と を使用する Web アプリケーションがHibernateありPostgreSQLます。
このアプリケーションにはいくつかのエンティティがあり、そのうちの 1 つが次のとおりです。
@Entity
public class UniverseTime extends Model {
@Required
public Date realDate;
// Day of month
@Required
public Long diesse;
// Month of year
@Required
public Long cycle;
// year
@Required
public Long soleme;
//next current cycle
@Required
@ManyToOne(fetch = FetchType.LAZY)
public Cycle currentCycle;
// Tell if this universe time is the global one
@Required
public Boolean global;
}
Web アプリケーションを実行すると、UniverseTime エンティティの保存中にロックがかかります。
このリンクhttp://wiki.postgresql.org/wiki/Lock_Monitoringから、何がロックされているかを把握しようとしました。
最初のコマンドで得られるものは次のとおりです。
db=# SELECT relation::regclass, * FROM pg_locks WHERE NOT granted; relation | locktype | database | relation | page | tuple | virtualxid | transactionid | classid | objid | objsubid | virtualtransaction | pid | mode | granted | fastpath
----------+---------------+----------+----------+------+-------+------------+---------------+---------+-------+----------+--------------------+------+-----------+---------+----------
| transactionid | | | | | | 2772 | | | | 14/1479 | 6901 | ShareLock | f | f
(1 row)
db=# SELECT relation::regclass, * FROM pg_locks;
relation | locktype | database | relation | page | tuple | virtualxid | transactionid | classid | objid | objsubid | virtualtransaction | pid | mode | granted | fastpath
--------------------+---------------+----------+----------+------+-------+------------+---------------+---------+-------+----------+--------------------+------+------------------+---------+----------
universetime_pkey | relation | 16393 | 22886 | | | | | | | | 4/16298 | 6880 | AccessShareLock | t | t
universetime_pkey | relation | 16393 | 22886 | | | | | | | | 4/16298 | 6880 | RowExclusiveLock | t | t
universetime | relation | 16393 | 22883 | | | | | | | | 4/16298 | 6880 | AccessShareLock | t | t
universetime | relation | 16393 | 22883 | | | | | | | | 4/16298 | 6880 | RowShareLock | t | t
universetime | relation | 16393 | 22883 | | | | | | | | 4/16298 | 6880 | RowExclusiveLock | t | t
hibernate_sequence | relation | 16393 | 17294 | | | | | | | | 4/16298 | 6880 | AccessShareLock | t | t
cycle_pkey | relation | 16393 | 22585 | | | | | | | | 4/16298 | 6880 | AccessShareLock | t | t
cycle_pkey | relation | 16393 | 22585 | | | | | | | | 4/16298 | 6880 | RowExclusiveLock | t | t
cycle | relation | 16393 | 22582 | | | | | | | | 4/16298 | 6880 | AccessShareLock | t | t
cycle | relation | 16393 | 22582 | | | | | | | | 4/16298 | 6880 | RowShareLock | t | t
cycle | relation | 16393 | 22582 | | | | | | | | 4/16298 | 6880 | RowExclusiveLock | t | t
| virtualxid | | | | | 4/16298 | | | | | 4/16298 | 6880 | ExclusiveLock | t | t
cycle_pkey | relation | 16393 | 22585 | | | | | | | | 14/1479 | 6901 | AccessShareLock | t | t
universetime_pkey | relation | 16393 | 22886 | | | | | | | | 14/1479 | 6901 | AccessShareLock | t | t
universetime_pkey | relation | 16393 | 22886 | | | | | | | | 14/1479 | 6901 | RowExclusiveLock | t | t
cycle | relation | 16393 | 22582 | | | | | | | | 14/1479 | 6901 | AccessShareLock | t | t
universetime | relation | 16393 | 22883 | | | | | | | | 14/1479 | 6901 | AccessShareLock | t | t
universetime | relation | 16393 | 22883 | | | | | | | | 14/1479 | 6901 | RowExclusiveLock | t | t
| virtualxid | | | | | 14/1479 | | | | | 14/1479 | 6901 | ExclusiveLock | t | t
pg_locks | relation | 16393 | 11090 | | | | | | | | 2/9902 | 5206 | AccessShareLock | t | t
| virtualxid | | | | | 2/9902 | | | | | 2/9902 | 5206 | ExclusiveLock | t | t
| transactionid | | | | | | 2772 | | | | 4/16298 | 6880 | ExclusiveLock | t | f
| transactionid | | | | | | 2772 | | | | 14/1479 | 6901 | ShareLock | f | f
| transactionid | | | | | | 2773 | | | | 14/1479 | 6901 | ExclusiveLock | t | f
universetime | tuple | 16393 | 22883 | 0 | 13 | | | | | | 14/1479 | 6901 | ExclusiveLock | t | f
(25 rows)
そして、最後のコマンドで得られるものは次のとおりです。
db=# SELECT bl.pid AS blocked_pid, a.usename AS blocked_user, ka.query AS blocking_statement, now() - ka.query_start AS blocking_duration, kl.pid AS blocking_pid, ka.usename AS blocking_user, a.query AS blocked_statement, now() - a.query_start AS blocked_duration FROM pg_catalog.pg_locks bl JOIN pg_catalog.pg_stat_activity a ON a.pid = bl.pid JOIN pg_catalog.pg_locks kl ON kl.transactionid = bl.transactionid AND kl.pid != bl.pid JOIN pg_catalog.pg_stat_activity ka ON ka.pid = kl.pid WHERE NOT bl.granted;
blocked_pid | blocked_user | blocking_statement | blocking_duration | blocking_pid | blocking_user | blocked_statement | blocked_duration
-------------+--------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------------------+--------------+---------------+----------------------------------------------------------------------------------------------------------------+------------------
6901 | postgres | select universeti0_.id as id30_0_, universeti0_.currentCycle_id as currentC7_30_0_, universeti0_.cycle as cycle30_0_, universeti0_.diesse as diesse30_0_, universeti0_.global as global30_0_, universeti0_.realDate as realDate30_0_, universeti0_.soleme as soleme30_0_ from UniverseTime universeti0_ where universeti0_.id=$1 | 00:07:36.576371 | 6880 | postgres | update UniverseTime set currentCycle_id=$1, cycle=$2, diesse=$3, global=$4, realDate=$5, soleme=$6 where id=$7 | 00:07:31.574721
(1 row)
この出力は読みにくいため、blocked_statement を次に示します。
select universeti0_.id as id30_0_, universeti0_.currentCycle_id as currentC7_30_0_, universeti0_.cycle as cycle30_0_, universeti0_.diesse as diesse30_0_, universeti0_.global as global30_0_, universeti0_.realDate as realDate30_0_, universeti0_.soleme as soleme30_0_ from UniverseTime universeti0_ where universeti0_.id=$1
そして、blocking_statement は次のとおりです。
update UniverseTime set currentCycle_id=$1, cycle=$2, diesse=$3, global=$4, realDate=$5, soleme=$6 where id=$7
よくわかりませんが、UPDATEクエリがクエリをブロックしているようですが、クエリがロックされて実行されないSELECTのはなぜですか? UPDATEそれは単純UPDATEです。すばやく実行してロックを解除する必要がありますが、そうではありません。なぜですか?