From Matthew Johnson-Roberson, "Small fix for operation thread to protect the access to _operations vector by functions getNumOperationsInQueue() and empty(). It is simply an addition of OpenThreads::ScopedLock<OpenThreads::Mutex> lock(_operationsMutex);

to protect against accessing while writing which was segfaulting in VPB
specifically in void ThreadPool::run(osg::Operation* op)
in the waiting loop

while (_operationQueue->getNumOperationsInQueue() >= _maxNumberOfOperationsInQueue)
"

include/osg/OperationThread

@@ -105,10 +105,10 @@ class OSG_EXPORT OperationQueue : public Referenced
         osg::ref_ptr<Operation> getNextOperation(bool blockIfEmpty = false);
 
         /** Return true if the operation queue is empty. */
-        bool empty() const { return _operations.empty(); }
+        bool empty();
         
         /** Return the num of pending operations that are sitting in the OperationQueue.*/
-        unsigned int getNumOperationsInQueue() const { return static_cast<unsigned int>(_operations.size()); }
+        unsigned int getNumOperationsInQueue();
 
         /** Add operation to end of OperationQueue, this will be 
           * executed by the operation thread once this operation gets to the head of the queue.*/

src/osg/OperationThread.cpp

@@ -55,6 +55,19 @@ OperationQueue::~OperationQueue()
 {
 }
 
+bool OperationQueue::empty() 
+{ 
+
+  OpenThreads::ScopedLock<OpenThreads::Mutex> lock(_operationsMutex);
+  return _operations.empty(); 
+}
+
+unsigned int OperationQueue::getNumOperationsInQueue()
+{
+  OpenThreads::ScopedLock<OpenThreads::Mutex> lock(_operationsMutex);
+  return static_cast<unsigned int>(_operations.size()); 
+}
+
 ref_ptr<Operation> OperationQueue::getNextOperation(bool blockIfEmpty)
 {
     if (blockIfEmpty && _operations.empty())