The <no Java callstack recorded> Function

The <no Java callstack recorded> function is similar to the <Unknown> function, but for Java threads, in the Java representation only. When the Collector receives an event from a Java thread, it unwinds the native stack and calls into the JVM software to obtain the corresponding Java stack. If that call fails for any reason, the event is shown in the Analyzer with the artificial function <no Java callstack recorded>. The JVM software might refuse to report a call stack either to avoid deadlock, or when unwinding the Java stack would cause excessive synchronization.