GZConnectionRequest and try an alternate approach?
That sounds like a deadlock or a race condition that you only see on the device due to the differences in performance. These things are notoriously hard to debug, especially on the device.
I would recommend migrating the code to use addToQueue if possible. It's simpler as it removes the need to deal with thread blocking. The code is a bit harder since it's asynchronous and I can't give you a direct equivalent. Something like this should generally work:
Log.p("getPageMap,pre addToQueue");
connectionRequest.addResponseListener(networkEvent -> {
Log.p("getPageMap,post addToQueue");
});
NetworkManager.getInstance().addToQueue(connectionRequest);
Alternatively, ff you want to debug this you can do the following:
Log the current thread - this can help understand what's going on. You can even see this in the debugger.
Print the stack trace every time you reach the first line (to check for recursion). You can do that by throwing and catching an exception then using printStackTrace().
Use the APIs in NetworkManager to inspect impact. E.g. use updateThreadCount to higher/lower values (it defaults to 2) to see if this changes results. Use enumurateQueue() to list the content of the queue.