APC PHP Apache prefork
We are having apache2 with MPM prefork (MaxClients 300) enabled, serving about 10 000 visitors prer day, and the site works excelent fast most of the day, but
every day one or twice it happens that Apache processes get stuck in "Sending reply" state ( viewed on server-status page ), and mysql "eats" all the RAM ( 4GB), and whole server stops responding
until services or the whole server is rebooted.
We did some investigation and it seems that after some page is cached in APC, the same page could not be found in cache after second or third try, its like something is
deleting cache entries from APC, and we have many miss hits in user cache, and I assume because of that the apache and mysql gets stuck not being able to handle many request.
APC is the lastest Version 3.1.9 ( the same problem was with 3.1.6 version of APC ) with PHP version 5.2.5 and Apache 2.2.3 on SLES 10 , the configuration of APC is:
APC Version 3.1.9
PHP Version 5.2.5
APC Host www.example.com (example) (*.*.*.*)
Server Software Apache/2.2.3 (Linux/SUSE)
Shared Memory 1 Segment(s) with 384.0 MBytes
(mmap memory, pthread mutex Locks locking)
Start Time 2011/07/10 15:05:04
Uptime 20 hours and 27 minutes
File Upload Support 1
File Cache Information
Cached Files 221 ( 8.0 MBytes)
Hits 3887429
Misses 349
Request Rate (hits, misses) 52.77 cache requests/second
Hit Rate 52.76 cache requests/second
Miss Rate 0.00 cache requests/second
Insert Rate 0.00 cache requests/second
Cache full count 0
User Cache Information
Cached Variables 8679 (175.7 MBytes)
Hits 54049
Misses 34862
Request Rate (hits, misses) 1.21 cache requests/second
Hit Rate 0.73 cache requests/second
Miss Rate 0.47 cache requests/second
Insert Rate 0.48 cache requests/second
Cache full count 0
Runtime Settings
apc.cache_by_default 1
apc.canonicalize 1
apc.coredump_unmap 0
apc.enable_cli 0
apc.enabled 1
apc.file_md5 0
apc.file_update_protection 2
apc.filters
apc.gc_ttl 3600
apc.include_once_override 0
apc.lazy_classes 0
apc.lazy_functions 0
apc.max_file_size 1M
apc.mmap_file_mask /tmp/apc.93USWj
apc.num_files_hint 1000
apc.preload_path
apc.report_autofilter 0
apc.rfc1867 0
apc.rfc1867_freq 0
apc.rfc1867_name APC_UPLOAD_PROGRESS
apc.rfc1867_prefix upload_
apc.rfc1867_ttl 3600
apc.serializer default
apc.shm_segments 1
apc.shm_size 384M
apc.slam_defense 1
apc.stat 1
apc.stat_ctime 0
apc.ttl 7200
apc.use_request_time 1
apc.user_entries_hint 4096
apc.user_ttl 7200
apc.write_lock 1
Thanks,
Zeljko
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