MariaDB Galera Cluster 很容易失去同步

MariaDB Galera Cluster 很容易失去同步

我们正在尝试调试 MariaDB 集群的问题。

我们在 Amazon EC2 中的实例上运行 Maria 10.0.19 c4.large;操作系统是 Ubuntu 14.04(Trusty)。

有三台机器聚集在一起,复制良好(我们可以create database foo;在一台机器上运行并在另一台机器上看到它,等等)。:当我们尝试从转储中恢复数据库时,所有三台机器都在运行并同步,出现错误:

$ du -sh *.sql
2.7G    sqldump.sql
$ cat sqldump.sql | sudo mysql
ERROR 1047 (08S01) at line 4361: WSREP has not yet prepared node for application use

这个错误似乎与导入所花的时间有关。如果我们service mysql stop在集群中的三个节点中的两个上运行,并对剩余的节点运行 SQL 命令,它工作正常。然后我们可以逐个启动集群中的每台机器,通过 SST 复制数据,所以这似乎是 Galera 配置的问题。

这不仅在运行大型 MySQL 导入时发生:在日常使用小型事务时也会发生。不过,大型导入是我们复制此问题最可靠的方法。

导入过程中的系统内存使用率不是特别高,CPU 使用率也不是特别高。网络流量远低于机器链路所能承受的范围,在我们的测试中,除了 SSH 连接之外没有其他流量。

有人可以帮忙了解导致此问题的原因吗?

以下是有关集群中的机器和 MariaDB 配置的更多详细信息:

乌本图:

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 14.04.2 LTS
Release:        14.04
Codename:       trusty

核心:

$ uname -a
Linux servername.domain 3.13.0-53-generic #89-Ubuntu SMP Wed May 20 10:34:39 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux

MySQL 配置(IP 地址、域名等wsrep_cluster_address故意被混淆):

$ find /etc/mysql/ -name "*.cnf" -exec cat {} \; | egrep -v "^#" | grep v "^$"
[mysqld]
server-id               = 965424531
bind-address            = *
max_connections         = 500
max_connect_errors      = 1000000
innodb_buffer_pool_size = 2635M
log_bin                        = /var/lib/mysql/mysql/mysql-bin
expire_logs_days               = 7
sync_binlog                    = 1
binlog_format                  = MIXED
log-slave-updates              = 1
slow_query_log                 = 1
slow_query_log_file            = /var/log/mysql/mysql-slow.log
[mysqld]
innodb_use_native_aio = 0
innodb_flush_method = O_DSYNC
[client]
[mysqld]
[mysqld_safe]
syslog
[mariadb]
[client]
port        = 3306
socket      = /var/run/mysqld/mysqld.sock
[mysqld_safe]
socket      = /var/run/mysqld/mysqld.sock
nice        = 0
[mysqld]
user        = mysql
pid-file    = /var/run/mysqld/mysqld.pid
socket      = /var/run/mysqld/mysqld.sock
port        = 3306
basedir     = /usr
datadir     = /var/lib/mysql
tmpdir      = /tmp
lc-messages-dir = /usr/share/mysql
skip-external-locking
bind-address        = 127.0.0.1
key_buffer          = 16M
max_allowed_packet  = 16M
thread_stack        = 192K
thread_cache_size   = 8
myisam-recover      = BACKUP
query_cache_limit   = 1M
query_cache_size    = 16M
log_error = /var/log/mysql/error.log
expire_logs_days = 10
max_binlog_size  = 100M
[mysqldump]
quick
quote-names
max_allowed_packet  = 16M
[isamchk]
key_buffer      = 16M
!includedir /etc/mysql/conf.d/
[mysqld]
wsrep_provider=/usr/lib/galera/libgalera_smm.so
wsrep_debug=ON
wsrep_cluster_name="clustername"
wsrep_cluster_address="gcomm://10.0.X.X,10.0.X.X"
wsrep_sst_method=xtrabackup-v2
wsrep_sst_auth=sstuser:sstpassword
wsrep_node_address="10.0.1.10"
wsrep_node_name="servername.domain"
binlog_format=ROW
wsrep_on=ON
default_storage_engine=InnoDB
innodb_autoinc_lock_mode=2
innodb_doublewrite=1
query_cache_size=0
innodb_log_file_size           = 256M

集群状态:

$ sudo mysql
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 288
Server version: 10.0.19-MariaDB-1~trusty-wsrep-log mariadb.org binary distribution, wsrep_25.10.r4144

Copyright (c) 2000, 2015, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MariaDB [(none)]> show status like '%wsrep%';
+------------------------------+---------------------------------------------------+
| Variable_name                | Value                                             |
+------------------------------+---------------------------------------------------+
| wsrep_local_state_uuid       | e856afdc-18af-11e5-a3a6-efccde439ba4              |
| wsrep_protocol_version       | 7                                                 |
| wsrep_last_committed         | 45764                                             |
| wsrep_replicated             | 2031                                              |
| wsrep_replicated_bytes       | 1527494811                                        |
| wsrep_repl_keys              | 9973524                                           |
| wsrep_repl_keys_bytes        | 79839767                                          |
| wsrep_repl_data_bytes        | 1447525060                                        |
| wsrep_repl_other_bytes       | 0                                                 |
| wsrep_received               | 1478                                              |
| wsrep_received_bytes         | 13040                                             |
| wsrep_local_commits          | 1750                                              |
| wsrep_local_cert_failures    | 0                                                 |
| wsrep_local_replays          | 0                                                 |
| wsrep_local_send_queue       | 0                                                 |
| wsrep_local_send_queue_max   | 2                                                 |
| wsrep_local_send_queue_min   | 0                                                 |
| wsrep_local_send_queue_avg   | 0.001140                                          |
| wsrep_local_recv_queue       | 0                                                 |
| wsrep_local_recv_queue_max   | 7                                                 |
| wsrep_local_recv_queue_min   | 0                                                 |
| wsrep_local_recv_queue_avg   | 0.043302                                          |
| wsrep_local_cached_downto    | 45564                                             |
| wsrep_flow_control_paused_ns | 3956186469                                        |
| wsrep_flow_control_paused    | 0.005006                                          |
| wsrep_flow_control_sent      | 0                                                 |
| wsrep_flow_control_recv      | 41                                                |
| wsrep_cert_deps_distance     | 4.487445                                          |
| wsrep_apply_oooe             | 0.000000                                          |
| wsrep_apply_oool             | 0.000000                                          |
| wsrep_apply_window           | 1.000000                                          |
| wsrep_commit_oooe            | 0.000000                                          |
| wsrep_commit_oool            | 0.000000                                          |
| wsrep_commit_window          | 1.000000                                          |
| wsrep_local_state            | 4                                                 |
| wsrep_local_state_comment    | Synced                                            |
| wsrep_cert_index_size        | 11438                                             |
| wsrep_causal_reads           | 0                                                 |
| wsrep_cert_interval          | 0.000000                                          |
| wsrep_incoming_addresses     | ,,                                                |
| wsrep_evs_delayed            |                                                   |
| wsrep_evs_evict_list         |                                                   |
| wsrep_evs_repl_latency       | 0.00059098/0.000958534/0.00469729/0.000375612/732 |
| wsrep_evs_state              | OPERATIONAL                                       |
| wsrep_gcomm_uuid             | 8bcfefe4-25f7-11e5-be32-062acc002ed5              |
| wsrep_cluster_conf_id        | 88                                                |
| wsrep_cluster_size           | 3                                                 |
| wsrep_cluster_state_uuid     | e856afdc-18af-11e5-a3a6-efccde439ba4              |
| wsrep_cluster_status         | Primary                                           |
| wsrep_connected              | ON                                                |
| wsrep_local_bf_aborts        | 0                                                 |
| wsrep_local_index            | 2                                                 |
| wsrep_provider_name          | Galera                                            |
| wsrep_provider_vendor        | Codership Oy <[email protected]>                 |
| wsrep_provider_version       | 3.9(rXXXX)                                        |
| wsrep_ready                  | ON                                                |
| wsrep_thread_count           | 2                                                 |
+------------------------------+---------------------------------------------------+
57 rows in set (0.00 sec)

答案1

首先,巨大的交易和LOAD DATA INFILE在 galera 集群上仍然是一个已知的限制,如果必须的话,建议将这些交易分成 5k-10k trx 或更少的 YMMV。

嘗試增加wsrep-max-ws-size

innodb_flush_log_at_trx_commit=0在所有节点上设置。

答案2

基于https://mariadb.com/kb/en/mariadb/mariadb-galera-cluster-known-limitations/

“事务大小。虽然 Galera 没有明确限制事务大小,但写入集作为单个内存驻留缓冲区进行处理,因此,极大的事务(例如 LOAD DATA)可能会对节点性能产生不利影响。为了避免这种情况,wsrep_max_ws_rows 和 wsrep_max_ws_size 系统变量默认将事务行限制为 128K,将事务大小限制为 1Gb。如有必要,用户可能希望增加这些限制。未来版本将增加对事务碎片的支持。”

目前尚不清楚您的 SQL 实际包含什么,但是大型交易可能会达到这些限制。

执行 mysqldump 的机器上的 max_allowed_pa​​cket 可能比您配置的要大。

您应该发布此类事件的 mysql 错误日志,因为这将提供有意义的信息。

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