Only wake up EngineWorkerScheduler if there are worker threads to be started.

1 files changed, 10 insertions, 2 deletions

diff --git a/src/engine/engineworkerscheduler.cpp b/src/engine/engineworkerscheduler.cpp
index c0ca0a4a3f..3b9fe77d7d 100644
--- a/src/engine/engineworkerscheduler.cpp
+++ b/src/engine/engineworkerscheduler.cpp
@@ -7,7 +7,8 @@
 #include "engine/engineworkerscheduler.h"
 
 EngineWorkerScheduler::EngineWorkerScheduler(QObject* pParent)
-        : m_scheduleFIFO(MAX_ENGINE_WORKERS),
+        : m_bWakeScheduler(false),
+          m_scheduleFIFO(MAX_ENGINE_WORKERS),
           m_bQuit(false) {
     Q_UNUSED(pParent);
 }
@@ -24,11 +25,18 @@ void EngineWorkerScheduler::workerReady(EngineWorker* pWorker) {
         // in this slot. Write the address of the variable pWorker, since it is
         // a 1-element array.
         m_scheduleFIFO.write(&pWorker, 1);
+        m_bWakeScheduler = true;
     }
 }
 
 void EngineWorkerScheduler::runWorkers() {
-    m_waitCondition.wakeAll();
+    // Wake the scheduler if we have written a worker-ready message to the
+    // scheduler. There is no race condition in accessing this boolean because
+    // both workerReady and runWorkers are called from the callback thread.
+    if (m_bWakeScheduler) {
+        m_bWakeScheduler = false;
+        m_waitCondition.wakeAll();
+    }
 }
 
 void EngineWorkerScheduler::run() {