- Release Notes and Announcements
- Release Notes
- Announcements
- Announcement on the Rule-Based Audit Feature for Database Audit
- Announcement on Some APIs with CAM Authentication Integrated
- Announcement on Some APIs with CAM Authentication Integrated
- Notice on Elimination of Some Indicators in Event Alarms
- Commercial Billing for Database Proxy
- TencentDB for MySQL Audit Upgrade
- Added Authentication APIs
- API Authentication Upgrade
- TencentDB for MySQL API 2.0 Discontinuation
- Monitoring Module Upgrade in Shanghai Region
- Monitoring Metric Optimization
- Network Architecture Upgrade
- Change of APIs for Querying the Specifications of Purchasable Database Instances
- Replacement of Certain Old Database Proxy APIs
- Added Advanced Monitoring Metrics
- Change of Calculation Formula for Memory Utilization
- Monitoring Module Upgrade and Optimization in Guangzhou and Shanghai Regions
- Monitoring Module Upgrade
- Parameter Template and Instance Purchase Process Optimization
- Binlog Will Take up Disk Space
- User Tutorial
- Product Introduction
- Tencent Kernel TXSQL
- Overview
- Kernel Version Release Notes
- Functionality Features
- Performance Features
- Security Features
- Stability Features
- TXRocks Engine
- Purchase Guide
- Billing Overview
- Selection Guide
- Purchase Methods
- Renewal
- Payment Overdue
- Refund
- Pay-as-You-Go to Monthly Subscription
- Instance Adjustment Fee
- Backup Space Billing
- Database Audit Billing Overview
- Commercial Billing and Activity Description for Database Proxy
- Description of the Database Proxy Billing Cycle
- Viewing Bills
- Getting Started
- Database Audit
- MySQL Cluster Edition
- Operation Guide
- Use Limits
- Operation Overview
- Instance Management and Maintenance
- Instance Upgrade
- CPU Elastic Expansion
- Read-Only/Disaster Recovery Instances
- Database Proxy
- Account Management
- Database Management Center (DMC)
- Parameter Configuration
- Network and Security
- Backup and Rollback
- Data Migration
- Monitoring and Alarms
- Operation Logs
- Tag
- Practical Tutorial
- Usage Specifications of TencentDB for MySQL
- Configuring Automatic Application Reconnection
- Impact of Modifying MySQL Source Instance Parameters
- Limits on Automatic Conversion from MyISAM to InnoDB
- Creating VPCs for TencentDB for MySQL
- Enhancing Business Load Capacity with TencentDB for MySQL
- Setting up 2-Region-3-DC Disaster Recovery Architecture
- Improving TencentDB for MySQL Performance with Read/Write Separation
- Migrating Data from InnoDB to RocksDB with DTS
- Building LAMP Stack for Web Application
- Building Drupal Website
- Building All-Scenario High-Availability Architecture
- Calling MySQL APIs in Python
- White Paper
- Troubleshooting
- API Documentation
- History
- Introduction
- API Category
- Data Import APIs
- Rollback APIs
- Parameter APIs
- Making API Requests
- Instance APIs
- StopCpuExpand
- StartCpuExpand
- DescribeCpuExpandStrategy
- AddTimeWindow
- BalanceRoGroupLoad
- CloseWanService
- CreateRoInstanceIp
- DeleteTimeWindow
- DescribeCdbZoneConfig
- DescribeDBFeatures
- DescribeDBInstanceCharset
- DescribeDBInstanceConfig
- DescribeDBInstanceGTID
- DescribeDBInstanceInfo
- DescribeDBInstanceRebootTime
- DescribeDBSwitchRecords
- DescribeRoGroups
- DescribeRoMinScale
- DescribeTagsOfInstanceIds
- DescribeTimeWindow
- IsolateDBInstance
- ModifyAutoRenewFlag
- ModifyDBInstanceName
- ModifyDBInstanceProject
- ModifyDBInstanceVipVport
- ModifyInstanceTag
- ModifyNameOrDescByDpId
- ModifyRoGroupInfo
- ModifyTimeWindow
- OfflineIsolatedInstances
- OpenDBInstanceEncryption
- OpenDBInstanceGTID
- OpenWanService
- ReleaseIsolatedDBInstances
- RenewDBInstance
- RestartDBInstances
- StartReplication
- StopReplication
- SwitchDBInstanceMasterSlave
- SwitchDrInstanceToMaster
- SwitchForUpgrade
- UpgradeDBInstanceEngineVersion
- CreateDBInstance
- CreateDBInstanceHour
- DescribeDBInstances
- UpgradeDBInstance
- DescribeDBZoneConfig
- CreateDeployGroup
- DeleteDeployGroups
- DescribeDeployGroupList
- Database Proxy APIs
- AdjustCdbProxy
- AdjustCdbProxyAddress
- CloseCDBProxy
- CloseCdbProxyAddress
- CreateCdbProxy
- CreateCdbProxyAddress
- DescribeCdbProxyInfo
- DescribeProxyCustomConf
- DescribeProxySupportParam
- ModifyCdbProxyAddressDesc
- ModifyCdbProxyAddressVipAndVPort
- ModifyCdbProxyParam
- ReloadBalanceProxyNode
- SwitchCDBProxy
- UpgradeCDBProxyVersion
- Database Audit APIs
- Security APIs
- Task APIs
- Account APIs
- Backup APIs
- CreateBackup
- DeleteBackup
- DescribeBackupDownloadRestriction
- DescribeBackupOverview
- DescribeBackupSummaries
- DescribeBinlogBackupOverview
- DescribeDataBackupOverview
- DescribeLocalBinlogConfig
- DescribeRemoteBackupConfig
- DescribeSlowLogs
- ModifyBackupDownloadRestriction
- ModifyLocalBinlogConfig
- ModifyRemoteBackupConfig
- DescribeBackups
- DescribeBackupConfig
- DescribeBackupDecryptionKey
- DescribeBackupEncryptionStatus
- DescribeBinlogs
- ModifyBackupConfig
- ModifyBackupEncryptionStatus
- Database APIs
- Monitoring APIs
- Log-related API
- Data Types
- Error Codes
- FAQs
- Service Agreement
- Reference
- Glossary
- Contact Us
- Preset Plugin List
- Release Notes and Announcements
- Release Notes
- Announcements
- Announcement on the Rule-Based Audit Feature for Database Audit
- Announcement on Some APIs with CAM Authentication Integrated
- Announcement on Some APIs with CAM Authentication Integrated
- Notice on Elimination of Some Indicators in Event Alarms
- Commercial Billing for Database Proxy
- TencentDB for MySQL Audit Upgrade
- Added Authentication APIs
- API Authentication Upgrade
- TencentDB for MySQL API 2.0 Discontinuation
- Monitoring Module Upgrade in Shanghai Region
- Monitoring Metric Optimization
- Network Architecture Upgrade
- Change of APIs for Querying the Specifications of Purchasable Database Instances
- Replacement of Certain Old Database Proxy APIs
- Added Advanced Monitoring Metrics
- Change of Calculation Formula for Memory Utilization
- Monitoring Module Upgrade and Optimization in Guangzhou and Shanghai Regions
- Monitoring Module Upgrade
- Parameter Template and Instance Purchase Process Optimization
- Binlog Will Take up Disk Space
- User Tutorial
- Product Introduction
- Tencent Kernel TXSQL
- Overview
- Kernel Version Release Notes
- Functionality Features
- Performance Features
- Security Features
- Stability Features
- TXRocks Engine
- Purchase Guide
- Billing Overview
- Selection Guide
- Purchase Methods
- Renewal
- Payment Overdue
- Refund
- Pay-as-You-Go to Monthly Subscription
- Instance Adjustment Fee
- Backup Space Billing
- Database Audit Billing Overview
- Commercial Billing and Activity Description for Database Proxy
- Description of the Database Proxy Billing Cycle
- Viewing Bills
- Getting Started
- Database Audit
- MySQL Cluster Edition
- Operation Guide
- Use Limits
- Operation Overview
- Instance Management and Maintenance
- Instance Upgrade
- CPU Elastic Expansion
- Read-Only/Disaster Recovery Instances
- Database Proxy
- Account Management
- Database Management Center (DMC)
- Parameter Configuration
- Network and Security
- Backup and Rollback
- Data Migration
- Monitoring and Alarms
- Operation Logs
- Tag
- Practical Tutorial
- Usage Specifications of TencentDB for MySQL
- Configuring Automatic Application Reconnection
- Impact of Modifying MySQL Source Instance Parameters
- Limits on Automatic Conversion from MyISAM to InnoDB
- Creating VPCs for TencentDB for MySQL
- Enhancing Business Load Capacity with TencentDB for MySQL
- Setting up 2-Region-3-DC Disaster Recovery Architecture
- Improving TencentDB for MySQL Performance with Read/Write Separation
- Migrating Data from InnoDB to RocksDB with DTS
- Building LAMP Stack for Web Application
- Building Drupal Website
- Building All-Scenario High-Availability Architecture
- Calling MySQL APIs in Python
- White Paper
- Troubleshooting
- API Documentation
- History
- Introduction
- API Category
- Data Import APIs
- Rollback APIs
- Parameter APIs
- Making API Requests
- Instance APIs
- StopCpuExpand
- StartCpuExpand
- DescribeCpuExpandStrategy
- AddTimeWindow
- BalanceRoGroupLoad
- CloseWanService
- CreateRoInstanceIp
- DeleteTimeWindow
- DescribeCdbZoneConfig
- DescribeDBFeatures
- DescribeDBInstanceCharset
- DescribeDBInstanceConfig
- DescribeDBInstanceGTID
- DescribeDBInstanceInfo
- DescribeDBInstanceRebootTime
- DescribeDBSwitchRecords
- DescribeRoGroups
- DescribeRoMinScale
- DescribeTagsOfInstanceIds
- DescribeTimeWindow
- IsolateDBInstance
- ModifyAutoRenewFlag
- ModifyDBInstanceName
- ModifyDBInstanceProject
- ModifyDBInstanceVipVport
- ModifyInstanceTag
- ModifyNameOrDescByDpId
- ModifyRoGroupInfo
- ModifyTimeWindow
- OfflineIsolatedInstances
- OpenDBInstanceEncryption
- OpenDBInstanceGTID
- OpenWanService
- ReleaseIsolatedDBInstances
- RenewDBInstance
- RestartDBInstances
- StartReplication
- StopReplication
- SwitchDBInstanceMasterSlave
- SwitchDrInstanceToMaster
- SwitchForUpgrade
- UpgradeDBInstanceEngineVersion
- CreateDBInstance
- CreateDBInstanceHour
- DescribeDBInstances
- UpgradeDBInstance
- DescribeDBZoneConfig
- CreateDeployGroup
- DeleteDeployGroups
- DescribeDeployGroupList
- Database Proxy APIs
- AdjustCdbProxy
- AdjustCdbProxyAddress
- CloseCDBProxy
- CloseCdbProxyAddress
- CreateCdbProxy
- CreateCdbProxyAddress
- DescribeCdbProxyInfo
- DescribeProxyCustomConf
- DescribeProxySupportParam
- ModifyCdbProxyAddressDesc
- ModifyCdbProxyAddressVipAndVPort
- ModifyCdbProxyParam
- ReloadBalanceProxyNode
- SwitchCDBProxy
- UpgradeCDBProxyVersion
- Database Audit APIs
- Security APIs
- Task APIs
- Account APIs
- Backup APIs
- CreateBackup
- DeleteBackup
- DescribeBackupDownloadRestriction
- DescribeBackupOverview
- DescribeBackupSummaries
- DescribeBinlogBackupOverview
- DescribeDataBackupOverview
- DescribeLocalBinlogConfig
- DescribeRemoteBackupConfig
- DescribeSlowLogs
- ModifyBackupDownloadRestriction
- ModifyLocalBinlogConfig
- ModifyRemoteBackupConfig
- DescribeBackups
- DescribeBackupConfig
- DescribeBackupDecryptionKey
- DescribeBackupEncryptionStatus
- DescribeBinlogs
- ModifyBackupConfig
- ModifyBackupEncryptionStatus
- Database APIs
- Monitoring APIs
- Log-related API
- Data Types
- Error Codes
- FAQs
- Service Agreement
- Reference
- Glossary
- Contact Us
- Preset Plugin List
Issue Description
A TencentDB for MySQL instance experiences a sudden surge or a continuous growth in memory utilization. You can view specific memory utilization monitoring data in the following chart:
Impact
Inefficient SQL statements or improper database parameters can cause the memory utilization to increase. An unexpected business peak may cause OOM (out of memory) of two-node and three-node TencentDB for MySQL instances, and when the instances are unavailable due to OOM, a source-replica switch will be triggered. During the switch, instances are usually unavailable for less than 60 seconds. If the switch occurs during peak hours, business stability and continuity will be seriously affected.
Solutions
In MySQL, memory can be roughly divided into two parts: globally shared memory and session-level private memory.
Shared memory is allocated upon the creation of an instance and shared by all connections.
Private memory is allocated by the system upon connection to the MySQL server.
Some special SQL statements or field types may cause the muliti-alloacation of cache to a single threadTherefore, all OOM exceptions are caused by the private memory of each connection. The risk of high memory utilization can be mitigated by limiting database connections and optimizing inefficient SQL statements. If this doesn't work, you can upgrade the memory configuration to improve the overall concurrency and stability of the database. For more information on memory parameters, see Memory Allocation.
Troubleshooting
1. Optimize slow SQL statements to reduce the session-level private memory usage. You can use DBbrain to analyze slow SQL statements.
2. Reduce invalid persistent connections by downgrading the connection pool configuration or concurrency level on the program side without affecting the business.You can use DBbrain to view the current session information.
3. Monitor memory utilization (optional and applicable to MySQL 5.7 and above): enable the performance schema feature, and query memory information from tables whose name starts with "memory_summary" in the performance_schema database. For example, the memory_summary_global_by_event_name table records global memory utilization.
4. After optimization, upgrade the configuration of your TencentDB for MySQL instance.
Note:
During the upgrade, your business can operate normally. After the upgrade, there will be a momentary disconnection. Make sure that your business has a reconnection mechanism.
To protect your business from being affected by insufficient memory or CPU resources, configure alarm policies for instance resources which help you identify potential resource shortage in advance. For more information, see Alarm Policies (TCOP).
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