private boolean requeue(Task pending) {
        long callback = pending.getCallbackAfterSeconds();
        if (callback < 0) {
            callback = 0;
        }
        queueDAO.remove(QueueUtils.getQueueName(pending), pending.getTaskId());
        long now = System.currentTimeMillis();
        callback = callback - ((now - pending.getUpdateTime()) / 1000);
        if (callback < 0) {
            callback = 0;
        }
        return queueDAO.pushIfNotExists(
                QueueUtils.getQueueName(pending),
                pending.getTaskId(),
                pending.getWorkflowPriority(),
                callback);
    }
This method removes the task from the un-acked Queue

@param taskId: the taskId that needs to be updated and removed from the unacked queue
@return True in case of successful removal of the taskId from the un-acked queue
core/src/main/java/com/netflix/conductor/service/ExecutionService.java