我有一个旧的django 1.9应用程序连接到mysql 5.7数据库。有时我会收到此错误：
[Fri Mar 20 10:27:19.482820 2020] [wsgi:error] [pid 15215] "
[Fri Mar 20 10:28:20.502889 2020] [wsgi:error] [pid 15215] [NXU ts_fw20] [2020-03-20 Fri 10:28:20.1584696500]ERROR "Exception during GET request (user: AnonymousUser): <QueryDict: {u'udid': [u'B8663A17-C121-4691-A561-E0F698CDD4EA'], u'client_os_version': [u'13.3.1'], u'client_app_version': [u'11.30.1.201910161040'], u'client_app_type': [u'Jukebox'], u'client_app_name': [u'p_ts_w_fw20']}> ->
[Fri Mar 20 10:28:20.502976 2020] [wsgi:error] [pid 15215] Traceback (most recent call last):
[Fri Mar 20 10:28:20.502991 2020] [wsgi:error] [pid 15215] File "/home/nuxie/virtualenv/110-fw20/production/lib/python2.7/site-packages/django/core/handlers/base.py", line 147, in get_response
[Fri Mar 20 10:28:20.503041 2020] [wsgi:error] [pid 15215] response = wrapped_callback(request, *callback_args, **callback_kwargs)
[Fri Mar 20 10:28:20.503101 2020] [wsgi:error] [pid 15215] File "/home/nuxie/virtualenv/110-fw20/production/lib/python2.7/site-packages/nxlib/core/services/utils/api.py", line 307, in wrapper
[Fri Mar 20 10:28:20.503114 2020] [wsgi:error] [pid 15215] user = authenticator.check_auth(request)
[Fri Mar 20 10:28:20.503123 2020] [wsgi:error] [pid 15215] File "/home/nuxie/virtualenv/110-fw20/production/lib/python2.7/site-packages/nxlib/core/networking/auth.py", line 21, in check_auth
[Fri Mar 20 10:28:20.503133 2020] [wsgi:error] [pid 15215] user = self.authenticate(credentials)
[Fri Mar 20 10:28:20.503142 2020] [wsgi:error] [pid 15215] File "/home/nuxie/virtualenv/110-fw20/production/lib/python2.7/site-packages/nxlib/core/services/utils/api.py", line 387, in authenticate
[Fri Mar 20 10:28:20.503151 2020] [wsgi:error] [pid 15215] user = auth.authenticate(username=username, password=password)
[Fri Mar 20 10:28:20.503160 2020] [wsgi:error] [pid 15215] File "/home/nuxie/virtualenv/110-fw20/production/lib/python2.7/site-packages/django/contrib/auth/__init__.py", line 74, in authenticate
[Fri Mar 20 10:28:20.503168 2020] [wsgi:error] [pid 15215] user = backend.authenticate(**credentials)
[Fri Mar 20 10:28:20.503177 2020] [wsgi:error] [pid 15215] File "/home/nuxie/virtualenv/110-fw20/production/lib/python2.7/site-packages/django/contrib/auth/backends.py", line 17, in authenticate
[Fri Mar 20 10:28:20.503186 2020] [wsgi:error] [pid 15215] user = UserModel._default_manager.get_by_natural_key(username)
[Fri Mar 20 10:28:20.503194 2020] [wsgi:error] [pid 15215] File "/home/nuxie/virtualenv/110-fw20/production/lib/python2.7/site-packages/django/contrib/auth/base_user.py", line 45, in get_by_natural_key
[Fri Mar 20 10:28:20.503203 2020] [wsgi:error] [pid 15215] return self.get(**{self.model.USERNAME_FIELD: username})
[Fri Mar 20 10:28:20.503211 2020] [wsgi:error] [pid 15215] File "/home/nuxie/virtualenv/110-fw20/production/lib/python2.7/site-packages/django/db/models/manager.py", line 122, in manager_method
[Fri Mar 20 10:28:20.503220 2020] [wsgi:error] [pid 15215] return getattr(self.get_queryset(), name)(*args, **kwargs)
[Fri Mar 20 10:28:20.503228 2020] [wsgi:error] [pid 15215] File "/home/nuxie/virtualenv/110-fw20/production/lib/python2.7/site-packages/django/db/models/query.py", line 381, in get
[Fri Mar 20 10:28:20.503237 2020] [wsgi:error] [pid 15215] num = len(clone)
[Fri Mar 20 10:28:20.503244 2020] [wsgi:error] [pid 15215] File "/home/nuxie/virtualenv/110-fw20/production/lib/python2.7/site-packages/django/db/models/query.py", line 240, in __len__
[Fri Mar 20 10:28:20.503253 2020] [wsgi:error] [pid 15215] self._fetch_all()
[Fri Mar 20 10:28:20.503261 2020] [wsgi:error] [pid 15215] File "/home/nuxie/virtualenv/110-fw20/production/lib/python2.7/site-packages/django/db/models/query.py", line 1074, in _fetch_all
[Fri Mar 20 10:28:20.503269 2020] [wsgi:error] [pid 15215] self._result_cache = list(self.iterator())
[Fri Mar 20 10:28:20.503278 2020] [wsgi:error] [pid 15215] File "/home/nuxie/virtualenv/110-fw20/production/lib/python2.7/site-packages/django/db/models/query.py", line 52, in __iter__
[Fri Mar 20 10:28:20.503286 2020] [wsgi:error] [pid 15215] results = compiler.execute_sql()
[Fri Mar 20 10:28:20.503294 2020] [wsgi:error] [pid 15215] File "/home/nuxie/virtualenv/110-fw20/production/lib/python2.7/site-packages/django/db/models/sql/compiler.py", line 846, in execute_sql
[Fri Mar 20 10:28:20.503302 2020] [wsgi:error] [pid 15215] cursor = self.connection.cursor()
[Fri Mar 20 10:28:20.503311 2020] [wsgi:error] [pid 15215] File "/home/nuxie/virtualenv/110-fw20/production/lib/python2.7/site-packages/django/db/backends/base/base.py", line 233, in cursor
[Fri Mar 20 10:28:20.503319 2020] [wsgi:error] [pid 15215] cursor = self.make_cursor(self._cursor())
[Fri Mar 20 10:28:20.503327 2020] [wsgi:error] [pid 15215] File "/home/nuxie/virtualenv/110-fw20/production/lib/python2.7/site-packages/django/db/backends/base/base.py", line 204, in _cursor
[Fri Mar 20 10:28:20.503345 2020] [wsgi:error] [pid 15215] self.ensure_connection()
[Fri Mar 20 10:28:20.503354 2020] [wsgi:error] [pid 15215] File "/home/nuxie/virtualenv/110-fw20/production/lib/python2.7/site-packages/django/db/backends/base/base.py", line 199, in ensure_connection
[Fri Mar 20 10:28:20.503363 2020] [wsgi:error] [pid 15215] self.connect()
[Fri Mar 20 10:28:20.503372 2020] [wsgi:error] [pid 15215] File "/home/nuxie/virtualenv/110-fw20/production/lib/python2.7/site-packages/django/db/utils.py", line 95, in __exit__
[Fri Mar 20 10:28:20.503380 2020] [wsgi:error] [pid 15215] six.reraise(dj_exc_type, dj_exc_value, traceback)
[Fri Mar 20 10:28:20.503389 2020] [wsgi:error] [pid 15215] File "/home/nuxie/virtualenv/110-fw20/production/lib/python2.7/site-packages/django/db/backends/base/base.py", line 199, in ensure_connection
[Fri Mar 20 10:28:20.503398 2020] [wsgi:error] [pid 15215] self.connect()
[Fri Mar 20 10:28:20.503406 2020] [wsgi:error] [pid 15215] File "/home/nuxie/virtualenv/110-fw20/production/lib/python2.7/site-packages/django/db/backends/base/base.py", line 171, in connect
[Fri Mar 20 10:28:20.503415 2020] [wsgi:error] [pid 15215] self.connection = self.get_new_connection(conn_params)
[Fri Mar 20 10:28:20.503423 2020] [wsgi:error] [pid 15215] File "/home/nuxie/virtualenv/110-fw20/production/lib/python2.7/site-packages/django/db/backends/mysql/base.py", line 264, in get_new_connection
[Fri Mar 20 10:28:20.503433 2020] [wsgi:error] [pid 15215] conn = Database.connect(**conn_params)
[Fri Mar 20 10:28:20.503441 2020] [wsgi:error] [pid 15215] File "/home/nuxie/virtualenv/110-fw20/production/lib/python2.7/site-packages/MySQLdb/__init__.py", line 81, in Connect
[Fri Mar 20 10:28:20.503450 2020] [wsgi:error] [pid 15215] return Connection(*args, **kwargs)
[Fri Mar 20 10:28:20.503458 2020] [wsgi:error] [pid 15215] File "/home/nuxie/virtualenv/110-fw20/production/lib/python2.7/site-packages/MySQLdb/connections.py", line 193, in __init__
[Fri Mar 20 10:28:20.503467 2020] [wsgi:error] [pid 15215] super(Connection, self).__init__(*args, **kwargs2)
[Fri Mar 20 10:28:20.503475 2020] [wsgi:error] [pid 15215] OperationalError: (1040, 'Too many connections')
我的初始MySQL设置：
max_connections 150
connect_timeout 10
delayed_insert_timeout 300
have_statement_timeout YES
innodb_flush_log_at_timeout 1
innodb_lock_wait_timeout 50
innodb_rollback_on_timeout OFF
interactive_timeout 28800
lock_wait_timeout 31536000
net_read_timeout 30
net_write_timeout 60
rpl_stop_slave_timeout 31536000
slave_net_timeout 60
wait_timeout 28800
bulk_insert_buffer_size 8388608
innodb_buffer_pool_chunk_size 134217728
innodb_buffer_pool_dump_at_shutdown ON
innodb_buffer_pool_dump_now OFF
innodb_buffer_pool_dump_pct 25
innodb_buffer_pool_filename ib_buffer_pool
innodb_buffer_pool_instances 1
innodb_buffer_pool_load_abort OFF
innodb_buffer_pool_load_at_startup ON
innodb_buffer_pool_load_now OFF
innodb_buffer_pool_size 134217728
innodb_change_buffer_max_size 25
innodb_change_buffering all
innodb_log_buffer_size 16777216
innodb_sort_buffer_size 1048576
join_buffer_size 262144
key_buffer_size 16777216
myisam_sort_buffer_size 8388608
net_buffer_length 16384
preload_buffer_size 32768
read_buffer_size 131072
read_rnd_buffer_size 262144
sort_buffer_size 262144
sql_buffer_result OFF
max_allowed_packet 16777216
slave_max_allowed_packet 1073741824
show global variables here的完整输出。
现在我正在使用max_connections等于311。
这里还有一些有关服务器的其他硬件信息。我不知道MySQL Host服务器上是否有任何SSD或NVME设备，因为它是不受我管理的虚拟机，我仅管理django应用程序。当然，现在我想避免mysql错误。
$ ps -ef|grep apache2|grep -v grep -c
11
MySQL服务状态：
$ sudo service mysql status
● mysql.service - MySQL Community Server
Loaded: loaded (/lib/systemd/system/mysql.service; enabled; vendor preset: enabled)
Active: active (running) since Fri 2020-03-20 10:28:33 CET; 3h 31min ago
Process: 17847 ExecStartPost=/usr/share/mysql/mysql-systemd-start post (code=exited, status=0/SUCCESS)
Process: 17834 ExecStartPre=/usr/share/mysql/mysql-systemd-start pre (code=exited, status=0/SUCCESS)
Main PID: 17846 (mysqld)
Tasks: 166
Memory: 494.0M
CPU: 57min 24.058s
CGroup: /system.slice/mysql.service
└─17846 /usr/sbin/mysqld
Mar 20 10:28:31 _ systemd[1]: Starting MySQL Community Server...
Mar 20 10:28:33 _ systemd[1]: Started MySQL Community Server.
CPU信息：
$ lscpu
Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
Byte Order: Little Endian
CPU(s): 4
On-line CPU(s) list: 0-3
Thread(s) per core: 1
Core(s) per socket: 4
Socket(s): 1
NUMA node(s): 1
Vendor ID: GenuineIntel
CPU family: 6
Model: 62
Model name: Intel(R) Xeon(R) CPU E5-2650L v2 @ 1.70GHz
Stepping: 4
CPU MHz: 1700.000
BogoMIPS: 3400.00
Hypervisor vendor: VMware
Virtualization type: full
L1d cache: 32K
L1i cache: 32K
L2 cache: 256K
L3 cache: 25600K
NUMA node0 CPU(s): 0-3
Flags: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts mmx fxsr sse sse2 ss ht syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts nopl xtopology tsc_reliable nonstop_tsc pni pclmulqdq ssse3 cx16 pcid sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx f16c rdrand hypervisor lahf_lm ibrs ibpb stibp kaiser fsgsbase tsc_adjust smep arat arch_capabilities
可用内存：
$ free -m
total used free shared buff/cache available
Mem: 32175 2277 1465 369 28432 28317
Swap: 975 2 972
ulimit的完整输出：
$ ulimit -a
core file size (blocks, -c) 0
data seg size (kbytes, -d) unlimited
scheduling priority (-e) 0
file size (blocks, -f) unlimited
pending signals (-i) 128535
max locked memory (kbytes, -l) 64
max memory size (kbytes, -m) unlimited
open files (-n) 24000
pipe size (512 bytes, -p) 8
POSIX message queues (bytes, -q) 819200
real-time priority (-r) 0
stack size (kbytes, -s) 8192
cpu time (seconds, -t) unlimited
max user processes (-u) 128535
virtual memory (kbytes, -v) unlimited
file locks (-x) unlimited
由于此article from Percona，我想也更改wait_timeout变量，但是我不确定要使用的值。
有人建议对我的mysql服务器进行一般的微调吗？
编辑：我也尝试过MySQLTuner-perl，但没有看到与我的实际问题有关的任何东西：
$ perl mysqltuner.pl --host 127.0.0.1
>> MySQLTuner 1.7.19 - Major Hayden <[email protected]>
>> Bug reports, feature requests, and downloads at http://mysqltuner.com/
>> Run with '--help' for additional options and output filtering
[--] Skipped version check for MySQLTuner script
[--] Performing tests on 127.0.0.1:3306
Please enter your MySQL administrative login: root
Please enter your MySQL administrative password: [OK] Currently running supported MySQL version 5.7.25-0ubuntu0.16.04.2
[OK] Operating on 64-bit architecture
-------- Log file Recommendations ------------------------------------------------------------------
[OK] Log file /var/log/mysql/error.log exists
[--] Log file: /var/log/mysql/error.log(744B)
[OK] Log file /var/log/mysql/error.log is readable.
[OK] Log file /var/log/mysql/error.log is not empty
[OK] Log file /var/log/mysql/error.log is smaller than 32 Mb
[OK] /var/log/mysql/error.log doesn't contain any warning.
[!!] /var/log/mysql/error.log contains 2 error(s).
[--] 0 start(s) detected in /var/log/mysql/error.log
[--] 0 shutdown(s) detected in /var/log/mysql/error.log
-------- Storage Engine Statistics -----------------------------------------------------------------
[--] Status: +ARCHIVE +BLACKHOLE +CSV -FEDERATED +InnoDB +MEMORY +MRG_MYISAM +MyISAM +PERFORMANCE_SCHEMA
[--] Data in MyISAM tables: 1.0K (Tables: 1)
[--] Data in InnoDB tables: 396.9M (Tables: 4650)
[OK] Total fragmented tables: 0
-------- Analysis Performance Metrics --------------------------------------------------------------
[--] innodb_stats_on_metadata: OFF
[OK] No stat updates during querying INFORMATION_SCHEMA.
-------- Security Recommendations ------------------------------------------------------------------
[OK] There are no anonymous accounts for any database users
[OK] All database users have passwords assigned
[!!] There is no basic password file list!
-------- CVE Security Recommendations --------------------------------------------------------------
[--] Skipped due to --cvefile option undefined
-------- Performance Metrics -----------------------------------------------------------------------
[--] Up for: 302d 0h 54m 4s (34M q [1.320 qps], 19K conn, TX: 44G, RX: 19G)
[--] Reads / Writes: 99% / 1%
[--] Binary logging is disabled
[--] Physical Memory : 31.4G
[--] Max MySQL memory : 3.5G
[--] Other process memory: 0B
[--] Total buffers: 192.0M global + 17.1M per thread (201 max threads)
[--] P_S Max memory usage: 72B
[--] Galera GCache Max memory usage: 0B
[OK] Maximum reached memory usage: 1.4G (4.31% of installed RAM)
[OK] Maximum possible memory usage: 3.5G (11.26% of installed RAM)
[OK] Overall possible memory usage with other process is compatible with memory available
[OK] Slow queries: 0% (0/34M)
[OK] Highest usage of available connections: 34% (70/201)
[OK] Aborted connections: 0.15% (30/19766)
[!!] name resolution is active : a reverse name resolution is made for each new connection and can reduce performance
[!!] Query cache may be disabled by default due to mutex contention.
[!!] Query cache efficiency: 0.0% (0 cached / 34M selects)
[OK] Query cache prunes per day: 0
[OK] Sorts requiring temporary tables: 4% (10K temp sorts / 205K sorts)
[OK] No joins without indexes
[!!] Temporary tables created on disk: 59% (46K on disk / 77K total)
[OK] Thread cache hit rate: 96% (700 created / 19K connections)
[!!] Table cache hit rate: 0% (416 open / 411K opened)
[!!] table_definition_cache(615) is lower than number of tables(4930)
[OK] Open file limit used: 0% (7/1K)
[OK] Table locks acquired immediately: 100% (2K immediate / 2K locks)
-------- Performance schema ------------------------------------------------------------------------
[--] Memory used by P_S: 72B
[--] Sys schema is installed.
-------- ThreadPool Metrics ------------------------------------------------------------------------
[--] ThreadPool stat is disabled.
-------- MyISAM Metrics ----------------------------------------------------------------------------
[!!] Key buffer used: 18.3% (3M used / 16M cache)
[OK] Key buffer size / total MyISAM indexes: 16.0M/48.0K
[OK] Read Key buffer hit rate: 99.6% (14K cached / 66 reads)
[OK] Write Key buffer hit rate: 100.0% (121 cached / 121 writes)
-------- InnoDB Metrics ----------------------------------------------------------------------------
[--] InnoDB is enabled.
[--] InnoDB Thread Concurrency: 0
[OK] InnoDB File per table is activated
[!!] InnoDB buffer pool / data size: 128.0M/396.9M
[!!] Ratio InnoDB log file size / InnoDB Buffer pool size (75 %): 48.0M * 2/128.0M should be equal to 25%
[OK] InnoDB buffer pool instances: 1
[--] Number of InnoDB Buffer Pool Chunk : 1 for 1 Buffer Pool Instance(s)
[OK] Innodb_buffer_pool_size aligned with Innodb_buffer_pool_chunk_size & Innodb_buffer_pool_instances
[OK] InnoDB Read buffer efficiency: 100.00% (18914488493 hits/ 18914570989 total)
[OK] InnoDB Write log efficiency: 96.81% (1249437 hits/ 1290575 total)
[OK] InnoDB log waits: 0.00% (0 waits / 41138 writes)
-------- AriaDB Metrics ----------------------------------------------------------------------------
[--] AriaDB is disabled.
-------- TokuDB Metrics ----------------------------------------------------------------------------
[--] TokuDB is disabled.
-------- XtraDB Metrics ----------------------------------------------------------------------------
[--] XtraDB is disabled.
-------- Galera Metrics ----------------------------------------------------------------------------
[--] Galera is disabled.
-------- Replication Metrics -----------------------------------------------------------------------
[--] Galera Synchronous replication: NO
[--] No replication slave(s) for this server.
[--] Binlog format: ROW
[--] XA support enabled: ON
[--] Semi synchronous replication Master: Not Activated
[--] Semi synchronous replication Slave: Not Activated
[--] This is a standalone server
-------- Recommendations ---------------------------------------------------------------------------
General recommendations:
Control error line(s) into /var/log/mysql/error.log file
Configure your accounts with ip or subnets only, then update your configuration with skip-name-resolve=1
When making adjustments, make tmp_table_size/max_heap_table_size equal
Reduce your SELECT DISTINCT queries which have no LIMIT clause
Increase table_open_cache gradually to avoid file descriptor limits
Read this before increasing table_open_cache over 64: https://zzz
Read this before increasing for MariaDB https://mariadb.com/kb/en/library/optimizing-table_open_cache/
This is MyISAM only table_cache scalability problem, InnoDB not affected.
See more details here: https://bugs.mysql.com/bug.php?id=49177
This bug already fixed in MySQL 5.7.9 and newer MySQL versions.
Beware that open_files_limit (1024) variable
should be greater than table_open_cache (431)
Before changing innodb_log_file_size and/or innodb_log_files_in_group read this: https://xxx
Variables to adjust:
query_cache_size (=0)
query_cache_type (=0)
query_cache_limit (> 1M, or use smaller result sets)
tmp_table_size (> 16M)
max_heap_table_size (> 16M)
table_open_cache (> 431)
table_definition_cache(615) > 4930 or -1 (autosizing if supported)
innodb_buffer_pool_size (>= 396.9M) if possible.
innodb_log_file_size should be (=16M) if possible, so InnoDB total log files size equals to 25% of buffer pool size.
我拆分了代码块，以期希望提高可读性。在星期一，我还将添加有关mysql全局状态，完整进程列表和iowait stats的完整信息（添加了全局变量链接here）。
我现在正在使用：
max_connections = 311ulimit -n 24000（检查ulimit -a的输出）。也具有默认的wait_timeout，我目前没有任何主要缺点。
提前感谢。
我注意到您在运行ulimit -n 1024时将ubuntu中的SET Open Files句柄设置为1024。系统需要更多可用的Open File句柄来支持4650 innodb表。建议使用ulimit -n 24000，然后使用ulimit -a检查设置（以列出当前限制）。我期待下周从生产实例中分析您的数据。