The PermGen space contains the internal representation of the Java classes that JVM holds. The Permanent Generation is the garbage data that is collected in the same way as heap’s other parts collected. It is a special area of memory that contains meta-data of the program’s classes and the program’s objects.

What is PermGen space used for?

The PermGen area of the Java heap is used to store metadata such as class declarations, methods and object arrays.

What is the difference between PermGen and MetaSpace?

In Java 8, PermGen method area replaced with MetaSpace. They have moved permGem to the separate memory in the native OS and that is called MetaSpace. It can by default auto increases its size. In MetaSpace, classes can load and unload during the lifespan of the JVM.

How do I fix Java Lang OutOfMemoryError PermGen space?

To fix it, increase the PermGen memory settings by using the following Java VM options. -XX:PermSize<size> – Set initial PermGen Size. -XX:MaxPermSize<size> – Set the maximum PermGen Size. In the next step, we will show you how to set the VM options in Tomcat, under Windows and Linux environment.

What is meta space?

Simply put, Metaspace is a new memory space – starting from the Java 8 version; it has replaced the older PermGen memory space. The most significant difference is how it handles memory allocation. Specifically, this native memory region grows automatically by default.

Is PermGen and method area same?

Method Area is a part of space in the PermGen and it is used to store the class structure and the code for methods and constructors. The biggest disadvantage of PermGen is that it contains a limited size which leads to an OutOfMemoryError.

Should I set MaxMetaspaceSize?

MaxMetaspaceSize is by default unlimited, so there is no need to change in most cases to another value. At this time, there are no other recommendations.

Is PermGen garbage collected?

The PermGen is garbage collected like the other parts of the heap. The thing to note here is that the PermGen contains meta-data of the classes and the objects i.e. pointers into the rest of the heap where the objects are allocated.

How can I increase my PermGen size?

To increase PermGen, we have the following commands: -XX:PermSize=N – sets the initial (and minimum size) of the Permanent Generation space. -XX:MaxPermSize=N – sets the maximum size of the Permanent Generation space.

Why does Java 8 remove PermGen space?

The main reason for removing PermGen in Java 8 is: It is very hard to predict the required size of PermGen. It is fixed size at startup, so difficult to tune. Future improvements were limited by PermGen space.

What is MetaSpace and heap memory?

Class is a java object living in Java heap, the class metadata itself are no Java objects and do not live in the Java heap. They live in a native memory region outside of the Java heap. That region is called Metaspace.

How do I buy MetaSpace?

How to buy MetaSpace REIT

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  6. Use your ETH to buy MetaSpace REIT in the trade tab.

What is the advantage of MetaSpace?

Advantages of MetaSpace

Take advantage of Java Specification property: Classes and associated metadata lifetimes match class loaders. Per loader storage area: Metaspace. Linear allocation only. No individual reclamation (except for Redefine Classes and class loading failure)

Is Metaspace garbage collected?

Metaspace garbage collection

Garbage collection of the dead classes and classloaders is triggered once the class metadata usage reaches the “MaxMetaspaceSize”. Proper monitoring & tuning of the Metaspace will obviously be required in order to limit the frequency or delay of such garbage collections.

Is Metaspace part of heap memory?

Metaspace is part of Native Memory and NOT part of Java Heap.

Is Metaspace in heap?

Metaspace is not part of the Java heap and is allocated out of the native memory. So it is unlimited and is limited only by the amount of native memory available on the machine. However, Metaspace size can be limited by using the MaxMetaspaceSize option.

Is string pool part of Metaspace?

the per-class constant pool is in Metaspace since JDK 8.

What should be Metaspace size?

Tuning Java heap size, metaspace size and other such items

Space Maximum size that can be allocated
Java heap 75% of (maxSizeOfAllSpaces – 100 MB)
Metaspace 10% of (maxSizeOfAllSpaces – 100 MB)
Other spaces 15% of (maxSizeOfAllSpaces – 100 MB)

What happens when Metaspace is full?

The MaxMetaspaceSize JVM option sets an upper limit on the commited size of the Metaspace, and if not configured large enough can cause java. lang. OutOfMemoryError: Metaspace. Also, as mentioned before, all of the space configured for the Compressed class space is reserved upfront, and can not grow later at runtime.

What is Metaspace size in Java?

Metaspace is introduced in Java 8 and default size of it is unlimited(limited to physical memory) with dynamic growth.