Fix RHI/Subpass sample for Vulkan. The issue was that we were exectui… (#4904)

* Fix RHI/Subpass sample for Vulkan. The issue was that we were exectuing the sub-pass groups more than once when parallel encoding was used.

Signed-off-by: moudgils <moudgils@amazon.com>

* Added a minor comment

Signed-off-by: moudgils <moudgils@amazon.com>

* Minor perf improvement

Signed-off-by: moudgils <moudgils@amazon.com>

Gems/Atom/RHI/Vulkan/Code/Source/RHI/FrameGraphExecuteGroupHandlerBase.cpp

@@ -27,6 +27,7 @@ namespace AZ
         {
             EndInternal();
             m_device->GetCommandQueueContext().GetCommandQueue(m_hardwareQueueClass).ExecuteWork(AZStd::move(m_workRequest));
+            m_isExecuted = true;
         }
 
         bool FrameGraphExecuteGroupHandlerBase::IsComplete() const
@@ -42,6 +43,11 @@ namespace AZ
             return true;
         }
 
+        bool FrameGraphExecuteGroupHandlerBase::IsExecuted() const
+        {
+            return m_isExecuted;
+        }
+
         template<class T>
         void InsertWorkRequestElements(T& destination, const T& source)
         {

Gems/Atom/RHI/Vulkan/Code/Source/RHI/FrameGraphExecuteGroupHandlerBase.h

@@ -41,6 +41,7 @@ namespace AZ
             void End();
 
             bool IsComplete() const;
+            bool IsExecuted() const;
 
         protected:
             virtual RHI::ResultCode InitInternal(Device& device, const AZStd::vector<RHI::FrameGraphExecuteGroup*>& executeGroups) = 0;
@@ -52,6 +53,7 @@ namespace AZ
             ExecuteWorkRequest m_workRequest;
             RHI::HardwareQueueClass m_hardwareQueueClass = RHI::HardwareQueueClass::Graphics;
             AZStd::vector<RHI::FrameGraphExecuteGroup*> m_executeGroups;
+            bool m_isExecuted = false;
         };
     }
 }

Gems/Atom/RHI/Vulkan/Code/Source/RHI/FrameGraphExecuter.cpp

@@ -177,8 +177,8 @@ namespace AZ
             auto findIter = m_groupHandlers.find(group.GetGroupId());
             AZ_Assert(findIter != m_groupHandlers.end(), "Could not find group handler for groupId %d", group.GetGroupId().GetIndex());
             FrameGraphExecuteGroupHandlerBase* handler = findIter->second.get();
-            // Wait until all execute groups of the handler has finished.
-            if (handler->IsComplete())
+            // Wait until all execute groups of the handler has finished and also make sure that the handler itself hasn't executed already (which is possible for parallel encoding).
+            if (!handler->IsExecuted() && handler->IsComplete())
             {
                 // This will execute the recorded work into the queue.
                 handler->End();