Precompilation hangs on Julia 1.10

[alexriss]

Precompilation of Blink within a module hangs on Julia 1.10-rc2 (and previous Julia 1.10 versions).

module TestModule

using Blink
using PrecompileTools

@setup_workload begin
    @compile_workload begin
        w = Window()
        close(w)
    end
end

end

using TestModule

Gives an never-ending loop of the following output:

[pid 59340] waiting for IO to finish:
 Handle type        uv_handle_t->data
 process[50656]     00000275c9a697e0->00000275bf2fcf60
 tcp[800]           00000275c47ab160->00000275bf241410
 tcp[796]           00000275c47aaca0->00000275bf231120
 tcp[948]           00000275c47aa580->00000275c0488650
 tcp[936]           00000275c47ab290->00000275c248b5d0
 tcp[940]           00000275ca535b20->00000275befb9410
 tcp[944]           00000275ca536cf0->00000275befb9500
 tcp[952]           00000275ca536370->00000275befb95f0
This means that a package has started a background task or event source that has not finished running. For precompilation to complete successfully, the event source needs to be closed explicitly. See the developer documentation on fixing precompilation hangs for more help.

One culprit seems to be the Mux/HTTP server. It needs to be closed. I have changed to code of Blink to do so, and it improves (but still does not complete):

[pid 19704] waiting for IO to finish:
 Handle type        uv_handle_t->data
 process[52256]     00000168d1d970f0->00000168c7635f20
 tcp[824]           00000168cccd8780->00000168c7598ec0
This means that a package has started a background task or event source that has not finished running. For precompilation to complete successfully, the event source needs to be closed explicitly. See the developer documentation on fixing precompilation hangs for more help.

Now there is only one more TCP port open. But I am not sure how to close this one. Any suggestions?

[alexriss]

Update: Also, the Electron shell socket connection should be closed.

I have made a PR that fixes the behavior: #318