From 5988f8cce68844e038a469e57cfd37c39ff6a2c7 Mon Sep 17 00:00:00 2001
From: Andrew Meadows <andrew@highfidelity.io>
Date: Fri, 24 May 2019 16:12:01 -0700
Subject: [PATCH 1/2] avoid calling removeOwnershipData() from multiple threads

---
 interface/src/Application.cpp                      |  1 +
 libraries/physics/src/PhysicalEntitySimulation.cpp | 14 ++++++++++++--
 libraries/physics/src/PhysicalEntitySimulation.h   |  2 ++
 3 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/interface/src/Application.cpp b/interface/src/Application.cpp
index a0cb790958..64cf375c25 100644
--- a/interface/src/Application.cpp
+++ b/interface/src/Application.cpp
@@ -6401,6 +6401,7 @@ void Application::update(float deltaTime) {
         PerformanceTimer perfTimer("simulation");
 
         getEntities()->preUpdate();
+        _entitySimulation->removeDeadEntities();
 
         auto t0 = std::chrono::high_resolution_clock::now();
         auto t1 = t0;
diff --git a/libraries/physics/src/PhysicalEntitySimulation.cpp b/libraries/physics/src/PhysicalEntitySimulation.cpp
index 3c730fc6cf..98d4e993bf 100644
--- a/libraries/physics/src/PhysicalEntitySimulation.cpp
+++ b/libraries/physics/src/PhysicalEntitySimulation.cpp
@@ -218,11 +218,21 @@ void PhysicalEntitySimulation::clearEntitiesInternal() {
 
 // virtual
 void PhysicalEntitySimulation::prepareEntityForDelete(EntityItemPointer entity) {
+    // this can be called on any thread
     assert(entity);
     assert(entity->isDead());
     QMutexLocker lock(&_mutex);
-    entity->clearActions(getThisPointer());
-    removeEntityInternal(entity);
+    _entitiesToDeleteLater.push_back(entity);
+}
+
+void PhysicalEntitySimulation::removeDeadEntities() {
+    // only ever call this on the main thread
+    QMutexLocker lock(&_mutex);
+    for (auto& entity : _entitiesToDeleteLater) {
+        entity->clearActions(getThisPointer());
+        removeEntityInternal(entity);
+    }
+    _entitiesToDeleteLater.clear();
 }
 // end EntitySimulation overrides
 
diff --git a/libraries/physics/src/PhysicalEntitySimulation.h b/libraries/physics/src/PhysicalEntitySimulation.h
index 817f92cb3c..f5213f7fef 100644
--- a/libraries/physics/src/PhysicalEntitySimulation.h
+++ b/libraries/physics/src/PhysicalEntitySimulation.h
@@ -80,6 +80,7 @@ protected: // only called by EntitySimulation
 
 public:
     virtual void prepareEntityForDelete(EntityItemPointer entity) override;
+    void removeDeadEntities();
 
     void buildPhysicsTransaction(PhysicsEngine::Transaction& transaction);
     void handleProcessedPhysicsTransaction(PhysicsEngine::Transaction& transaction);
@@ -121,6 +122,7 @@ private:
     VectorOfEntityMotionStates _owned;
     VectorOfEntityMotionStates _bids;
     SetOfEntities _deadAvatarEntities;
+    std::vector<EntityItemPointer> _entitiesToDeleteLater;
     workload::SpacePointer _space;
     uint64_t _nextBidExpiry;
     uint32_t _lastStepSendPackets { 0 };

From a6a877d930c50d68c2e6931ca15a9645cb399c5c Mon Sep 17 00:00:00 2001
From: Andrew Meadows <andrew@highfidelity.io>
Date: Fri, 24 May 2019 16:17:55 -0700
Subject: [PATCH 2/2] clear _entitiesToDeleteLater on shutdown

---
 libraries/physics/src/PhysicalEntitySimulation.cpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/libraries/physics/src/PhysicalEntitySimulation.cpp b/libraries/physics/src/PhysicalEntitySimulation.cpp
index 98d4e993bf..7bbf1854fa 100644
--- a/libraries/physics/src/PhysicalEntitySimulation.cpp
+++ b/libraries/physics/src/PhysicalEntitySimulation.cpp
@@ -214,6 +214,7 @@ void PhysicalEntitySimulation::clearEntitiesInternal() {
     _entitiesToRemoveFromPhysics.clear();
     _entitiesToAddToPhysics.clear();
     _incomingChanges.clear();
+    _entitiesToDeleteLater.clear();
 }
 
 // virtual