Hi this message is to announce the version 2.0 of the *[countertree + suballocator]* library. 1 year ago I presented the request for the evaluation of the [countertree+ suballocator] version 1.0. The approval process is stopped due to the absence of review managers, and in the meanwhile I continued with the develop of this version 2.0. Actually the most important libraries and environments for parallel development, *don't provide parallel algorithms for th**e** data structures based on trees* ( set , multiset, map and multimap), and all the operations with these data structures are done with 1 thread. This is due to the difficult to divide the element of the tree between an arbitrary number of threads. (If you want to access to the element in the position 1000, you must go sequentially forward from the position 0 or sequentially backward from the last position. The [countertree + suballocator] library provide data structures set, multiset,map and multimap compatibles with the STL data structures *plus the access to the elements by their position like in a vector, and random access iterators*, You can manage it like a vector. Many parallel algorithms designed for vectors, can be used without changes with the countertree data structures. This make *easy **the **design **of **parallel algorithms* for these data structures. In the library there are a concurrent and a non concurrent versions of all the data structures. The non concurrent version are designed for to be executed inside 1 thread, or for to be accessed by several threads only in read operations (like the STL data structures), they provide a bit more speed than the concurrent version. The concurrent version is *thread safe with all the operations*, one thread can be read and other writing over the same data structure in a safe mode ( as you can see in 2.3 -examples) The concurrent library provide the full set of functions of the STL , plus an *additional set of functions*. These functions have the mission of resolve the problems appeared in the concurrent development. By example, you have a map, find an iterator from a key and with the iterator modify the element, but in the middle, other thread delete the element, and when try to access with the iterator, the program crash, and it is very difficult to reproduce the error for to debug. These additional functions make a pack with the two things, first with a read lock which permit concurrent reads, and when obtain the iterator with an exclusive lock for to modify. These additional functions *prevent the problems* like the previously described, with an *easy interface* for to understand and use for the final user. I don't know if exist any other library with tree based structures with random access iterators. I had search for and didn't find. If someone knows someone, please, say me, I am interested to know something new and collect good ideas. I suppose it don't exist because i didn't see parallel support for data structures based on trees, in any library or parallel tools. I request help to the Boost community because I am in the *moment “perhaps” *. Perhaps I forgot something, perhaps something is wrong, perhaps someone decision was not correct, perhaps it can be done in other way... *Please*, is someone see any fail, any omission, any alternative or simply any comment, please say me, in order to reach the final objective, *provide to the C++ community a good, fast, robust and reliable tool.* In my opinion, this library or other with similar functionality, is the last big part needed for to begin to think about a *concurrent STL* . You can find concurrent libraries with vectors and arrays. You have too, concurrent libraries with containers based on hash functions. With the countertree library you have concurrent set, multiset,map and multimap. The concurrent linked list can be implemented with the concurrent vector_tree ( other data structure of the library). The concurrent STL is a very big project, and must involve many agents and perspectives. From the users associations, to big computers makers and big data providers, passing by the compiler makers, the parallel tools providers... But I am sure the *Boost community* will play a central role by prestige, knowledge and experience designing libraries You can find the documentation and the code in the GitHub https://github.com/fjtapia/countertree_2.0 or you can see online in my dropbox page : https://dl.dropboxusercontent.com/u/8437476/works/countertree_2.0/index.htmlhttps://dl.dropboxusercontent.com/u/8437476/works/countertree_2.0/doc/index.... If you prefer download a file with all the code and the documentation : https://github.com/fjtapia/countertree_2.0/blob/master/doc/countertree_2.0.z... Sincerely yours Francisco Tapia fjtapia@gmail.com ** I you don't try the library, perhaps the most interested parts of the documentation is the 1.5.- Next improvements. Where explain the future parallel algorithms for the library and how they can improve others areas of the computation with the augmented trees.*