Drop Large TableでMySQLがハングアップし、接続に長時間かかる

Question

MySqlは、5,000万レコードの大きなテーブルを削除しようとすると、接続と嗜眠を受け付けが遅くなります。直ちに使用されていた接続は、今接続するのに20〜30秒かかります。

テーブルのmysqlcheck結果を実行大丈夫、しかし、SHOW ENGINE INNODB STATUSは右見ていない：これは、その後、多くの行継続

+--------+------+--------------------------------------------------------------- -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- --------------------------------------------------------------------------------

：

をそれはこれの多くの行で始まり

----------------------------------------------+ 
| InnoDB |  | 
===================================== 
2017-01-31 19:03:05 0x7f2be82e5700 INNODB MONITOR OUTPUT 
===================================== 
Per second averages calculated from the last 35 seconds 
----------------- 
BACKGROUND THREAD 
----------------- 
srv_master_thread loops: 19 srv_active, 0 srv_shutdown, 1234 srv_idle 
srv_master_thread log flush and writes: 1253 
---------- 
SEMAPHORES 
---------- 
OS WAIT ARRAY INFO: reservation count 91 
OS WAIT ARRAY INFO: signal count 74 
RW-shared spins 0, rounds 58, OS waits 23 
RW-excl spins 0, rounds 205, OS waits 0 
RW-sx spins 0, rounds 0, OS waits 0 
Spin rounds per wait: 58.00 RW-shared, 205.00 RW-excl, 0.00 RW-sx 
------------ 
TRANSACTIONS 
------------ 
Trx id counter 40192594 
Purge done for trx's n:o < 40190602 undo n:o < 0 state: running but idle 
History list length 2280 
LIST OF TRANSACTIONS FOR EACH SESSION: 
---TRANSACTION 421306474252112, not started 
0 lock struct(s), heap size 1136, 0 row lock(s) 
-------- 
FILE I/O 
-------- 
I/O thread 0 state: waiting for completed aio requests (insert buffer thread) 
I/O thread 1 state: waiting for completed aio requests (log thread) 
I/O thread 2 state: waiting for completed aio requests (read thread) 
I/O thread 3 state: waiting for completed aio requests (read thread) 
I/O thread 4 state: waiting for completed aio requests (read thread) 
I/O thread 5 state: waiting for completed aio requests (read thread) 
I/O thread 6 state: waiting for completed aio requests (write thread) 
I/O thread 7 state: waiting for completed aio requests (write thread) 
I/O thread 8 state: waiting for completed aio requests (write thread) 
I/O thread 9 state: waiting for completed aio requests (write thread) 
Pending normal aio reads: [0, 0, 0, 0] , aio writes: [0, 0, 0, 0] , 
ibuf aio reads:, log i/o's:, sync i/o's: 
Pending flushes (fsync) log: 0; buffer pool: 0 
369979 OS file reads, 61 OS file writes, 15 OS fsyncs 
286.85 reads/s, 16384 avg bytes/read, 0.00 writes/s, 0.00 fsyncs/s 
------------------------------------- 
INSERT BUFFER AND ADAPTIVE HASH INDEX 
------------------------------------- 
Ibuf: size 1, free list len 2193, seg size 2195, 0 merges 
merged operations: 
insert 0, delete mark 0, delete 0 
discarded operations: 
insert 0, delete mark 0, delete 0 
Hash table size 1182691, node heap has 0 buffer(s) 
Hash table size 1182691, node heap has 3 buffer(s) 
Hash table size 1182691, node heap has 3 buffer(s) 
Hash table size 1182691, node heap has 6 buffer(s) 
Hash table size 1182691, node heap has 2 buffer(s) 
Hash table size 1182691, node heap has 2 buffer(s) 
Hash table size 1182691, node heap has 1 buffer(s) 
Hash table size 1182691, node heap has 0 buffer(s) 
0.00 hash searches/s, 0.00 non-hash searches/s 
--- 
LOG 
--- 
Log sequence number 310536690314 
Log flushed up to 310536690314 
Pages flushed up to 310536690314 
Last checkpoint at 310536690305 
0 pending log flushes, 0 pending chkp writes 
16 log i/o's done, 0.00 log i/o's/second 
---------------------- 
BUFFER POOL AND MEMORY 
---------------------- 
Total large memory allocated 4397727744 
Dictionary memory allocated 39828543 
Buffer pool size 262112 
Free buffers  0 
Database pages  262095 
Old database pages 96806 
Modified db pages 0 
Pending reads  1 
Pending writes: LRU 0, flush list 0, single page 0 
Pages made young 103, not young 6145557 
0.00 youngs/s, 92166.80 non-youngs/s 
Pages read 369591, created 34, written 37 
286.88 reads/s, 0.00 creates/s, 0.00 writes/s 
Buffer pool hit rate 999/1000, young-making rate 0/1000 not 368/1000 
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s 
LRU len: 262095, unzip_LRU len: 0 
I/O sum[120336]:cur[304], unzip sum[0]:cur[0] 
---------------------- 
INDIVIDUAL BUFFER POOL INFO 
---------------------- 
---BUFFER POOL 0 
Buffer pool size 32764 
Free buffers  0 
Database pages  32761 
Old database pages 12102 
Modified db pages 0 
Pending reads  0 
Pending writes: LRU 0, flush list 0, single page 0 
Pages made young 12, not young 782981 
0.00 youngs/s, 12008.66 non-youngs/s 
Pages read 46266, created 0, written 3 
36.46 reads/s, 0.00 creates/s, 0.00 writes/s 
Buffer pool hit rate 999/1000, young-making rate 0/1000 not 369/1000 
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s 
LRU len: 32761, unzip_LRU len: 0 
I/O sum[15042]:cur[38], unzip sum[0]:cur[0] 
---BUFFER POOL 1 
Buffer pool size 32764 
Free buffers  0 
Database pages  32760 
Old database pages 12090 
Modified db pages 0 
Pending reads  0 
Pending writes: LRU 0, flush list 0, single page 0 
Pages made young 23, not young 714985 
0.00 youngs/s, 10882.83 non-youngs/s 
Pages read 43701, created 0, written 0 
33.54 reads/s, 0.00 creates/s, 0.00 writes/s 
Buffer pool hit rate 999/1000, young-making rate 0/1000 not 361/1000 
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s 
LRU len: 32760, unzip_LRU len: 0 
I/O sum[15042]:cur[38], unzip sum[0]:cur[0] 
---BUFFER POOL 2 
Buffer pool size 32764 
Free buffers  0 
Database pages  32762 
Old database pages 12102 
Modified db pages 0 
Pending reads  1 
Pending writes: LRU 0, flush list 0, single page 0 
Pages made young 12, not young 826273 
0.00 youngs/s, 12544.36 non-youngs/s 
Pages read 47653, created 0, written 0 
40.11 reads/s, 0.00 creates/s, 0.00 writes/s 
Buffer pool hit rate 999/1000, young-making rate 0/1000 not 363/1000 
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s 
LRU len: 32762, unzip_LRU len: 0 
I/O sum[15042]:cur[38], unzip sum[0]:cur[0] 
---BUFFER POOL 3 
Buffer pool size 32764 
Free buffers  0 
Database pages  32763 
Old database pages 12103 
Modified db pages 0 
Pending reads  0 
Pending writes: LRU 0, flush list 0, single page 0 
Pages made young 11, not young 789399 
0.00 youngs/s, 10819.38 non-youngs/s 
Pages read 46867, created 0, written 0 
34.46 reads/s, 0.00 creates/s, 0.00 writes/s 
Buffer pool hit rate 999/1000, young-making rate 0/1000 not 364/1000 
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s 
LRU len: 32763, unzip_LRU len: 0 
I/O sum[15042]:cur[38], unzip sum[0]:cur[0] 
---BUFFER POOL 4 
Buffer pool size 32764 
Free buffers  0 
Database pages  32762 
Old database pages 12089 
Modified db pages 0 
Pending reads  0 
Pending writes: LRU 0, flush list 0, single page 0 
Pages made young 24, not young 716775 
0.00 youngs/s, 10601.24 non-youngs/s 
Pages read 45316, created 0, written 0 
32.43 reads/s, 0.00 creates/s, 0.00 writes/s 
Buffer pool hit rate 999/1000, young-making rate 0/1000 not 371/1000 
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s 
LRU len: 32762, unzip_LRU len: 0 
I/O sum[15042]:cur[38], unzip sum[0]:cur[0] 
---BUFFER POOL 5 
Buffer pool size 32764 
Free buffers  0 
Database pages  32762 
Old database pages 12094 
Modified db pages 0 
Pending reads  0 
Pending writes: LRU 0, flush list 0, single page 0 
Pages made young 20, not young 816196 
0.00 youngs/s, 12974.26 non-youngs/s 
Pages read 47369, created 0, written 0 
39.77 reads/s, 0.00 creates/s, 0.00 writes/s 
Buffer pool hit rate 999/1000, young-making rate 0/1000 not 378/1000 
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s 
LRU len: 32762, unzip_LRU len: 0 
I/O sum[15042]:cur[38], unzip sum[0]:cur[0] 
---BUFFER POOL 6 
Buffer pool size 32764 
Free buffers  0 
Database pages  32764 
Old database pages 12113 
Modified db pages 0 
Pending reads  0 
Pending writes: LRU 0, flush list 0, single page 0 
Pages made young 1, not young 739215 
0.00 youngs/s, 11328.79 non-youngs/s 
Pages read 46339, created 34, written 34 
34.51 reads/s, 0.00 creates/s, 0.00 writes/s 
Buffer pool hit rate 999/1000, young-making rate 0/1000 not 373/1000 
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s 
LRU len: 32764, unzip_LRU len: 0 
I/O sum[15042]:cur[38], unzip sum[0]:cur[0] 
---BUFFER POOL 7 
Buffer pool size 32764 
Free buffers  0 
Database pages  32761 
Old database pages 12113 
Modified db pages 0 
Pending reads  0 
Pending writes: LRU 0, flush list 0, single page 0 
Pages made young 0, not young 759733 
0.00 youngs/s, 11007.29 non-youngs/s 
Pages read 46080, created 0, written 0 
35.60 reads/s, 0.00 creates/s, 0.00 writes/s 
Buffer pool hit rate 999/1000, young-making rate 0/1000 not 367/1000 
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s 
LRU len: 32761, unzip_LRU len: 0 
I/O sum[15042]:cur[38], unzip sum[0]:cur[0] 
-------------- 
ROW OPERATIONS 
-------------- 
0 queries inside InnoDB, 0 queries in queue 
1 read views open inside InnoDB 
Process ID=2785, Main thread ID=139826948695808, state: sleeping 
Number of rows inserted 0, updated 0, deleted 0, read 14 
0.00 inserts/s, 0.00 updates/s, 0.00 deletes/s, 0.00 reads/s 
---------------------------- 
END OF INNODB MONITOR OUTPUT 
============================ 
+--------+------+--------------------------------------------------------------- 
                          --------------------------------------------------------------------------------                        --------------------------------------------------------------------------------                        --------------------------------------------------------------------------------                        -------------------------------------------------------------------------------- 

最後に、出力はダッシュの多くの行とプラスとしてi始めた。

トラブルシューティングと修理の追加手順についてお知らせください。

Answer 1

innoDBが異常動作していると思われる場合は、エンジンが何をしているかを見ることができます。これは高価なので、通常の状況下では行わないでください。

は、InnoDBは、問題についての情報を取得するために監視を有効（ セクション14.17、「InnoDBのモニタ」を参照してください）：マニュアルは、次のよう述べています。問題が のパフォーマンス関連であるか、サーバーがハングアップしているように見える場合は、 標準のMonitorでInnoDBの内部 の状態に関する情報を出力できるようにする必要があります。ロックに問題がある場合は、ロック モニタを有効にします。テーブルまたはその他のデータの作成に問題がある場合は、 ディクショナリ操作で、InnoDB内部データディクショナリの内容 を表モニタで印刷できるようにします。表スペース情報を表示するには、 表スペースモニターを使用可能にします。

InnoDBは一時的に 以下の条件で、標準のInnoDBモニタの出力を可能にします：

• 長いセマフォ

• InnoDBがバッファプールに

• 67％以上を空きブロックを見つけることができません待ちますは、ロック・ヒープまたは適応ハッシュ・インデックスによって占有されます。

https://dev.mysql.com/doc/refman/5.6/en/innodb-troubleshooting.html https://dev.mysql.com/doc/refman/5.6/en/innodb-monitors.html

Answer 2

それは、後にすべての問題の一致を表示され、大きなテーブル低下の問題が原因ではありませんでした。これはネットワーク上のDNSの問題でした。

を/etc/my.cnf（私のシステムはCentOS）に追加してサーバを再起動しても正常に接続されているようです。

[mysqld] 
skip-name-resolve