[Boost-bugs] [Boost C++ Libraries] #7657: Serious performance and memory consuption hit if condition_variable methods condition notify_one or notify_all is used repeatedly

Subject: [Boost-bugs] [Boost C++ Libraries] #7657: Serious performance and memory consuption hit if condition_variable methods condition notify_one or notify_all is used repeatedly
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2012-11-07 16:00:17

#7657: Serious performance and memory consuption hit if condition_variable methods
condition notify_one or notify_all is used repeatedly
-------------------------------------------------------+--------------------
 Reporter:  Petr Dannhofer <petr.dannhofer@…>          |       Owner:  anthonyw   
     Type:  Bugs                                       |      Status:  new        
Milestone:  To Be Determined                           |   Component:  thread     
  Version:  Boost 1.52.0                               |    Severity:  Showstopper
 Keywords:                                             |  
-------------------------------------------------------+--------------------
 platform: Win32, MSVS11

 condition_variable::generations member contains list of
 basic_cv_list_entry instances. As notify_one or notify_all is called, each
 instance member release is called, setting basic_cv_list_entry::notified
 member to true. There is no code which set basic_cv_list_entry::notified
 to false again, so the entry stays notified forever.

 Items from condition_variable::generations are deleted only when there are
 no waiters for the entry. The waiters are removed in
 entry_manager::~entry_manager. New addition to 1.52 version is that waiter
 is removed only if the entry is not notified (line 198
 thread/win32/condition_variable.hpp).

 As result, new entries are added for every get_wait_entry() call, which
 means for every wait call (as waiter can be added only to unnotified
 entry, which is the same story all over again),
 condition_variable::generations vector grows infinitely, consuming memory
 and processor time for useless searches for entries that could be removed.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/7657>
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