MySQL（MariaDB - 10.0.16-MariaDB-1（Debian）奇怪的性能问题

Question

我在Dual Xeon CPU上运行版本10.0.16-MariaDB-1（Debian GNU/Linux 8.1（jessie）），共32个内核128 GB的RAM。这是一个专用DB服务器，并已从最近的Percona DB服务器迁移过来。我的配置是这样的，

################################################################################ 
# DATE: 19-01-2014 
# DESCRIPTION: MySQL config 
# RAM: 128GB RAM dedicated server 
# Connections: 1000 connections 
################################################################################ 

[mysql] 
# CLIENT # 
port       = 1979 
socket       = /var/run/mysqld/mysqld.sock 

[mysqld] 

## Files 
back_log   = 300 
open-files-limit  = 8192 
#open-files    = 1024 

# GENERAL # 
user       = mysql 
default-storage-engine   = InnoDB 
port       = 1979 
socket       = /var/run/mysqld/mysqld.sock 
pid-file      = /var/run/mysqld/mysql.pid 

# DATA STORAGE # 
datadir      = /var/lib/mysql 

# LOGGING # 
log-error      = /var/log/mysql/mysql-error.log 
log-queries-not-using-indexes = 0 
slow-query-log     = 0 
slow-query-log-file   = /var/log/mysql/mysql-slow.log 

## Per-Thread Buffers * (max_connections) = total per-thread mem usage 
thread_stack   = 512K #default: 32bit: 192K, 64bit: 256K 
sort_buffer_size  = 2M  #default: 2M, larger may cause perf issues 
read_buffer_size  = 2M  #default: 128K, change in increments of 4K 
read_rnd_buffer_size  = 2M  #default: 256K     
join_buffer_size  = 2M  #default: 128K 
binlog_cache_size  = 128K #default: 32K, size of buffer to hold TX queries 
## total per-thread buffer memory usage: 17664000K = 17.250GB 

## Query Cache 
query_cache_size  = 64M #global buffer 
query_cache_limit    = 2M #max query result size to put in cache 

## Connections 
max_connections = 900 #multiplier for memory usage via per-thread buffers 
max_connect_errors  = 1000 #default: 10 
concurrent_insert = 2 
connect_timeout   = 10 #default -5.1.22: 5, +5.1.22: 10 
max_allowed_packet  = 32M #max size of incoming data to allow 

## Default Table Settings 
sql_mode   = NO_AUTO_CREATE_USER 

## Table and TMP settings 
max_heap_table_size   = 1G #recommend same size as tmp_table_size 
bulk_insert_buffer_size   = 1G #recommend same size as tmp_table_size 
tmp_table_size     = 1G #recommend 1G min 
tmpdir       = /dev/shm  #Recommend using RAMDISK for tmpdir 

## Table cache settings 
#table_cache   = 512 #5.0.x <default: 64> 
#table_open_cache  = 512 #5.1.x, 5.5.x <default: 64> 

query-cache-type = 1 

## Thread settings 
thread_concurrency  = 32 #recommend 2x CPU cores 
thread_cache_size  = 400 #recommend 5% of max_connections 

## InnoDB Plugin Independent Settings 
innodb_data_home_dir   = /var/lib/mysql 
innodb_data_file_path  = ibdata1:128M;ibdata2:10M:autoextend 
innodb_log_file_size  = 768M #64G_RAM+ = 768, 24G_RAM+ = 512, 8G_RAM+ = 256, 2G_RAM+ = 128 
innodb_log_files_in_group = 4 #combined size of all logs <4GB. <2G_RAM = 2, >2G_RAM = 4 
innodb_buffer_pool_size  = 96G #global buffer 
innodb_additional_mem_pool_size = 8M #global buffer 
innodb_status_file   #extra reporting 
innodb_file_per_table   #enable always 
innodb_flush_log_at_trx_commit = 2 
innodb_table_locks  = 0 #preserve table locks 
innodb_log_buffer_size  = 128M #global buffer 
innodb_lock_wait_timeout = 600 
#innodb_thread_concurrency = 0 
innodb_commit_concurrency = 8 #recommend 4x num disks 
innodb_flush_method  = O_DIRECT_NO_FSYNC #O_DIRECT = local/DAS, O_DSYNC = SAN/iSCSI 
innodb_support_xa  = 0  #recommend 0, disable xa to negate extra disk flush 
innodb_fast_shutdown = 1 
skip-innodb-doublewrite 
skip-host-cache 
# skip-name-resolve 

## Binlog sync settings 
## XA transactions = 1, otherwise set to 0 for best performance 
sync_binlog   = 0 

## TX Isolation 
#transaction-isolation  = REPEATABLE-READ #REPEATABLE-READ req for ACID, SERIALIZABLE req XA 

## Per-Thread Buffer memory utilization equation: 
#(read_buffer_size + read_rnd_buffer_size + sort_buffer_size + thread_stack + join_buffer_size + binlog_cache_size) * max_connections 

## Replication 
#server_id   = 1 
#log_bin    = /var/log/mysql/mysql-bin.log 
#log_bin_index  = /var/log/mysql/mysql-bin.log.index 
#relay_log   = /var/log/mysql/mysql-relay-bin 
#relay_log_index  = /var/log/mysql/mysql-relay-bin.index 
#expire_logs_days = 10 
#max_binlog_size  = 100M 
#log_slave_updates = 1 
#auto-increment-increment = 2 
#auto-increment-offset = 1 

## Global Buffer memory utilization equation: 
# innodb_buffer_pool_size + innodb_additional_mem_pool_size + innodb_log_buffer_size + key_buffer_size + query_cache_size 
long_query_time = 3 
innodb_checksum_algorithm=NONE 
interactive_timeout = 300 
wait_timeout = 40 
myisam_repair_threads = 8 
myisam-block-size = 8096 
innodb_adaptive_hash_index = off 
innodb_use_sys_malloc 
innodb_sync_array_size = 4 
innodb_read_ahead_threshold = 56 
innodb_purge_threads = 4 
innodb_adaptive_flushing = off 
innodb_use_native_aio = off 
innodb_random_read_ahead 
optimizer_search_depth = 24 
table_definition_cache = 400 
table_open_cache = 2048 
delay-key-write = ALL 
innodb_checksum_algorithm = innodb 
innodb_write_io_threads = 64 
innodb_read_io_threads = 64 
thread_pool_size = 16 
thread_handling = pool-of-threads 

innodb_disable_sort_file_cache 
innodb_buffer_pool_instances = 32 
innodb_adaptive_hash_index = off 

[mysqldump] 
quick 
quote-names 
max_allowed_packet  = 128M 

我无法连接到服务器并开始查询多台主机。这个问题我我面对的是随机数据库服务器停止接受连接，所有的连接开始堆积起来，并在大约3或5秒恢复正常当我运行show processlist我看到很多连接堆积等待connected但由于数据库服务器停止接受连接，最终连接池变满，不允许进一步的连接。

在这个停电期间，我无法看到DB服务器上发生了什么，因为即使连接已建立，我也不会给我任何信息。 iostat -d -x 1不会显示任何不寻常的磁盘，CPU也大多是空闲的。 TCP连接堆积如山，因为客户端需要打开连接，因为它们需要推送数据。

我无法弄清楚这里有什么问题。这是特定于我的数据库，或机器或配置的东西。在这里，我需要一些帮助来确定和纠正问题。

谢谢。

Answer 1

thread_stack = 512K＃默认：32位：192K，64位：256K

我还没有听说过需要超过256K的。你是否发现需要512K？加上

的max_connections = 900

您可能需要过程500MB。 （当然，这是不是一个大问题，因为你有公羊128GB）

回到问题...

打开与long_query_time时间= 1的下一个出现后slow_log，运行PT-查询针对慢速记录进行摘要。那里可能会有一些惊喜。请注意，在3-5秒暂停期间挂起的查询将注册为几秒钟，即使它们只需要几毫秒。还有一个风险是，它不会指出暂停的真正原因。