console core:archive freezes (no replies)

Hello Community,

i have a problem with piwik which i cant solve on my own. I hope someone can help me.

After i start the archiving with the console, the process freezes after the outputline "Starting Scheduled tasks...".
At the same time in the directory /piwik/tmp/climulti a file got created (*.output) which grows until the filesystem is full. Also the php process uses over 90%.

Command:

su www-data -c "/usr/bin/php5 /var/www/piwik/console core:archive --url=http://piwik/"

Output:

INFO CoreConsole[2014-10-01 15:19:30] [8474b] ---------------------------
INFO CoreConsole[2014-10-01 15:19:30] [8474b] INIT
INFO CoreConsole[2014-10-01 15:19:30] [8474b] Piwik is installed at: http://piwik/index.php
INFO CoreConsole[2014-10-01 15:19:30] [8474b] Running Piwik 2.7.0 as Super User
INFO CoreConsole[2014-10-01 15:19:30] [8474b] ---------------------------
INFO CoreConsole[2014-10-01 15:19:30] [8474b] NOTES
INFO CoreConsole[2014-10-01 15:19:30] [8474b] - If you execute this script at least once per hour (or more often) in a crontab, you may disable 'Browser trigger archiving' in Piwik UI > Settings > General Settings.
INFO CoreConsole[2014-10-01 15:19:30] [8474b]   See the doc at: [piwik.org]
INFO CoreConsole[2014-10-01 15:19:30] [8474b] - Reports for today will be processed at most every 150 seconds. You can change this value in Piwik UI > Settings > General Settings.
INFO CoreConsole[2014-10-01 15:19:30] [8474b] - Reports for the current week/month/year will be refreshed at most every 3600 seconds.
INFO CoreConsole[2014-10-01 15:19:30] [8474b] - Archiving was last executed without error 16 hours 16 min ago
INFO CoreConsole[2014-10-01 15:19:30] [8474b] - Will process 1 websites with new visits since 16 hours 16 min , IDs: 4
INFO CoreConsole[2014-10-01 15:19:30] [8474b] ---------------------------
INFO CoreConsole[2014-10-01 15:19:30] [8474b] START
INFO CoreConsole[2014-10-01 15:19:30] [8474b] Starting Piwik reports archiving...
INFO CoreConsole[2014-10-01 15:19:31] [8474b] Archived website id = 4, period = day, 8 visits in last last2 days, 8 visits today, Time elapsed: 0.578s
INFO CoreConsole[2014-10-01 15:19:31] [8474b] Archived website id = 4, period = week, 8 visits in last last2 weeks, 8 visits this week, Time elapsed: 0.583s
INFO CoreConsole[2014-10-01 15:19:32] [8474b] Archived website id = 4, period = month, 8 visits in last last2 months, 8 visits this month, Time elapsed: 0.580s
INFO CoreConsole[2014-10-01 15:19:32] [8474b] Archived website id = 4, period = year, 8 visits in last last2 years, 8 visits this year, Time elapsed: 0.591s
INFO CoreConsole[2014-10-01 15:19:32] [8474b] Archived website id = 4, 4 API requests, Time elapsed: 2.335s [1/1 done]
INFO CoreConsole[2014-10-01 15:19:32] [8474b] Done archiving!
INFO CoreConsole[2014-10-01 15:19:32] [8474b] ---------------------------
INFO CoreConsole[2014-10-01 15:19:32] [8474b] SUMMARY
INFO CoreConsole[2014-10-01 15:19:32] [8474b] Total visits for today across archived websites: 8
INFO CoreConsole[2014-10-01 15:19:32] [8474b] Archived today's reports for 1 websites
INFO CoreConsole[2014-10-01 15:19:32] [8474b] Archived week/month/year for 1 websites
INFO CoreConsole[2014-10-01 15:19:32] [8474b] Skipped 1 websites: no new visit since the last script execution
INFO CoreConsole[2014-10-01 15:19:32] [8474b] Skipped 0 websites day archiving: existing daily reports are less than 150 seconds old
INFO CoreConsole[2014-10-01 15:19:32] [8474b] Skipped 0 websites week/month/year archiving: existing periods reports are less than 3600 seconds old
INFO CoreConsole[2014-10-01 15:19:32] [8474b] Total API requests: 4
INFO CoreConsole[2014-10-01 15:19:32] [8474b] done: 1/1 100%, 8 vtoday, 1 wtoday, 1 wperiods, 4 req, 2368 ms, no error
INFO CoreConsole[2014-10-01 15:19:32] [8474b] Time elapsed: 2.368s
INFO CoreConsole[2014-10-01 15:19:32] [8474b] ---------------------------
INFO CoreConsole[2014-10-01 15:19:32] [8474b] SCHEDULED TASKS
INFO CoreConsole[2014-10-01 15:19:32] [8474b] Starting Scheduled tasks...

Files in /piwik/tmp/climulti

-rw-r--r--  1 www-data www-data 581M Oct  1 17:21 73f4e635968716383123c52aef7611434390ce430388abdf60284f3ec8dea0c3590eccc9c4ddda19feaa93aefc2242c47f350.output
-rw-r--r--  1 www-data www-data    5 Oct  1 17:19 73f4e635968716383123c52aef7611434390ce430388abdf60284f3ec8dea0c3590eccc9c4ddda19feaa93aefc2242c47f350.pid

Process:

31692 www-data  20   0  157m  25m 7504 R  92.1  1.3   2:08.75 php5