DataTerminology.comNEW
Also known as: Race Condition
Condition where concurrent operations access shared data without proper synchronization, causing inconsistent or non-deterministic outcomes.
DESCRIPTION
A data race occurs when two or more threads access the same memory location concurrently, at least one writes, and there is no synchronization ordering. Data races lead to undefined behavior, heisenbugs, and intermittent failures. Preventing them requires mutual exclusion (locks), atomic operations, lock-free algorithms with memory ordering, or transactional memory. Detection tools like thread sanitizers and static analysis can identify races. Designing with immutability and message passing also reduces risk.
ALTERNATIVE DEFINITIONS
Rust Nomicon
A data race occurs when two or more threads access the same memory location at the same time, at least one of the accesses is a write, and there is no synchronization between the threads.
Uses the canonical three-condition definition for data races in systems programming.
Microsoft Learn
A race condition occurs when two or more threads can access shared data and they try to change it at the same time.
Highlights shared data modification without appropriate thread coordination.
Wikipedia
A race condition is a behavior where the output is dependent on the sequence or timing of other uncontrollable events.
Describes the broader timing-dependent behavior beyond just memory data races.
RELATED TERMS
Thread Safety Deadlock Atomicity Locking Memory Model Happens-Before Optimistic Concurrency Transactional Memory Synchronization
COMPETING TERMS
Mutual Exclusion
KNOWLEDGE AREAS
Software Engineering Infrastructure Observability & Telemetry Testing & Validation
TARGET AUDIENCE
Software Developer DevOps Engineer Data Engineer MLOps Engineer Cloud Architect
EXTERNAL SOURCES
- Wikipedia - Race condition
- Rust - Data races and memory safety
- cppreference - C++ memory model and data races
TOP QUESTIONS
What causes a Data Race?
Concurrent reads and writes to shared memory without synchronization cause data races. Even infrequent overlaps can trigger undefined behavior.
Category: Requirements
How do you prevent a Data Race?
Use locks, atomic operations, or message passing to coordinate access. Immutability and ownership models also reduce shared-state hazards.
Category: BestPractice
How is a Data Race different from a Deadlock?
A data race is unsynchronized concurrent access; a deadlock is permanent waiting due to cyclic lock dependencies. Both are concurrency hazards with different causes.
Category: Misunderstandings
How can you detect Data Races?
Use dynamic tools like ThreadSanitizer and static analysis, plus code reviews focused on shared-state patterns.
Category: Testing
What is the risk of ignoring Data Races?
They yield non-deterministic bugs, data corruption, and security vulnerabilities. Production impact can be severe and hard to reproduce.
Category: Risks
Do lock-free algorithms avoid Data Races?
Only if they use correct atomic operations and memory ordering. Incorrect lock-free code can still race.
Category: Opinion
What is happens-before in preventing Data Races?
Happens-before ordering ensures visibility and ordering between operations, preventing races when properly established.
Category: Example
Are Data Races possible in garbage-collected languages?
Yes. GC doesn’t prevent races on shared objects; synchronization is still required for thread safety.
Category: Misunderstandings
What are hot topics in Data Race prevention?
Ownership types, memory-safe languages, and automated race detection in CI pipelines are gaining adoption.
Category: Topic