一、问题

是什么

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二、找到影响位置

整个寻找过程应该找到key_BINLOG_COND_done这个取值，然后去看他是在那里被定义到相应的mutex/cond上，然后查找mutex/cond的作用即可。

• 定义：
  static PSI_cond_info all_server_conds[]=
  {
  { &key_PAGE_cond, “PAGE::cond”, 0},
  { &key_COND_active, “TC_LOG_MMAP::COND_active”, 0},
  { &key_COND_pool, “TC_LOG_MMAP::COND_pool”, 0},
  { &key_BINLOG_COND_done, “MYSQL_BIN_LOG::COND_done”, 0},
  { &key_BINLOG_update_cond, “MYSQL_BIN_LOG::update_cond”, 0},

• 注册：
  register_cond_class

• 初始化：

MYSQL_BIN_LOG::set_psi_keys

• 建立条件变量：

Stage_manager::init

• 使用：

  */
  if (!leader) //如果不是 leader
  {
    mysql_mutex_lock(&m_lock_done);//加锁
    while (thd->get_transaction()->m_flags.pending) //唤醒时 设置每个事物的状态 为ture
      mysql_cond_wait(&m_cond_done, &m_lock_done);//释放锁 等待条件满足 pending=false
    mysql_mutex_unlock(&m_lock_done);//解锁 
  }

• 栈帧

Breakpoint 2, MYSQL_BIN_LOG::set_psi_keys (this=0x2e83640, key_LOCK_index=7, key_LOCK_commit=3, key_LOCK_commit_queue=4, key_LOCK_done=5, key_LOCK_flush_queue=6, 
    key_LOCK_log=8, key_LOCK_binlog_end_pos=9, key_LOCK_sync=10, key_LOCK_sync_queue=11, key_LOCK_xids=12, key_COND_done=4, key_update_cond=5, key_prep_xids_cond=6, 
    key_file_log=2, key_file_log_index=4, key_file_log_cache=3, key_file_log_index_cache=5) at /mysqldata/percona-server-locks-detail-5.7.22/sql/binlog.h:539
539         m_key_COND_done= key_COND_done;
(gdb) bt
#0  MYSQL_BIN_LOG::set_psi_keys (this=0x2e83640, key_LOCK_index=7, key_LOCK_commit=3, key_LOCK_commit_queue=4, key_LOCK_done=5, key_LOCK_flush_queue=6, 
    key_LOCK_log=8, key_LOCK_binlog_end_pos=9, key_LOCK_sync=10, key_LOCK_sync_queue=11, key_LOCK_xids=12, key_COND_done=4, key_update_cond=5, key_prep_xids_cond=6, 
    key_file_log=2, key_file_log_index=4, key_file_log_cache=3, key_file_log_index_cache=5) at /mysqldata/percona-server-locks-detail-5.7.22/sql/binlog.h:539
#1  0x0000000000edcee4 in init_common_variables () at /mysqldata/percona-server-locks-detail-5.7.22/sql/mysqld.cc:2974
#2  0x0000000000ee117f in mysqld_main (argc=82, argv=0x2f26738) at /mysqldata/percona-server-locks-detail-5.7.22/sql/mysqld.cc:4938
#3  0x0000000000ed8504 in main (argc=4, argv=0x7fffffffe3f8) at /mysqldata/percona-server-locks-detail-5.7.22/sql/main.cc:25
建立条件变量
Breakpoint 3, Stage_manager::init (this=0x2e84858, key_LOCK_flush_queue=6, key_LOCK_sync_queue=11, key_LOCK_commit_queue=4, key_LOCK_done=5, key_COND_done=4)
    at /mysqldata/percona-server-locks-detail-5.7.22/sql/binlog.h:156
156         mysql_mutex_init(key_LOCK_done, &m_lock_done, MY_MUTEX_INIT_FAST);
(gdb) bt
#0  Stage_manager::init (this=0x2e84858, key_LOCK_flush_queue=6, key_LOCK_sync_queue=11, key_LOCK_commit_queue=4, key_LOCK_done=5, key_COND_done=4)
    at /mysqldata/percona-server-locks-detail-5.7.22/sql/binlog.h:156
#1  0x000000000187cbea in MYSQL_BIN_LOG::init_pthread_objects (this=0x2e83640) at /mysqldata/percona-server-locks-detail-5.7.22/sql/binlog.cc:3601
#2  0x0000000000edcef3 in init_common_variables () at /mysqldata/percona-server-locks-detail-5.7.22/sql/mysqld.cc:2983
#3  0x0000000000ee117f in mysqld_main (argc=82, argv=0x2f26738) at /mysqldata/percona-server-locks-detail-5.7.22/sql/mysqld.cc:4938
#4  0x0000000000ed8504 in main (argc=4, argv=0x7fffffffe3f8) at /mysqldata/percona-server-locks-detail-5.7.22/sql/main.cc:25

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