doc: clarify UV_THREADPOOL_SIZE env var usage

preveen-stack · marco-ippolito · commit 955690e6cf17 · 2025-01-24T22:18:40.000+01:00
Setting of UV_THREADPOOL_SIZE from inside process using process.env.UV_THREADPOOL_SIZE is not guaranteed to work as the thread pool would have been created as part of the runtime initialisation much before user code is run. update doc/api/cli.md PR-URL: #55832 Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com> Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
diff --git a/doc/api/cli.md b/doc/api/cli.md
@@ -3165,8 +3165,10 @@ reason any of these APIs takes a long time, other (seemingly unrelated) APIs
 that run in libuv's threadpool will experience degraded performance. In order to
 mitigate this issue, one potential solution is to increase the size of libuv's
 threadpool by setting the `'UV_THREADPOOL_SIZE'` environment variable to a value
-greater than `4` (its current default value). For more information, see the
-[libuv threadpool documentation][].
+greater than `4` (its current default value). However, setting this from inside
+the process using `process.env.UV_THREADPOOL_SIZE=size` is not guranteed to work
+as the threadpool would have been created as part of the runtime initialisation
+much before user code is run. For more information, see the [libuv threadpool documentation][].
 
 ### `UV_USE_IO_URING=value`
 
