Update: reimpleemnt whole of CoreCLR's ConcurrentQueue (same as in shipped mscorlib) - added extra telemetry to track segment alloc/retire, general tries, gc activity This time didn't rip out the segment growing logic, and looks like if it safely fits in one segment, it can be consistently used. Going to confirm if extra large segment is enough, then it'll be a viable candidate Tests: ran unit tests and AllocDeallocMTShortLived(32,False) perf test