Hi, I have a problem, I need to access a shared memory segment from several process and all at the same time. I was looking at boost::interprocess threads but I'm not sure how to implement the mutex. this is the code I have(working): #include <boost/interprocess/managed_shared_memory.hpp> #include <boost/interprocess/containers/vector.hpp> #include <boost/interprocess/containers/string.hpp> #include <boost/interprocess/containers/map.hpp> #include <boost/interprocess/allocators/allocator.hpp> #include <cstdlib> #include <string> #include <iostream> #include <map> #include <sstream> using namespace boost::interprocess; typedef managed_shared_memory::segment_manager SegmentManager; typedef allocator<void, SegmentManager> VoidAllocator; typedef allocator<char, SegmentManager> CharAllocator; typedef basic_string<char, std::char_traits<char>, CharAllocator> BasicString; class Action { int id; BasicString task; public: Action(int num, const char *name, const VoidAllocator &void_alloc) :id(num), task(name,void_alloc) {} void setId(int num); void setTask(BasicString newTask); int getId(); }; int Action::getId() { return id; } void Action::setId(int num) { id = num; } void Action::setTask(BasicString newTask) { task = newTask; } typedef allocator<Action, SegmentManager> ActionAllocator; typedef std::pair<const BasicString, Action> MapValueType; typedef std::pair<BasicString, Action> MovableToMapValueType; typedef allocator<MapValueType, SegmentManager> MapValueTypeAllocator; typedef map<BasicString, Action, std::less<BasicString>, MapValueTypeAllocator> MyMap; void CreateAndFill() { managed_shared_memory segment(create_only, "MySharedMemory", 65536); VoidAllocator alloc_inst(segment.get_segment_manager()); MyMap *myMap = segment.construct<MyMap>("Map" )(std::less<BasicString>(),alloc_inst); std::string keyword; std::string helper; int i=0; for(int adder = 0; adder<=1000; adder++) { keyword = "Hello"; std::stringstream out; out << adder; helper = out.str(); keyword = keyword + helper;//Creates a string "Hello" + adder BasicString key(keyword.c_str(), alloc_inst);//string to BasicString Action action(i,"ActionContent", alloc_inst);//puts values of Action object MapValueType value(key, action); myMap->insert(value); i++; } } int main(int argc, char** argv) { //Remove shared memory on construction and destruction struct shm_remove { shm_remove() {shared_memory_object::remove("MySharedMemory"); } ~shm_remove() {shared_memory_object::remove("MySharedMemory"); } }remover; CreateAndFill(); } How and where do I have to set the mutex?? Is this anonymous or named? Thanks! Dann