Question

In the answer to this question ovanes states:

Please be aware that
boost::lexical_cast is much slower as
atoi. I also use it very often in a
performance non-critical code. The
problem with lexical_cast is that it
uses stringstream for conversion. If
you are working in a multi-threaded
environement any stream class from the
standard lib will use locks on a mutex
for every character being inserted,
even if the stream object is used from
a single thread.Your number consisting
of 17 chars will involve 17 mutex
locks when put into stream. – ovanes
Jun 22 at 11:59

Which begs the question, when do <iostream> objects lock a mutex? Is this true for objects from <sstream> as well? If so can this be prevented?

Answer 1

The current C++ standard (C++03) does not contain anything about multi-threading.

Because of this, how a library uses mutexes would depend on the specific implementation.