Calendar never finishes loading events in future months

[wom-bat]

Steps to reproduce

1. Visit the calendar app
2. Select month view
3. click on the > button at six times to go forward six months

Expected behaviour

I expect to see the events in the calendar in six months from noe

Actual behaviour

The display hangs, with the progress markers rotating next to each selected calendar. Events never appear. I see six apache2 processes using 100% cpu on the server.

Server configuration

Operating system:
Linux Debian Unstable
Web server:
Apache2
Database:
Mysql
PHP version:
PHO5
ownCloud version: (see your admin page)
10.0.4.1.1 (from the owncloud debian repository)
Calendar version: (see the apps page)
1.5.7
Updated from an older installed version or fresh install:
Updated
Signing status (ownCloud 9.0 and above):
OK

Login as admin user into your cloud and access 
http://example.com/index.php/settings/integrity/failed 
paste the results here.

List of activated apps:

If you have access to your command line run e.g.:
sudo -u www-data php occ app:list
from within your instance's installation folder

• comments: 0.3.0
• configreport: 0.1.1
• contacts: 1.5.4
• dav: 0.3.2
• federatedfilesharing: 0.3.1
• federation: 0.1.0
• files: 1.5.1
• files_external: 0.7.1
• files_pdfviewer: 0.8.2
• files_reader: 1.2.3
• files_sharing: 0.10.1
• files_texteditor: 2.2.1
• files_trashbin: 0.9.1
• files_versions: 1.3.0
• files_videoplayer: 0.9.8
• gallery: 16.0.2
• impersonate: 0.1.2
• market: 0.2.3
• music: 0.5.6
• notifications: 0.3.2
• provisioning_api: 0.5.0
• systemtags: 0.3.0
• templateeditor: 0.1
• updatenotification: 0.2.1
• user_external: 0.4
  Disabled:
• encryption
• external
• firstrunwizard
• theme-example

ownCloud configuration:
The process control (PCNTL) extensions are required in case you want to interrupt long running commands - see http://php.net/manual/en/book.pcntl.php
{
"system": {
"installed": true,
"dbtype": "mysql",
"dbname": "OwnCloud",
"dbuser": "REMOVED SENSITIVE VALUE",
"dbpassword": "REMOVED SENSITIVE VALUE",
"dbhost": "localhost",
"dbtableprefix": "oc_",
"passwordsalt": "REMOVED SENSITIVE VALUE",
"forcessl": false,
"blacklisted_files": [
".htaccess"
],
"overwritehost": "",
"overwriteprotocol": "",
"overwritewebroot": "",
"overwritecondaddr": "",
"overwrite.cli.url": "/owncloud",
"proxy": "",
"proxyuserpwd": "REMOVED SENSITIVE VALUE",
"theme": "",
"default_language": "en",
"3rdpartyroot": "",
"3rdpartyurl": "",
"defaultapp": "files",
"knowledgebaseenabled": true,
"appstoreenabled": true,
"mail_smtpdebug": false,
"mail_smtpmode": "sendmail",
"mail_smtphost": "127.0.0.1",
"mail_smtpport": "25",
"mail_smtptimeout": 10,
"mail_smtpauthtype": "LOGIN",
"trashbin_retention_obligation": "180, auto",
"allow_user_to_change_display_name": true,
"appcodechecker": "",
"updatechecker": false,
"log_type": "owncloud",
"log_query": true,
"logfile": "",
"loglevel": 0,
"memcache.local": "\OC\Memcache\APCu",
"memcache.locking": "\OC\Memcache\Redis",
"redis": {
"host": "localhost",
"port": 6379
},
"remember_login_cookie_lifetime": 1296000,
"session_lifetime": 86400,
"custom_csp_policy": "default-src 'self'; script-src 'self' 'unsafe-eval'; style-src 'self' 'unsafe-inline'; frame-src *; img-src *; font-src 'self' data:; media-src *",
"xframe_restriction": true,
"customclient_desktop": "",
"customclient_android": "",
"customclient_ios": "",
"logdateformat": "F d, Y H:i:s",
"instanceid": "520ae046af5fb",
"datadirectory": "/var/www/owncloud/data",
"version": "10.0.4.4",
"trusted_domains": [
"chubb.wattle.id.au",
"220.239.167.83"
],
"secret": "REMOVED SENSITIVE VALUE",
"debug": true,
"appstore.experimental.enabled": true,
"user_backends": [
{
"class": "OC_User_IMAP",
"arguments": [
"{chubb.wattle.id.au:143/imap/tls}"
]
}
],
"mail_from_address": "owncloud",
"mail_domain": "chubb.wattle.id.au",
"maintenance": false
}
}

Are you using external storage, if yes which one: local/smb/sftp/...
local
Are you using encryption: o

Are you using an external user-backend, if yes which one: LDAP/ActiveDirectory/Webdav/...
IMAP

[wom-bat]

mysql show full processlist shows no activity during this time.

[wom-bat]

Backtrace on Apache2 shows:
#0 0x00007f7606dd9919 in timelib_update_ts ()
from /usr/lib/apache2/modules/libphp5.so
#1 0x00007f7606db3509 in zim_DateTimeImmutable_setDate ()
from /usr/lib/apache2/modules/libphp5.so
#2 0x00007f76070302aa in dtrace_execute_internal ()
from /usr/lib/apache2/modules/libphp5.so
#3 0x00007f75ff3d7864 in xdebug_execute_internal (
current_execute_data=0x7f760c4ce500, fci=0x0, return_value_used=0)
at /build/xdebug-2.3.3/xdebug-2.3.3/xdebug.c:1767
#4 0x00007f76070f0c90 in ?? () from /usr/lib/apache2/modules/libphp5.so
#5 0x00007f760707efe0 in execute_ex ()
from /usr/lib/apache2/modules/libphp5.so
#6 0x00007f7607030148 in dtrace_execute_ex ()
from /usr/lib/apache2/modules/libphp5.so
#7 0x00007f75ff3d6f72 in xdebug_execute_ex (execute_data=0x7f760c4ce500)
at /build/xdebug-2.3.3/xdebug-2.3.3/xdebug.c:1644
#8 0x00007f76070f11d3 in ?? () from /usr/lib/apache2/modules/libphp5.so
#9 0x00007f760707efe0 in execute_ex ()
from /usr/lib/apache2/modules/libphp5.so
#10 0x00007f7607030148 in dtrace_execute_ex ()
from /usr/lib/apache2/modules/libphp5.so
#11 0x00007f75ff3d6f72 in xdebug_execute_ex (execute_data=0x7f760c4ce3d0)
at /build/xdebug-2.3.3/xdebug-2.3.3/xdebug.c:1644
#12 0x00007f76070f11d3 in ?? () from /usr/lib/apache2/modules/libphp5.so
#13 0x00007f760707efe0 in execute_ex ()
from /usr/lib/apache2/modules/libphp5.so
#14 0x00007f7607030148 in dtrace_execute_ex ()
from /usr/lib/apache2/modules/libphp5.so
#15 0x00007f75ff3d6f72 in xdebug_execute_ex (execute_data=0x7f760c4ce280)
at /build/xdebug-2.3.3/xdebug-2.3.3/xdebug.c:1644
#16 0x00007f76070f11d3 in ?? () from /usr/lib/apache2/modules/libphp5.so
#17 0x00007f760707efe0 in execute_ex ()
from /usr/lib/apache2/modules/libphp5.so
#18 0x00007f7607030148 in dtrace_execute_ex ()
from /usr/lib/apache2/modules/libphp5.so
#19 0x00007f75ff3d6f72 in xdebug_execute_ex (execute_data=0x7f760c4ce130)
at /build/xdebug-2.3.3/xdebug-2.3.3/xdebug.c:1644
#20 0x00007f76070f11d3 in ?? () from /usr/lib/apache2/modules/libphp5.so
#21 0x00007f760707efe0 in execute_ex ()
from /usr/lib/apache2/modules/libphp5.so
#22 0x00007f7607030148 in dtrace_execute_ex ()
from /usr/lib/apache2/modules/libphp5.so
#23 0x00007f75ff3d6f72 in xdebug_execute_ex (execute_data=0x7f760c4cdf50)
at /build/xdebug-2.3.3/xdebug-2.3.3/xdebug.c:1644
#24 0x00007f76070f11d3 in ?? () from /usr/lib/apache2/modules/libphp5.so
#25 0x00007f760707efe0 in execute_ex ()
...
#114

[wom-bat]

Stepping through shows zim_DateTimeImmutable_setDate() being called over and over again.

[wom-bat]

There are 600 rows in oc_calendarobjects with many repeating events.

[wom-bat]

I can get the same effect by clicking forward by weeks in the week view. The first few weeks display, then the display stops and apache2 goes to 100% CPU.

[wom-bat]

This is related to #904 and has t4eh same cause.