session_dictionary.slap randomly failing

#0 0x0000003b9e20c94c in pthread_kill () from /lib64/libpthread-2.12.90.so
#1 0x00000000008dd1f1 in write_core (sig=11) at drizzled/signal_handler.cc:98
#2 0x00000000008dd3d5 in drizzled_handle_segfault (sig=11) at drizzled/signal_handler.cc:156
#3 <signal handler called>
#4 0x0000000000000000 in ?? ()
#5 0x000000000072296c in boost::detail::sp_counted_base::release (this=0x36aafd0) at /usr/include/boost/smart_ptr/detail/sp_counted_base_gcc_x86.hpp:145
#6 0x00000000007229fb in boost::detail::shared_count::~shared_count (this=0x7f4f2fffe1a8, __in_chrg=<value optimized out>) at /usr/include/boost/smart_ptr/detail/shared_count.hpp:217
#7 0x000000000078327a in boost::shared_ptr<std::basic_string<char, std::char_traits<char>, std::allocator<char> > const>::~shared_ptr (this=0x7f4f2fffe1a0, __in_chrg=<value optimized out>) at /usr/include/boost/smart_ptr/shared_ptr.hpp:169
#8 0x0000000000b8106d in ProcesslistTool::Generator::populate (this=0x7f4f0802a550) at plugin/session_dictionary/processlist.cc:84
#9 0x00000000008baa48 in drizzled::plugin::TableFunction::Generator::sub_populate (this=0x7f4f0802a550, field_size=9) at drizzled/plugin/table_function.cc:163
#10 0x00000000009c151d in FunctionCursor::rnd_next (this=0x7f4f1c00c9e0) at plugin/function_engine/cursor.cc:87
#11 0x00000000008c3a2c in drizzled::rr_sequential (info=0x7f4f08007a48) at drizzled/records.cc:273
#12 0x0000000000904dba in drizzled::sub_select (join=0x7f4f08005460, join_tab=0x7f4f080079c0, end_of_records=false) at drizzled/sql_select.cc:3335
#13 0x00000000009049a2 in drizzled::do_select (join=0x7f4f08005460, fields=0x0, table=0x7f4f08029270) at drizzled/sql_select.cc:3095
#14 0x000000000083fee7 in drizzled::Join::exec (this=0x7f4f08005460) at drizzled/join.cc:1334
#15 0x00000000008fe72a in drizzled::mysql_select (session=0x36ab350, rref_pointer_array=0x36ac138, tables=0x7f4f08004fc0, wild_num=0, fields=..., conds=0x0, og_num=1, order=0x7f4f08005360, group=0x0, having=0x0, select_options=2147500032, result=0x7f4f08005440, unit=0x36abd80, select_lex=0x36abf80) at drizzled/sql_select.cc:430
#16 0x00000000008fe03d in drizzled::handle_select (session=0x36ab350, lex=0x36abd60, result=0x7f4f08005440, setup_tables_done_option=0) at drizzled/sql_select.cc:149
#17 0x00000000008fa7c7 in drizzled::execute_sqlcom_select (session=0x36ab350, all_tables=0x7f4f08004fc0) at drizzled/sql_parse.cc:544
#18 0x0000000000952637 in drizzled::statement::Select::execute (this=0x7f4f08006ff0) at drizzled/statement/select.cc:32
#19 0x00000000008fa465 in drizzled::mysql_execute_command (session=0x36ab350) at drizzled/sql_parse.cc:479
#20 0x00000000008fb0ad in drizzled::mysql_parse (session=0x36ab350, inBuf=0x7f4f08006df8 "SELECT a.ID FROM data_dictionary.processlist as a, data_dictionary.processlist as b ORDER BY ID", length=95) at drizzled/sql_parse.cc:751
#21 0x00000000008f9d54 in drizzled::dispatch_command (command=drizzled::COM_QUERY, session=0x36ab350, packet=0x36b2c11 "SELECT a.ID FROM data_dictionary.processlist as a, data_dictionary.processlist as b ORDER BY ID", packet_length=95) at drizzled/sql_parse.cc:227
#22 0x00000000008ca54e in drizzled::Session::executeStatement (this=0x36ab350) at dri...

See https://svn.boost.org/trac/boost/ticket/4415

I believe boost::weak_ptr needs to be used in our implementation, but I need to find out more about it.

To reproduce "./dtr --suite=session_dictionary slap --repeat-test=1000 --fast"

Attached thread apply all bt full output. My guess is thread 13 and thread 1 race or something similar.

ok, so copying a shared_ptr from another thread is not always a good idea. The internal accounting is thread-safe but if you reset() or delete whilst reading, this isn't thread safe.

This is causing lots of issues for the processlist table if sessions are in constant flux (created/deleted rapidly). Hence session_dictionay.slap test was failing randomly.

The fix I have committed fixes some of this and is crashes less-often, but it still can crash in other harder to fix places.

scrapping my work, have been working with krow on this in the background and he has a better solution

Re-assigning to Brian as he is working on a fix for this.

Setting as fixed released, this failure no longer happens

Brian is still seeing this when you run with --repeat=30