Fixed: PHP Session Store Error Using Memcached
12,404
Solution 1
I believe the solution here is to call session_write_close() as soon as you're done writing data to the session. It will still be available for reading, but no more writes can be made. This explains it a bit.
Long-running requests will cause the biggest problem. PHP won't close/unlock the session until the request completes if session_write_close() is never called.
You can also try implementing locking manually, locking only the fields you need to lock. There have been numerous bugs and issues with session locking via Memcache over the yeard.
Solution 2
I am using below config fixed the problem.
[session]
session.lazy_write = 0
[memcached]
memcached.sess_locking = On
memcached.sess_lock_wait = 150000
memcached.sess_lock_max_wait = 30;
memcached.sess_lock_expire = 0;
memcached.sess_consistent_hash = Off
memcached.sess_remove_failed = 1
memcached.sess_number_of_replicas = 0
memcached.sess_binary = Off
memcached.sess_randomize_replica_read = Off
memcached.sess_connect_timeout = 1000
memcached.sess_sasl_username = NULL
memcached.sess_sasl_password = NULL
memcached.compression_type = "fastlz"
memcached.compression_factor = "1.3"
memcached.compression_threshold = 2000
memcached.serializer = "igbinary"
memcached.use_sasl = Off
memcached.store_retry_count = 2
Author by
Osushi
Updated on June 04, 2022Comments
-
Osushi almost 2 years
The error message displays on my server:
$ sudo tail /var/log/php-fpm/5.5/www-error.log PHP Warning: session_start(): Unable to clear session lock recordWhen my server stores session, it uses the memcached on ElastiCache(AWS).
Here is my environments:*Memcached(ElastiCache) -version 1.4.14 -1 Node -cache.t2.micro $ nginx -v nginx version: nginx/1.6.2 # use unix domain socket (fastcgi_pass unix:/var/run/php-fpm/php-fpm.sock;) $ php-fpm -v PHP 5.5.24 (fpm-fcgi) (built: Apr 17 2015 18:04:41) Copyright (c) 1997-2015 The PHP Group Zend Engine v2.5.0, Copyright (c) 1998-2015 Zend Technologies with Zend OPcache v7.0.4-dev, Copyright (c) 1999-2015, by Zend Technologies $ pecl list Installed packages, channel pecl.php.net: ========================================= Package Version State ... memcached 2.2.0 stable ...Here is data:
$ cat /etc/php-5.5.ini ... ... ; http://php.net/session.save-handler ; session.save_handler = files session.hash_bits_per_character = 5 session.hash_function = 0 session.use_trans_sid = 0 session.cache_expire = 180 session.cache_limiter = nocache session.referer_check = session.bug_compat_warn = Off session.bug_compat_42 = Off session.gc_maxlifetime = 1440 session.gc_divisor = 1000 session.gc_probability = 1 session.serialize_handler = php session.cookie_httponly = session.cookie_path = / session.cookie_lifetime = 0 session.auto_start = 0 session.name = PHPSESSID session.use_only_cookies = 1 session.use_cookies = 1 ... ... $ cat /etc/php-5.5.d/memcached.ini extension=memcached.so session.save_handler=memcached session.save_path="*******.cache.amazonaws.com:11211" memcached.sess_locking = On memcached.sess_lock_wait = 150000 memcached.sess_lock_max_wait = 0; memcached.sess_lock_expire = 0; memcached.sess_prefix = "memc.sess.key." memcached.sess_consistent_hash = Off memcached.sess_remove_failed = 0 memcached.sess_number_of_replicas = 0 memcached.sess_binary = Off memcached.sess_randomize_replica_read = Off memcached.sess_connect_timeout = 1000 memcached.sess_sasl_username = NULL memcached.sess_sasl_password = NULL memcached.compression_type = "fastlz" memcached.compression_factor = "1.3" memcached.compression_threshold = 2000 memcached.serializer = "igbinary" memcached.use_sasl = Off memcached.store_retry_count = 2 $ php -i | grep memcached /etc/php-5.5.d/memcached.ini, memcached memcached support => enabled libmemcached version => 1.0.8 memcached.compression_factor => 1.3 => 1.3 memcached.compression_threshold => 2000 => 2000 memcached.compression_type => fastlz => fastlz memcached.serializer => igbinary => igbinary memcached.sess_binary => no value => no value memcached.sess_connect_timeout => 1000 => 1000 memcached.sess_consistent_hash => no value => no value memcached.sess_lock_expire => 0 => 0 memcached.sess_lock_max_wait => 0 => 0 memcached.sess_lock_wait => 150000 => 150000 memcached.sess_locking => no value => no value memcached.sess_number_of_replicas => 0 => 0 memcached.sess_prefix => memc.sess.key. => memc.sess.key. memcached.sess_randomize_replica_read => no value => no value memcached.sess_remove_failed => 0 => 0 memcached.sess_sasl_password => no value => no value memcached.sess_sasl_username => no value => no value memcached.store_retry_count => 2 => 2 memcached.use_sasl => no value => no value Registered save handlers => files user memcached session.save_handler => memcached => memcached $ yum list installed | grep memcached libmemcached.x86_64 1.0.8-2.6.amzn1 @amzn-main memcached.x86_64 1.4.15-9.12.amzn1 @amzn-main php55-pecl-memcached.x86_64 2.2.0-5.14.amzn1 @amzn-updates $ cat /etc/php-fpm-5.5.d/www.conf php_value[session.save_handler] = memcached php_value[session.save_path] = "*******.cache.amazonaws.com:11211" $ memcached-tool *******.cache.amazonaws.com:11211 display # Item_Size Max_age Pages Count Full? Evicted Evict_Time OOM 1 96B 0s 1 0 yes 0 0 0 2 120B 55039s 1 4 yes 0 0 0 4 192B 1439s 2 2226 yes 0 0 0 5 240B 0s 1 0 yes 0 0 0 6 304B 14477s 1 1 yes 0 0 0 7 384B 9557s 1 1 yes 0 0 0 8 480B 268s 1 1 yes 0 0 0 9 600B 2014s 1 1 yes 0 0 0 $ memcached-tool *******.cache.amazonaws.com:11211 stats accepting_conns 1 auth_cmds 0 auth_errors 0 bytes 470256 bytes_read 5006739226 bytes_written 2668634300 cas_badval 0 cas_hits 0 cas_misses 0 cmd_config_get 489750 cmd_config_set 1 cmd_flush 1 cmd_get 15601270 cmd_set 33168188 cmd_touch 0 conn_yields 0 connection_structures 260 curr_config 1 curr_connections 9 curr_items 2581 decr_hits 0 decr_misses 0 delete_hits 15438339 delete_misses 10047 evicted_unfetched 0 evictions 0 expired_unfetched 7474894 get_hits 8113028 get_misses 7488242 hash_bytes 524288 hash_is_expanding 0 hash_power_level 16 incr_hits 0 incr_misses 0 libevent 1.4.13-stable limit_maxbytes 477102080 listen_disabled_num 0 pid 1 pointer_size 64 reclaimed 7476127 reserved_fds 5 rusage_system 1539.028000 rusage_user 838.464000 threads 1 time 1436772530 total_connections 15600239 total_items 31043112 touch_hits 0 touch_misses 0 uptime 7346275 version 1.4.14Strangely, this error happens about once time per weekly, but yesterday, it happens about 2000 times.
When this error is happens, the server also happens busy status.
It disappears over time.■Cloud Watch Log:
■New Relic Application Log:
I don't know what it's happening. If you have good solution, please let me know.
Update at 2020/10/8
It was long time, I solved this issue:
When user access came many, it seems that the DNS can't solve on AWS EC2.
https://aws.amazon.com/jp/premiumsupport/knowledge-center/dns-resolution-failures-ec2-linux/
Here is fixed patch.
$ wget https://raw.githubusercontent.com/awslabs/aws-support-tools/master/EC2/AutomateDnsmasq/AutomateDnsmasq.sh $ chmod +x AutomateDnsmasq.sh $ sudo ./AutomateDnsmasq.sh -> Finally, you must restart php server.