LispWorks supports Symmetric Multiprocessing (SMP) on Microsoft Windows, Mac OS X, Linux, FreeBSD and x86/x64 Solaris platforms. Where functionality differs from other platforms, the documentation refers to "SMP LispWorks" or "Non-SMP LispWorks", as appropriate.
This section describes changes made in the multiprocessing interface since version 6.1.
New APIs allow you to ensure hash table entries in a thread-safe way. This means attempting to get a value, and if that fails setting and returning a new value (potentially having constructed the new value in a complicated way). See "Modifying a hash table with multiprocessing" in the LispWorks User Guide and Reference Manual .
mp:mailbox-wait are new. Also the documentation of interrupts and communication between processes has been improved. See sections "Processes basics" and "Communication between processes and synchronization" in the
LispWorks User Guide and Reference Manual
LispWorks Release Notes and Installation Guide - 2 Mar 2015