forks-0.24

Changes for version 0.24

Threads API consistency changes *****
Changed $thr->wantarray return value to 0-length string (was string '0') to meet standard wantarray scalar context return value.
Added support for exit() and threads->exit() methodology and behavior.
Added support for $thr->error() feature.
Added a warning (and disallowing thread detach) if attempting to detach a thread that another thread is currently waiting to join.
Internal behavior changes *****
Added ability to swap primary process (main<->shared) that is parent of all processes in threaded application (via $ENV{THREADS_DAEMON_MODEL}); should help support co-existance with some fork-aware modules, like POE.
Rewrote signal handling methodology to resolve stability issues with inter-thread and external process signaling.
Addressed the limit of 65535 shared variables: you may now create up to 2^31-1 (2+ billion) shared variables. Note: shared variables are currently not memory deallocated even if they go out of scope in all threads; thus, it's NOT recommended to create too many (1k+) unless you have a requirement to do so. Shared var mem deallocation (when no longer referenced by any thread) will be addressed in a future release.
Improved behavior of signal() and scope-exit unlock ordinal to insure that all threads, no matter what type of waiting they were performing, have an equal chance to receive the signal or re-acquire the lock. The old behavior gave preference towards regular waiting events for signal, and timedwaiting events waiting to reacquire the lock for unlock ordinal.
Deprecated and removed deadlock detection 'resolve_signal' feature (as this could not be supported in new forks.pm signal handling logic).
Bug fixes *****
Shared variable in push() on shared array now works.
Eliminated slow memory leak when creating many joinable threads: the shared process now reclaims all shared memory allocated for joinable threads, as long as the application (periodically) joins then after they complete.
Eliminated "Performing cleanup for dead thread 0" errors when compiling a script (i.e. perl -c script.pl). This fix also eliminates double "syntax OK" reports when compiling a script.
Fixed a case where detach after thread had already completed could result in incorrect thread group exit state reporting.
Corrected a bug regarding recursive variable unlocking (was deleting instead of decrementing lock count).
Fixed a few issues in test scripts regarding mis-reported errors related to older threads.pm installs or non-threaded Perl targets.
Forks now starts correctly if called with 'require' or if forks::import is skipped for any reason.
Added additional check in server to shutdown if main thread dies in a hard way (no notification to server or thread group).
Added some extra protection in thread signaling (to insure that process exists before signaling it).
Added some protection in test suite for issues with race-conditions in Test::More.
Fixed race condition in forks07.t that could cause test to report an error.
Fixed race issue in forks04.t that could cause script to error out on Perl instances with old native threads.pm libraries or no threads.pm library.
Miscellaneous changes *****
Added additional thread environment protection regarding fork occuring outside forks.pm module. Also silenced a few warnings that might have occured in such cases.
Silenced a few more unnecessary run-time warnings in specific exception and error cases.
Rewrote END behavior for more stability and better cleanup during thread (process) group exit.
Added internal hooks to allow external modules to override default forks.pm fork logic. This should allow more flexibility to integrate forks with application-scope modifying environments (i.e. mod_perl, POE, Coro, etc.).
Removed dependency on Reaper module.
Updated version requirement for Scalar::Util module.
Upgraded to ppport.h 3.11.
Fixed some XS portability issues with older versions of Perl (5.8.1 and older).