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PostgreSQL 锁等待跟踪

3 minute read

背景

PostgreSQL 在打印LONG SQL时，锁等待的时间也会算在内，并且目前在日志中没有将锁等待的时间单独打印出来。

shared_preload_libraries='auto_explain'  
auto_explain.log_min_duration='1s'  
auto_explain.log_analyze=true  
auto_explain.log_buffers=true  
auto_explain.log_timing=true  
auto_explain.log_triggers=true  
auto_explain.log_verbose=true  
auto_explain.log_nested_statements=true  
  
pg_ctl restart -m fast

例子:

session A:

postgres=# create table test2(id int, info text);  
CREATE TABLE  
postgres=# insert into test2 values (1,'test');  
INSERT 0 1  
postgres=# begin;  
BEGIN  
postgres=# update test2 set info='a' where id=1;  
UPDATE 1

session B:

postgres=# update test2 set info='b' ;  
wait

session A:

postgres=# end;  
COMMIT

session B:

UPDATE 1

查看日志如下：

2016-03-15 15:44:23.618 CST,"postgres","postgres",106815,"[local]",56e7bc6c.1a13f,3,"UPDATE",2016-03-15 15:40:28 CST,3/12,574614687,LOG,00000,"duration: 32038.420 ms  plan:  
Query Text: update test2 set info='b' ;  
Update on test2  (cost=0.00..22.70 rows=1270 width=10) (actual time=32038.418..32038.418 rows=0 loops=1)  
  Buffers: shared hit=5  
  ->  Seq Scan on test2  (cost=0.00..22.70 rows=1270 width=10) (actual time=0.014..0.015 rows=1 loops=1)  
        Buffers: shared hit=1",,,,,,,,"explain_ExecutorEnd, auto_explain.c:333","psql"  
2016-03-15 15:44:23.618 CST,"postgres","postgres",106815,"[local]",56e7bc6c.1a13f,4,"UPDATE",2016-03-15 15:40:28 CST,3/0,0,LOG,00000,"duration: 32039.289 ms  statement: update test2 set info='b' ;",,,,,,,,"exec_simple_query, postgres.c:1181","psql"

等待时间也被计算在内了。

如果要分析锁等待的话，最好加上如下参数：

log_lock_waits = on  
deadlock_timeout = 1s

那么在日志中，可以看到会话等待锁的时间超过deadlock_timeout时，会打印一条日志，告诉你在等待那个PID，等待什么锁：

2016-03-15 16:30:57.129 CST,"postgres","postgres",10220,"[local]",56e7c3df.27ec,32,"UPDATE waiting",2016-03-15 16:12:15 CST,3/17,574614691,LOG,00000,"process 10220 still waiting for ShareLock on transaction 574614690 after 1000.036 ms","Process holding the lock: 9725. Wait queue: 10220.",,,,"while updating tuple (0,5) in relation ""test2""","update test2 set info='b' ;",,"ProcSleep, proc.c:1323","psql"

在获取到锁之后，又会打印一条日志：

2016-03-15 16:32:36.323 CST,"postgres","postgres",10220,"[local]",56e7c3df.27ec,33,"UPDATE waiting",2016-03-15 16:12:15 CST,3/17,574614691,LOG,00000,"process 10220 acquired ShareLock on transaction 574614690 after 100194.020 ms",,,,,"while updating tuple (0,5) in relation ""test2""","update test2 set info='b' ;",,"ProcSleep, proc.c:1327","psql"

分析以上两条日志，和long sql的日志关联起来，就可以知道LONG SQL的锁等待花了多少时间。

如果要跟踪更详细的锁信息，需要修改一下头文件，重新编译：

vi src/include/pg_config_manual.h  
#define LOCK_DEBUG  
  
make clean  
make distclean  
configure again  
make -j 32  
make install -j 32  
  
vi $PGDATA/postgresql.conf  
trace_locks = true  

pg_ctl restart -m fast

以上CASE，可以跟踪到如下锁信息：

2016-03-15 16:12:08.389 CST,,,9725,"",56e7c3d8.25fd,1,"",2016-03-15 16:12:08 CST,,0,LOG,00000,"connection received: host=[local]",,,,,,,,"BackendInitialize, postmaster.c:4081",""  
2016-03-15 16:12:08.390 CST,"postgres","postgres",9725,"[local]",56e7c3d8.25fd,2,"authentication",2016-03-15 16:12:08 CST,2/11,0,LOG,00000,"connection authorized: user=postgres database=postgres",,,,,,,,"PerformAuthentication, postinit.c:259",""  
2016-03-15 16:12:08.391 CST,"postgres","postgres",9725,"[local]",56e7c3d8.25fd,3,"startup",2016-03-15 16:12:08 CST,2/0,0,LOG,00000,"LockReleaseAll: lockmethod=1",,,,,,,,"LockReleaseAll, lock.c:1951","psql"  
2016-03-15 16:12:08.391 CST,"postgres","postgres",9725,"[local]",56e7c3d8.25fd,4,"startup",2016-03-15 16:12:08 CST,2/0,0,LOG,00000,"LockReleaseAll done",,,,,,,,"LockReleaseAll, lock.c:2198","psql"  
2016-03-15 16:12:13.968 CST,"postgres","postgres",9725,"[local]",56e7c3d8.25fd,5,"UPDATE",2016-03-15 16:12:08 CST,2/12,0,LOG,00000,"LockAcquire: lock [13241,53029] RowExclusiveLock",,,,,,"update test2 set info='a' where id=1;",8,"LockAcquireExtended, lock.c:724","psql"  
2016-03-15 16:12:13.969 CST,"postgres","postgres",9725,"[local]",56e7c3d8.25fd,6,"UPDATE",2016-03-15 16:12:08 CST,2/12,0,LOG,00000,"LockAcquire: lock [13241,53029] RowExclusiveLock",,,,,,"update test2 set info='a' where id=1;",,"LockAcquireExtended, lock.c:724","psql"  
2016-03-15 16:12:15.815 CST,,,10220,"",56e7c3df.27ec,1,"",2016-03-15 16:12:15 CST,,0,LOG,00000,"connection received: host=[local]",,,,,,,,"BackendInitialize, postmaster.c:4081",""  
2016-03-15 16:12:15.816 CST,"postgres","postgres",10220,"[local]",56e7c3df.27ec,2,"authentication",2016-03-15 16:12:15 CST,3/15,0,LOG,00000,"connection authorized: user=postgres database=postgres",,,,,,,,"PerformAuthentication, postinit.c:259",""  
2016-03-15 16:12:15.817 CST,"postgres","postgres",10220,"[local]",56e7c3df.27ec,3,"startup",2016-03-15 16:12:15 CST,3/0,0,LOG,00000,"LockReleaseAll: lockmethod=1",,,,,,,,"LockReleaseAll, lock.c:1951","psql"  
2016-03-15 16:12:15.817 CST,"postgres","postgres",10220,"[local]",56e7c3df.27ec,4,"startup",2016-03-15 16:12:15 CST,3/0,0,LOG,00000,"LockReleaseAll done",,,,,,,,"LockReleaseAll, lock.c:2198","psql"  
2016-03-15 16:12:16.777 CST,"postgres","postgres",10220,"[local]",56e7c3df.27ec,5,"UPDATE",2016-03-15 16:12:15 CST,3/16,0,LOG,00000,"LockAcquire: lock [13241,53029] RowExclusiveLock",,,,,,"update test2 set info='b' ;",8,"LockAcquireExtended, lock.c:724","psql"  
2016-03-15 16:12:16.778 CST,"postgres","postgres",10220,"[local]",56e7c3df.27ec,6,"UPDATE",2016-03-15 16:12:15 CST,3/16,0,LOG,00000,"LockAcquire: lock [13241,53029] RowExclusiveLock",,,,,,"update test2 set info='b' ;",,"LockAcquireExtended, lock.c:724","psql"  
2016-03-15 16:12:16.778 CST,"postgres","postgres",10220,"[local]",56e7c3df.27ec,7,"UPDATE",2016-03-15 16:12:15 CST,3/16,574614689,LOG,00000,"LockAcquire: lock [13241,53029] ExclusiveLock",,,,,,"update test2 set info='b' ;",,"LockAcquireExtended, lock.c:724","psql"  
2016-03-15 16:12:16.778 CST,"postgres","postgres",10220,"[local]",56e7c3df.27ec,8,"UPDATE",2016-03-15 16:12:15 CST,3/16,574614689,LOG,00000,"LockAcquire: new: lock(0x7f88ead65ed8) id(13241,53029,0,3,3,1) grantMask(0) req(0,0,0,0,0,0,0)=0 grant(0,0,0,0,0,0,0)=0 wait(0) type(ExclusiveLock)",,,,,,"update test2 set info='b' ;",,"LOCK_PRINT, lock.c:319","psql"  
2016-03-15 16:12:16.778 CST,"postgres","postgres",10220,"[local]",56e7c3df.27ec,9,"UPDATE",2016-03-15 16:12:15 CST,3/16,574614689,LOG,00000,"LockAcquire: new: proclock(0x7f88eadf4878) lock(0x7f88ead65ed8) method(1) proc(0x7f88eb0211f0) hold(0)",,,,,,"update test2 set info='b' ;",,"PROCLOCK_PRINT, lock.c:331","psql"  
2016-03-15 16:12:16.778 CST,"postgres","postgres",10220,"[local]",56e7c3df.27ec,10,"UPDATE",2016-03-15 16:12:15 CST,3/16,574614689,LOG,00000,"LockCheckConflicts: no conflict: proclock(0x7f88eadf4878) lock(0x7f88ead65ed8) method(1) proc(0x7f88eb0211f0) hold(0)",,,,,,"update test2 set info='b' ;",,"PROCLOCK_PRINT, lock.c:331","psql"  
2016-03-15 16:12:16.778 CST,"postgres","postgres",10220,"[local]",56e7c3df.27ec,11,"UPDATE",2016-03-15 16:12:15 CST,3/16,574614689,LOG,00000,"GrantLock: lock(0x7f88ead65ed8) id(13241,53029,0,3,3,1) grantMask(80) req(0,0,0,0,0,0,1)=1 grant(0,0,0,0,0,0,1)=1 wait(0) type(ExclusiveLock)",,,,,,"update test2 set info='b' ;",,"LOCK_PRINT, lock.c:319","psql"  
2016-03-15 16:17:05.528 CST,"postgres","postgres",9725,"[local]",56e7c3d8.25fd,7,"COMMIT",2016-03-15 16:12:08 CST,2/0,574614688,LOG,00000,"LockReleaseAll: lockmethod=1",,,,,,"end;",,"LockReleaseAll, lock.c:1951","psql"  
2016-03-15 16:17:05.528 CST,"postgres","postgres",9725,"[local]",56e7c3d8.25fd,8,"COMMIT",2016-03-15 16:12:08 CST,2/0,574614688,LOG,00000,"LockReleaseAll done",,,,,,"end;",,"LockReleaseAll, lock.c:2198","psql"  
2016-03-15 16:17:05.528 CST,"postgres","postgres",10220,"[local]",56e7c3df.27ec,12,"UPDATE",2016-03-15 16:12:15 CST,3/16,574614689,LOG,00000,"LockRelease: lock [13241,53029] ExclusiveLock",,,,,,"update test2 set info='b' ;",,"LockRelease, lock.c:1758","psql"  
2016-03-15 16:17:05.528 CST,"postgres","postgres",10220,"[local]",56e7c3df.27ec,13,"UPDATE",2016-03-15 16:12:15 CST,3/16,574614689,LOG,00000,"LockRelease: found: lock(0x7f88ead65ed8) id(13241,53029,0,3,3,1) grantMask(80) req(0,0,0,0,0,0,1)=1 grant(0,0,0,0,0,0,1)=1 wait(0) type(ExclusiveLock)",,,,,,"update test2 set info='b' ;",,"LOCK_PRINT, lock.c:319","psql"  
2016-03-15 16:17:05.528 CST,"postgres","postgres",10220,"[local]",56e7c3df.27ec,14,"UPDATE",2016-03-15 16:12:15 CST,3/16,574614689,LOG,00000,"LockRelease: found: proclock(0x7f88eadf4878) lock(0x7f88ead65ed8) method(1) proc(0x7f88eb0211f0) hold(80)",,,,,,"update test2 set info='b' ;",,"PROCLOCK_PRINT, lock.c:331","psql"  
2016-03-15 16:17:05.528 CST,"postgres","postgres",10220,"[local]",56e7c3df.27ec,15,"UPDATE",2016-03-15 16:12:15 CST,3/16,574614689,LOG,00000,"UnGrantLock: updated: lock(0x7f88ead65ed8) id(13241,53029,0,3,3,1) grantMask(0) req(0,0,0,0,0,0,0)=0 grant(0,0,0,0,0,0,0)=0 wait(0) type(ExclusiveLock)",,,,,,"update test2 set info='b' ;",,"LOCK_PRINT, lock.c:319","psql"  
2016-03-15 16:17:05.528 CST,"postgres","postgres",10220,"[local]",56e7c3df.27ec,16,"UPDATE",2016-03-15 16:12:15 CST,3/16,574614689,LOG,00000,"UnGrantLock: updated: proclock(0x7f88eadf4878) lock(0x7f88ead65ed8) method(1) proc(0x7f88eb0211f0) hold(0)",,,,,,"update test2 set info='b' ;",,"PROCLOCK_PRINT, lock.c:331","psql"  
2016-03-15 16:17:05.528 CST,"postgres","postgres",10220,"[local]",56e7c3df.27ec,17,"UPDATE",2016-03-15 16:12:15 CST,3/16,574614689,LOG,00000,"CleanUpLock: deleting: proclock(0x7f88eadf4878) lock(0x7f88ead65ed8) method(1) proc(0x7f88eb0211f0) hold(0)",,,,,,"update test2 set info='b' ;",,"PROCLOCK_PRINT, lock.c:331","psql"  
2016-03-15 16:17:05.528 CST,"postgres","postgres",10220,"[local]",56e7c3df.27ec,18,"UPDATE",2016-03-15 16:12:15 CST,3/16,574614689,LOG,00000,"CleanUpLock: deleting: lock(0x7f88ead65ed8) id(13241,53029,0,3,3,1) grantMask(0) req(0,0,0,0,0,0,0)=0 grant(0,0,0,0,0,0,0)=0 wait(0) type(INVALID)",,,,,,"update test2 set info='b' ;",,"LOCK_PRINT, lock.c:319","psql"  
2016-03-15 16:17:05.528 CST,"postgres","postgres",10220,"[local]",56e7c3df.27ec,19,"UPDATE",2016-03-15 16:12:15 CST,3/16,574614689,LOG,00000,"LockAcquire: lock [13241,53029] AccessShareLock",,,,,,"update test2 set info='b' ;",,"LockAcquireExtended, lock.c:724","psql"  
2016-03-15 16:17:05.528 CST,"postgres","postgres",10220,"[local]",56e7c3df.27ec,20,"UPDATE",2016-03-15 16:12:15 CST,3/16,574614689,LOG,00000,"LockRelease: lock [13241,53029] AccessShareLock",,,,,,"update test2 set info='b' ;",,"LockRelease, lock.c:1758","psql"  
2016-03-15 16:17:05.528 CST,"postgres","postgres",10220,"[local]",56e7c3df.27ec,21,"UPDATE",2016-03-15 16:12:15 CST,3/16,574614689,LOG,00000,"duration: 288750.628 ms  plan:  
Query Text: update test2 set info='b' ;  
Update on test2  (cost=0.00..22.70 rows=1270 width=10) (actual time=288750.624..288750.624 rows=0 loops=1)  
  Buffers: shared hit=5  
  ->  Seq Scan on test2  (cost=0.00..22.70 rows=1270 width=10) (actual time=0.013..0.015 rows=1 loops=1)  
        Buffers: shared hit=1",,,,,,,,"explain_ExecutorEnd, auto_explain.c:333","psql"  
2016-03-15 16:17:05.529 CST,"postgres","postgres",10220,"[local]",56e7c3df.27ec,22,"UPDATE",2016-03-15 16:12:15 CST,3/0,574614689,LOG,00000,"LockReleaseAll: lockmethod=1",,,,,,"update test2 set info='b' ;",,"LockReleaseAll, lock.c:1951","psql"  
2016-03-15 16:17:05.529 CST,"postgres","postgres",10220,"[local]",56e7c3df.27ec,23,"UPDATE",2016-03-15 16:12:15 CST,3/0,574614689,LOG,00000,"LockReleaseAll done",,,,,,"update test2 set info='b' ;",,"LockReleaseAll, lock.c:2198","psql"  
2016-03-15 16:17:05.529 CST,"postgres","postgres",10220,"[local]",56e7c3df.27ec,24,"UPDATE",2016-03-15 16:12:15 CST,3/0,0,LOG,00000,"duration: 288751.635 ms  statement: update test2 set info='b' ;",,,,,,,,"exec_simple_query, postgres.c:1181","psql"

锁的解释需要对照src/include/storage/lock.h

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