Timer jobs perform infrastructure tasks for the timer service, such as clearing the timer job history and recycling the timer service, and tasks for Wep Applications, such as sending e-mail alerts. A timer job contains a definition of the service to run and specifies how frequently the service is started. The SharePoint 2010 Timer service (SPTimerv4) runs timer jobs. Many features in SharePoint Server rely on timer jobs to run services according to a schedule. All delay actions utilize the SharePoint timer service. If there is a greater issue with this service it can affect any action that utilizes delays. The effect on these actions might be they do not continue at the expected time, or they never continue.