Serial COM freeze. CTRL C release it. No idea where to begin debug. Embedded Linux Applications

Question

I am running multiple applications on a cortex armv7 CPU running Linux. All running apps are C++ embedded. my std::cout (and printf) are outgoing to my serial COM.

Occasionally I have noticed that after a while, the COM port will be blank. I am able to connect and disconnect but will always see the black screen. I am also able to disconnect the USB cable and reconnect but will again see the black screen.

Only when I press "CTRL C" inside the screen I see my prints again. Attached is a photo containing my running apps CPU % and Mem % showing that no ONE app is jamming up the UART line.

Note: I am running a dual CPU meaning I can have up to 200% of CPU usage.

I am printing once every 100 [mS]

Any idea why the COM would suddenly freeze? Any idea where I can start to check?