...one of the most highly
regarded and expertly designed C++ library projects in the
world. — Herb Sutter and Andrei
The Boost.Regex library is thread safe when Boost is: you can verify that
Boost is in thread safe mode by checking to see if
is defined: this macro is set automatically by the config system when threading
support is turned on in your compiler.
and its typedefs regex and wregex are thread safe, in that compiled regular
expressions can safely be shared between threads. The matching algorithms
are all re-entrant and thread safe. Class
match_results is now thread safe,
in that the results of a match can be safely copied from one thread to another
(for example one thread may find matches and push
match_results instances onto a queue,
while another thread pops them off the other end), otherwise use a separate
The POSIX API functions are all re-entrant and thread safe, regular expressions compiled with regcomp can also be shared between threads.
The class RegEx is only thread safe if each thread gets its own RegEx instance (apartment threading) - this is a consequence of RegEx handling both compiling and matching regular expressions.
Finally note that changing the global locale invalidates all compiled regular
expressions, therefore calling
from one thread while another uses regular expressions will produce unpredictable
There is also a requirement that there is only one thread executing prior to the start of main().