I was browsing the boost::format docs and did not find anything about the Thread safety of boost::format.  Essentially I want to craft a bunch of error handling methods like this:

void ProcessError(...args...)
{
     static boost::format formatter(...);  //Try to save the cost of creating this for every single error

    //do stuff

    LOG(boost::str(formatter % ...args...);   
}

This method would be called from many, many threads.  Is this considered safe?  Is there some general information about the thread safety of boost::format methods somewhere in the docs?