我在Linux上运行30个脚本(PHP CLI),每个脚本都在更新(循环)MySQL数据库中的数据。
当我在终端输入“mysqladmin proc
”时,我可以看到很多行已被锁定10-30秒。大多数是Update
队列。如何更快地提高性能?我正在使用InnoDB引擎。
PHP脚本看起来像这样:
//status and process are indexed.
$SQL = "SELECT * FROM data WHERE status = 0 AND process = '1'";
$query = $db->prepare($SQL);
$query->execute();
//about 100,000+ rows for each script
while ($row = $query->fetch(PDO::FETCH_ASSOC)) {
checking($row);
sleep(2);
}
function checking($data) {
$error = errorCheck($data['number']);
if ($error) {
//number indexed
$SQLUpdate = "UPDATE data SET status = 2, error='$error' WHERE number = " . $data['number'];
$update = $db->prepare($SQLUpdate);
$update->execute();
return false
}
//good?
$SQLUpdate = "UPDATE data SET status = 1 WHERE number = " . $data['number'];
$update = $db->prepare($SQLUpdate);
$update->execute();
$SQLInsert = "INSERT INTO tbl_done .....";
$SQLInsert = $db->prepare($SQLInsert);
$SQLInsert->execute();
}
top
命令:
top - 10:48:54 up 17 days, 10:30, 2 users, load average: 1.06, 1.05, 1.01
Tasks: 188 total, 1 running, 187 sleeping, 0 stopped, 0 zombie
Cpu(s): 25.8%us, 0.1%sy, 0.0%ni, 74.1%id, 0.0%wa, 0.0%hi, 0.1%si, 0.0%st
Mem: 4138464k total, 1908724k used, 2229740k free, 316224k buffers
Swap: 2096440k total, 16k used, 2096424k free, 592384k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
32183 mysql 15 0 903m 459m 4800 S 101.8 11.4 876:53.66 mysqld
-
/etc/my.cnf
[mysqld]
set-variable = max_connections=500
safe-show-database
max_user_connections=200
key_buffer_size = 16M
query_cache_size = 350M
tmp_table_size = 200M
max_heap_table_size = 200M
thread_cache_size = 4
table_cache = 800
thread_concurrency = 8
innodb_buffer_pool_size = 400M
innodb_log_file_size = 128M
query_cache_limit = 500M
innodb_flush_log_at_trx_commit = 2
服务器规格:英特尔酷睿2四核Q8300,2.5 GHz,4GB内存。
'mysqladmin proc':
+------+-----------------+-----------+----------------+---------+------+----------+-------------------------------------------------------------------------------
| Id | User | Host | db | Command | Time | State | Info
+------+-----------------+-----------+----------------+---------+------+----------+--------------------------------------------------------------------------------
| 265 | user | localhost | xxxxxxxxxxxxxx | Query | 15 | Updating | UPDATE data SET status = '2', error = 'Unknown error' WHERE number= 0xxxxx
| 269 | user | localhost | xxxxxxxxxxxxxx | Query | 17 | Updating | UPDATE data SET status = '2', error = 'Invalid ....' WHERE number= 0xxx
| 280 | user | localhost | xxxxxxxxxxxxxx | Query | 7 | Updating | UPDATE data SET status = 1 WHERE f = 0xxxx
| 300 | user | localhost | xxxxxxxxxxxxxx | Query | 1 | Updating | UPDATE data SET status = '2', error = 'Unknown ....' WHERE number= 0xx
| 314 | user | localhost | xxxxxxxxxxxxxx | Query | 13 | Updating | UPDATE data SET status = '2', error = 'Invalid....' WHERE number= 0xxxx
| 327 | user | localhost | xxxxxxxxxxxxxx | Query | 11 | Updating | UPDATE data SET status = '2', error = 'Unknown ....' WHERE number= 0xxxx
| 341 | user | localhost | xxxxxxxxxxxxxx | Sleep | 2 | | NULL
| 350 | user | localhost | xxxxxxxxxxxxxx | Query | 7 | Updating | UPDATE data SET status = '2', error = 'Unknown ....' WHERE number= 0xxx
| 360 | user | localhost | xxxxxxxxxxxxxx | Query | 5 | Updating | UPDATE data SET status = 1 WHERE number = 0xxxx
说明:
+----+-------------+-------+-------------+----------------+----------------+---------+------+-------+----------------------------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+-------+-------------+----------------+----------------+---------+------+-------+----------------------------------------------+
| 1 | SIMPLE | data | index_merge | process,status | process,status | 52,1 | NULL | 16439 | Using intersect(process,status); Using where |
+----+-------------+-------+-------------+----------------+----------------+---------+------+-------+----------------------------------------------+
答案 0 :(得分:2)
执行select
查询时,您将获取正在读取的行的读锁定。在check方法中,您尝试更新当前正在读取(=已锁定)的行。因此,一旦select查询释放读锁定,MySQL就会对更新查询进行排队。但是,由于您每行都暂停执行两秒钟,因此增加了锁定释放的延迟,从而延迟了等待更新队列的每个查询。您可以阅读有关innodb lock modes的更多信息。
我建议修改代码:
offset
和limit
语句来实现此目的。<强>更新强>
您正在使用fetch
从结果集中检索行。根据{{3}}:
从与PDOStatement对象关联的结果集中获取一行
为了一次检索所有行,您应该使用fetchAll
,但要注意documentation状态下的性能问题:
使用此方法获取大型结果集将导致对系统和可能的网络资源的大量需求。
这就是为什么我建议限制查询来检索一定数量的行,而不是整个结果集(包含100.000+行)。您可以通过修改查询来限制返回的行数:
SELECT * FROM data WHERE status = 0 AND process = '1' LIMIT 10000 OFFSET 0
然后当您第二次运行查询时,运行查询,如:
SELECT * FROM data WHERE status = 0 AND process = '1' LIMIT 10000 OFFSET 10000
您可以这样继续,直到没有返回任何结果。
答案 1 :(得分:0)
您将错误的行更新为status = 2,然后将所有行更新为status = 1 - 假设这是拼写错误(缺少其他行)
如果你真的在每行之间睡2秒,选择“限制1”会更明智,并且每2秒重新运行一次选择查询 - 如果数字不是唯一的话,这可以解释你的锁定