Circular dependency
A circular dependency is a dependency relationship in which a chain of direct or indirect dependencies eventually returns to an earlier participant, forming a cycle.
100 Java Mistakes and How to Avoid Them
A circular dependency is a dependency cycle in which class initialization directly or indirectly requires initialization of a class that depends back on the original class.
- How it is used
- Warns against initialization-time dependency cycles that expose null state or deadlock concurrent Java code.
- How deep it goes
- Explains field ordering, class-initialization locks, enum construction, and implicit switch behavior; defers broader dependency-design techniques.
- Examples
- Uses mutually initializing classes, parallel construction of A and B, jstack output, mutually referring enums, and an enum constructor switch.
- What you can do after
- Diagnose/debug with jstack class-initializer frames and recognize initialization cycles that can yield nulls or deadlock.
Read how 100 Java Mistakes and How to Avoid Them explains circular dependency →
Go by Example
An import cycle is a circular dependency among Go packages that prevents the package import graph from being acyclic.
- How it is used
- Prevents compile-time import failures while organizing maintainable Go services into packages with explicit dependency directions.
- How deep it goes
- Defines the error and works through layered package organization, while deferring interfaces and later service packages.
- Examples
- Uses mutually importing http and net packages, then a link core, link/rest API, linkd server, and alternative CLI tools.
- What you can do after
- Apply it by arranging focused Go packages so higher-level services import foundational packages without reverse dependencies.
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A circular dependency is a dependency relationship in which two or more modules or components depend on one another directly or through an intermediate dependency.
- How it is used
- Diagnoses import or instantiation failures discovered while creating unit tests for interconnected Python classes.
- How deep it goes
- Defines direct and indirect cycles, demonstrates their failure point, and sketches decoupling fixes without detailing broader dependency-management patterns.
- Examples
- Uses a visitor, Asset, FundingDetails, and DepreciationStrategy cycle, then shows revised class references.
- What you can do after
- Diagnose/debug with unit-test failures and reduce cycles by removing direct class instantiation or references.
Terraform in Depth: Infrastructure as Code with Terraform and OpenTofu
A circular dependency is a dependency relationship in which a chain of resources forms a closed cycle, causing each resource to depend directly or indirectly on another resource in the same chain.
- How it is used
- Diagnoses Terraform planning failures caused by resource relationships that cannot be ordered.
- How deep it goes
- Defines cycles, demonstrates a three-resource failure, and gives a variable-based workaround without detailing broader resolution tools.
- Examples
- Uses authentication and logging services, three null_resource instances, a Cycle plan error, and a shared build_id variable.
- What you can do after
- Diagnose Terraform cycle errors and refactor shared values into variables or local values to remove unnecessary resource dependencies.
Go in Action, Second Edition
A circular dependency is a dependency cycle in which packages or modules depend on one another directly or through an intermediate chain.
- How it is used
- Uses package dependency rules to guide project organization and separation of concerns.
- How deep it goes
- Defines direct and indirect cycles and compiler rejection, but gives no code-level refactoring procedure.
- Examples
- Uses package A and B dependency cycles plus a directory structure containing domain, storage, API, and worker modules.
- What you can do after
- Diagnose compiler-rejected package cycles and organize executables, shared libraries, and internal implementation packages.
Read how Go in Action, Second Edition explains circular dependency →
Related concepts
- deadlockproduces · A deadlock is a state in concurrent execution where two or more activities are indefinitely blocked by dependencies on resources, events, or progress that cannot become available.
- directed acyclic graphcontrasts with · A directed acyclic graph is a graph with directed edges and no directed cycles.
- forwardRefaddressed by · forwardRef is an API mechanism for referring to or forwarding a reference to a value or component that may be defined later.
- multi-tier applicationaddressed by · A multi-tier application is an application organized into distinct tiers that separate responsibilities and interact through defined dependencies or interfaces.
- compile-time errorproduces · A compile-time error is a diagnostic failure detected during compilation or compile-time checking that prevents source code from compiling successfully.
- Gocontrasts with · Go is a statically typed, compiled, garbage-collected programming language with built-in support for concurrency.
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