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 ///libs/ in worker.js thread。 so I need copyt it to other path.