Today I wrote a locking class for the "many readers/single writer, with recursion (MRSW-R)" - problem (ie. shared recursive locking). The current version is for Linux/Unix like systems only. Anybody seriously interessted in stress testing / performance testing it drop me a note. This locker has automatic "Upgrade" (and also "Downgrade") feature built-in, ie. nothing sepereate needed (see examples below). It's just a small mutex class and one locker class which can do both read and write locking (ie. just pass the kind via ctor-param...). (of course one can derive seperate classes for Read and Write) Of course it uses boost (especially atomic primitives like atomic_inc32(), atomic_dec32() etc.) Examples: TCLockVar LV; // this is our special mtx var void f() // called from many threads { TCLock L(LV); // a Read-Lock ... } void g() // called from many threads { TCLock L(LV, true); // a Write-Lock ... } void h() // called from many threads { TCLock L(LV); // a Read-Lock ... if (fNeedToUpdate) { TCLock L(LV, true); // a Write-Lock within a Read-Lock; that's OK! :-) ... } ... } Just drop me an email if interessted in stress testing TCLock. -- U.Mutlu www.mutluit.com