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I guess the root cause is memory leak due to dynamic loading. Limiting Metaspace to a number or throwing more memory at it would simply delay OOM. Limiting metaspace still causes OutOfMemoryError: Metaspace exception but in this case task manager dies instead of YARN killing it. Use the Java Flight Recordings to identify the memory leak. After your recording showing the leak, you can look at the Object Statistics. Look at one long recording, then look at which classes grew the most in heap usage over the recording. Applications are expected to release the memory resources after their use, but if an application does not release the memory then that application has memory leak, which eventually crashes with the OutOfMemoryError. This is the most common performance-related error you can find. One common indication of a memory leak is the java.lang.OutOfMemoryError exception. In this case, the garbage collector cannot make space available to accommodate a new object, and the heap cannot be expanded further. Also, this error may be thrown when there is insufficient native memory to support the loading of a Java class.
- Jdk8 Metaspace
- Java Metaspace Out Of Memory
- Java Metaspace Memory Leak Detection
- Java Metaspace Memory Leak Foam
Jdk8 Metaspace
In this post, we will see example code of memory leak in Java. Afterward, we will connect the Java application to JConsole to compare the memory usage of the application with and without memory leaks. The deep dive into the memory monitoring tool of JConsole will allow us to see how the Heap memory is divided into different spaces and how the Garbage collector efficiently manages the memory of the Java Application.
Garbage Collection in Java
In Java, the Garbage Collector (GC) is responsible for freeing up the memory utilized by unused objects. Any object that doesn’t have a reference to it is eligible for Garbage collection as seen in the image below. The Reference to a Dog object – Buddy is set to null in the second part of the image hence it becomes eligible for GC.
What is a Memory Leak in Java
A memory leak is caused when the program fails to release unused memory which can lead to either unexpected results or application crash. Even though there is no official definition of a memory leak in Java we can broadly divide it into two categories for ease of understanding.
- Memory leaks caused by objects that are unreachable from running code.
- Memory leaks caused by objects that are reachable from running code but won’t be used again.
The first kind of memory leak occurs when the reference to the object is no longer present in the running code but the Garbage Collector is still not able to free up space for these objects. An example code of this is posted here.
Java Metaspace Out Of Memory
![Leak Leak](/uploads/1/1/9/8/119878104/770998771.png)
The second kind of memory leak is mostly due to faulty logic in the program where the reference to unused objects is kept in the running code (even though the object will never be used again) which doesn’t allow the GC to reclaim the memory. Some developer considers this leak as, not an “actual memory leak” because setting the reference to null would allow GC to reclaim the memory. However, if the code is already deployed there is no way to set the reference of unused objects to null. In the following section, we will consider the example of this kind of leak.
Java Metaspace Memory Leak Detection
Example of Memory Leak in a Java Program
Let’s consider a real-life example of a Dog Shelter where Dogs are added to the shelter and removed from the shelter when they are adopted. The complete example is hosted on Github.
The Dog.java class has three variables described below.
Java Metaspace Memory Leak Foam
- microchip ID – uniquely identifies the dog.
- name – an optional variable representing the name of the dog.
- byte array – to expedite the memory leak we have a byte array of 10Mb.
![Leak Leak](https://plumbr.eu/wp-content/uploads/2016/03/native-memory-leak-symptoms.png)
/** The Unique MicroChip ID of the dog. */ |
privateint microChipID; |
/** The name of the dog. */ |
privateString name; |
/** Extra memory space for each instance to speed up the memory leak. */ |
privatebyte[] toExpediteLeak; |