函数sem_wait( sem_t *sem )被用来阻塞当前线程直到信号量sem的值大于0,解除阻塞后将sem的值减一,表明公共资源经使用后减少。函数sem_trywait ( sem_t *sem )是函数sem_wait()的非阻塞版本,它直接将信号量sem的值减一。 函数sem_destroy(sem_t *sem)用来释放信号量sem。 信号量用sem_init函数创建的,下...
执行器、索引管理等，目前主要负责CDW PG优化器方面的研发工作。
wait_event_type|wait_event|state |query |datid |datname|pid |leader_pid|usesysid|usename|application_name |client_addr |client_hostname|client_port|backend_start |xact_start |query_start |state_change |wait_event_type|wait_event|state |backend_xid|backend_xmin|query |backend_type | ---...
wait_event|ClientRead state|idleintransactionbackend_xid|1286297004backend_xmin|query|truncatea;backend_type|client backend 如果当前状态没有找到具体是哪条SQL导致的锁,则需要从审计日志中查找(开启log_statements='all')。重点关注wait_event_type和state字段。这里说明该holder执行完事务后处于空闲状态,正等待客...
Wait Event TypeWait Event NameDescription LWLock ShmemIndexLock Waiting to find or allocate space in shared memory. OidGenLock Waiting to allocate or assign an OID. XidGenLock Waiting to allocate or assign a transaction id. ProcArrayLock Waiting to get a snapshot or clearing a transaction id ...
WaitEventSet的等待超时如何实现?我们了解到,它和epoll有关,首先先了解下epoll_wait这个函数:int epoll_wait( int epfd,//epoll_create函数返回的epoll实例的句柄 struct epoll_event * events, //出参。Epoll将发生的事件集合从内核复制到该数组 int maxevents,...
Wait eventDefinition Client:ClientRead This event occurs when Aurora PostgreSQL is waiting to receive data from the client. Client:ClientWrite This event occurs when Aurora PostgreSQL is waiting to write data to the client. CPU This event occurs when a thread is active in CPU or is waiting for...
This wait event occurs when operations write to the temporary files. For more information, see IO:BufFileRead and IO:BufFileWrite. IO:ControlFileRead A process is waiting for a read from the pg_control file. IO:ControlFileSync A process is waiting for the pg_control file to reach durable...
wait_event_type : 会话状态,Lock表示被阻塞无法获取锁资源 wait_event : 等待事件 query : 会话执行相关查询 ## 事务三查看锁等待 ## 可以看到28363会话正在等待27152会话 db1=# select pid,pg_blocking_pids(pid),wait_event_type,wait_event,query from pg_stat_activity ; ...
wait_event_type "wait_event_type(等待类型)" --,a.wait_event "wait_event(等待事件)" --,a.state "state(状态)" --,a.query "sql(执行的sql)" --,a.backend_type "backend_type(后端类型)" from pg_stat_activity a left join pg_roles b on (a.usesysid = b.oid) where a.state = '...