Impacted versions:
9.0, 10.0, 11.0 (Maybe 8.0)
I don't know if it is really an expected behaviour for odoo but I like to expose it

Steps to reproduce:

1. Open an ir.cron record and change it to:
 - interval: minutes
 - next execution date: now + 1 minute

2. Open the odoo server log

Note: I'm using workers=3 but I don't know if there is possible to reproduce it without workers.

Current behavior:

You will see for each cron execution the following output
```txt
...
2018-06-01 16:18:33,432 20686 INFO 333561-11-0-42aff9-all odoo.modules.registry: Invalidating all model caches after database signaling.
...
2018-06-01 16:17:21,527 20687 INFO 333561-11-0-42aff9-all odoo.modules.loading: loading 1 modules...
2018-06-01 16:17:21,535 20687 INFO 333561-11-0-42aff9-all odoo.modules.loading: 1 modules loaded in 0.01s, 0 queries
2018-06-01 16:17:21,594 20687 INFO 333561-11-0-42aff9-all odoo.modules.loading: loading 206 modules...
2018-06-01 16:17:21,718 20687 INFO 333561-11-0-42aff9-all odoo.modules.loading: 206 modules loaded in 0.12s, 0 queries
2018-06-01 16:17:21,989 20687 INFO 333561-11-0-42aff9-all odoo.modules.loading: Modules loaded.
```

Expected behavior:
 - Review if the method that run from the cron really requires a invalidate cache and delete all registries.
 - Disable "minutes" for cron interval because all cache are deleted then is not valid use them.

Video/Screenshot link (optional):

 - [![IMAGE ALT TEXT HERE](https://img.youtube.com/vi/Be4FIeQjgjk/0.jpg)](https://youtu.be/Be4FIeQjgjk)
openerp/service/server.py
self.alive = False
    def sleep(self):
        try:
            select.select([self.multi.socket], [], [], self.multi.beat)
        except select.error, e:
            if e[0] not in [errno.EINTR]:
                raise
    def process_limit(self):
        
        if self.ppid != os.getppid():
            _logger.info("Worker (%s) Parent changed", self.pid)
            self.alive = False
        
        if self.request_count >= self.request_max:
            _logger.info("Worker (%d) max request (%s) reached.", self.pid, self.request_count)
            self.alive = False
        
        rss, vms = memory_info(psutil.Process(os.getpid()))
        if vms > config['limit_memory_soft']:
            _logger.info('Worker (%d) virtual memory limit (%s) reached.', self.pid, vms)
            self.alive = False      
        
        soft, hard = resource.getrlimit(resource.RLIMIT_AS)
        resource.setrlimit(resource.RLIMIT_AS, (config['limit_memory_hard'], hard))
        
        r = resource.getrusage(resource.RUSAGE_SELF)
        cpu_time = r.ru_utime + r.ru_stime
        def time_expired(n, stack):