Andrey Semashev <andrey.semashev@gmail.com> writes:
On 01/11/2010 05:22 PM, Stefan Strasser wrote:
even though I understand the need for it now, it still seems odd that we use a std::map to simply access a value in another memory segment.
have you thought about dynamically allocating an index into a (thread-specific) vector instead of a key based on the thread_specific_ptr's address? IIUC that would allow constant-time access in all cases.
Yes, that's what I did in my patch in ticket #2361. One inconvenience with that approach is to restrain the size of the vector if thread_specific_ptrs are constantly created/destroyed. I did not solve it in my patch but it should be quite doable.
I really hope Anthony will take a look at it and come up with a vector-based solution. Or I can finish the patch myself, if it has any chance of getting into SVN. Anthony?
Boost 1.35 used a vector for the thread_specific_ptr data, but there were complaints about the excessive memory usage. The map version has a smaller memory footprint. It is possible that an alternative scheme (such as using a sorted vector as a map) might yield something that is more reasonable on both fronts. Anthony -- Author of C++ Concurrency in Action http://www.stdthread.co.uk/book/ just::thread C++0x thread library http://www.stdthread.co.uk Just Software Solutions Ltd http://www.justsoftwaresolutions.co.uk 15 Carrallack Mews, St Just, Cornwall, TR19 7UL, UK. Company No. 5478976