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MySQL User Camp: Multi-threaded Slaves
 

MySQL User Camp: Multi-threaded Slaves

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The agenda of this talk was to introduce MySQL Replication and then follow it up with Multi-threaded slaves(MTS) support. The presentation introduces Multi threading slaves by database which is a part ...

The agenda of this talk was to introduce MySQL Replication and then follow it up with Multi-threaded slaves(MTS) support. The presentation introduces Multi threading slaves by database which is a part of MySQL-5.6 as well as multi-threading policy introduced in MySQL-5.7.2. Finally there is a brief coverage of the new replication monitoring tables to monitor MySQL Replication. These tables are part of MySQL Performance Schema.

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    MySQL User Camp: Multi-threaded Slaves MySQL User Camp: Multi-threaded Slaves Presentation Transcript

    • MySQL Replication and Multi-threaded Slaves Shivji Kumar Jha, Software Developer, MySQL Replication Team
    • Safe Harbour Statement The following is intended to outline our general product direction. It is intended for information purposes only, and may not be incorporated into any contract. It is not a commitment to deliver any material, code, or functionality, and should not be relied upon in making purchasing decisions. The development, release, and timing of any features or functionality described for Oracle’s products remains at the sole discretion of Oracle. `2 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • Agenda Why Replication?  Replication Internals- A Simple Introduction  Why Multi-threaded Slaves (MTS)?  Different policies for Multi-threading Slaves  `3  Keeping track of replication threads Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • Replication: Copy Changes Master → Slave  MySQL Master Server – Changes data – Sends changes to slave  MySQL Slave Server – Receives changes from master – Applies received changes to database M `4 S Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • Why Replication? – Scalability  Read scale-out M write clients `5 S read clients Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • Why Replication? – Scalability  Read scale-out M write clients `6 S More reads? read clients Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • Why Replication? – Scalability  Read scale-out M write clients `7 S More reads? More slaves! read clients Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • Why Replication? – Scalability  Read scale-out S M S More reads? More slaves! M S S write clients write clients `8 read clients Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 | read clients
    • Why Replication? – Redundancy  If master crashes, promote slave to master B A C `9 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • Why Replication? – Redundancy  If master crashes, promote slave to master B Crash A C `10 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • Why Replication? – Redundancy  If master crashes, promote slave to master B is the new master B A C `11 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • Why Replication? – Disaster recovery C A A B C B Image from www.ginkgomaps.com `12 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • But how do you copy changes to slave? `13 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • But how do you copy changes to slave? Are there LOGS floating around? `14 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • Introducing replication LOGS... `15 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • Replication Logs  MySQL Master Server M – Changes data (Writes) Binary log – Saves changes in Binary log  MySQL Slave Server – Copies changes to Relay log – Reads Relay log – Applies changes. `16 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 | Relay log S
    • All Changes Written to Binary Log Client binary log A `17 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • All Changes Written to Binary Log Client create table t (a int); binary log A `18 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • All Changes Written to Binary Log Client create table t (a int); binary log create... A Table t `19 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. |
    • All Changes Written to Binary Log Client create table t (a int); insert into t values (1); binary log create... A Table t `20 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • All Changes Written to Binary Log Client create table t (a int); insert into t values (1); binary log A create... insert... Table t 1 `21 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • Slave Initiates Replication 1. Slave sends request to start replication to master Client relay log binary log B A 2. Master sends stream of replication data to slave `22 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • Slave Copies, Applies Same Changes Client create... binary log A `23 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 | relay log B
    • Slave Copies, Applies Same Changes Client create... binary log relay log create... A Table t `24 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 | B
    • Slave Copies, Applies Same Changes Client create... binary log relay log create... create... A Table t `25 B Table t Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • Slave Copies, Applies Same Changes Client create... insert... binary log A relay log create... insert... create... Table t 1 `26 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 | B Table t
    • Slave Copies, Applies Same Changes Client create... insert... binary log A relay log create... insert... create... insert... Table t 1 `27 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 | B Table t 1
    • OK makes sense ! `28 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • But I see clients applying changes at Master, who applies at Slave? `29 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • But I see clients applying changes at Master, who applies at Slave? Do you have some internal replication threads? `30 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • Introducing replication THREADS... `31 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • Replication Threads (4.0-5.5) Client create... insert... relay log binary log A create... insert... create... network insert... SQL THREAD IO THREAD Writes into relay log at slave `32 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 | B Reads from relay log. Applies transactions at slave
    • Replication Threads (4.0-5.5) Create... insert... Client Client insert... More clients on master... Client relay log binary log A `33 create... insert... Insert... create... network insert... SQL THREAD IO THREAD Insert... Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 | B
    • Replication Threads (4.0-5.5) Create... insert... Client Client insert... More clients on master... Client Slave starts to lag behind master relay log binary log A `34 create... insert... Insert... create... network insert... SQL THREAD IO THREAD Insert... Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 | B
    • Replication Threads (4.0-5.5) Create... insert... Client Client insert... More clients on master... Client Slave starts to lag behind master relay log binary log A create... insert... Insert... create... network insert... SQL THREAD IO THREAD Insert... Table t 1 2 3 `35 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 | B Table t 1 2
    • Lets Parallelize slave as well... `36 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • Lets Parallelize slave as well... Introducing parallelization by Database `37 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • Replication Threads (5.6+) create... Client insert... insert... Reads & assigns to worker(s) Client Client w create.. O insert... R K COORDINATOR E insert.. THREAD R S binary log A `38 create(db1) insert(db2) insert(db3) network IO THREAD Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 | db1 B db2 db3 create(db1) insert(db2) insert(db3) Worker threads apply concurrently on diff dbs relay log
    • Replication Threads (5.6+) Setting up Parallelization by database mysql> STOP SLAVE; mysql> SET GLOBAL slave_parallel_workers=1; mysql> START SLAVE; `39 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • Replication Threads (5.6+) More databases? More workers! mysql> STOP SLAVE; mysql> SET GLOBAL slave_parallel_workers=2; mysql> START SLAVE; `40 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • What if I have a a loaded Database? Image credits: http://www.easetechnology.co.uk/ask-an-expert/ `41 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • Lets Parallelize slave somewhat similar to master `42 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • Lets Parallelize slave somewhat similar to master 5.7.2 Introducing parallelization by Master concurrency `43 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • Replication Threads (4.0-5.5) Create... insert... Client Client insert... More clients on master... Client Slave starts to lag behind master relay log binary log A Table t 1 2 3 `44 create... insert... Insert... create... network insert... SQL THREAD IO THREAD Insert... REVISITING THE OLD SLIDE !!! Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 | B Table t 1 2
    • Replication Threads (5.7+) create... Client insert... insert... Reads & assigns to worker(s) Client Client COORDINATOR THREAD binary log A create... insert... Insert... network IO THREAD capture parallelization info on master `45 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 | create... insert... Insert... relay log w O R K E R S B db1 db2 Worker threads apply concurrently
    • Replication Threads (5.7+) create... Client insert... insert... Reads & assigns to worker(s) Client Client COORDINATOR THREAD binary log A create... insert... Insert... network IO THREAD Save parallelization info in binary log `46 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 | create... insert... Insert... relay log w O R K E R S B db1 db2 Worker threads apply concurrently
    • Replication Threads (5.7+) create... Client insert... insert... Reads & assigns to worker(s) Client Client COORDINATOR THREAD binary log A create... insert... Insert... network IO THREAD Send parallelization info to slave `47 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 | create... insert... Insert... relay log w O R K E R S B db1 db2 Worker threads apply concurrently
    • Replication Threads (5.7+) create... Client insert... insert... Reads & assigns to worker(s) Client Client COORDINATOR THREAD binary log A create... insert... Insert... network IO THREAD Use parallelization info to assign `48 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 | create... insert... Insert... relay log w O R K E R S B db1 db2 Worker threads apply concurrently
    • Replication Threads (5.7+)   `49 Leverage parallelization information obtained from the execution on the master: — Transactions that reach the prepare phase on the same data snapshot are non-contending; — Write to the binary log on which snapshot id each transaction prepared;  This identifies the commit parent of each transaction. — The commit parent is stepped every time transactions commit. Meanwhile, at the slave: — Transactions with the same commit parent can be executed in parallel; — Commit sequence at the slave may not be the same as that on the master, but it is still a correct execution history. Copyright © 2013, Oracle and/or its affiliates. All rights reserved. |
    • Higher Slave Throughput: Intra-Schema MTS Concurrent Execution History on the Master T1 T2 T3 Time Execution Commit Prepare Commit `50 commit_parent++ Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | Prepare
    • Higher Slave Throughput: Intra-Schema MTS Concurrent Execution History on the Master Parallel on the Slave. T1 T2 T3 Time Execution Commit Prepare Commit `51 commit_parent++ Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | Prepare Not parallel on the slave.
    • Replication Threads (5.7+) Setting up Parallelization by master concurrency mysql> STOP SLAVE; mysql> SET GLOBAL slave_parallel_type=[ 'logical_clock' | 'database' ]; mysql> SET GLOBAL slave_parallel_workers=3; mysql> START SLAVE; database=>parallelize by database logical_clock=>parallelize by master concurrency `52 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • Too many threads here and there! How do I monitor? Knew that was coming! Check out replication Performance_Schema `53 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • Performance Schema (5.5+)  Inspect internal execution of the server at runtime  Exposed within performance_schema database  Records various run time statistics via in-built instrumentation points  Tracks latency for various events: File I/O, Mutexes, Read/Write Locks, Table I/O, Table Locks, Stages, Statements, Idle etc..  `54 Its a long growing list Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • Replication Performance Schema Tables (5.7+) replication 5.7.2 execution connection configuration status configuration Coordinator thread / SQL thread `55 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 | status Worker thread(s)
    • The REPLICATION P_S Tables  We have six performance schema tables for replication: 5.7.2 (MySQL-5.7.2):  replication_connection_configuration  replication_connection_status (IO thread status)  replication_execute_configuration  replication_execute_status  replication_execute_status_by_coordinator  replication_execute_status_by_worker Tables for monitoring MTS `56 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • Monitoring The Coordinator Thread 5.7.2 mysql> select * from performance_schema.replication_execute_status_by_coordinatorG *************************** 1. row ***************************            THREAD_ID: 13        SERVICE_STATE: ON    LAST_ERROR_NUMBER: 0   LAST_ERROR_MESSAGE: LAST_ERROR_TIMESTAMP: 0000-00-00 00:00:00 `57 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 | No error in thread
    • Monitoring The Coordinator Thread 5.7.2 mysql> select * from performance_schema.replication_execute_status_by_coordinatorG *************************** 1. row ***************************            THREAD_ID: 13        SERVICE_STATE: ON Oops! There was an error    LAST_ERROR_NUMBER: 1146   LAST_ERROR_MESSAGE:...'Table 'test.t' doesn't exist'... LAST_ERROR_TIMESTAMP: 2013-11-04 13:37:23 `58 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • Monitoring Worker Threads 5.7.2 mysql> SET GLOBAL slave_parallel_workers= 2; mysql> select * from performance_schema.replication_execute_status_by_workerG *************************** 1. row ***************************             WORKER_ID: 0             THREAD_ID: 16         SERVICE_STATE: ON LAST_SEEN_TRANSACTION: 2b3e03a6-453f-11e3-8668-0021ccb3570d:3     LAST_ERROR_NUMBER: 0    LAST_ERROR_MESSAGE: LAST_ERROR_TIMESTAMP: 0000-00-00 00:00:00 *************************** 2. row ***************************             WORKER_ID: 1             THREAD_ID: 17 one row per worker thread         SERVICE_STATE: ON ... `59 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • Monitoring Worker Threads 5.7.2 mysql> SET GLOBAL slave_parallel_workers= 2; mysql> select * from performance_schema.replication_execute_status_by_workerG *************************** 1. row ***************************             WORKER_ID: 0             THREAD_ID: 16         SERVICE_STATE: ON LAST_SEEN_TRANSACTION: 2b3e03a6-453f-11e3-8668-0021ccb3570d:3     LAST_ERROR_NUMBER: 0    LAST_ERROR_MESSAGE: LAST_ERROR_TIMESTAMP: 0000-00-00 00:00:00 *************************** 2. row ***************************             WORKER_ID: 1             THREAD_ID: 17 The newest transaction this worker is aware         SERVICE_STATE: ON ... `60 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 | of
    • Monitoring Worker Threads 5.7.2 mysql> SET GLOBAL slave_parallel_workers= 2; mysql> select * from performance_schema.replication_execute_status_by_workerG *************************** 1. row ***************************             WORKER_ID: 0             THREAD_ID: 16         SERVICE_STATE: ON LAST_SEEN_TRANSACTION: 2b3e03a6-453f-11e3-8668-0021ccb3570d:3     LAST_ERROR_NUMBER: 0    LAST_ERROR_MESSAGE: No error in this worker LAST_ERROR_TIMESTAMP: 0000-00-00 00:00:00 *************************** 2. row ***************************             WORKER_ID: 1             THREAD_ID: 17         SERVICE_STATE: ON ... `61 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 | thread
    •  A lot more to explore in MySQL-5.6, keep reading...  MySQL-5.7 is our current development branch. We want your valuable feedback.  Suggest Features, report bugs, contribute patches.  `62   We Want Your Feedback MySQL-5.6 is our latest GA release. Help make MySQL-5.7 even better! Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    •   Replication Logs  Replication Threads  Summary Introduction to MySQL Replication Multi-threaded Slave (MTS) – Need for Parallelization – Parallelize by database – Parallelize by master concurrency  Keeping track of replication threads – Performance Schema – Replication info. in Performance Schema `63 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • Read More About MySQL Replication `64 Find MySQL Official Documentation at http://dev.mysql.com/doc/refman/5.7/en/replication.html Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    •  Read More About MultiThreaded Slaves `65 Parallelization by database - Luis's blog - Andrei's blog  Parallelization by master concurrency - Rohit's blog  Replication Performance Schema - Official MySQL documentation - Shiv's blog Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |
    • Questions! Email: shivji.jha@oracle.com Blog: shivjijha.blogspot.in `66 Copyright © 2013, Oracle and/or its affiliates. All rights reserved. | MySQL User Camp | Bangalore, India | 8 November 2013 |