Wait Class Question

Application hung the database again.  This time i'm seeing :

Wait Classes by Total Wait Time

Wait Class Waits Total Wait Time (sec) Avg Wait (ms) % DB time Avg Active Sessions
Scheduler 418,600 386,163 923 86.4 217.1
Concurrency 8,115 18,949 2335 4.2 10.7
Other 7,083 15,600 2202 3.5 8.8
DB CPU   2,739   .6 1.5

Is this scheduler scheduling processor time or what?
What are some of the conditions that lead to scheduler being at the top of waits?

Top 10 Foreground Events by Total Wait Time


Event Waits Total Wait Time (sec) Wait Avg(ms) % DB time Wait Class
resmgr:cpu quantum 418,149 386.1K 923 86.4 Scheduler
buffer busy waits 1,220 9124 7479 2.0 Concurrency
xoxomosAsked:
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Geert GOracle dbaCommented:
the scheduler executes procedures which typically run in background

you'll probably find the queries from in those procedures in the top 10 queries also
tuning them will bring down the scheduler wait time

concurrency is a process causing a lock (like select for update) and taking some time until the commit happens
> in extreme cases, or a bad design:
select for update is triggered by a user, the user goes for a coffee and triggers a commit after the coffee
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xoxomosAuthor Commented:
Thanks
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