How to avoid repeated downloading of dynamic library under multithreading

Version of emscripten/emsdk: 3.1.15

If I use Multi-Thread and Side-Module, my project can run successful. But my dynamic libraries(about 30MB) will download some times，
one in main thread and others by my worker.js(PTHREAD_POOL_SIZE=30), this will waste lots of time and network bandwidth(about 1G).

① But in fact, I should only need to load it once，it will be fast and more reasonable, how can I share thoes dynamic libraries for other thread?
② What's more, the path of the dynamic library has changed。 When I set my dynamic libraries as below.
var Module = {
dynamicLibraries : [
"libs/XXX.so",
.....
],
}
it downloads libraries from //libs in main thread, however，it downloads libraries from //<worker.js-directory>/libs/ in worker.js thread。 so I need copyt it to other path.

Reproduce the multithreaded side-module setup with dynamicLibraries, comparing the main thread and worker.js requests and their resolved paths. Done means determining whether the libraries are downloaded once and whether the same library path works from both execution contexts.