[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"$ffvGO9xt0ZANdGV99FRxpsiO6Pp8mX6cKLBnjG9DXr98":3},{"item":4,"related":44},{"id":5,"type":6,"title":7,"slug":8,"summary":9,"body":10,"coverUrl":11,"productScreenshots":12,"productLinks":13,"authorName":14,"authorUrl":15,"authorSubject":16,"category":17,"tags":22,"sourceLabel":35,"sourceName":36,"sourceUrl":37,"status":38,"seoTitle":7,"seoDescription":9,"canonicalUrl":35,"isFeatured":39,"sno":40,"sortOrder":41,"publishedAt":42,"updatedAt":43,"createdAt":43},"07fe8e6e-82b0-46cc-9015-c6d027564430","article","pidfd：进程号会被重用，怎样才能稳定指向一个进程？","linux-pidfd-stable-process-reference","Linux pidfd 用文件描述符稳定引用一个进程，避免退出后的 PID 被重用而误操作新进程。本文介绍它的等待、信号用途和版本边界。","Linux 用进程 ID（PID）标识进程，但 PID 是会被回收和重新使用的数字。假设一个管理程序记录下 PID 1234，目标进程退出后，系统稍后把 1234 分给另一个进程；如果旧管理程序再按 PID 发信号，它可能误操作新进程。这类“标识被复用”的竞态，正是 pidfd 想缓解的问题。\n\npidfd 是指向进程的文件描述符。可以把它理解为一张仍指向同一个对象的号码牌，而 PID 更像一段可能再次分配的座位号。文件描述符可以被等待、轮询，也能用于某些进程操作；即使原进程已经结束，它也不会悄悄改指向后来复用该 PID 的另一个进程。管理程序由此能够更稳妥地关联进程生命周期。\n\n例如，服务管理器创建子进程后，可以保留 pidfd 并通过 `poll` 或 `epoll` 等机制等待它终止；合适的接口还允许通过 pidfd 向目标发送信号。Linux 提供 `pidfd_open` 等系统调用，也支持创建进程时取得相应句柄的方式。相比反复读取数字 PID 再执行操作，这种对象句柄模式可以缩小检查与使用之间的竞态窗口。\n\n不过 pidfd 并不是万能的进程管理抽象。不同 pidfd 相关系统调用和标志支持情况，依赖 Linux 内核版本；可执行的操作也有权限检查。它解决的是“稳定引用某个进程”的身份问题，不替代进程树管理、资源限制、信号语义或容器生命周期协调。程序还得在适当时机关闭文件描述符，否则句柄本身会占用进程资源。\n\npidfd 对 shell 脚本或短命令未必必要，但对长期运行的服务管理器、运行时、容器编排组件和需要严谨处理并发退出的系统程序很有意义。判断是否需要它，可以先问：目标进程退出与 PID 复用之间，是否可能与自己的操作并发？如果可能，用可持有的句柄通常比只保存一个数字更稳妥。\n\n这个设计和文件描述符访问文件的理念相似：程序持有的是内核认可的对象引用，而不是寄希望于一个可能变化的名字始终指向原对象。\n\n来源：[Linux `pidfd_open(2)` 手册](https:\u002F\u002Fman7.org\u002Flinux\u002Fman-pages\u002Fman2\u002Fpidfd_open.2.html)","\u002Fuploads\u002F2026-10-06\u002F699e59f8-693f-47cb-87b1-c51764d1a679.jpg",[],[],"Foundit","https:\u002F\u002Ffoundit.cn","foundit-ai-editorial",{"id":18,"name":19,"slug":20,"description":21},"6179d3b6-dc34-4483-9ded-3cd9f1b37a47","科普","abbreviation","介绍各领域新兴概念",[23,27,31],{"id":24,"name":25,"slug":26},"144abe77-0dc6-4f66-a176-20bddb1c0bfa","编程","coding",{"id":28,"name":29,"slug":30},"7c76bfc2-f80f-4ee0-a95d-27bd8708b434","技术","slug",{"id":32,"name":33,"slug":34},"a202d639-99a6-488a-a712-4d4c6ffd7e15","开发","dev",null,"Linux pidfd_open(2) Manual","https:\u002F\u002Fman7.org\u002Flinux\u002Fman-pages\u002Fman2\u002Fpidfd_open.2.html","published",false,45,0,"2026-10-06T00:00:00.000Z","2026-10-06T07:51:27.054Z",[45,53,61],{"id":46,"type":6,"title":47,"slug":48,"summary":49,"coverUrl":50,"authorName":14,"sno":40,"publishedAt":51,"createdAt":52},"4ce57934-2b23-41a1-800e-bb2d8ab36684","Wasm Component Model：不同语言写的模块怎样用同一套接口协作？","wasm-component-model-wit-interfaces","WebAssembly Component Model 用有类型的接口描述组件如何交换数据与调用功能，WIT 则帮助表达这些接口。本文用模块化电器说明跨语言组合的意义，也指出它不代表程序脱离运行时就能在任何环境原样运行。","\u002Fuploads\u002F2026-10-17\u002F0eb1c88d-dc1f-486d-8194-54f72dd215ec.jpg","2026-10-17T00:00:00.000Z","2026-10-17T03:08:52.474Z",{"id":54,"type":6,"title":55,"slug":56,"summary":57,"coverUrl":58,"authorName":14,"sno":40,"publishedAt":59,"createdAt":60},"15988123-6303-4ab1-ba01-dcc41f36329f","Futex：Linux 的锁为什么大多数时候根本不需要进内核？","futex-fast-userspace-locking","Futex 把无竞争时的锁操作留在用户态，只有真正需要睡眠和唤醒时才进入内核，是 Linux 高性能锁的关键低层构件。","\u002Fuploads\u002F2026-09-26\u002F90e98cc8-e57b-4dea-afc7-2afe7550d483.jpg","2026-09-27T00:00:00.000Z","2026-09-26T16:25:54.119Z",{"id":62,"type":6,"title":63,"slug":64,"summary":65,"coverUrl":66,"authorName":14,"sno":67,"publishedAt":59,"createdAt":68},"69224a1f-e0fc-4431-a3bd-acc1d81523d0","io_uring：Linux 如何用两个环形队列批量处理异步 I\u002FO？","io-uring-async-io-rings","io_uring 通过提交队列和完成队列连接应用与内核，让大量 I\u002FO 请求可以批量提交与收取结果，减少固定交互成本。","\u002Fuploads\u002F2026-09-26\u002F0eb80204-5abc-41e2-8c8a-0e1ac633b209.jpg",46,"2026-09-26T16:25:57.069Z"]