Add category "thread"

`./run_benchmarks --category thread` now runs all benchmarks from
benchmarks.yml with the category of "thread".

Added a benchmark with this new category for benchmarking how long it
takes when there's mixed IO-bound and heavy CPU-bound work.

Author: luke-gruber

benchmarks.yml

@@ -235,6 +235,14 @@ throw:
   single_file: true
   ractor: true
 
+#
+# Thread benchmarks
+#
+threads_io_with_cpu:
+  desc: Benchmark to test how long I/O takes to complete when there's a mix of IO-bound and CPU-bound threads.
+  category: thread
+  single_file: true
+
 #
 # Ractor scaling benchmarks
 #

benchmarks/threads_io_with_cpu.rb

@@ -0,0 +1,69 @@
+require_relative '../harness/loader'
+
+require "socket"
+num_cpu_threads = 1
+num_io_threads = 1
+
+server_started = false
+
+def start_tcp_server(&started)
+  Thread.new do
+    server = TCPServer.new('localhost', 0) # random open port
+    started.call(server.local_address.ip_port)
+
+    loop do
+      client = server.accept
+      client.close
+      # Don't get request or generate response, it makes the benchmark take too long
+    end
+  end
+end
+
+def open_tcp_connection(host, port)
+  TCPSocket.open(host, port) { }
+end
+
+def fib(n)
+  return n if n <= 1
+  fib(n - 1) + fib(n - 2)
+end
+
+server_started = false
+port = nil
+start_tcp_server do |server_port|
+  server_started = true
+  port = server_port
+end
+loop until server_started
+
+io_requests_threshold = 5 # per thread
+
+run_benchmark(5) do
+  io_threads = num_io_threads.times.map do
+    Thread.new do
+      io_requests_made = 0
+      loop do
+        open_tcp_connection("localhost", port)
+        io_requests_made += 1
+        if io_requests_made >= io_requests_threshold
+          break
+        end
+      end
+    end
+  end
+
+  stop_looping = false
+
+  cpu_threads = num_cpu_threads.times.map do
+    Thread.new do
+      loop do
+        fib(30)
+        break if stop_looping
+      end
+    end
+  end
+
+  io_threads.each(&:join)
+  stop_looping = true
+  cpu_threads.join
+end

lib/argument_parser.rb

@@ -68,7 +68,7 @@ def parse(argv)
         args.out_override = v
       end
 
-      opts.on("--category=headline,other,micro,ractor", "when given, only benchmarks with specified categories will run") do |v|
+      opts.on("--category=headline,other,micro,thread,ractor", "when given, only benchmarks with specified categories will run") do |v|
         args.categories += v.split(",")
         if args.categories == ["ractor"]
           args.harness = "harness-ractor"