A simple multithreaded application using 100 threads where each thread executes the following loop results in exceptions thrown by the boost::regex() constructor:

for (int i=0;i<1000;++i) boost::regex("[a-z]{1}");

The exceptions thrown are either "Invalid content of repeat range" or "Unmatched { or \{".

Since the regular expression used is valid and does not throw when executed in a single threaded environment I expect some static variable to be used by BoostRegex internally.

Should BoostRegex be threadsafe?

We use Red Hat Enterprise Linux 3 (gcc 3.2.3) as our development platform.

Remark: The problem disappears when the curly braces are escaped by \\ or when using a "std::string" instead of a "const char*" argument.

Best regards, Peter.