what is permgen
Java Performance PermGen. In this article, I look into what it means when a Java program runs into a OutOfMemoryError: PermGen Space error. I first explain what the permanent generation heap space is, after which I explain the usual cause of the Permgen Space error and I give some pointers on how to avoid it.he OutOfMemoryError: PermGen Space error occurs when the permanent generation heap is full. Although this error can occur in normal circumstances, usually, this error is caused by a memory leak.