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Class loading, memory regions, garbage collectors, and reading a heap dump or GC log.
5 questions in Java & Spring.
Most likely into reaching the safepoint. Every application thread has to arrive at a poll point before the operation can begin, and one late thread stalls all of them, so the pause is time-to-safepoint plus the actual work. Safepoint logging separates the two.
Loaders delegate to their parent before searching themselves, so the JDK always wins a name clash. ClassNotFoundException means a loader was asked for bytes it could not find; NoClassDefFoundError means the JVM needed a class that was there at compile time, or one whose static initialiser had already failed.
Test the candidate's ability to design custom memory management strategies, focusing on memory fragmentation, deterministic allocation times, and safety-critical constraints. Use this hardware answer to show the decision, trade-off, and evidence rather than a memorised definition.
Read the message text first, because it names which region ran out. Then use the GC log to see whether the live set after each full collection is trending upward, which means a leak, or flat and close to the ceiling, which means the heap is simply too small. A heap dump tells you what is retaining the memory.
Analyse JVM tuning strategies to prevent Stop-The-World (STW) pauses and ensure predictable microsecond response times for game server logic. It also connects garbage collection to the point an interviewer is testing.