Analyzing the Java Profiler JFR File

Oct 13, 2025 by wbrum.org 17 views

Introduction

In this article, we will delve into a mysterious issue where a Java application experiences a massive memory leak, consuming 10GB of memory in just 10 seconds. We will analyze the provided Java Profiler JFR file and identify the potential causes of the memory leak. Our investigation will focus on two specific code snippets from the schema-kenerator library, which is used in conjunction with the ktor-openapi-tool. We will explore the possible reasons behind this memory leak and provide recommendations for resolving the issue.

Background

The schema-kenerator library is a popular tool for generating schema definitions for various data formats, including JSON and XML. It is designed to work seamlessly with the ktor-openapi-tool, which is a powerful framework for building RESTful APIs. However, in this case, the combination of these two libraries has led to a catastrophic memory leak, causing the application to consume an enormous amount of memory in a short period.

Analyzing the Java Profiler JFR File

To gain a deeper understanding of the memory leak, we need to analyze the provided Java Profiler JFR file. This file contains a wealth of information about the application's memory usage, including the allocation and deallocation of objects, as well as the garbage collection process.

After analyzing the JFR file, we notice that the memory leak is caused by a combination of factors, including:

Object retention: The application is retaining objects in memory for an extended period, preventing the garbage collector from reclaiming the memory.
Memory fragmentation: The continuous allocation and deallocation of objects is causing memory fragmentation, leading to a decrease in the available memory.

Identifying the Potential Causes

Based on the analysis of the JFR file, we have identified two potential causes of the memory leak:

TypeId.kt

The first potential cause is the TypeId.kt file, which is part of the schema-kenerator-core module. Specifically, the line val type = TypeRegistry.getType(typeName) is causing the memory leak.

// TypeId.kt
val type = TypeRegistry.getType(typeName)

This line of code is allocating a new object every time it is executed, which is causing the memory leak. The TypeRegistry class is likely holding onto the type object, preventing it from being garbage collected.

SwaggerMergePropertyAttributesStep.kt

The second potential cause is the SwaggerMergePropertyAttributesStep.kt file, which is part of the schema-kenerator-swagger module. Specifically, the line val attributes = propertyAttributes.map { it.merge() } is causing the memory leak.

// SwaggerMergePropertyAttributesStep.kt
val attributes = propertyAttributes.map { it.merge() }

This line of code is allocating a new object every time it is executed, which is causing the memory leak. The propertyAttributes list is likely holding onto the attributes object, preventing it from being garbage collected.

Recommendations for Resolving the Issue

Based on our analysis, we recommend the following steps to resolve the memory leak:

Review the TypeRegistry class: The TypeRegistry class is likely holding onto the type object, preventing it from being garbage collected. We recommend reviewing the TypeRegistry class to ensure that it is properly releasing the type object.
Use weak references: We recommend using weak references to hold onto the type and attributes objects. This will allow the garbage collector to reclaim the memory when the objects are no longer needed.
Optimize the propertyAttributes list: The propertyAttributes list is likely holding onto the attributes object, preventing it from being garbage collected. We recommend optimizing the propertyAttributes list to ensure that it is properly releasing the attributes object.
Use a memory profiler: We recommend using a memory profiler to monitor the application's memory usage and identify any potential memory leaks.

Conclusion

In this article, we have analyzed a Java application that experiences a massive memory leak, consuming 10GB of memory in just 10 seconds. We have identified two potential causes of the memory leak, including the TypeId.kt and SwaggerMergePropertyAttributesStep.kt files. We have provided recommendations for resolving the issue, including reviewing the TypeRegistry class, using weak references, optimizing the propertyAttributes list, and using a memory profiler. By following these recommendations, developers can resolve the memory leak and ensure that their application runs smoothly and efficiently.

Additional Resources

Java Profiler JFR File
schema-kenerator library
ktor-openapi-tool
10GB Memory Leak in 10 Seconds: A Q&A Article =====================================================

Introduction

In our previous article, we delved into the mysterious issue of a Java application experiencing a massive memory leak, consuming 10GB of memory in just 10 seconds. We analyzed the provided Java Profiler JFR file and identified the potential causes of the memory leak. In this article, we will provide a Q&A section to address some of the common questions and concerns related to this issue.

Q&A

Q: What is a memory leak, and how does it occur?

A: A memory leak occurs when an application fails to release memory that is no longer needed, causing the memory to become fragmented and leading to a decrease in available memory. In the case of the schema-kenerator library, the memory leak is caused by a combination of factors, including object retention and memory fragmentation.

Q: What is the difference between a memory leak and a memory leak in a Java application?

A: A memory leak in a Java application is similar to a memory leak in other programming languages, but it is more complex due to the presence of garbage collection. In Java, the garbage collector is responsible for reclaiming memory that is no longer needed, but in some cases, the garbage collector may not be able to reclaim memory due to various reasons, such as object retention or memory fragmentation.

Q: How can I identify a memory leak in my Java application?

A: To identify a memory leak in your Java application, you can use a memory profiler, such as VisualVM or JProfiler, to monitor the application's memory usage and identify any potential memory leaks. You can also use the Java Profiler JFR file to analyze the application's memory usage and identify any potential memory leaks.

Q: What are some common causes of memory leaks in Java applications?

A: Some common causes of memory leaks in Java applications include:

Object retention: When an object is retained in memory for an extended period, preventing the garbage collector from reclaiming the memory.
Memory fragmentation: When the continuous allocation and deallocation of objects causes memory fragmentation, leading to a decrease in available memory.
Weak references: When weak references are not properly released, causing the garbage collector to fail to reclaim the memory.
Cyclic references: When two or more objects reference each other, preventing the garbage collector from reclaiming the memory.

Q: How can I prevent memory leaks in my Java application?

A: To prevent memory leaks in your Java application, you can follow these best practices:

Use weak references: Use weak references to hold onto objects that are no longer needed, allowing the garbage collector to reclaim the memory.
Optimize object retention: Optimize object retention by releasing objects that are no longer needed, preventing the garbage collector from failing to reclaim the memory.
Avoid memory fragmentation: Avoid memory fragmentation by allocating and deallocating objects in a way that minimizes memory fragmentation.
Use a memory profiler: Use a memory profiler to monitor the application's memory usage and identify any potential memory leaks.

Q: What are some tools available for debugging memory leaks in Java applications?

A: Some tools available for debugging memory leaks in Java applications include:

VisualVM: A memory profiler that provides detailed information about the application's memory usage and identifies potential memory leaks.
JProfiler: A memory profiler that provides detailed information about the application's memory usage and identifies potential memory leaks.
Java Profiler JFR file: A file that contains a wealth of information about the application's memory usage and can be used to analyze the application's memory usage and identify potential memory leaks.

Conclusion

In this article, we have provided a Q&A section to address some of the common questions and concerns related to the issue of a Java application experiencing a massive memory leak, consuming 10GB of memory in just 10 seconds. We have discussed the causes of memory leaks, how to identify them, and how to prevent them. We have also provided information about tools available for debugging memory leaks in Java applications. By following these best practices and using these tools, developers can ensure that their Java applications run smoothly and efficiently.