computeIfAbsent

Cognitive Technology Team

Jun 10, 2024 · Backend Development

Recursive Update Bug in ConcurrentHashMap.computeIfAbsent Causing Infinite Loop and CPU Spike

The article explains a bug in Java's ConcurrentHashMap.computeIfAbsent that can cause recursive updates and infinite loops, leading to CPU spikes, and shows that newer Java versions throw an IllegalStateException while recommending avoiding nested computeIfAbsent/putIfAbsent calls, with a code example.

ConcurrentHashMapJavabackend

0 likes · 3 min read

Recursive Update Bug in ConcurrentHashMap.computeIfAbsent Causing Infinite Loop and CPU Spike

macrozheng

May 14, 2021 · Backend Development

Master Java 8 Map Enhancements: Simplify Code with getOrDefault, computeIfAbsent, and merge

This tutorial shows how Java 8's new Map methods—getOrDefault, computeIfAbsent, and merge—can replace verbose null‑checking patterns, prevent NullPointerExceptions, and make common tasks like grouping values or counting words concise and readable.

JDK8JavacomputeIfAbsent

0 likes · 8 min read

Master Java 8 Map Enhancements: Simplify Code with getOrDefault, computeIfAbsent, and merge

macrozheng

Aug 13, 2020 · Backend Development

Why JDK 8’s computeIfAbsent Can Deadlock: A Deep Dive into the Bug

This article explores a JDK 8 bug in ConcurrentHashMap’s computeIfAbsent method that can cause an infinite loop, explains how the issue was discovered, reproduces it with test code, analyzes the root cause, and shows the fix introduced in JDK 9.

ConcurrentHashMapJDKJava8

0 likes · 16 min read

Why JDK 8’s computeIfAbsent Can Deadlock: A Deep Dive into the Bug