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###############################################################################
# Bug#17283409  4-WAY DEADLOCK: ZOMBIES, PURGING BINLOGS, SHOW PROCESSLIST,
#                        SHOW BINLOGS
# Problem:  A deadlock was occuring when 4 threads were involved in acquiring
#                locks
#     Thread 1: Dump thread ( Slave is reconnecting, so on Master, a new dump
#                    thread is trying kill zombie dump threads. It acquired
#                    thread's LOCK_thd_data and it is about to acquire
#                    mysys_var->current_mutex ( which LOCK_log)
#     Thread 2: Application thread is executing show binlogs and acquired
#                    LOCK_log and it is about to acquire LOCK_index.
#     Thread 3: Applicaiton thread is executing Purge binary logs and acquired
#                    LOCK_index and it is about to acquire LOCK_thread_count.
#     Thread 4: Application thread is executing show processlist and acquired
#                    LOCK_thread_count and it is about to acquire zombie dump
#                    thread's LOCK_thd_data.
#     Deadlock : Thread 1 -> Thread 2 -> Thread 3-> Thread 4 -> Thread 1
# The same above deadlock was observed when thread 4 is replaced with another
# thread which is executing 'SELECT * FROM information_schema.processlist'
# command and acquired LOCK_thread_count and it is about to acquire zombie
# dump thread's LOCK_thd_data.
# Fix: Introuced a new lock (Lock_thread_remove) which will guard the thread
# deletion (exit process) and the same lock is used in show processlist
# execution instead of LOCK_thread_count. i.e., After the patch, Server allows
# new threads to join the system but it will not any threads to execute its
# 'cleanup' process.  Now the new lock order is: LOCK_thread_remove ->
# LOCK_thd_data -> LOCK_log -> LOCK_index -> LOCK_thread_count Both the above
# scenarios are tested with the below test code and it proves that there is no
# deadlock after the fix.
###############################################################################
--source include/have_debug_sync.inc
--source include/have_binlog_format_statement.inc
--source include/master-slave.inc

connect(master2,127.0.0.1,root,,test,$MASTER_MYPORT,);
connect(master3,127.0.0.1,root,,test,$MASTER_MYPORT,);
--connection master
# Create atleast one binary log, otherwise purge logs command, show binary
# logs command do not hit the DEBUG_SYNC points.
FLUSH LOGS;
SET @save_debug=@@global.debug;
SET GLOBAL DEBUG='+d,before_dump_thread_acquires_current_mutex,processlist_acquiring_dump_threads_LOCK_thd_data';

# Iteration 1 with "SHOW PROCESSLIST command"
# Iteration 2 with "SELECT * FROM information_schema.processlist"
--let $iter=2
while ($iter)
{
  --connection slave
  --source include/stop_slave.inc
  --source include/start_slave.inc
  # Thread 1
  --connection master
  --echo "Wait_for dump_thread_signal"
  SET DEBUG_SYNC='now WAIT_FOR dump_thread_signal';

  # Thread 2
  --connection master1
  SET DEBUG_SYNC='show_binlogs_after_lock_log_before_lock_index SIGNAL parked1 WAIT_FOR go';
  --send SHOW BINARY LOGS

  --connection master
  echo "Wait_for parked1";
  SET DEBUG_SYNC='now WAIT_FOR parked1';

  # Thread 3
  --connection master2
  SET DEBUG_SYNC='purge_logs_after_lock_index_before_thread_count SIGNAL parked2 WAIT_FOR go';
  --send PURGE BINARY LOGS BEFORE '9999-12-31'

  --connection master
  echo "Wait_for parked2";
  SET DEBUG_SYNC='now WAIT_FOR parked2';

  # Thread 4
  --connection master3
  SET DEBUG_SYNC='processlist_after_LOCK_thd_count_before_LOCK_thd_data SIGNAL parked3 WAIT_FOR go';
  if ($iter == 1)
  {
    --let $query=SHOW PROCESSLIST
  }
  if ($iter == 2)
  {
    --let $query=SELECT * FROM information_schema.processlist
  }
  --send_eval $query

  --connection master
  echo "Wait_for parked3";
  SET DEBUG_SYNC='now WAIT_FOR parked3';

  --connection master
  SET DEBUG_SYNC='now SIGNAL go';

  # Output of each command vary depends on other tests ran in suite(output vary
  # in Pb2 runs), so lets ignore output. Anyways, we are interested in seeing
  # that there is no deadlock.
  --disable_result_log
  --connection master1
  --reap
  --connection master2
  --reap
  --connection master3
  --reap
  --enable_result_log

  --dec $iter
}

--echo "Cleanup"
--disconnect master2
--disconnect master3

--connection master
SET DEBUG_SYNC='RESET';
SET GLOBAL DEBUG=@save_debug;
source include/rpl_end.inc;