{"id":16490103,"url":"https://github.com/tansudasli/java-concurrency","last_synced_at":"2026-04-28T17:34:24.474Z","repository":{"id":120587174,"uuid":"603377311","full_name":"tansudasli/java-concurrency","owner":"tansudasli","description":"java concurrency, parallel , reactive, multithreading programming concepts","archived":false,"fork":false,"pushed_at":"2023-02-20T17:27:59.000Z","size":181,"stargazers_count":0,"open_issues_count":0,"forks_count":0,"subscribers_count":1,"default_branch":"main","last_synced_at":"2025-06-05T05:41:36.250Z","etag":null,"topics":["concurrency","gradle","java19","multithreading","parallel-computing","reactive-programming"],"latest_commit_sha":null,"homepage":"","language":"Java","has_issues":true,"has_wiki":null,"has_pages":null,"mirror_url":null,"source_name":null,"license":null,"status":null,"scm":"git","pull_requests_enabled":true,"icon_url":"https://github.com/tansudasli.png","metadata":{"files":{"readme":"README.md","changelog":null,"contributing":null,"funding":null,"license":null,"code_of_conduct":null,"threat_model":null,"audit":null,"citation":null,"codeowners":null,"security":null,"support":null,"governance":null,"roadmap":null,"authors":null,"dei":null,"publiccode":null,"codemeta":null}},"created_at":"2023-02-18T10:23:33.000Z","updated_at":"2023-03-04T13:15:35.000Z","dependencies_parsed_at":null,"dependency_job_id":"83239d62-17d5-44ae-b6dc-9f19bce1eb5d","html_url":"https://github.com/tansudasli/java-concurrency","commit_stats":null,"previous_names":[],"tags_count":0,"template":false,"template_full_name":null,"purl":"pkg:github/tansudasli/java-concurrency","repository_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/tansudasli%2Fjava-concurrency","tags_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/tansudasli%2Fjava-concurrency/tags","releases_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/tansudasli%2Fjava-concurrency/releases","manifests_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/tansudasli%2Fjava-concurrency/manifests","owner_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners/tansudasli","download_url":"https://codeload.github.com/tansudasli/java-concurrency/tar.gz/refs/heads/main","sbom_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/tansudasli%2Fjava-concurrency/sbom","scorecard":null,"host":{"name":"GitHub","url":"https://github.com","kind":"github","repositories_count":286080680,"owners_count":32392299,"icon_url":"https://github.com/github.png","version":null,"created_at":"2022-05-30T11:31:42.601Z","updated_at":"2026-04-28T14:34:11.604Z","status":"ssl_error","status_checked_at":"2026-04-28T14:32:37.009Z","response_time":56,"last_error":"SSL_read: unexpected eof while reading","robots_txt_status":"success","robots_txt_updated_at":"2025-07-24T06:49:26.215Z","robots_txt_url":"https://github.com/robots.txt","online":false,"can_crawl_api":true,"host_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub","repositories_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories","repository_names_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repository_names","owners_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners"}},"keywords":["concurrency","gradle","java19","multithreading","parallel-computing","reactive-programming"],"created_at":"2024-10-11T13:46:37.668Z","updated_at":"2026-04-28T17:34:24.470Z","avatar_url":"https://github.com/tansudasli.png","language":"Java","funding_links":[],"categories":[],"sub_categories":[],"readme":"# java fundamentals  -  concurrency \n\nThis project is about async programming concepts such as \n- multithreading, \n- parallel programming,\n- streams,\n- concurrency, and\n- reactive programming\n\nRoadmap is \n```\nsync -\u003e async (Future, Forks, CompletableFuture) -\u003e reactive -\u003e loom (sync. style old way multithreading\n```\n\n## Thread concepts\n```\nframe problem  - \u003e create  - \u003e start  - \u003e join\n```\n\n  - **strategy** (how to define the problem for multi-threading)\n    - dependent vs independent tasks\n    - void vs return something\n    - computations vs IO\n    - long-running vs short-running\n  - **pooling** (better thread efficiency)\n  - **concurrency**\n    - Thread-safety\n      - accessing same field \n        - lock \u0026 synchronized\n        - Atomic classes\n        - concurrent data structures\n        - ThreadLocal\u003cT\u003e (1 obj = 1 thread)\n        - local variables (1 obj = 1 task)\n    - Throttling (semaphore)\n    - Backpressure\n  - **Interruptions**\n    - timeout\n    - flow \n      - join, sleep\n    - Intercommunication (accessing respectively (producer-consumer) - wait \u0026 notify)\n\n\n\u003cdetails\u003e\n\u003csummary\u003e\nRunnable (1995) thread = task, void\n\u003c/summary\u003e\n\n ```new Thread(Class::task).start();```\n\n\u003c/details\u003e\n\n\u003cdetails\u003e\n\u003csummary\u003e\n\u003cT\u003e Callable \u003cT\u003e (2004) returns T + pooling\n\u003c/summary\u003e\n \n  - better @thread creation via pooling\n  - We can use executors for both Callable \u0026 Runnable interfaces!\n  - Callable returns something!\n  - Runnable is void!\n  - Future is async, .get is blocking.\n\n```\n  executorService = Executors.newFixedThreadPool(n)\n  executorService.submit(Class::task).get()    - \u003e returns Future\n \n  .execute()     //void (async), fire \u0026 forget\n  .invokeAll()   //waits, then returns result immediately (sync),\n  .submit()      //waits, then returns Future (async)\n \n  executorService.shutdown()\n```\n\n\u003c/details\u003e\n\n\u003cdetails\u003e\n\u003csummary\u003e\nFork/Join (2011) dividing into smart subtasks \u0026 merging for parallel programming\n\u003c/summary\u003e\n \n```\n pool = ForkJoinPool.commonPool()\n pool.execute(task)       void (async), fire \u0026 forget\n pool.invoke(task)        waits, then returns result immediately (sync)\n pool.submit(task).get()  waits, then returns Future\u003cT\u003e (async)\n\n subtask = ...\n subTask.fork()\n subTask.join() or subTask.invoke() or invokeAll()\n```\n\n```\n              Future\u003cT\u003e\n                 |\n            ForkJoinTask\u003cT\u003e\n        |                   |\n RecursiveAction        RecursiveTask\u003cT\u003e\n (void)\n\n```\n\n\u003c/details\u003e\n\n\u003cdetails\u003e\n\u003csummary\u003e\nparallelStreams (2011)  parallel programming, processing in-memory data, mostly non-blocking,\n\u003c/summary\u003e\n\n    -  uses ForkJoinPool.commonPool() behind the scenes!\n \n \n\u003c/details\u003e\n\n\u003cdetails\u003e\n\u003csummary\u003e\n CompletableFuture (2014) async computations \u0026 trigger dependant computations\n\u003c/summary\u003e\n\n   -  better @ functional programming than ForkJoinPool \u0026 parallelStreams\n   -  better @ basic exceptional cases than ForkJoinPool\n   -  uses ForkJoinPool.commonPool() behind the scenes!\n\n```\n  where t1,t2.. are dependent tasks of T\n  \n  T ... T ...  T ... T            :::independent Tasks\n  :\n t1    t1\n  :\n t2    t2\n  :\n t2\n \n```\n```\n  CompletableFuture.supplyAsync(::getT1)\n            .thenApply(::getT2)\n            .exceptionally(e  - \u003e new handleTException(e))\n            .\n```\n - If you use your custom pool use use thenApplyAsync  - \u003e .thenApplySync(::getTx, ioPool)\n - For more complex exception handling use  - \u003e .thenCombine(........)\n\n\u003c/details\u003e \n\n\u003cdetails\u003e\n\u003csummary\u003e\nreactiveStreams (2015) ..\n\u003c/summary\u003e\n\n   - better @ complex exception handling\n   - better @ thread handling\n   - \n   - \nMany frameworks (spring webflux or RxJava) available. Main problem is \n - so many APIs to learn\n - callback hell, \n - hard to debug and test\n\n\n\u003c/details\u003e\n\n\u003cdetails\u003e\n\u003csummary\u003e\n Project loom (2022) lightweight thread == task, handling numerous blocking requests/responses\n\u003c/summary\u003e\n\n  -  jdk19 preview\n  -  lightweight thread == task,  no way to cut this bound!!\n  -  creating 1m thread {now, it costs 2tb ram, 20min startup time \u0026 context switching}\n  -  CompletionState/CompletableFuture\n  - So, threads will be two types (platform or virtual)\n\n\u003c/details\u003e\n\n## how to run\nProject scope and java command scopes have different things! So Some key points to consider are:\n\n- ` ./gradlew clean build jar jmhJar`\n- `java  - cp core/build/libs/java-concurrency-1.0-SNAPSHOT.jar org.core.Main..... ` to run Mainxxx classes.\n- `java  - cp core/build/libs/java-concurrency-1.0-SNAPSHOT-jmh.jar org.core.TasksThreadSafeBenchmark` to run JMH benchmark tests. Or you can \nrun via IDE (install jetbrains-jmh plugin).\n ","project_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Ftansudasli%2Fjava-concurrency","html_url":"https://awesome.ecosyste.ms/projects/github.com%2Ftansudasli%2Fjava-concurrency","lists_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Ftansudasli%2Fjava-concurrency/lists"}