web/backend: Allow multiple workers

web/backend/Dockerfile

@@ -6,7 +6,7 @@ WORKDIR /app
 COPY Project.toml /app/Backend/
 COPY src /app/Backend/src
 RUN julia --project=. -e 'using Pkg; Pkg.develop(path="Backend"); Pkg.add("HiGHS"); Pkg.add("JuMP"); Pkg.precompile()'
-COPY docker/startup.jl ./
+COPY startup.jl ./
 
 # Set timezone to Chicago
 ENV TZ=America/Chicago
@@ -17,4 +17,4 @@ ENV UCJL_HOST="0.0.0.0"
 ENV UCJL_PORT="9000"
 
 # Run the server
-CMD ["julia", "--threads", "1", "--procs", "1", "--project=.", "startup.jl"]
+CMD ["julia", "--threads", "1", "--procs", "4", "--project=.", "startup.jl"]

web/backend/Project.toml

@@ -8,7 +8,9 @@ CodecZlib = "944b1d66-785c-5afd-91f1-9de20f533193"
 Dates = "ade2ca70-3891-5945-98fb-dc099432e06a"
 Distributed = "8ba89e20-285c-5b6f-9357-94700520ee1b"
 HTTP = "cd3eb016-35fb-5094-929b-558a96fad6f3"
+HiGHS = "87dc4568-4c63-4d18-b0c0-bb2238e4078b"
 JSON = "682c06a0-de6a-54ab-a142-c8b1cf79cde6"
+JuMP = "4076af6c-e467-56ae-b986-b466b2749572"
 Logging = "56ddb016-857b-54e1-b83d-db4d58db5568"
 Printf = "de0858da-6303-5e67-8744-51eddeeeb8d7"
 Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
@@ -19,7 +21,9 @@ CodecZlib = "0.7.8"
 Dates = "1.11.0"
 Distributed = "1.11.0"
 HTTP = "1.10.19"
+HiGHS = "1.20.1"
 JSON = "0.21.4"
+JuMP = "1.29.2"
 Logging = "1.11.0"
 Printf = "1.11.0"
 Random = "1.11.0"

web/backend/src/jobs.jl

@@ -9,8 +9,8 @@ Base.@kwdef mutable struct JobProcessor
     pending = RemoteChannel(() -> Channel{String}(Inf))
     processing = RemoteChannel(() -> Channel{String}(Inf))
     shutdown = RemoteChannel(() -> Channel{Bool}(1))
-    worker_pid = nothing
-    monitor_task = nothing
+    worker_pids = []
+    worker_tasks = []
     work_fn = nothing
 end
 
@@ -56,7 +56,13 @@ function worker_loop(pending, processing, shutdown, work_fn)
 end
 
 function start(processor::JobProcessor)
-    processor.monitor_task = @spawn begin
+    # Get list of available worker processes
+    worker_pids = workers()
+    @info "Starting job processor with $(length(worker_pids)) worker(s)"
+
+    # Start a worker loop on each worker process
+    for pid in worker_pids
+        task = @spawnat pid begin
             worker_loop(
                 processor.pending,
                 processor.processing,
@@ -64,18 +70,26 @@ function start(processor::JobProcessor)
                 processor.work_fn,
             )
         end
+        push!(processor.worker_pids, pid)
+        push!(processor.worker_tasks, task)
+    end
     return
 end
 
 function stop(processor::JobProcessor)
+    # Send shutdown signal (all workers will see it)
     put!(processor.shutdown, true)
-    if processor.monitor_task !== nothing
+
+    # Wait for all worker tasks to complete
+    for (i, task) in enumerate(processor.worker_tasks)
         try
-            wait(processor.monitor_task)
+            wait(task)
+            @info "Worker $(processor.worker_pids[i]) stopped"
         catch e
-            @warn "Error waiting for worker task" exception=e
+            @warn "Error waiting for worker $(processor.worker_pids[i])" exception=e
         end
     end
+
     return
 end
 

web/backend/startup.jl

@@ -1,10 +1,7 @@
-#!/usr/bin/env julia
-
 # UnitCommitment.jl: Optimization Package for Security-Constrained Unit Commitment
 # Copyright (C) 2025, UChicago Argonne, LLC. All rights reserved.
 # Released under the modified BSD license. See COPYING.md for more details.
 
-# Load required packages
 using HiGHS
 using JuMP
 using Backend
@@ -15,10 +12,16 @@ const UCJL_PORT = parse(Int, get(ENV, "PORT", "9000"))
 println("Starting UnitCommitment Backend Server...")
 println("Host: $UCJL_HOST")
 println("Port: $UCJL_PORT")
-println("Press Ctrl+C to stop the server")
 
 Backend.setup_logger()
-server = Backend.start_server(UCJL_HOST, UCJL_PORT; optimizer = optimizer_with_attributes(HiGHS.Optimizer, "mip_rel_gap" => 0.001))
+server = Backend.start_server(
+    UCJL_HOST,
+    UCJL_PORT;
+    optimizer = optimizer_with_attributes(
+        HiGHS.Optimizer, "mip_rel_gap" => 0.001,
+        "threads" => 1,
+    )
+)
 try
     wait()
 catch e