Multithreaded test execution

[racoltdev]

[racoltdev]

The only bar to this would be semaphores or other lock mechanism on the log file. Multithreading would have to be enabled by some fork variant to hold posix/windows compatability.

[racoltdev]

Posix pthreads will work for this. For further discussion on windows compatibility, see "Doesn't run on Windows/posix" #8

[racoltdev]

To restate the goal of this issue: I would like to enable per file granularity multithreading. Implementing per test granularity is both expensive and unlikely to find heavy use, as it is not uncommon for tests to rely on each other in some capacity, although it may be a focus of future development.

[racoltdev]

Although pthread is easier to handle for general multithreaded applications, it does not work with exec functions because exec will replace the execution environment of both the "parent" and "child" in a pthread system since they share memory space. Fork is the only viable option for per file granularity. In terms of maintaining posix compatibility, no changes should be made to test_runner fork() and execl() calls, although other changes may be made to ensure locks are given up if a test exits unexpectedly. Discussion of Windows compatibility has moved to #9.