Хорошо, ребята.
спасибо всем, кто ответил.
Я разместил заявку в службу поддержки в AWS, и это рекомендация, вставлять все здесь, это долго, но я надеюсь, что это работает для многих людей, сталкивающихся с этой проблемой. Идея состоит в том, чтобы поймать ситуацию до того, как она произойдет:
To monitor the number of connections made to the database, you can create a cloudwatch alarm based on the Database connections metrics that will trigger a lambda function when a certain threshold is reached. This lambda function can then terminate idle connections by calling a procedure that terminates idle connections.
Please find the query that creates a procedure to log and terminate long running inactive sessions
:
1. Add view to get all current inactive sessions in the cluster
CREATE OR REPLACE VIEW inactive_sessions as (
select a.process,
trim(a.user_name) as user_name,
trim(c.remotehost) as remotehost,
a.usesysid,
a.starttime,
datediff(s,a.starttime,sysdate) as session_dur,
b.last_end,
datediff(s,case when b.last_end is not null then b.last_end else a.starttime end,sysdate) idle_dur
FROM
(
select starttime,process,u.usesysid,user_name
from stv_sessions s, pg_user u
where
s.user_name = u.usename
and u.usesysid>1
and process NOT IN (select pid from stv_inflight where userid>1
union select pid from stv_recents where status != 'Done' and userid>1)
) a
LEFT OUTER JOIN (
select
userid,pid,max(endtime) as last_end from svl_statementtext
where userid>1 and sequence=0 group by 1,2) b ON a.usesysid = b.userid AND a.process = b.pid
LEFT OUTER JOIN (
select username, pid, remotehost from stl_connection_log
where event = 'initiating session' and username <> 'rsdb') c on a.user_name = c.username AND a.process = c.pid
WHERE (b.last_end > a.starttime OR b.last_end is null)
ORDER BY idle_dur
);
2. Add table for logging information about long running transactions that was terminated
CREATE TABLE IF NOT EXISTS terminated_inactive_sessions (
process int,
user_name varchar(50),
remotehost varchar(50),
starttime timestamp,
session_dur int,
idle_dur int,
terminated_on timestamp DEFAULT GETDATE()
);
3. Add procedure to log and terminate any inactive transactions running for longer than 'n' amount of seconds
CREATE OR REPLACE PROCEDURE terminate_and_log_inactive_sessions (n INTEGER)
AS $$
DECLARE
expired RECORD ;
BEGIN
FOR expired IN SELECT process, user_name, remotehost, starttime, session_dur, idle_dur FROM inactive_sessions where idle_dur >= n
LOOP
EXECUTE 'INSERT INTO terminated_inactive_sessions (process, user_name, remotehost, starttime, session_dur, idle_dur) values (' || expired.process || ' , ''' || expired.user_name || ''' , ''' || expired.remotehost || ''' , ''' || expired.starttime || ''' , ' || expired.session_dur || ' , ' || expired.idle_dur || ');';
EXECUTE 'SELECT PG_TERMINATE_BACKEND(' || expired.process || ')';
END LOOP ;
END ;
$$ LANGUAGE plpgsql;
4. Execute the procedure by running the following command:
call terminate_and_log_inactive_sessions(100);
Here is a sample lambda function that attempts to close idle connections by querying the view 'inactive_sessions' created above, which you can use as a reference.
#Current time
now = datetime.datetime.now()
query = "SELECT process, user_name, session_dur, idle_dur FROM inactive_sessions where idle_dur >= %d"
logger = logging.getLogger()
logger.setLevel(logging.INFO)
def lambda_handler(event, context):
try:
conn = psycopg2.connect("dbname=" + db_database + " user=" + db_user + " password=" + db_password + " port=" + db_port + " host=" + db_host)
conn.autocommit = True
except:
logger.error("ERROR: Unexpected error: Could not connect to Redshift cluster.")
sys.exit()
logger.info("SUCCESS: Connection to RDS Redshift cluster succeeded")
with conn.cursor() as cur:
cur.execute(query % (session_idle_limit))
row_count = cur.rowcount
if row_count >=1:
result = cur.fetchall()
for row in result:
print("terminating session with pid %s that has been idle for %d seconds at %s" % (row[0],row[3],now))
cur.execute("SELECT PG_TERMINATE_BACKEND(%s);" % (row[0]))
conn.close()
else:
conn.close()