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Java / Java 17 Garbage Collection Interview Questions

What is a humongous object in G1 GC?

A humongous object is any object at least 50% the size of a single G1 region - large arrays are the most common example. Rather than being allocated normally into Eden, it's placed directly into one or more contiguous humongous regions reserved just for it.

This special-cases large allocations because copying a huge object during a normal evacuation pause would be disproportionately expensive; instead, humongous regions are typically reclaimed in bulk once the object becomes unreachable, without a copy step.

Frequent humongous allocations can still hurt performance by fragmenting the heap and triggering earlier, more frequent concurrent cycles - a common fix is increasing -XX:G1HeapRegionSize so fewer objects cross the 50% humongous threshold.

An object is classified as humongous in G1 when it is:
A common way to reduce the frequency of humongous allocations is to:

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