JVM Interview Topics: ClassLoader, Memory Areas, Garbage Collection, and Performance Tuning
This article compiles essential JVM interview topics, covering ClassLoader mechanisms, Java memory layout, garbage collection concepts and algorithms, as well as practical performance tuning techniques, providing links to detailed resources and common interview questions for each area.
1. ClassLoader
Class loading process
Types of class loaders and their loading scopes
Parent delegation model
Why parent delegation is used
Reasons to break the parent delegation model
How to break the parent delegation model
How to create a custom class loader
Hot deployment principle
Common interview questions
2. Java Memory Areas
Java memory structure
Heap allocation algorithm for object creation
Object layout in memory
Object location mechanisms
Algorithms to determine if an object can be reclaimed
Methods to judge object reclamation eligibility
Components of the Java heap
When StackOverflowError is thrown
Whether memory leaks exist in Java and a brief description
What a stack frame is and its contents
Execution flow of a method
Whether the method area can be reclaimed
Byte size of an object
Why the heap and stack are separated
Starting point of the stack
Why primitive types are not stored in the heap
Parameter passing in Java: value vs reference
Why recursion is not recommended
Why parameters greater than two should be encapsulated in an object
Common interview questions
3. Garbage Collection (GC)
What GC is and why it is needed
Can GC execution be guaranteed?
Types of object reference categories
Garbage collection algorithms
Reason for generational GC
How generational GC works
Different garbage collectors
Detailed introduction to CMS collector
Detailed introduction to G1 collector
GC log analysis
When Minor GC and Full GC occur
Collectors for young and old generations and their differences
Meaning of stack allocation
Object allocation rules
4. Practical Performance Tuning
Parameters used to print GC information in projects
Common tuning tools
Diagnosing frequent Full GC despite low memory usage
Handling stack overflow in long‑running systems
Optimizing CPU usage when it stays at 100%
Investigating memory spikes
Performance bottleneck tuning for large projects
Real‑world tuning scenarios
GC common parameters
Parallel GC common parameters
CMS common parameters
G1 common parameters
Additional recommended interview series and resources are listed at the end of the article.
Signed-in readers can open the original source through BestHub's protected redirect.
This article has been distilled and summarized from source material, then republished for learning and reference. If you believe it infringes your rights, please contactand we will review it promptly.
Selected Java Interview Questions
A professional Java tech channel sharing common knowledge to help developers fill gaps. Follow us!
How this landed with the community
Was this worth your time?
0 Comments
Thoughtful readers leave field notes, pushback, and hard-won operational detail here.