Hello, We're using boost::thread library in a consumer application. Part of the requirements for the application is to continue operation when the user changes local time. Our problem is that if local time is set backwards X minutes during a call to this_thread::sleep(duration) the thread sleeps for X minutes+duration. This happens on MacOS in release build, but not in debug. On Windows behavior is correct. I didn't have a chance to check other platforms. I believe that the intention of this_thread::sleep(duration) is to suspend thread execution for <duration> period regardless of local clock setting, and provide consistent behavior across all platforms and build configurations. Looking into the code of libs/thread/src/pthread/thread.cpp I see that problematic flow may occur in case of detail::get_current_thread_data() is returning null. Apparently this is what causes different behavior in debug and release. The "offendinng" code tries to make sure that absolute point in time (current time + requested delay) is reached using 5 attempts and calculating necessary sleep duration each time. So if during the first sleep local clock is set backwards, second sleep will try to "compensate" for the new difference. The simplest workaround for the problem I could think of is to replace the first statement of the sleep(...) function: detail::thread_data_base* const thread_info= detail::get_current_thread_data(); with this one: detail::thread_data_base* const thread_info= get_or_make_current_thread_data(); Would it create any unwanted side effects? Is there a better way to deal with is problem? Thanks in advance, Mark This message is confidential and intended only for the addressee. If you have received this message in error, please immediately notify the postmaster@nds.com and delete it from your system as well as any copies. The content of e-mails as well as traffic data may be monitored by NDS for employment and security purposes. To protect the environment please do not print this e-mail unless necessary. An NDS Group Limited company. www.nds.com