With Zabbix 2.0.6, housekeeper was launched every 24 hours and lasted about 75 min.
At one point increased the duration of the process so I tried to change the frequency every hour. The duration of the process becoming 40 min.
Lately the housekeeper launched around 02:00 am did not end until I restarted the Zabbix server and everything came back normal.
I upgraded to Zabbix version 2.0.8 and for a few days everything is back to normal. Then the housekeeper started around 02:00 am not terminated and from a few days, the process of housekeeper is always 100%.