LSP is sending way too many didChange events, making it unusable

[holyjak]

Sometimes LSP sends many didChange events even though I barely change any file. The backend I use, clojure-lsp, does non-trivial analysis on changed files and thus consumes all my CPU for no good reason. Here is an example from its log of what it received:

10:49:42.427Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:49:43.231Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:49:44.008Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:49:44.104Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:49:44.134Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:49:44.389Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:49:44.557Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:49:44.591Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:49:44.699Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:49:44.740Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:49:45.815Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:49:57.554Z DEBUG [clojure-lsp.server:?] - :didChange 1ms
10:49:57.648Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:49:58.123Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:49:58.262Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:49:58.408Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:49:58.444Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:49:58.516Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:49:58.642Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:49:59.363Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:50:00.515Z DEBUG [clojure-lsp.server:?] - :didChange 1027ms
10:50:01.369Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:50:01.486Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:50:01.501Z DEBUG [clojure-lsp.server:?] - :didSave 0ms
10:50:01.501Z DEBUG [clojure-lsp.server:?] - :didSave 0ms
10:50:22.613Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:50:22.817Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:50:25.195Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:50:25.322Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:50:25.489Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:50:32.575Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:50:34.988Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:50:35.779Z DEBUG [clojure-lsp.server:?] - :didChange 1ms
10:50:35.938Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:50:36.076Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:50:36.093Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:50:36.110Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:50:36.208Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:50:36.363Z DEBUG [clojure-lsp.server:?] - :didChange 1ms
10:50:36.391Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:50:36.407Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:50:38.700Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:50:41.500Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:50:42.941Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:50:43.061Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:50:43.090Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:50:52.149Z DEBUG [clojure-lsp.server:?] - :didChange 0ms
10:50:55.584Z DEBUG [clojure-lsp.server:?] - :didSave 0ms

It is not clojure-lsp issue because when I use it from VS Code, it works just fine. So the cause seems indeed to be that LSP sends too many of these didChange events in a short time window.