Обсуждение: released savepoint blocking further statements
LOG: 00000: execute <unnamed>: SELECT "position_types".* FROM "position_types" WHERE "position_types"."id" = $1 LIMIT $2 FOR UPDATE
DETAIL: parameters: $1 = '1401', $2 = '1'
LOCATION: exec_execute_message, postgres.c:1963
LOG: 00000: process 79469 still waiting for ShareLock on transaction 8453886 after 1000.345 ms
DETAIL: Process holding the lock: 79440. Wait queue: 79469.
CONTEXT: while locking tuple (1,139) in relation "position_types"
LOCATION: ProcSleep, proc.c:1323
STATEMENT: SELECT "position_types".* FROM "position_types" WHERE "position_types"."id" = $1 LIMIT $2 FOR UPDATE
[2.] I've tried to use the query Lock Monitoring wiki from to find out what is blocking:
it shows that 79469 | RELEASE SAVEPOINT active_record_2_47 is the current_statement_in_blocking_process.
https://wiki.postgresql.org/wiki/Lock_Monitoring
SELECT bl.pid AS blocked_pid,
a.usename AS blocked_user,
ka.query AS current_statement_in_blocking_process,
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 | current_statement_in_blocking_process | blocking_duration | blocking_pid | blocking_user | blocked_statement | blocked_duration
-------------+--------------+---------------------------------------+-------------------+--------------+---------------+-------------------------------------------------------------------------------------------------------+------------------
79469 | boga | RELEASE SAVEPOINT active_record_2_47 | 00:10:44.781475 | 79440 | boga | SELECT "position_types".* FROM "position_types" WHERE "position_types"."id" = $1 LIMIT $2 FOR UPDATE | 00:08:39.344037
(1 row)
[3.] But according to pg logs that statement that RELEAS SAVEPOINT was executed fine:
LOCATION: exec_execute_message, postgres.c:2034
LOG: 00000: statement: RELEASE SAVEPOINT active_record_2_47
LOCATION: exec_simple_query, postgres.c:946
LOG: 00000: duration: 0.038 ms
On Thu, Apr 7, 2016 at 1:26 AM, Mikl=C3=B3s Fazekas <mfazekas@szemafor.com>= wrote: > [2.] I've tried to use the query Lock Monitoring wiki from to find out wh= at > is blocking: > > it shows that 79469 | RELEASE SAVEPOINT active_record_2_47 is the > current_statement_in_blocking_process. > > https://wiki.postgresql.org/wiki/Lock_Monitoring > > SELECT bl.pid AS blocked_pid, > > a.usename AS blocked_user, > ka.query AS current_statement_in_blocking_process, > 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 =3D bl.pid > JOIN pg_catalog.pg_locks kl ON kl.transactionid =3D > bl.transactionid AND kl.pid !=3D bl.pid > JOIN pg_catalog.pg_stat_activity ka ON ka.pid =3D kl.pid > WHERE NOT bl.GRANTED; That is probably not the current statement in the blocking process. It is likely that the blocking process is in the state "idle in transaction", and the RELEASE SAVEPOINT is actually the most recent statement, not the current statement. I've updated the wiki to clarify that, but it could use some more polishing= . So your savepoint release has executed successfully, but the outer transaction is still holding on to locks which block the other process. You have to convince that outer transaction to either commit or rollback. Cheers, Jeff
Miklós
On Thu, Apr 7, 2016 at 1:26 AM, Miklós Fazekas <mfazekas@szemafor.com> wrote:
> [2.] I've tried to use the query Lock Monitoring wiki from to find out what
> is blocking:
>
> it shows that 79469 | RELEASE SAVEPOINT active_record_2_47 is the
> current_statement_in_blocking_process.
>
> https://wiki.postgresql.org/wiki/Lock_Monitoring
>
> SELECT bl.pid AS blocked_pid,
>
> a.usename AS blocked_user,
> ka.query AS current_statement_in_blocking_process,
> 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;
That is probably not the current statement in the blocking process.
It is likely that the blocking process is in the state "idle in
transaction", and the RELEASE SAVEPOINT is actually the most recent
statement, not the current statement.
I've updated the wiki to clarify that, but it could use some more polishing.
So your savepoint release has executed successfully, but the outer
transaction is still holding on to locks which block the other
process. You have to convince that outer transaction to either commit
or rollback.
Cheers,
Jeff