Why can JMC, JConsole, JVisualVM never connect to a hung java process, although jstack can?

Question

Java

There is a Java application that sometimes starts to consume 100% of the CPU (all 8 cores to the eyeballs, on Linux). When trying to connect to it using JMC, JConsole, or JVisualVM, none of them are up to the trivial task they seem to be designed for. Connections are local , i.e. on the same car. At the same time, the console jstack can sometimes get a stack even without the forced mode (flag -F).
Why is this happening? And also can anyone advise a normal tool for debugging such spontaneously arising problems. I draw your attention to the fact that the problem is with a local connection to the JVM. An attempt to search for at least some information in Google stumbles upon the fact that everyone complains about the impossibility of remote connection, as if it's only me who has such a problem, which obviously cannot be.