Speed up multithreading by avoiding superfluous waits when pruning

vaeth · Feb 27, 2017 · eacfb87 · eacfb87
1 parent 768be40
commit eacfb87
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Showing 3 changed files with 14 additions and 5 deletions.
diff --git a/ChangeLog b/ChangeLog
@@ -1,5 +1,8 @@
 # ChangeLog for chessproblem
 
+*chessproblem-2.4
+	- Speed up multithreading by avoiding superfluous waits when pruning
+
 *chessproblem-2.3
 	- Rename PushGuard->push_guard and PushGuardDisarmable->unique_push
 	  in analogy to std::lock_guard and std::unique_lock.

diff --git a/configure.ac b/configure.ac
@@ -5,7 +5,7 @@
 #  Martin V\"ath <martin@mvath.de>
 
 dnl keep version in same line as AC_INIT for possible usage in scripts
-AC_INIT([chessproblem], [2.3],
+AC_INIT([chessproblem], [2.4],
   [https://github.com/vaeth/chessproblem/issues/],
   [chessproblem],
   [https://github.com/vaeth/chessproblem/])

diff --git a/src/chessproblem.cc b/src/chessproblem.cc
@@ -532,12 +532,18 @@ void ChessProblem::SolverThread(chessproblem::Communicate *communicate,
   if (SingleThreadedMode()) {  // Only a shortcut
     return;
   }
-  for (auto& t : threads) {
-    t.join();
-  }
   if (subthread) {  // We are at the end of a subthread
     delete field;
-    DecreaseThreads();
+    DecreaseThreads();  // We might be not ready, but we will only wait
+  }
+  if (communicate->GotSignal()) {
+    for (auto& t : threads) {  // No need to wait for exiting threads
+      t.detach();
+    }
+  } else {
+    for (auto& t : threads) {
+      t.join();
+    }
   }
 }
 #endif  // NO_CHESSPROBLEM_THREADS