0.29 February 2 2009
***** Bug fixes *****
Shared variables that reference shared variables now consistently report the
same thread-local reference memory address.
Code refs can now be used as hash keys.
Fix spurious warnings regarding mismatched Time::HiRes prototypes.
Explicit mg_get in is_shared() to insure tied scalar fetched before ref check.
***** Threads API consistency changes *****
Can now store CODE refs in shared variables if using Storable >= 2.05.
Can now use CODE refs as shared variable keys (stringified values work as
expected).
Bumped threads::shared $VERSION to 1.27 to match version-supported features
and behavior.
***** Miscellaneous changes *****
Add Makefile build option to upgrade Storable to support using CODE refs in
shared variable keys, if Storable < 2.05.
Round test suite sleep time check sensitivity to eliminate false positives on
some (hardware) platforms.
Using more portable prototype definitions with some versions of Test::HiRes.
Scalar::Util 1.11 or later now required.
Sys::SigAction 0.11 or later now required, as this correctly handles the
'safe' sigaction attribute.
Fix typo in croak error text in cond_timedwait.
0.28 December 30 2008
***** Bug fixes *****
join() and detach() now correctly propagate and throw exceptions to threads,
in such cases as joining or detaching an already joined or detached thread.
Threads now supports circular self-referential shared variables
(i.e. my $x:shared; $x = \$x;) and consistently returns the correct REF value;
circular-referental sets of variables are also supported, if defined before
sharing with shared_clone()).
forks::shared function is_shared() now understands REF type input and circular
referential shared variables.
is_shared() should now return a consistent address in all threads and for
all variable types; however, note since it refences memory in the shared
process, do NOT use the return value to perform direct memory access (not that
it was intended for this purpose, anyway).
Using single-declaration form of 'use constant' for Perl 5.6.x compatibility.
Explicitly registering 'threads' warnings pragma, for Perl 5.6.x compatibility.
Added more XS prototype compatibility with 5.6.x, allowing second forms of
cond_wait and cond_timedwait to be better supported.
Added second forms of cond_wait and cond_timedwait to Perl < 5.8 source filters
(eliminates segfaults).
Identified and implemented additional internal state conditions when error
'Cannot detach a joined thread' should occur.
threads->list(threads::all) no longer returns threads that already have a
thread blocking to join them.
Corrected a few uses of hash and array iterators that modify structure in loop
(using each() for hashes, separate array copy).
***** Threads API consistency changes *****
forks::shared now implements standard threads::shared function shared_clone().
Scalars that have a value and are shared afterwards will retain the shared
value when running in native threads emulation mode.
Restartable system calls (platform-dependent) and sleep (including Time::HiRes
sleep, usleep, and nanosleep) should no longer be interrupted by CHLD signal,
unless CHLD signal handler is defined in user code. This should more accurately
represent process behavior with slow system calls, as would be expected with
native ithreads.
Bumped threads $VERSION to 1.71 and threads::shared $VERSION to 1.26 to match
version-supported features and behavior.
forks::shared share() now correctly checks the function prototype when disabled
(e.g. when forks::shared is loaded without or before forks).
CLONE method/function is now supported in main:: package (was ignored).
CLONE_SKIP method/function is now supported.
Usage details at: http://perldoc.perl.org/perl593delta.html#'CLONE_SKIP()'
threads->object(0) now returns undef (main thread is not considered an object).
Support for 'array' context type (alias for already supported 'list' type) when
creating a new thread.
Thread attempting to join self (while non-detached) returns an error.
Now correctly storing/returning stack size settings, although not internally used
for anything useful at this time.
Core function rand() is now reseeded in each new thread (via srand()).
***** Miscellaneous changes *****
Added THREADS_NATIVE_EMULATION environment variable to allow users to have forks
behave more like native ithreads ("buggy" behaviors and all).
Removed source filter requirement for Perl 5.9+. (Now using internal PL_sharehook
instead of Attribute::Handlers whenver possible, including with Perl 5.8.x.)
Removed use of AUTOLOAD in forks::shared; may see a minor shared variable access
performance improvement.
Added signal blocking when doing fork() system call, to insure most reliable
thread startup behavior (i.e. custom CHLD signal handler won't create instability).
Made minor changes to the test suite to improve descriptions and suppress a few
unnecessary warnings.
Added internal patching mechanism to allow Test::More to work with Perl
5.8.1 and older (primarily for test suite backward compatibility).
Silenced spurious Test::More "WOAH! ..." warnings in test suite, regarding Test::More
being unaware of global test counting when mixing forks and threads.
Added extra parameter error checking to XS code.
Modified internal data manipulation for broadcast() to protect against occasional
memory corruption with Perl 5.6.x (delete() on array appeared to cause rare segfaults).
Added 'if' CPAN module to package requirements, for Perl 5.6 support (test suite).
Updated to ppport.h 3.14.
0.27 January 27 2008
***** Bug fixes *****
forks::shared now supports perl 5.9.0 and later (with a source filter). The
requirement for a source filter is hopefully just a temporary solution until
Attribute::Handlers can access the 'shared' attribute again (which perl 5.9
and later currently prevent, perhaps because they consider it a reserved word).
Corrected perl 5.6 support, regarding incompatible XS function Perl prototypes
(broken since 0.16).
All internal %INC manipulation is now done at compilation (require) time. This
corrects cases where modules that 'use threads::shared' before forks::shared has
been loaded actually load ithreads-native threads::shared.
Corrected bug regarding handling forks-server operation deferred signals (which
was preventing them from being executed when they should be executed).
***** Miscellaneous changes *****
Forks now uses Perl core module Attribute::Handlers for 'shared' variable
attribute handling. This also insures compatibility with any other modules
that may use Attribute::Handlers.
Removed BUS, FPE, ILL, SEGV, and SYS from list of "forks-aware" signal handlers
for better cross-platform portability.
Added POD strongly encouraging use of forks and forks::shared as FIRST modules.
Now tracking last known CORE::GLOBAL::exit at require time, and resetting at
END. This should insure that cases where forks wasn't first module to be loaded
allows for other modules to still use their own custom exit methods.
Moved 5.6.x source filter from forks.pm to forks::shared.pm, where it belongs.
Added appropriate disabled functions (without prototypes) for perl 5.6.x when
forks::shared is disabled if was loaded without loading forks first).
0.26 September 30 2007
***** Bug fixes *****
Eliminated some warnings on platforms that do not implement all signals forks
can monitor.
Added boolean hook $forks::DEFER_INIT_BEGIN_REQUIRE to allow external
modules to override forks server functions if forks loaded in a BEGIN block.
***** Miscellaneous changes *****
Added some logic in CHLD reapers for better cross-platform stability.
Updated to ppport.h 3.12.
0.25 August 12 2007
***** Bug fixes *****
Updated internal PID tracking to U32 size for increased portability across
different kernels and kernel configurations. This corrects irregular issues
with locks on such systems.
Rewrote signal handling engine to be more portable and stable. Changes
eliminated behavior on BSD kernels that would cause processes to improperly
exit with an ABRT-triggered core dump.
***** Miscellaneous changes *****
Added some protections in test suite for non-mixed fork/thread safe
Test::More module.
Added tests for new signal handling engine.
0.24 July 9 2007
***** 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).
0.23 8 April 2007
***** Test suite fixes *****
Corrected issue in forks04.t that would cause irrelevant but terminal
compilation errors if real threads.pm (1.34 or later) weren't present.
***** Miscellaneous changes *****
Silenced a warning during external fork (non-thread) process exit.
Added some internal hooks to allow add-on modules (e.g. forks::BerkeleyDB)
the opportunity to clean up global thread resources during shutdown.
0.22 19 March 2007
***** Internal behavior changes *****
Thread manager process now forcefully kills any still active threads
when it exits. This is intended to best simulate standard thread.pm
thread cleanup during process exit.
***** Bug fixes *****
Corrected bug in shared server shutdown preventing complete cleanup.
Corrected some platform and perl build sensitivities in the test suite.
***** Miscellaneous changes *****
Added additional stability against fork() outside of forks.pm.
Tweaked some warnings and disabled some debug logging.
0.21 17 March 2007
This revision includes *many* core changes and improvements, so be sure
to perform full testing with existing forks-enabled applications before
upgrading.
All changes have been exposed to extensive regression testing, so you may
expect all new features to be reasonably stable unless otherwise noted
with a *WARNING* tag.
***** New features *****
Enabled complete thread context support. Be sure to specify the context,
either implicit or directly. This also means you may not get what you
expect if you return values in a context that doesn't match your spec.
Add optional, automatic deadlock detection (warnings) in threads::shared.
Also added is_deadlocked() method (manual deadlock detection) for threads.
Added set_deadlock_option class method to forks::shared (threads::shared).
Aware of thread params at thread creation, e.g. threads->new({}, sub {});
Added complete support for $thr->wantarray and thread->wantarray.
Added complete support for thread state: is_running, is_joinable,
is_detached().
Added additional support to threads->list(), with package variables:
threads::all, threads::running, and threads::joinable.
Added support for 'use forks qw(stringify)'where the TID is returned
for a threads object in string context.
Added detailed last known state of all threads on main thread exit (or
server process unexpected exit), like:
Perl exited with active threads:
x running and unjoined
y finished and unjoined
z running and detached
Added stubs for get_stack_size and set_stack_size, although they don't
do anything (yet).
Added support for threads->_handle and $thr->_handle, although it
currently does not guarantee a reference to the same memory address
each time (will be addressed in a later release).
Added support for inter-thread signaling using $thr->kill('SIG...').
*WARNING* This feature is still highly experimental and has known
issues when sending a signal to a process sending or receiving socket
data pertaining to a threads operation. This will be addressed in
a future release.
Added question during build process to allow forks to override threads
namespace if target Perl does not have native threading built in.
Added POD describing this feature and behavior implications.
***** Bug fixes *****
Corrected bug in threads::shared::scalar that prevented tieing without
a pre-existing scalar reference.
Localizing $? in END block to insure that main thread exit code isn't
accidentally overwritten during shutdown.
Corrected several cases where internal auto-vivification was not intended,
but might cause internal variable state issues.
Corrected bug where fork() followed by ->isthread() in a child process
while parent process (a thread) was already waiting on a separate thread
could cause internal synchronization issues.
Corrected bug in ->list where scalar context would return last object,
not the number of waiting threads.
Added additional protection in END block against external fork() occuring
outside our knowledge causing synchronization havoc with the thread process
group.
Removed delete from %DETACHED on thread exit, as this property is used for
internal thread type and state checking.
Updated some error handling to suppress some undefined variable warnings.
***** Internal behavior improvements *****
Added silent overload of Config.pm 'useithreads' property to insure all
modules and scripts see a true value when forks is loaded.
Added explicit signal trapping of all untrapped normal and error signals
for consistent and safe thread exit behavior.
Added defensive error handling around non-blocking server sockets to
protect against interruptions or busy resources during read or write.
This should also make UNIX socket support more stable on certain target
architectures.
Added defensive logic to cleanup internal resources for threads that
appear to have exited in an unsafe manner (and that may have left
forks::shared resources in a unclean state) or were terminated with SIGKILL.
Rewrote _length(), _send(), and _receive() internal functions to protect
against signal interruptions, busy resources, socket disconnections, full
socket buffers, and miscellaneous socket errors, including adding retry
logic where appropriate.
Updated _join() server function with much more intelligent logic regarding
the state of a thread during the join process and a few more error cases
that it needed to check for.
threads->yield() now does a 1 ms sleep.
***** Threads API consistency changes *****
Can now signal unlocked variable using cond_signal and cond_broadcast.
Note: Signaling locked returns 1; signaling unlocked returns undef.
Modified lock, cond_signal, and cond_broadcast to return undef (instead
of 1) to be consistent with threads.pm.
Overloaded != for thread objects.
A failed thread spawn (fork) now prints a warning and returns undef
instead of dieing out.
Detach twice on the same thread now throws an error.
Improved format and content of internal warnings, and warnings now
respect warnings state in caller for category 'threads'.
Bumped threads $VERSION to 1.26, threads::shared to 1.04 to match
version-supported features and behavior.
*** Miscellaneous changes ***
Implemented initial framework for better message handling. This should
help reduce overall CPU usage, and hopefully improve performance, using
custom filter definition for request and response messages that do not
require Storable freeze/thaw. Requests that currently implement this
are: _lock and _unlock. Responses that currently implement this are:
any generic boolean response.
Made Time::HiRes a prerequisite now. This means that fractional
cond_timedwait is now supported by default.
Optimized sigset masking: now only one set is created at compile time
and reused during execution.
Now safely runs in taint mode when any potentially tainted environment
vars are defined.
Suppressing unnecessary warnings in the case that 'test' does not exist
in /bin or /usr/bin.
Silenced thread socket errors during thread shutdown process, unless
debugging is enabled.
Added basic blocking join poll checks, to help prevent against forever
blocking join() cases in abnormal thread death circumstances.
Thread shutdown now expects a response (to insure synchronized shutdown
agreement with server process).
General improvements in thread shutdown stability (primarily server-side).
0.20 5 October 2006
Fixed rare thread start race condition where parent thread would block
indefinitely if child thread were to spawn, complete, and exit before
the parent could obtain the TID associated with the child thread.
Corrected a few cases in server timedwait handling, cond_broadcast,
and cond_signal where a lock could be prematurely transferred to
another thread if the main thread (tid 0) were holding the lock at
the time the event expired.
Modified cond_timedwait to support fractional seconds (if Time::HiRes
is loaded before forks).
Minor changes to forks.xs for backwards compatibility with gcc 2.96.
Minor cleanup in (forks.xs) bless reference handling.
When using INET sockets, peer address is validated against the loopback
address (IPv4 127.0.0.1) before accepting the connection; otherwise,
socket is immediately closed and a warning is emitted.
Added THREADS_IP_MASK env param to allow override of default IP mask
filter.
Misc cleanup of internal server environment variable handling.
Moved some server code into separate subroutines.
0.19 21 May 2006
Implemented an exported bless() function allow transparent bless()
across threads with forks::shared.
Implemented exported is_shared function in forks::shared.
Implemented custom CHLD signal handler to cleanup zombie process.
This change was introduced to resolve an issue on some platforms
where using $SIG{CHLD}='IGNORE' resulted in the perl core system()
function returning -1 instead of the exit code of the system call.
This signal handler is only used if the target system's system()
call returns -1 on success when $SIG{CHLD}='IGNORE'.
Added THREADS_SIGCHLD_IGNORE to allow users to force forks to use
$SIG{CHLD}='IGNORE' on systems where a custom CHLD signal handler
is automatically installed to support correct exit code of perl
core system() function.
Added THREADS_NICE env param to allow user to adjust forks.pm server
process POSIX::nice value when running as root. If unset, no change
is made to the server process priority. This differs from the
historical behavior of forks.pm defaulting to nice -19 when run as
root.
Patched XS code to be ANSI C86 compliant (again). Code was unintentionally
changed to require a minimum of ANSI C89 compliance since 0.17. This
should allow all gcc 2.95.x and other C86-compliant compilers to once
again build forks.pm.
Fixed prototype mismatch warning when disabling cond_wait when forks
is not used before forks::shared.
Added patch to quietly ignore sharing an already shared variable.
forks::shared used to bombs out in such cases (e.g. $a:shared; share($a);).
Updated to ppport.h 3.06.
Implemented separate package versions for forks and threads. threads
package version will represent the most recent threads.pm release that
this module is functionally compatible with.
Disabled call to server process on shared variable DESTROY calls to
decrease server communication load, as none of the affected TIE classes
implement custom DESTROY methods.
0.18 7 December 2005
Introduction of UNIX socket support. Socket descriptors are written
to /var/tmp and given rw access by all by default for best support
on multi-user systems.
Importing SOMAXCONN and using for socket server listener max socket
connections (was hard coded at 10) for best (and system-level flexible)
thread spawn stability under high load.
0.17 14 May 2005 (unreleased)
Added method cond_timedwait and added second forms of cond_wait and
cond_timedwait per the ithread specification (where signal var
differs from lock var). All elements of perl ithread interface are
now implemented, with respect to perl 5.8.7.
Added eval wrapper around new thread code execution to trap die
events; thus, join() is now more robust (fewer chances for runtime
hangs on '$thread->join' due to premature child thread termination).
Fixed bug in _islocked in case where if main thread tried to unlock
an already unlocked variable, it would not correctly enter if case
and return undef or croak() due to undef value in @LOCKED resolving
to numeric 0.
0.16 8 April 2004
Changed semantics of debugging function: must now specify environment
variable THREADS_DEBUG to be able to enable and disable debugging.
If the environment variable does not exist at compile time, then all
of the debugging code is optimised away. So performance in production
environments should be better than before.
29 March 2004
Goto &sub considered evil with regards to performance and memory
leaking. Therefore removed goto's where appropriate.
0.15 14 January 2004
Just got too much mail from people attempting to use forks.pm on
Windows. Decided to add check for Win32 to Makefile.PL to have it
die when attempting to run on Windows. Added documentation to
explain this.
0.14 7 January 2004
Removed dependency on load.pm: it really doesn't make sense in a
forked environment: I don't know what I was thinking in that respect.
Added dependency on IO::Socket 1.18: we do need auto-flushing sockets
(which seems to be pretty standard nowadays, but just to make sure).
Fixed problem with large values / structures being passed with some
help from Jan-Pieter Cornet at the Amsterdam PM Meeting. Spotted by
Paul Golds. Added test for it.
0.13 4 January 2004
Looked at fixing the problem with signalling unlocked variables.
Unfortunately, there does not seem to be a quick solution. Need to
abandon this idea right now until I have more time. Updated
documentation to let the world know there is an inconsistency.
Documented the THREADS_DEBUG environment variable and made sure it is
unset during testing.
Updated ppport.h to 2.009. Didn't expect any problems with 5.8.1,
but you never know.
0.12 2 January 2004
Fixed problem with signalling thread 0. Spotted by Stephen Adkins.
0.11 28 December 2003
Added automatic required modules update using Devel::Required.
Added requirement for Devel::Required, so that optional modules
are listed as required on the appropriate systems.
0.10 11 November 2003
Added check for processes dieing at the length check of a message.
Not 100% sure whether this will be the best way to handle the main
thread dieing, e.g. when it exits before all threads have been
joined.
0.09 24 October 2003
Apparently, Test::Harness cannot handle testing "threaded" scripts
using an unthreaded Perl. Added test for threadedness of the Perl
being used: if so, skips testing Thread::Queue. Spotted by several
CPAN testers.
0.08 24 October 2003
Shared entities that were also blessed as an object, were not
correctly handled (ref() versus Scalar::Util::reftype() ). Spotted
by Jack Steadman. Now fixed by using reftype() rather than ref().
Dependency on Scalar::Util added (not sure when that became core).
Added tests to excercise Thread::Queue (if available).
10 October 2003
Changed async() to make it a little faster by removing an extra call
from the stack.
0.07 27 September 2003
Added error detection in case lock or cond_xxx were called on unshared
variables or cond_xxx were called on an unlocked variable. Added tests
for it in the test-suite.
Added dummy package declaration to forks::shared.pm for CPAN's sake.
Cleaned up the attribute handler code in forks::shared.pm a bit.
0.06 27 September 2003
Finally grokked the documentation about attributes. This allowed me
to finally write the handler for the ":shared" attribute. Which in
the end turned out to be surprisingly simple.
Adapted the test-suite to test usage of the ":shared" attribute as
opposed to sharing variables with the "share" subroutine.
0.05 26 September 2003
Increased dependency on load.pm to 0.11: versions of load.pm before
that had issues with running under taint.
Debug statements can now be activated by setting the environment
variable THREADS_DEBUG to true. As this is still experimental, this
feature is only described in the CHANGELOG for now.
Fixed several issues when running under taint. Test-suite now runs
in tainted mode just to be on the safe side.
Removed some debug statements from the test-suite.
0.04 10 August 2003
Implemented .xs file munging and source-filter to be able to truly
support forks.pm under Perl 5.6.x. Thanks to Juerd Waalboer for the
idea of the source filter.
It is now confirmed that forks.pm won't work under 5.005, so the
minimum version of Perl is now set to 5.6.0 in the Makefile.PL.
7 August 2003
Tested under 5.8.1-RC4. The WHOA! messags seem to have disappeared
but instead a warning has appeared that cannot be suppressed. This
was caused by my attempt to activate the :shared attribute. Since
that doesn't work anyway, I removed the offending code and the
warning went away.
Fixed some warnings in the test-suite.
Fixed another warning in forks.pm. Reported by Bradley W. Langhorst.
0.03 2 April 2003
Fixed a warning in forks.pm. Reported by Bradley W. Langhorst.
0.02 17 January 2003
Added dummy -package forks- to forks.pm to fool CPAN into thinking
it really is the forks.pm module, when in fact it is of course
threads.pm.
Fixed some warnings in t/forks01.t.
28 October 2002
Made sure length packing uses Network order.
0.01 27 October 2002
First public version of forks.pm. Thanks to Lars Fenneberg for all
the help so far.