{"id":15030084,"url":"https://github.com/reactor/blockhound","last_synced_at":"2025-05-14T01:04:14.970Z","repository":{"id":38272730,"uuid":"160411870","full_name":"reactor/BlockHound","owner":"reactor","description":"Java agent to detect blocking calls from non-blocking threads.","archived":false,"fork":false,"pushed_at":"2025-04-03T06:31:38.000Z","size":534,"stargazers_count":1406,"open_issues_count":13,"forks_count":98,"subscribers_count":36,"default_branch":"master","last_synced_at":"2025-04-03T06:48:13.554Z","etag":null,"topics":[],"latest_commit_sha":null,"homepage":"","language":"Java","has_issues":true,"has_wiki":null,"has_pages":null,"mirror_url":null,"source_name":null,"license":"apache-2.0","status":null,"scm":"git","pull_requests_enabled":true,"icon_url":"https://github.com/reactor.png","metadata":{"files":{"readme":"README.md","changelog":null,"contributing":null,"funding":null,"license":"LICENSE","code_of_conduct":null,"threat_model":null,"audit":null,"citation":null,"codeowners":null,"security":null,"support":"docs/supported_testing_frameworks.md","governance":null,"roadmap":null,"authors":null,"dei":null,"publiccode":null,"codemeta":null}},"created_at":"2018-12-04T20:00:53.000Z","updated_at":"2025-04-03T06:30:33.000Z","dependencies_parsed_at":"2023-02-14T19:46:05.615Z","dependency_job_id":"48084c51-4840-4371-b881-199cf08f6e7a","html_url":"https://github.com/reactor/BlockHound","commit_stats":{"total_commits":257,"total_committers":23,"mean_commits":"11.173913043478262","dds":0.6070038910505837,"last_synced_commit":"2f5a2c0d10250cb1b61f194ae7779ac2134684c5"},"previous_names":[],"tags_count":18,"template":false,"template_full_name":null,"repository_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/reactor%2FBlockHound","tags_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/reactor%2FBlockHound/tags","releases_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/reactor%2FBlockHound/releases","manifests_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/reactor%2FBlockHound/manifests","owner_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners/reactor","download_url":"https://codeload.github.com/reactor/BlockHound/tar.gz/refs/heads/master","host":{"name":"GitHub","url":"https://github.com","kind":"github","repositories_count":248208692,"owners_count":21065205,"icon_url":"https://github.com/github.png","version":null,"created_at":"2022-05-30T11:31:42.601Z","updated_at":"2022-07-04T15:15:14.044Z","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":[],"created_at":"2024-09-24T20:12:24.258Z","updated_at":"2025-04-10T11:34:30.889Z","avatar_url":"https://github.com/reactor.png","language":"Java","funding_links":[],"categories":[],"sub_categories":[],"readme":"# BlockHound\n\n[![](https://img.shields.io/badge/dynamic/xml.svg?label=Release\u0026color=green\u0026query=%2F%2Fmetadata%2Fversioning%2Flatest\u0026url=https%3A%2F%2Frepo1.maven.org%2Fmaven2%2Fio%2Fprojectreactor%2Ftools%2Fblockhound%2Fmaven-metadata.xml)](https://repo1.maven.org/maven2/io/projectreactor/tools/blockhound/)\n[![](https://img.shields.io/badge/dynamic/xml.svg?label=Milestone\u0026color=blue\u0026query=%2F%2Fmetadata%2Fversioning%2Flatest\u0026url=https%3A%2F%2Frepo.spring.io%2Fmilestone%2Fio%2Fprojectreactor%2Ftools%2Fblockhound%2Fmaven-metadata.xml)](https://repo.spring.io/milestone/io/projectreactor/tools/blockhound/)\n[![](https://img.shields.io/badge/dynamic/xml.svg?label=Snapshot\u0026color=orange\u0026query=%2F%2Fmetadata%2Fversioning%2Flatest\u0026url=https%3A%2F%2Frepo.spring.io%2Fsnapshot%2Fio%2Fprojectreactor%2Ftools%2Fblockhound%2Fmaven-metadata.xml)](https://repo.spring.io/snapshot/io/projectreactor/tools/blockhound/)\n[![Gitter](https://badges.gitter.im/reactor/BlockHound.svg)](https://gitter.im/reactor/BlockHound)\n\nJava agent to detect blocking calls from non-blocking threads.\n\n## How it works\nBlockHound will transparently instrument the JVM classes and intercept blocking calls (e.g. IO) if they are performed from threads marked as \"non-blocking operations only\" (ie. threads implementing Reactor's `NonBlocking` marker interface, like those started by `Schedulers.parallel()`). If and when this happens (but remember, this should never happen! :stuck_out_tongue_winking_eye:), an error will be thrown. Here is an example:\n```java\n// Example.java\nBlockHound.install();\n\nMono.delay(Duration.ofSeconds(1))\n    .doOnNext(it -\u003e {\n        try {\n            Thread.sleep(10);\n        }\n        catch (InterruptedException e) {\n            throw new RuntimeException(e);\n        }\n    })\n    .block();\n```\n\nWill result in:\n```\nreactor.blockhound.BlockingOperationError: Blocking call! java.lang.Thread.sleep\n\tat java.base/java.lang.Thread.sleep(Native Method)\n\tat com.example.Example.lambda$exampleTest$0(Example.java:16)\n```\nNote that it points to the exact place where the blocking call got triggered. In this example it was `Example.java:16`.\n\n## Getting it\n\nDownload it from Maven Central repositories (stable releases only) or repo.spring.io:\n\n_Gradle_\n\n```groovy\nrepositories {\n  mavenCentral()\n  // maven { url 'https://repo.spring.io/milestone' }\n  // maven { url 'https://repo.spring.io/snapshot' }\n}\n\ndependencies {\n  testImplementation 'io.projectreactor.tools:blockhound:$LATEST_RELEASE'\n  // testImplementation 'io.projectreactor.tools:blockhound:$LATEST_MILESTONE'\n  // testImplementation 'io.projectreactor.tools:blockhound:$LATEST_SNAPSHOT'\n}\n```\n\n\u003cdetails\u003e\n\u003csummary\u003ewith Kotlin DSL\u003c/summary\u003e\n\n```kotlin\nrepositories {\n    mavenCentral()\n    // maven(\"https://repo.spring.io/milestone\")\n    // maven(\"https://repo.spring.io/snapshot\")\n}\n\ndependencies {\n    testImplementation(\"io.projectreactor.tools:blockhound:$LATEST_RELEASE\")\n    // testImplementation(\"io.projectreactor.tools:blockhound:$LATEST_MILESTONE\")\n    // testImplementation(\"io.projectreactor.tools:blockhound:$LATEST_SNAPSHOT\")\n}\n```\n\u003c/details\u003e\n\n_Maven_\n\n```xml\n\u003cdependencies\u003e\n  \u003cdependency\u003e\n    \u003cgroupId\u003eio.projectreactor.tools\u003c/groupId\u003e\n    \u003cartifactId\u003eblockhound\u003c/artifactId\u003e\n    \u003cversion\u003e$LATEST_RELEASE\u003c/version\u003e\n  \u003c/dependency\u003e\n\u003c/dependencies\u003e\n```\n\nWhere:\n\n|||\n|-|-|\n|`$LATEST_RELEASE`|[![](https://img.shields.io/badge/dynamic/xml.svg?label=\u0026color=green\u0026query=%2F%2Fmetadata%2Fversioning%2Flatest\u0026url=https%3A%2F%2Frepo1.maven.org%2Fmaven2%2Fio%2Fprojectreactor%2Ftools%2Fblockhound%2Fmaven-metadata.xml)](https://repo1.maven.org/maven2/io/projectreactor/tools/blockhound/)|\n|`$LATEST_MILESTONE`|[![](https://img.shields.io/badge/dynamic/xml.svg?label=\u0026color=blue\u0026query=%2F%2Fmetadata%2Fversioning%2Flatest\u0026url=https%3A%2F%2Frepo.spring.io%2Fmilestone%2Fio%2Fprojectreactor%2Ftools%2Fblockhound%2Fmaven-metadata.xml)](https://repo.spring.io/milestone/io/projectreactor/tools/blockhound/)|\n|`$LATEST_SNAPSHOT`|[![](https://img.shields.io/badge/dynamic/xml.svg?label=\u0026color=orange\u0026query=%2F%2Fmetadata%2Fversioning%2Flatest\u0026url=https%3A%2F%2Frepo.spring.io%2Fsnapshot%2Fio%2Fprojectreactor%2Ftools%2Fblockhound%2Fmaven-metadata.xml)](https://repo.spring.io/snapshot/io/projectreactor/tools/blockhound/)|\n\n## JDK13+ support\n\nfor JDK 13+, it is no longer allowed redefining native methods. So for the moment, as a temporary work around, please use the\n`-XX:+AllowRedefinitionToAddDeleteMethods` jvm argument:\n\n_Maven_\n\n```xml\n    \u003cplugin\u003e\n        \u003cgroupId\u003eorg.apache.maven.plugins\u003c/groupId\u003e\n            \u003cartifactId\u003emaven-surefire-plugin\u003c/artifactId\u003e\n                \u003cversion\u003e2.22.2\u003c/version\u003e\n                \u003cconfiguration\u003e\n                    \u003cargLine\u003e-XX:+AllowRedefinitionToAddDeleteMethods\u003c/argLine\u003e\n                \u003c/configuration\u003e\n    \u003c/plugin\u003e\n```\n\n_Gradle_\n\n```groovy\n    tasks.withType(Test).all {\n        if (JavaVersion.current().isCompatibleWith(JavaVersion.VERSION_13)) {\n            jvmArgs += [\n                \"-XX:+AllowRedefinitionToAddDeleteMethods\"\n            ]\n        }\n    }\n```\n\n\u003cdetails\u003e\n\u003csummary\u003ewith Kotlin DSL\u003c/summary\u003e\n\n```kotlin\ntasks.withType\u003cTest\u003e().all {\n    if (JavaVersion.current().isCompatibleWith(JavaVersion.VERSION_13)) {\n        jvmArgs(\"-XX:+AllowRedefinitionToAddDeleteMethods\")\n    }\n}\n```\n\u003c/details\u003e\n\n## Built-in integrations\nAlthough BlockHound supports [the SPI mechanism to integrate with](https://github.com/reactor/BlockHound/blob/master/docs/custom_integrations.md), it comes with a few built-in integrations:\n1. [Project Reactor](https://projectreactor.io)  \n  Version 3.2.x is supported out of the box.  \n  Starting with `reactor-core` version 3.3.0, there is [a built-in integration in Reactor itself](https://github.com/reactor/reactor-core/blob/v3.3.0.RELEASE/reactor-core/src/main/java/reactor/core/scheduler/ReactorBlockHoundIntegration.java) that uses [the SPI](https://github.com/reactor/BlockHound/blob/master/docs/custom_integrations.md).\n2. [RxJava 2](https://github.com/ReactiveX/RxJava/) is supported.  \n    RxJava 3 and further versions of RxJava will require an SPI to be implemented, either by the framework or user. See [this PR to RxJava](https://github.com/ReactiveX/RxJava/pull/6692) with an example of the SPI's implementation.\n\n# Quick Start\nSee [the docs](./docs/README.md).\n\n-------------------------------------\n_Licensed under [Apache Software License 2.0](www.apache.org/licenses/LICENSE-2.0)_\n\n_Sponsored by [Pivotal](https://pivotal.io)_\n","project_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Freactor%2Fblockhound","html_url":"https://awesome.ecosyste.ms/projects/github.com%2Freactor%2Fblockhound","lists_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Freactor%2Fblockhound/lists"}