{"Entry":{"collection":"guc","key":"io_worker_launch_interval","name":"io_worker_launch_interval","aliases":[],"metadata":{"baseline":false,"boot_human":"Not specified","boot_val":null,"category":"Resource Usage / I/O","category_zh":"","changed_in":[],"changes":[{"documentation_changed":false,"fields":{},"from":"18","status":"added","to":"19"}],"content_hash":"9372c1442bee052d6660980dc036db96e48fb7b966f6791c6e5e7134b74fedae","context":"","default_changed_in":[],"default_history":[{"from":"19","to":"19","value":"100 ms"}],"editorial":{"advice":{"olap":"Use representative scans, prefetch, and spill phases. Increase concurrency or worker capacity only while throughput rises without unacceptable CPU overhead, memory pressure, or storage saturation.","oltp":"Benchmark with the production storage stack and concurrency. Optimize tail latency and queue depth, not only average throughput, and retain capacity for WAL, checkpoints, and foreground reads.","small":"Prefer auto or the upstream worker limits. Validate with pg_test_timing or I/O statistics as applicable; a larger pool on a small node can add context switching without useful parallelism."},"mechanism":["PostgreSQL describes io_worker_launch_interval as follows: “Minimum time before launching a new I/O worker process, for io_method=worker.” A configuration reload applies the value to the server without a full restart. The atlas measures it in PG19 Beta 3; boot_val is the compiled or initialized baseline, not proof of a running cluster's effective setting.","These controls govern the elastic background-worker pool used only when io_method is worker. io_min_workers keeps warm capacity, io_max_workers caps the pool, io_worker_launch_interval damps short bursts, and io_worker_idle_timeout lets unused workers retire; they do not raise a backend's separate io_max_concurrency ceiling.","Read it together with io_min_workers, io_max_workers, io_worker_idle_timeout, io_method. Check SHOW and pg_settings on the target server, verify the source and pending_restart fields, and compare workload, logs, and resource metrics before and after any change."],"pitfalls":["Treating the measured boot_val for io_worker_launch_interval as proof of the effective value on an initialized or managed cluster.","Applying a change as though it were immediate while pg_settings reports sighup context.","Changing this setting in isolation without checking the linked limits, observability, and rollback path.","Depending on beta behavior in production without retesting the PostgreSQL 19 final release."],"references":[{"title":"PostgreSQL 19 Beta 4: io_worker_launch_interval","url":"https://www.postgresql.org/docs/19/runtime-config-resource.html#GUC-IO-WORKER-LAUNCH-INTERVAL"},{"title":"PostgreSQL 19 release notes","url":"https://www.postgresql.org/docs/19/release-19.html"}],"related":["io_min_workers","io_max_workers","io_worker_idle_timeout","io_method","io_max_concurrency","io_combine_limit"],"summary":"io_worker_launch_interval — Minimum time before launching a new I/O worker process, for io_method=worker. Observed in PG19 Beta 4; its last measured boot default is 100 ms in PG19 Beta 4, with sighup context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA."},"enumvals":[],"first_version":"19","group":"Resource Usage","group_slug":"resource","imported_at":"2026-09-27T17:57:31.415839+08:00","intro_commit":{"authored_at":"2026-04-08T19:06:14+12:00","discussion":["https://postgr.es/m/CA%2BhUKG%2Bm4xV0LMoH2c%3DoRAdEXuCnh%2BtGBTWa7uFeFMGgTLAw%2BQ%40mail.gmail.com"],"hash":"d1c01b79d4ae90e52bf9db9c05c9de17b7313e85","subject":"aio: Adjust I/O worker pool automatically.","url":"https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=d1c01b79d4ae90e52bf9db9c05c9de17b7313e85"},"key":"io_worker_launch_interval","last_version":"20","max_val":"","min_val":"","name":"io_worker_launch_interval","position":188,"present_in":["19","20"],"short_desc":"Sets the minimum time before another I/O worker can be launched.","short_desc_zh":"","source_rev":"english-manuals:edb9b1d6ac3d39b8afaff8aa01d396033623ce3e3019a7e75a225b8a2ed0e01c","unit":"","vartype":"integer"}},"Definition":{"Collection":"guc","Key":"io_worker_launch_interval","SourceDatabase":"center","Version":"20","SourceTable":"guc","SourceKey":"io_worker_launch_interval","SourceRevision":"english-manuals:edb9b1d6ac3d39b8afaff8aa01d396033623ce3e3019a7e75a225b8a2ed0e01c","Facts":{"boot_val":null,"category":"I/O","context":"","description":"Sets the minimum time before another I/O worker can be launched. This avoids creating too many for an unsustained burst of activity. The default is 100ms. This parameter can only be set in the postgresql.conf file or on the server command line. Only has an effect if io_method is set to worker.","doc":{"anchor":"GUC-IO-WORKER-LAUNCH-INTERVAL","file":"runtime-config-resource.html","lang":"en","sha256":"ea0a5d7b8e66421d046db778b5fd97f6b61f6e0c6d784a5df79583500a5e1497","slug":"devel"},"documented":true,"enumvals":[],"extra_desc":"","lang":"en","max_val":null,"metadata_version":"","min_val":null,"name":"io_worker_launch_interval","short_desc":"","source":"english-manual","unit":"","vartype":"integer"},"ManualEvidence":{"doc":{"anchor":"GUC-IO-WORKER-LAUNCH-INTERVAL","file":"runtime-config-resource.html","lang":"en","sha256":"ea0a5d7b8e66421d046db778b5fd97f6b61f6e0c6d784a5df79583500a5e1497","slug":"devel"}},"MeasuredEvidence":{"metadata_version":""}},"Text":{"Collection":"guc","Key":"io_worker_launch_interval","SourceDatabase":"pgweb","Version":"20","Locale":"zh-Hans","Title":"io_worker_launch_interval","Summary":"","BodyHTML":"\u003cp\u003e设置启动另一个 I/O 工作进程之前的最短时间。这样可以避免为短暂的突发活动创建过多工作进程。默认值为 100ms。此参数只能在\u003ccode\u003epostgresql.conf\u003c/code\u003e文件中或服务器命令行中设置。\u003c/p\u003e\u003cp\u003e仅当\u003ca href=\"/docs/devel/runtime-config-resource.html#GUC-IO-METHOD\" rel=\"nofollow\"\u003eio_method\u003c/a\u003e设置为\u003ccode\u003eworker\u003c/code\u003e时才有效。\u003c/p\u003e","SourceRevision":"2026-09-11@29c86d9","ContentHash":"a051e216101a84f2f074417b1294639ce1ad585a81874dc2eadd83c5a8d52482","Payload":{"carried_from":"19","carry_reason":"手册不含 pg_settings 事实，沿用 19","doc_html":"\u003cp\u003e设置启动另一个 I/O 工作进程之前的最短时间。这样可以避免为短暂的突发活动创建过多工作进程。默认值为 100ms。此参数只能在\u003ccode class=\"filename\"\u003epostgresql.conf\u003c/code\u003e文件中或服务器命令行中设置。\u003c/p\u003e\u003cp\u003e仅当\u003ca href=\"/docs/devel/runtime-config-resource.html#GUC-IO-METHOD\"\u003eio_method\u003c/a\u003e设置为\u003ccode class=\"literal\"\u003eworker\u003c/code\u003e时才有效。\u003c/p\u003e","doc_same_as":""}},"RequestedLocale":"zh-Hans","Fallback":false,"Versions":["19","20"],"Locales":["en","zh-Hans"],"Signatures":null,"Spellings":null,"SQLState":null,"Evidence":null}