php - 固定 : PHP Session Store Error Using Memcached

Question

错误消息显示在我的服务器上:

$ sudo tail /var/log/php-fpm/5.5/www-error.log
PHP Warning:  session_start(): Unable to clear session lock record

当我的服务器存储 session 时，它使用 ElastiCache(AWS) 上的 memcached。
这是我的环境:

*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
...

这是数据:

$ 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      1.4.14

奇怪的是，这个错误大约每周发生一次，但是昨天，它发生了大约 2000 次。
发生此错误时，服务器也会出现繁忙状态。
它会随着时间的推移而消失。

■云观察日志:

■新遗迹应用日志:

我不知道这是怎么回事。如果您有好的解决方案，请告诉我。

---

2020/10/8更新

时间很长，我解决了这个问题:

当用户访问多的时候，AWS EC2上好像DNS解析不了。

https://aws.amazon.com/jp/premiumsupport/knowledge-center/dns-resolution-failures-ec2-linux/

这里是修复补丁。

$ 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.

Answer 1

我相信这里的解决方案是在您完成向 session 写入数据后立即调用 session_write_close()。它仍可用于读取，但不能再进行写入。 This稍微解释一下。

长时间运行的请求将导致最大的问题。如果从未调用 session_write_close()，PHP 将不会关闭/解锁 session ，直到请求完成。

您也可以尝试手动实现锁定，只锁定您需要锁定的字段。多年来，通过 Memcache 锁定 session 存在许多错误和问题。