Received a
request that scheduler jobs are not started today. Googled the issue and
verified all the possibilities and found some entries in the alertlog file
regarding background process CJQ status as follows
Starting background
process CJQ0
ALTER SYSTEM SET
job_queue_processes=1000 SCOPE=BOTH;
CJQ0 started with
pid=37, OS id=2668.
.
Stopping
background process CJQ0.
.
ALTER SYSTEM SET
job_queue_processes=0 SCOPE=BOTH;.
.
ALTER SYSTEM SET
job_queue_processes=0 SCOPE=BOTH;
2) ps -ef|grep cjq returned no rows
3) check for the CJQ process from v$process.
select
spid,program,background from v$program;
we couldn't find a
program w.r.to CJQ process.
Confirmed that CJQ is not running because of
that reason jobs aren't started today and then bounced the database which will
starts all the background process but no luck even after restarting the
database. The CJQ background process is responsible
for initiating the scheduler jobs which will spawn
multiple child processes. On further investigating the issue found scheduler
has been disabled and enabling scheduler will start the CJQ process. So it is good to perform below steps
before performing restart of the database to check scheduler status.
Scheduler Status:
1) select
OWNER,OBJECT_NAME,OBJECT_ID,CREATED,LAST_DDL_TIME,TIMESTAMP from dba_objects
where object_name='SCHEDULER_DISABLED';
OWNER
OBJECT_NAME
OBJECT_ID CREATED LAST_DDL_
TIMESTAMP
----------
------------------------------ ---------- --------- ---------
-------------------
SYS SCHEDULER_DISABLED ******* ********* ********* ******************
If the above query returns a row means
SCHEDULER has been disabled.
2) ps -ef|grep $ORACLE_SID|grep -i cjq0
//** Here no record will be returned **//
3) exec
dbms_scheduler.set_scheduler_attribute('SCHEDULER_DISABLED','FALSE');
PL/SQL procedure successfully completed.
4) select * from dba_objects where
object_name='SCHEDULER_DISABLED';
no rows selected
5) !ps -ef|grep $ORACLE_SID|grep -i cjq0
oracle 1947
1 0 11:24 ? 00:00:00 ora_cjq0_VIPOLTP
6) select count(*) from dba_scheduler_running_jobs;
COUNT(*)
----------
13
Conclusion:
If scheduler jobs
are not started
· Check CJQ process
is running or not
· Check the
alertlog for the string “Stopping background process CJQ0”
· Perform the above
steps and get confirm whether scheduler was disabled or not, if scheduler was
disabled then enable it then CJQ will start and jobs will be initiated.
·
In our case
scheduler was disabled and changed the number of process but not enabled the
scheduler.
·
Database restart
will start all the background process, but if SCHEDULER is disabled then CJQ
background process will not start even after database startup.
·
CJQ background
process is responsible for initiating DBA_SCHEDULER_JOBS as well as DBA_JOBS.
If CJQ is not running then these scheduled job will not start any more.
Thanks,
V V
Source : Internet
This is one of
the most common Scheduler questions asked.
Here we list some of the common problems and their solutions.
1) job_queue_processes may be too low (this is the
most common problem)
The value of job_queue_processes limits the total number of dbms_scheduler
and dbms_job jobs that can be running at a given time.
To check whether this is the case check the current value of
job_queue_processes with
SQL> select value from v$parameter where name='job_queue_processes';
Then check the number of running jobs
SQL> select count(*) from dba_scheduler_running_jobs;
SQL> select count(*) from dba_jobs_running;
If this is the problem you can increase the parameter using
SQL> alter system set job_queue_processes=1000;
2) max_job_slave_processes may be too low
If this parameter is not NULL then it limits how many dbms_scheduler jobs can
be running at a time. To check whether this is the problem, check the current
value using
SQL> select value from dba_scheduler_global_attribute
where attribute_name='MAX_JOB_SLAVE_PROCESSES';
Then check the number of running jobs
SQL> select count(*) from dba_scheduler_running_jobs;
If this is the problem you can increase the number or just NULL it out using
SQL> exec
dbms_scheduler.set_scheduler_attribute('max_job_slave_processes',null)
3) sessions may be too low
This parameter limits the number of sessions at any time. Every Scheduler job
requires 2 sessions. To check whether this is the problem, check the current
valule using
SQL> select value from v$parameter where name='sessions';
Then check the current number of sessions using
SQL> select count(*) from v$session ;
If the numbers are too close you can increase the maximum using
SQL> alter system set job_queue_processes=200;
4) Have you recently applied a timezone update
patch or upgraded the database
to a version with newer timezone information ? If you skipped any steps when
updating the timezone information, jobs may not run. To check whether this
is the case try doing
SQL> select * from sys.scheduler$_job;
and
SQL> select * from sys.scheduler$_window;
and make sure they finish without errors.
If it throws a timezone warning, reapply the upgrade or
timezone patch making sure to follow all the steps.
5) Is the database running in restricted mode
?
If the database is running in restricted mode then no jobs will run (unless
you are using 11g and use the ALLOW_RUNS_IN_RESTRICTED_MODE attribute).
To check this use
SQL> select logins from v$instance ;
If logins is restricted you can disable the restricted mode using
SQL> ALTER SYSTEM DISABLE RESTRICTED SESSION;
6) Is the job scheduled to run on an instance
which is down ?
You can check this by seeing whether instance_id is set for the job (check the
dba_scheduler_jobs view), and if so you should check whether that instance is
up.
7) Is the job scheduled to run on a service which
has not been started on any instances ?
You can check this by checking what job_class a job points to and then checking
whether that class points to a service. If it does, make sure the service has
been started on at least one running instance. You can start a service on an
instance using dbms_service.start_service.
8) Is the Resource Manager in effect with a
restrictive resource plan ?
If a restrictive resource plan is in effect, scheduler jobs may not have
sufficient resources allocated so they may not run. You can check what resource
plan is in effect by doing
SQL> select name from V$RSRC_PLAN ;
If no plan is in effect or the plan in effect is INTERNAL_PLAN then the
resource manager is not in effect. If the resource manager is in effect you can
disable it by doing
SQL>alter system set resource_manager_plan = '';
9) Has the Scheduler been disabled ? This is not a supported action
but it is possible that someone has done it anyway. To check this do
SQL> select value from dba_scheduler_global_attribute where
attribute_name='SCHEDULER_DISABLED'
If this query returns TRUE then you can fix this using
SQL> exec
dbms_scheduler.set_scheduler_attribute('scheduler_disabled','false');
Reasons why jobs may run late
1) The first thing to check is the timezone that
the job is scheduled with
SQL> select owner, job_name, next_run_date from dba_scheduler_jobs ;
If the jobs are in the wrong timezone they may not run at the expected
time. If the next_run_date is using an absolute timezone offset (like
+08:00) instead of a named timezone (like US/PACIFIC) then the jobs may not
run as expected if daylight savings is in effect - they may run an hour
early or late.
2) It may be that at the time the job was
scheduled to run, one of the several
limits above may have been temporarily reached causing the job to be delayed.
Check if the limits above are high enough and if possible check them during
the time that the job is being delayed.
3) One possible reason that one of the above
limits may be hit is that a
maintenance window may have come into effect. Maintenance windows are Oracle
Scheduler windows that belong to the window group named
MAINTENANCE_WINDOW_GROUP. During a scheduled maintenance window, several
maintenance tasks are run using jobs. This may cause one of the limits listed
above to be hit and user jobs to be delayed. See the admin guide for more info
about this (chapter 24).
To get a list of maintenance windows use
SQL> select * from dba_scheduler_wingroup_members;
To see when the windows run use
SQL> select * from dba_scheduler_windows;
To fix this you can either increase the limits or reschedule the maintenance
windows to run at more convenient times.
Diagnosing other Problems
If none of this works, here are some further steps you can take to try to
figure out what is going on.
1) Check whether there are any errors in the alert
log. If the database is
having trouble allocating memory or has run out of disk space or any other
catastrophic errors have occurred, you should resolve those first. You can
find the location of the alert log by using
SQL> select value from v$parameter where name = 'background_dump_dest';
The alert log will be in this directory with a name starting with
"alert".
2) Check whether if a job coordinator trace file
and if it does, check if it
contains any errors. If this exists, it will be located in the
'background_dump_dest' directory which you can find as above and will look
something like SID-cjq0_nnnn.trc . If there are any errors here they may
hint at why jobs are not running.
3) If either of the above indicates that the
SYSAUX tablespace (where the scheduler stores its logging tables) is full, you
can use the dbms_scheduler.purge_log procedure to clear out old log entries.
4) See if there is a window currently open. If
there is, you can try closing it to see if that helps .
SQL> select * from DBA_SCHEDULER_GLOBAL_ATTRIBUTE where
attribute_name='CURRENT_OPEN_WINDOW';
SQL> exec DBMS_SCHEDULER.close_window ('WEEKNIGHT_WINDOW');
5)try running a simple run-once job and see if it runs
SQL>begin
dbms_scheduler.create_job (
job_name => 'test_job',
job_type => 'plsql_block',
job_action => 'null;',
enabled => true);
end;
/
SQL> -- wait a while
SQL> select * from user_scheduler_job_run_details where job_name='TEST_JOB';
6) If a simple run-once job doesn't run, you can
try restarting the scheduler as follows.
SQL> exec dbms_scheduler.set_scheduler_attribute('SCHEDULER_DISABLED',
'TRUE');
SQL> alter system set job_queue_processes=0;
SQL> exec dbms_ijob.set_enabled(FALSE);
SQL>
SQL> alter system flush shared_pool;
SQL> alter system flush shared_pool;
SQL>
SQL> exec dbms_ijob.set_enabled(TRUE);
SQL> alter system set job_queue_processes=99;
SQL> exec dbms_scheduler.set_scheduler_attribute('SCHEDULER_DISABLED',
'FALSE');
