Postgresql lock锁等待检查

2022-05-19 05:06:54

查看锁等待sql

with    
t_wait as    
(    
  select a.mode,a.locktype,a.database,a.relation,a.page,a.tuple,a.classid,a.granted,   
  a.objid,a.objsubid,a.pid,a.virtualtransaction,a.virtualxid,a.transactionid,a.fastpath,    
  b.state,b.query,b.xact_start,b.query_start,b.usename,b.datname,b.client_addr,b.client_port,b.application_name   
    from pg_locks a,pg_stat_activity b where a.pid=b.pid and not a.granted   
),   
t_run as   
(   
  select a.mode,a.locktype,a.database,a.relation,a.page,a.tuple,a.classid,a.granted,   
  a.objid,a.objsubid,a.pid,a.virtualtransaction,a.virtualxid,a.transactionid,a.fastpath,   
  b.state,b.query,b.xact_start,b.query_start,b.usename,b.datname,b.client_addr,b.client_port,b.application_name   
    from pg_locks a,pg_stat_activity b where a.pid=b.pid and a.granted   
),   
t_overlap as   
(   
  select r.* from t_wait w join t_run r on   
  (   
    r.locktype is not distinct from w.locktype and   
    r.database is not distinct from w.database and   
    r.relation is not distinct from w.relation and   
    r.page is not distinct from w.page and   
    r.tuple is not distinct from w.tuple and   
    r.virtualxid is not distinct from w.virtualxid and   
    r.transactionid is not distinct from w.transactionid and   
    r.classid is not distinct from w.classid and   
    r.objid is not distinct from w.objid and   
    r.objsubid is not distinct from w.objsubid and   
    r.pid <> w.pid   
  )    
),    
t_unionall as    
(    
  select r.* from t_overlap r    
  union all    
  select w.* from t_wait w    
)    
select locktype,datname,relation::regclass,page,tuple,virtualxid,transactionid::text,classid::regclass,objid,objsubid,   
string_agg(   
'Pid: '||case when pid is null then 'NULL' else pid::text end||chr(10)||   
'Lock_Granted: '||case when granted is null then 'NULL' else granted::text end||' , Mode: '||case when mode is null then 'NULL' else mode::text end||' , FastPath: '||case when fastpath is null then 'NULL' else fastpath::text end||' , VirtualTransaction: '||case when virtualtransaction is null then 'NULL' else virtualtransaction::text end||' , Session_State: '||case when state is null then 'NULL' else state::text end||chr(10)||   
'Username: '||case when usename is null then 'NULL' else usename::text end||' , Database: '||case when datname is null then 'NULL' else datname::text end||' , Client_Addr: '||case when client_addr is null then 'NULL' else client_addr::text end||' , Client_Port: '||case when client_port is null then 'NULL' else client_port::text end||' , Application_Name: '||case when application_name is null then 'NULL' else application_name::text end||chr(10)||    
'Xact_Start: '||case when xact_start is null then 'NULL' else xact_start::text end||' , Query_Start: '||case when query_start is null then 'NULL' else query_start::text end||' , Xact_Elapse: '||case when (now()-xact_start) is null then 'NULL' else (now()-xact_start)::text end||' , Query_Elapse: '||case when (now()-query_start) is null then 'NULL' else (now()-query_start)::text end||chr(10)||    
'SQL (Current SQL in Transaction): '||chr(10)||  
case when query is null then 'NULL' else query::text end,    
chr(10)||'--------'||chr(10)    
order by    
  (  case mode    
    when 'INVALID' then 0   
    when 'AccessShareLock' then 1   
    when 'RowShareLock' then 2   
    when 'RowExclusiveLock' then 3   
    when 'ShareUpdateExclusiveLock' then 4   
    when 'ShareLock' then 5   
    when 'ShareRowExclusiveLock' then 6   
    when 'ExclusiveLock' then 7   
    when 'AccessExclusiveLock' then 8   
    else 0   
  end  ) desc,   
  (case when granted then 0 else 1 end)  
) as lock_conflict  
from t_unionall   
group by   
locktype,datname,relation,page,tuple,virtualxid,transactionid::text,classid,objid,objsubid;

如果觉得写SQL麻烦，可以将它创建为视图

create view v_locks_monitor as   
with    
t_wait as    
(    
  select a.mode,a.locktype,a.database,a.relation,a.page,a.tuple,a.classid,a.granted,   
  a.objid,a.objsubid,a.pid,a.virtualtransaction,a.virtualxid,a.transactionid,a.fastpath,    
  b.state,b.query,b.xact_start,b.query_start,b.usename,b.datname,b.client_addr,b.client_port,b.application_name   
    from pg_locks a,pg_stat_activity b where a.pid=b.pid and not a.granted   
),   
t_run as   
(   
  select a.mode,a.locktype,a.database,a.relation,a.page,a.tuple,a.classid,a.granted,   
  a.objid,a.objsubid,a.pid,a.virtualtransaction,a.virtualxid,a.transactionid,a.fastpath,   
  b.state,b.query,b.xact_start,b.query_start,b.usename,b.datname,b.client_addr,b.client_port,b.application_name   
    from pg_locks a,pg_stat_activity b where a.pid=b.pid and a.granted   
),   
t_overlap as   
(   
  select r.* from t_wait w join t_run r on   
  (   
    r.locktype is not distinct from w.locktype and   
    r.database is not distinct from w.database and   
    r.relation is not distinct from w.relation and   
    r.page is not distinct from w.page and   
    r.tuple is not distinct from w.tuple and   
    r.virtualxid is not distinct from w.virtualxid and   
    r.transactionid is not distinct from w.transactionid and   
    r.classid is not distinct from w.classid and   
    r.objid is not distinct from w.objid and   
    r.objsubid is not distinct from w.objsubid and   
    r.pid <> w.pid   
  )    
),    
t_unionall as    
(    
  select r.* from t_overlap r    
  union all    
  select w.* from t_wait w    
)    
select locktype,datname,relation::regclass,page,tuple,virtualxid,transactionid::text,classid::regclass,objid,objsubid,   
string_agg(   
'Pid: '||case when pid is null then 'NULL' else pid::text end||chr(10)||   
'Lock_Granted: '||case when granted is null then 'NULL' else granted::text end||' , Mode: '||case when mode is null then 'NULL' else mode::text end||' , FastPath: '||case when fastpath is null then 'NULL' else fastpath::text end||' , VirtualTransaction: '||case when virtualtransaction is null then 'NULL' else virtualtransaction::text end||' , Session_State: '||case when state is null then 'NULL' else state::text end||chr(10)||   
'Username: '||case when usename is null then 'NULL' else usename::text end||' , Database: '||case when datname is null then 'NULL' else datname::text end||' , Client_Addr: '||case when client_addr is null then 'NULL' else client_addr::text end||' , Client_Port: '||case when client_port is null then 'NULL' else client_port::text end||' , Application_Name: '||case when application_name is null then 'NULL' else application_name::text end||chr(10)||    
'Xact_Start: '||case when xact_start is null then 'NULL' else xact_start::text end||' , Query_Start: '||case when query_start is null then 'NULL' else query_start::text end||' , Xact_Elapse: '||case when (now()-xact_start) is null then 'NULL' else (now()-xact_start)::text end||' , Query_Elapse: '||case when (now()-query_start) is null then 'NULL' else (now()-query_start)::text end||chr(10)||    
'SQL (Current SQL in Transaction): '||chr(10)||  
case when query is null then 'NULL' else query::text end,    
chr(10)||'--------'||chr(10)    
order by    
  (  case mode    
    when 'INVALID' then 0   
    when 'AccessShareLock' then 1   
    when 'RowShareLock' then 2   
    when 'RowExclusiveLock' then 3   
    when 'ShareUpdateExclusiveLock' then 4   
    when 'ShareLock' then 5   
    when 'ShareRowExclusiveLock' then 6   
    when 'ExclusiveLock' then 7   
    when 'AccessExclusiveLock' then 8   
    else 0   
  end  ) desc,   
  (case when granted then 0 else 1 end)  
) as lock_conflict  
from t_unionall   
group by   
locktype,datname,relation,page,tuple,virtualxid,transactionid::text,classid,objid,objsubid ;

eg：

create table table_lock(id int primary key, info text);  
insert into table_lock values (1,'a');  
  
#session A
begin;  
update table_lock set info='aa' where id=1;  
select * from table_lock;  

#session B
begin;
select * from table_lock;  
 
#session C
begin;
insert into table_lock values (2,'b');  

#session D
begin;  
truncate table_lock;  
  
waiting......  
#or
#ALTER TABLE XXX RENAME TO XXXXX;

#session E
select * from table_lock;  
  
waiting......

eg：

Pid: 1980
Lock_Granted: false , Mode: AccessExclusiveLock , FastPath: false , VirtualTransaction: 9/4 , Session_State: active
Username: test , Database: postgres , Client_Addr: NULL , Client_Port: -1 , Application_Name: psql
Xact_Start: 2019-02-11 15:35:33.054468+08 , Query_Start: 2019-02-11 15:35:34.283192+08 , Xact_Elapse: 00:01:18.422846 , Query_Elapse: 00:01:17.194122
SQL (Current SQL in Transaction): 
truncate table_lock;
--------
Pid: 1894
Lock_Granted: true , Mode: RowExclusiveLock , FastPath: false , VirtualTransaction: 5/128 , Session_State: idle in transaction
Username: test , Database: postgres , Client_Addr: NULL , Client_Port: -1 , Application_Name: psql
Xact_Start: 2019-02-11 15:17:48.342793+08 , Query_Start: 2019-02-11 15:17:48.344543+08 , Xact_Elapse: 00:19:03.134521 , Query_Elapse: 00:19:03.132771
SQL (Current SQL in Transaction): 
insert into table_lock values (2,'b');
--------
# 处理方法
# 1. 前面的锁查询SQL，已经清晰的显示了每一个发生了锁等待的对象，Lock_Granted: true阻塞了Lock_Granted: false
# 2. 同时按锁的大小排序，第一行的锁最大（Mode: AccessExclusiveLock级别最高）
# 要快速解出这种状态，terminate最大的锁对应的PID即可。

postgres=# select pg_terminate_backend(1980);
-[ RECORD 1 ]--------+--
pg_terminate_backend | t

or

服务器查看

[postgres@pg2 data]$ ps -ef |grep idle |grep -v grep
postgres  1953  1887  0 13:42 ?        00:00:00 postgres: pg postgres [local] idle
postgres  2066  1887  0 14:52 ?        00:00:00 postgres: pg postgres 192.168.6.1(53182) idle in transaction
[postgres@pg2 data]$ ps -ef |grep idle |grep -v grep
postgres  2066  1887  0 14:52 ?        00:00:00 postgres: pg postgres 192.168.6.1(53182) idle in transaction
[postgres@pg2 data]$

idle in transaction状态

查看状态可用以下语句

select pid, state from pg_stat_activity;

杀掉阻塞进程

select pg_terminate_backend(2066);

注意：此处不要使用操作系统命令kill -9,其会造成所有活动进程被终止，数据库重启。

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