This is davinci's watchdog code.

Manifest.toml

# This file is machine-generated - editing it directly is not advised

julia_version = "1.11.2"
manifest_format = "2.0"
project_hash = "f3e12818d79d35ab70781d89b14a3d00c4df0f7c"

[[deps.Artifacts]]
uuid = "56f22d72-fd6d-98f1-02f0-08ddc0907c33"
version = "1.11.0"

[[deps.Base64]]
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version = "1.11.0"

[[deps.BitFlags]]
git-tree-sha1 = "0691e34b3bb8be9307330f88d1a3c3f25466c24d"
uuid = "d1d4a3ce-64b1-5f1a-9ba4-7e7e69966f35"
version = "0.1.9"

[[deps.CodecZlib]]
deps = ["TranscodingStreams", "Zlib_jll"]
git-tree-sha1 = "bce6804e5e6044c6daab27bb533d1295e4a2e759"
uuid = "944b1d66-785c-5afd-91f1-9de20f533193"
version = "0.7.6"

[[deps.ConcurrentUtilities]]
deps = ["Serialization", "Sockets"]
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[[deps.Dates]]
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[[deps.ExceptionUnwrapping]]
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uuid = "460bff9d-24e4-43bc-9d9f-a8973cb893f4"
version = "0.1.11"

[[deps.HTTP]]
deps = ["Base64", "CodecZlib", "ConcurrentUtilities", "Dates", "ExceptionUnwrapping", "Logging", "LoggingExtras", "MbedTLS", "NetworkOptions", "OpenSSL", "PrecompileTools", "Random", "SimpleBufferStream", "Sockets", "URIs", "UUIDs"]
git-tree-sha1 = "c67b33b085f6e2faf8bf79a61962e7339a81129c"
uuid = "cd3eb016-35fb-5094-929b-558a96fad6f3"
version = "1.10.15"

[[deps.InteractiveUtils]]
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version = "1.11.0"

[[deps.JLLWrappers]]
deps = ["Artifacts", "Preferences"]
git-tree-sha1 = "a007feb38b422fbdab534406aeca1b86823cb4d6"
uuid = "692b3bcd-3c85-4b1f-b108-f13ce0eb3210"
version = "1.7.0"

[[deps.Libdl]]
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version = "1.11.0"

[[deps.Logging]]
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[[deps.LoggingExtras]]
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[[deps.Markdown]]
deps = ["Base64"]
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[[deps.MbedTLS]]
deps = ["Dates", "MbedTLS_jll", "MozillaCACerts_jll", "NetworkOptions", "Random", "Sockets"]
git-tree-sha1 = "c067a280ddc25f196b5e7df3877c6b226d390aaf"
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version = "1.1.9"

[[deps.MbedTLS_jll]]
deps = ["Artifacts", "Libdl"]
uuid = "c8ffd9c3-330d-5841-b78e-0817d7145fa1"
version = "2.28.6+0"

[[deps.MozillaCACerts_jll]]
uuid = "14a3606d-f60d-562e-9121-12d972cd8159"
version = "2023.12.12"

[[deps.NetworkOptions]]
uuid = "ca575930-c2e3-43a9-ace4-1e988b2c1908"
version = "1.2.0"

[[deps.OpenSSL]]
deps = ["BitFlags", "Dates", "MozillaCACerts_jll", "OpenSSL_jll", "Sockets"]
git-tree-sha1 = "38cb508d080d21dc1128f7fb04f20387ed4c0af4"
uuid = "4d8831e6-92b7-49fb-bdf8-b643e874388c"
version = "1.4.3"

[[deps.OpenSSL_jll]]
deps = ["Artifacts", "JLLWrappers", "Libdl"]
git-tree-sha1 = "7493f61f55a6cce7325f197443aa80d32554ba10"
uuid = "458c3c95-2e84-50aa-8efc-19380b2a3a95"
version = "3.0.15+3"

[[deps.PrecompileTools]]
deps = ["Preferences"]
git-tree-sha1 = "5aa36f7049a63a1528fe8f7c3f2113413ffd4e1f"
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version = "1.2.1"

[[deps.Preferences]]
deps = ["TOML"]
git-tree-sha1 = "9306f6085165d270f7e3db02af26a400d580f5c6"
uuid = "21216c6a-2e73-6563-6e65-726566657250"
version = "1.4.3"

[[deps.Printf]]
deps = ["Unicode"]
uuid = "de0858da-6303-5e67-8744-51eddeeeb8d7"
version = "1.11.0"

[[deps.Random]]
deps = ["SHA"]
uuid = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
version = "1.11.0"

[[deps.SHA]]
uuid = "ea8e919c-243c-51af-8825-aaa63cd721ce"
version = "0.7.0"

[[deps.Serialization]]
uuid = "9e88b42a-f829-5b0c-bbe9-9e923198166b"
version = "1.11.0"

[[deps.SimpleBufferStream]]
git-tree-sha1 = "f305871d2f381d21527c770d4788c06c097c9bc1"
uuid = "777ac1f9-54b0-4bf8-805c-2214025038e7"
version = "1.2.0"

[[deps.Sockets]]
uuid = "6462fe0b-24de-5631-8697-dd941f90decc"
version = "1.11.0"

[[deps.TOML]]
deps = ["Dates"]
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version = "1.0.3"

[[deps.Test]]
deps = ["InteractiveUtils", "Logging", "Random", "Serialization"]
uuid = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
version = "1.11.0"

[[deps.TranscodingStreams]]
git-tree-sha1 = "0c45878dcfdcfa8480052b6ab162cdd138781742"
uuid = "3bb67fe8-82b1-5028-8e26-92a6c54297fa"
version = "0.11.3"

[[deps.URIs]]
git-tree-sha1 = "67db6cc7b3821e19ebe75791a9dd19c9b1188f2b"
uuid = "5c2747f8-b7ea-4ff2-ba2e-563bfd36b1d4"
version = "1.5.1"

[[deps.UUIDs]]
deps = ["Random", "SHA"]
uuid = "cf7118a7-6976-5b1a-9a39-7adc72f591a4"
version = "1.11.0"

[[deps.Unicode]]
uuid = "4ec0a83e-493e-50e2-b9ac-8f72acf5a8f5"
version = "1.11.0"

[[deps.Zlib_jll]]
deps = ["Libdl"]
uuid = "83775a58-1f1d-513f-b197-d71354ab007a"
version = "1.2.13+1"

Project.toml

[deps]
HTTP = "cd3eb016-35fb-5094-929b-558a96fad6f3"

watchdog.jl

# https://discourse.julialang.org/t/best-practices-for-managing-websocket-http-server-lifecycle/124434
using Base.Threads
using HTTP
using HTTP: WebSockets

ws_watchdog = []
ws_array = []
ws_ip = "127.0.0.1"
ws_port = 8080

function start_ws_watchdog()
    ## on first run

    # terminate any running watchdog(s) - by InterruptException
    terminate_active_watchdog!()

    # terminate any active websockets
    terminate_active_ws!()

    sleep(1)

    # start new watchdog
    watchdog_task = @spawn try

        #ws_array |> empty!

        while true
            try

                # start websocket server if there's none or they're all done/closed
                if isempty(ws_array) || all(ws -> istaskdone(ws.task), ws_array) || all(ws -> !isopen(ws.listener.server), ws_array)
                    start_ws_server()
                end

            catch e

                if isa(e, Base.IOError) && occursin("EADDRINUSE", e.msg)
                    # port already in use, re-start was too early
                    @warn "WARNING - ws start, port already in use $e"
                    sleep(1)
                    terminate_active_ws!()
                else
                    rethrow(e)
                end
            end

            sleep(5)
        end

    catch e
        if isa(e, InterruptException)
            @warn "LOG - Websocket watchdog terminated"
        else
            @error "ERROR - ws watchdog, $e"
            rethrow(e)
        end
    end

    @info "LOG - New watchdog started: $watchdog_task"

    # save watchdog task reference
    push!(ws_watchdog, watchdog_task)
end

function start_ws_server()
    # start new server (it spawns its on task)
    ws_server = WebSockets.listen!(ws_ip, ws_port; verbose = true) do ws

        _info = "LOG - New Websocket server started: $(ws_server.task)"
        @info _info

        for msg in ws

            @spawn try

                # save received messages as-is
                lock(msg_lock)
                push!(ws_msg_log_raw, msg)
                unlock(msg_lock)

                parsed_msg = JSON3.read(msg, Dict) |> dict_keys_to_sym

                # save parsed message
                setindex!(parsed_msg, "received", :type)
                lock(msg_lock)
                push!(ws_msg_log, parsed_msg)
                unlock(msg_lock)

                # pass msg on
                msg_handler(ws, parsed_msg)

            catch e
                @error "ERROR - Message handler error, $e"
            end
        end

    end

    # saves server handler & task for reference
    push!(ws_array, ws_server)
end

function terminate_active_ws!()
    for ws in filter(ws -> !istaskdone(ws.task) || !isempty(ws.connections) || isopen(ws.listener.server), ws_array)
        HTTP.forceclose(ws)
        _num_conn = ws.connections |> length
        @warn "WARNING - Terminating ws server: $(ws.task) - $_num_conn connections"
    end
end

function terminate_active_watchdog!()
    for task in ws_watchdog
        if !istaskdone(task)
            schedule(task, InterruptException(), error=true)
            @warn "WARNING - Terminating ws watchdog: $task"
        end
    end
end

Instructions

• After you clone this gist, do the following.

In a terminal:

julia --project

Then in the Julia REPL.

julia> ]
(cff4e8fd81740a60e95ba563cae37597) pkg> instantiate
julia> include("watchdog.jl")
julia> start_ws_watchdog()

In another terminal:

wscat --connect ws://localhost:8080

Discussion

https://discourse.julialang.org/t/best-practices-for-managing-websocket-http-server-lifecycle/124434