{
  "schema_version": "1.0",
  "codex": "thecodex.expert/coding",
  "type": "concept",
  "slug": "concepts/concurrency",
  "name": "Concurrency",
  "section": "CS Concepts",
  "canonical_definition": "Concurrency is the ability of a program to have multiple computations in progress at the same time \u2014 interleaving on one CPU core or running in parallel on multiple cores \u2014 requiring synchronisation mechanisms to prevent conflicts over shared mutable state.",
  "confidence": "high",
  "last_verified": "2026-06-01",
  "source_count": 4,
  "url": "https://thecodex.expert/coding/concepts/concurrency/",
  "concept_relationship": {
    "requires_first": [
      "concepts/functions",
      "concepts/scope"
    ],
    "enables": [
      "concepts/concurrency-vs-parallelism",
      "concepts/synchronous-vs-asynchronous"
    ],
    "commonly_confused_with": [
      "concurrent != parallel",
      "GIL != thread safety in Python",
      "async/await is not multithreading"
    ]
  },
  "sources": [
    {
      "num": 1,
      "citation": "Java Language Specification \u00a717",
      "tier": 1
    },
    {
      "num": 2,
      "citation": "Python GIL docs",
      "tier": 1
    },
    {
      "num": 3,
      "citation": "ISO C++11 \u00a729",
      "tier": 1
    },
    {
      "num": 4,
      "citation": "Hewitt 1973 Actor model IJCAI",
      "tier": 1
    }
  ]
}