Douglas C. Schmidt[
^] is perhaps one of the more knowledgeable authors on the subject, and he created
ACE[
^], an open source project with a license suitable for commercial use.
Umar Syyid created the
ACE tutorial[
^] a long time ago, but it's still a relevant source of information.
You should also take a look at the
Boost Thread library[
^]
Best regards
Espen Harlinn