提交: 6364b03e62e62258f90af6af39fe4497c2927054 - launch_thread_performance (hg)

Comparing performance of a task queued to an existing thread vs. new thread for each task.

Commit MetaInfo

• 修訂: 6364b03e62e62258f90af6af39fe4497c2927054 (tree)
• 時間: 2017-03-24 02:23:40
• 作者: Eric Hopper <hopper@omni...>
• Commiter: Eric Hopper

Log Message

Just threads vs. raw function call for now.

Change Summary

• add: do_something.cpp
• add: test_thread.cpp

差異

diff -r 000000000000 -r 6364b03e62e6 do_something.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/do_something.cpp	Thu Mar 23 10:23:40 2017 -0700
@@ -0,0 +1,3 @@
+extern void do_something()
+{
+}

diff -r 000000000000 -r 6364b03e62e6 test_thread.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test_thread.cpp	Thu Mar 23 10:23:40 2017 -0700
@@ -0,0 +1,59 @@
+#include <chrono>
+#include <thread>
+#include <future>
+#include <iostream>
+
+extern void do_something();
+
+typedef long long unsigned int calls_p_sec_t;
+typedef ::std::function<void ()> the_call_t;
+
+template <typename T>
+calls_p_sec_t calls_per_second(const T &thecall, unsigned int interval)
+{
+   auto now = []() -> auto {
+      return ::std::chrono::high_resolution_clock::now();
+   };
+   typedef ::std::chrono::duration<long double> timediff_t;
+   unsigned long long count = 0;
+   const auto start = now();
+
+   long double curtime_as_ldbl = (timediff_t(now() - start)).count();
+   while (curtime_as_ldbl < interval) {
+      thecall();
+      ++count;
+      curtime_as_ldbl = (timediff_t(now() - start)).count();
+   }
+   return count / interval;
+}
+
+int main()
+{
+   using ::std::cout;
+   using ::std::async;
+   using ::std::thread;
+   using ::std::launch;
+   cout << "  Do nothing calls per second: "
+        << calls_per_second([]() { }, 5) << '\n';
+   cout << "       Empty calls per second: "
+        << calls_per_second([]() { do_something(); }, 5) << '\n';
+   cout << "  New thread calls per second: "
+        << calls_per_second(
+              []() {
+                 thread t{ do_something };
+                 t.join();
+              },
+              5
+           )
+        << '\n';
+   cout << "Async launch calls per second: "
+        << calls_per_second(
+              []() {
+                 auto fut = async(launch::async | launch::deferred, do_something);
+                 fut.wait();
+              },
+              5
+           )
+        << '\n';
+   return 0;
+}