This document summarizes benchmarks of MySQL multi-thread slave performance using different numbers of slave_parallel_workers threads on Oracle Cloud MySQL instances. It finds that using 16 threads provides the best performance, processing queries faster and keeping the slave less behind the master compared to lower thread counts. CPU usage is also lower with 16 threads even though more threads are used.

1. Copyright © 2016 Oracle and/or its affiliates. All rights reserved. |
MySQL Multi Thread Slave
Performance Evaluation on OPC (OC3)
MySQL Global Business Unit
Shinya Sugiyama

2. Copyright © 2016 Oracle and/or its affiliates. All rights reserved.
Environment
2
Oracle Cloud MySQL Service
Master and Slave Instance: OC3 (1OCPU(2 vCPU), 7.5 GB Mem)
MySQL Version: MySQL5.7.16
Monitoring: MySQL Enterprise Monitor (Separate Instance)

3. Copyright © 2016 Oracle and/or its affiliates. All rights reserved.
Benchmark
Changed parameter:
slave_parallel_workers
Thread 1, 2, 4, 8, 16,32
Other Parameter is OPC MySQL Service Default (Only Server ID was Changed)
3
+------------------------+-------+
| Variable_name | Value |
+------------------------+-------+
| slave_parallel_workers | 8 |
+------------------------+-------+
/u01/bin/mysql/bin/mysqlslap --no-defaults --create-schema=SLAP --engine=InnoDB --auto-generate-sql
--auto-generate-sql-add-autoincrement --number-int-cols=3 --number-char-cols=5 --concurrency=10 --
auto-generate-sql-write-number=50000 --auto-generate-sql-execute-number=50000 --auto-generate-sql-
load-type=mixed -h localhost -u oracle
+-----------------------------+-------+
| Variable_name | Value |
+-----------------------------+-------+
| slave_preserve_commit_order | ON |
+-----------------------------+-------+
+---------------------+---------------+
| Variable_name | Value |
+---------------------+---------------+
| slave_parallel_type | LOGICAL_CLOCK |
+---------------------+---------------+

4. Copyright © 2016 Oracle and/or its affiliates. All rights reserved.
Benchmark1
4
[oracle@study01-mysql-1 ~]$ ./mysqlslap.sh
Benchmark
Running for engine InnoDB
Average number of seconds to run all queries: 185.845 seconds
Minimum number of seconds to run all queries: 185.845 seconds
Maximum number of seconds to run all queries: 185.845 seconds
Number of clients running queries: 10
Average number of queries per client: 50000
Study02: slave_parallel_workers = 1
Study03: slave_parallel_workers = 16
CPU USAGE:
Elapsed time is much longer in case of
parallel_workers 1 . CPU usage of
parallel_workers 16 is less than 1 even
total thread number is larger than 1.
QUERIES and DELAY
parallel_workers 16 is much faster than
parallel_workers 1, so Behind_master is
resolved soon.

5. Copyright © 2016 Oracle and/or its affiliates. All rights reserved.
Benchmark2
5
[oracle@study01-mysql-1 ~]$ ./mysqlslap.sh
Benchmark
Running for engine InnoDB
Average number of seconds to run all queries: 190.973 seconds
Minimum number of seconds to run all queries: 190.973 seconds
Maximum number of seconds to run all queries: 190.973 seconds
Number of clients running queries: 10
Average number of queries per client: 50000
Study02: slave_parallel_workers = 2
Study03: slave_parallel_workers = 16
CPU USAGE:
Elapsed time is longer in case of
parallel_workers 2 . CPU usage of
parallel_workers 16 is less than 2 even
total thread number is larger than 2.
QUERIES and DELAY
parallel_workers 16 is faster than
parallel_workers 2, so Behind_master is
resolved soon.

6. Copyright © 2016 Oracle and/or its affiliates. All rights reserved.
Benchmark3
6
[oracle@study01-mysql-1 ~]$ ./mysqlslap.sh
Benchmark
Running for engine InnoDB
Average number of seconds to run all queries: 186.468 seconds
Minimum number of seconds to run all queries: 186.468 seconds
Maximum number of seconds to run all queries: 186.468 seconds
Number of clients running queries: 10
Average number of queries per client: 50000
Study02: slave_parallel_workers = 4
Study03: slave_parallel_workers = 16
CPU USAGE:
Elapsed time is little longer in case of
parallel_workers 4 . CPU usage of
parallel_workers 16 is less than 4 even
total thread number is larger than 4.
QUERIES and DELAY
parallel_workers 16 is still faster than
parallel_workers 4, so Behind_master is
resolved little faster than 4.

7. Copyright © 2016 Oracle and/or its affiliates. All rights reserved.
Benchmark4
7
[oracle@study01-mysql-1 ~]$ ./mysqlslap.sh
Benchmark
Running for engine InnoDB
Average number of seconds to run all queries: 188.104 seconds
Minimum number of seconds to run all queries: 188.104 seconds
Maximum number of seconds to run all queries: 188.104 seconds
Number of clients running queries: 10
Average number of queries per client: 50000
Study02: slave_parallel_workers = 8
Study03: slave_parallel_workers = 16
CPU USAGE:
Elapsed time is almost same beteen
parallel_workers 8 and parallel_workers
16.
QUERIES and DELAY
There is not much difference between
parallel_workers 8 and parallel_workers
16, so Behind_master is almost same.

8. Copyright © 2016 Oracle and/or its affiliates. All rights reserved.
Trial (トライアル)
8
■ Oracle MySQL Cloud Service
English
https://cloud.oracle.com/mysql
日本語サイト
https://cloud.oracle.com/ja_JP/mysql
■ MySQL Enterprise Monitor Trial
http://edelivery.oracle.com/
https://www-jp.mysql.com/trials/