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Guide contents

Language Core

1.Types, Variables, and Expressions
2.Strings and Text
3.Classes, Interfaces, and Inheritance
4.Exceptions
5.Object Contracts: equals, hashCode, and Comparison
6.Immutability, Defensive Copying, and Object Lifecycle
7.Records and Sealed Types
8.Pattern Matching
9.Packages, Modules, and Reflection
10.Enums and Annotations

Generics

11.Generic Types, Bounds, and Wildcards
12.Type Erasure

Lambdas and Optional

13.Lambdas and Functional Interfaces
14.Optional, Null Handling, and API Design

Collections

15.Lists, Deques, and Iteration
16.HashMap Internals
17.Sorted Maps, Sets, and Priority Queues
18.Primitive Collections and Memory Cost

Streams

19.Streams and Collectors
20.Gatherers, Parallel Streams, and Stream Cost

Testing

21.JUnit 5
22.Mockito
23.Testcontainers and Testing Concurrent Code

Concurrency

24.Threads, synchronized, wait and notify
25.Locks and Synchronizers
26.Executors and CompletableFuture
27.Concurrent Collections
28.Virtual Threads in Depth

CPU and Memory Hardware

29.CPU Caches and Locality
30.Cache Coherence, False Sharing, Branch Prediction, and NUMA

Java Memory Model

31.Visibility, Atomicity, and Reordering
32.Happens-Before and volatile
33.Safe Publication and final Fields

Atomics and Lock-Free Code

34.Atomic Classes and CAS
35.VarHandle, Access Modes, and Fences
36.Ring Buffers and Lock-Free Queues
37.The LMAX Disruptor Pattern

JVM Internals

38.Bytecode and Class Loading
39.Object Layout and Allocation
40.Stack, Heap, Metaspace, and Code Cache
41.Safepoints, Warmup, and Deoptimization

JIT Compilation

42.Tiered Compilation, Inlining, and Intrinsics
43.Escape Analysis, Loop Optimizations, and Generated Assembly

Garbage Collection

44.GC Fundamentals
45.G1 in Depth
46.ZGC and Shenandoah
47.Serial, Parallel, Epsilon, and GC Tuning

Off-Heap Memory

48.ByteBuffer, Direct Buffers, and Memory-Mapped Files
49.The Foreign Function and Memory API

Linux for Java

50.Processes, Threads, and Scheduling
51.Virtual Memory, Page Faults, and perf

Performance Tooling

52.Benchmarking with JMH
53.JFR, async-profiler, and Flame Graphs
54.Measuring Latency: Percentiles and Coordinated Omission

Networking and I/O

55.Streams, Readers, and Files
56.NIO Channels and Selectors
57.TCP, UDP, Multicast, and the HTTP Client
58.Binary Protocols and Encoding

Low-Latency Java

59.Allocation-Free and Cache-Friendly Code
60.Agrona, Aeron, SBE, and Chronicle

Fintech Correctness

61.Money, BigDecimal, and Rounding
62.Idempotency, Ledgers, and Reconciliation

Trading Systems

63.Market Data, Orders, and FIX
64.Project: Limit Order Book
65.Project: Matching Engine
66.Project: Market Data Handler

Java 17 to 25 Reference

67.What Changed from Java 17 to Java 25

Interview Questions

68.Core Java, Generics, Collections, and Streams
69.Concurrency, Memory Model, and Lock-Free Code
70.JVM, JIT, GC, and Performance
71.Low-Latency, Networking, Fintech, and Trading

Language Core

1.Types, Variables, and Expressions
2.Strings and Text
3.Classes, Interfaces, and Inheritance
4.Exceptions
5.Object Contracts: equals, hashCode, and Comparison
6.Immutability, Defensive Copying, and Object Lifecycle
7.Records and Sealed Types
8.Pattern Matching
9.Packages, Modules, and Reflection
10.Enums and Annotations

Generics

11.Generic Types, Bounds, and Wildcards
12.Type Erasure

Lambdas and Optional

13.Lambdas and Functional Interfaces
14.Optional, Null Handling, and API Design

Collections

15.Lists, Deques, and Iteration
16.HashMap Internals
17.Sorted Maps, Sets, and Priority Queues
18.Primitive Collections and Memory Cost

Streams

19.Streams and Collectors
20.Gatherers, Parallel Streams, and Stream Cost

Testing

21.JUnit 5
22.Mockito
23.Testcontainers and Testing Concurrent Code

Concurrency

24.Threads, synchronized, wait and notify
25.Locks and Synchronizers
26.Executors and CompletableFuture
27.Concurrent Collections
28.Virtual Threads in Depth

CPU and Memory Hardware

29.CPU Caches and Locality
30.Cache Coherence, False Sharing, Branch Prediction, and NUMA

Java Memory Model

31.Visibility, Atomicity, and Reordering
32.Happens-Before and volatile
33.Safe Publication and final Fields

Atomics and Lock-Free Code

34.Atomic Classes and CAS
35.VarHandle, Access Modes, and Fences
36.Ring Buffers and Lock-Free Queues
37.The LMAX Disruptor Pattern

JVM Internals

38.Bytecode and Class Loading
39.Object Layout and Allocation
40.Stack, Heap, Metaspace, and Code Cache
41.Safepoints, Warmup, and Deoptimization

JIT Compilation

42.Tiered Compilation, Inlining, and Intrinsics
43.Escape Analysis, Loop Optimizations, and Generated Assembly

Garbage Collection

44.GC Fundamentals
45.G1 in Depth
46.ZGC and Shenandoah
47.Serial, Parallel, Epsilon, and GC Tuning

Off-Heap Memory

48.ByteBuffer, Direct Buffers, and Memory-Mapped Files
49.The Foreign Function and Memory API

Linux for Java

50.Processes, Threads, and Scheduling
51.Virtual Memory, Page Faults, and perf

Performance Tooling

52.Benchmarking with JMH
53.JFR, async-profiler, and Flame Graphs
54.Measuring Latency: Percentiles and Coordinated Omission

Networking and I/O

55.Streams, Readers, and Files
56.NIO Channels and Selectors
57.TCP, UDP, Multicast, and the HTTP Client
58.Binary Protocols and Encoding

Low-Latency Java

59.Allocation-Free and Cache-Friendly Code
60.Agrona, Aeron, SBE, and Chronicle

Fintech Correctness

61.Money, BigDecimal, and Rounding
62.Idempotency, Ledgers, and Reconciliation

Trading Systems

63.Market Data, Orders, and FIX
64.Project: Limit Order Book
65.Project: Matching Engine
66.Project: Market Data Handler

Java 17 to 25 Reference

67.What Changed from Java 17 to Java 25

Interview Questions

68.Core Java, Generics, Collections, and Streams
69.Concurrency, Memory Model, and Lock-Free Code
70.JVM, JIT, GC, and Performance
71.Low-Latency, Networking, Fintech, and Trading

Home/Java Deep Dive/JVM Internals

JVM Internals

Bytecode, class loading, object layout, allocation, runtime data areas, safepoints, warmup, and deoptimization.

4 lessons

38.Bytecode and Class Loading
39.Object Layout and Allocation
40.Stack, Heap, Metaspace, and Code Cache
41.Safepoints, Warmup, and Deoptimization

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