Garbage collection on intern’d strings, String Pool, and perm-space

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String literals are interned. As of Java 7, the HotSpot JVM puts interned Strings in the heap, not permgen.

Prior to java 7, hotspot put interned Strings in permgen. However, interned Strings in permgen were garbage collected. Apparently, Class objects in permgen are also collectable, so everything in permgen is collectable, though permgen collection might not be enabled by default in some old JVMs.

String literals, being interned, would be a reference held by the declaring Class object to the String object in the intern pool. So the interned literal String would only be collected if the Class object that referred to it were also collected.

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