A simple interface between the pthreads (POSIX Threads) API and PHP5 (should work on PHP4 too, in theory).
PHP has been let down among modern SAPI languages in the past due to its lack of a proper threads API. This extension (developed against 5.2.6) allows for a native threads implementation in PHP, rather than some hacky workaround.
It is currently in very early development although there has been a lot of progress.
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