oracle 链接数问题
各位高手们。我当前环境是linux + oracle 11g rac
数据库的ip 是 192.168.40.1 ，40.2， 40.3， 40.4
现在每天都要检查数据库的链接数情况。
发现了一个问题
我用
select USERNAME,MACHINE,PROGRAM,CLIENT_INFO from v$session order by client_info;
查询。
每天将近200个链接是由数据库自己的IP连接的。
usernamemachine program client_info
ROEEE jyptdb2.gzcepc.com oracle@jyptdb2.gzcepc.com (TNS V1-V3) 192.168.40.2
QYJYOA jyptdb2.gzcepc.com oracle@jyptdb2.gzcepc.com (TNS V1-V3) 192.168.40.2
JYZXZJK jyptdb2.gzcepc.com oracle@jyptdb2.gzcepc.com (TNS V1-V3) 192.168.40.2
JYZXZJK jyptdb2.gzcepc.com oracle@jyptdb2.gzcepc.com (TNS V1-V3) 192.168.40.2
JYZXZJK jyptdb2.gzcepc.com oracle@jyptdb2.gzcepc.com (TNS V1-V3) 192.168.40.2
ROEEE jyptdb2.gzcepc.com oracle@jyptdb2.gzcepc.com (TNS V1-V3) 192.168.40.2
还有100个左右的链接是没有用户名和ip的空连接。
usernamemachine program client_info
jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (LMHB)
jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (J009)
jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (O002)
jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (J001)
jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (MMAN)
jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (RSMN)
以上情况是否是正常的？
如果非正常，如何排除这些问题链接。
感谢！
一般没有username的，可能是后台进程，建议你加上user_type列，全部贴出来 xifenfei 发表于 2014-10-23 16:26
一般没有username的，可能是后台进程，建议你加上user_type列，全部贴出来
飞总，有没user_type这个列哦。
那些有用户名的，是不是程序本身链接的？ 说错了，是TYPE列v$session.type xifenfei 发表于 2014-10-23 16:36
说错了，是TYPE列v$session.type
632 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (LMHB) BACKGROUND
633 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (Q002) BACKGROUND
634 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (GCR0) BACKGROUND
635 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (O002) BACKGROUND
636 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (J005) USER
637 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (J007) USER
638 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (MMAN) BACKGROUND
639 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (RSMN) BACKGROUND
640 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (CJQ0) BACKGROUND
641 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (J011) USER
642 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (PMON) BACKGROUND
643 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (DBW0) BACKGROUND
644 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (J000) USER
645 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (J009) USER
646 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (PSP0) BACKGROUND
647 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (DBW1) BACKGROUND
648 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (O000) BACKGROUND
649 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (VKTM) BACKGROUND
650 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (LGWR) BACKGROUND
651 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (GEN0) BACKGROUND
652 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (CKPT) BACKGROUND
653 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (ARC0) BACKGROUND
654 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (J001) USER
655 SYS jyptdb1.gzcepc.com oraagent.bin@jyptdb1.gzcepc.com (TNS V1-V3) USER
656 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (DIAG) BACKGROUND
657 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (SMON) BACKGROUND
658 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (ARC1) BACKGROUND
659 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (Q001) BACKGROUND
660 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (J004) USER
661 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (DBRM) BACKGROUND
662 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (RECO) BACKGROUND
663 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (ARC2) BACKGROUND
664 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (J010) USER
665 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (PING) BACKGROUND
666 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (RBAL) BACKGROUND
667 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (ARC3) BACKGROUND
668 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (GTX1) BACKGROUND
669 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (J003) USER
670 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (J008) USER
671 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (ACMS) BACKGROUND
672 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (ASMB) BACKGROUND
673 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (GTX0) BACKGROUND
674 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (J013) USER
675 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (DIA0) BACKGROUND
676 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (MMON) BACKGROUND
677 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (RCBG) BACKGROUND
678 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (J006) USER
679 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (J014) USER
680 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (LMON) BACKGROUND
681 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (MMNL) BACKGROUND
682 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (GTX3) BACKGROUND
683 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (LMD0) BACKGROUND
684 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (QMNC) BACKGROUND
685 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (W000) BACKGROUND
686 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (Q004) BACKGROUND
687 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (J012) USER
688 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (LMS0) BACKGROUND
689 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (MARK) BACKGROUND
690 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (SMCO) BACKGROUND
691 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (LMS1) BACKGROUND
692 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (GTX2) BACKGROUND
693 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (J002) USER
694 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (RMS0) BACKGROUND
695 jyptdb1.gzcepc.com oracle@jyptdb1.gzcepc.com (LCK0) BACKGROUND 除了少数user进程job相关进程，其他都是属于oracle 后台进程，属于正常情况
Oracle常见后台进程及其功能汇总
NameExpanded NameShort DescriptionLong DescriptionExternal Properties
ABMRAuto BMR Background ProcessCoordinates execution of tasks such as filtering duplicate block media recovery requests and performing flood controlWhen a process submits a block media recovery request to ABMR, it dynamically spawns slave processes (BMRn) to perform the recovery. ABMR and BMRn terminate after being idle for a long time.See Also: Oracle Database Backup and Recovery User's GuideDatabase instance
ACFSASM Cluster File System CSS ProcessTracks the cluster membership in CSS and informs the file system driver of membership changesACFS delivers CSS membership changes to the Oracle cluster file system. These membership changes are required for the file system to maintain file system consistency within the cluster.ASM instance, Oracle RAC
ACMSAtomic Control File to Memory Service ProcessCoordinates consistent updates to a control file resource with its SGA counterpart on all instances in an Oracle RAC environmentThe ACMS process works with a coordinating caller to ensure that an operation is executed on every instance in Oracle RAC despite failures. ACMS is the process in which a distributed operation is called. As a result, this process can exhibit a variety of behaviors. In general, ACMS is limited to small, nonblocking state changes for a limited set of cross-instance operations.Database instance, Oracle RAC
APnnLogical Standby / Streams Apply Process Coordinator ProcessObtains transactions from the reader server and passes them to apply serversThe coordinator process name is APnn, where nn can include letters and numbers.See Also: Oracle Streams Concepts and AdministrationDatabase instance, Data Guard, Oracle Streams
ARBnASM Rebalance ProcessRebalances data extents within an ASM disk groupPossible processes are ARB0-ARB9 and ARBA.ASM instance
ARCnArchiver ProcessCopies the redo log files to archival storage when they are full or an online redo log switch occursARCn processes exist only when the database is in ARCHIVELOG mode and automatic archiving is enabled, in which case ARCn automatically archives online redo log files. LGWR cannot reuse and overwrite an online redo log group until it has been archived.The database starts multiple archiver processes as needed to ensure that the archiving of filled online redo logs does not fall behind. Possible processes include ARC0-ARC9 and ARCa-ARCt.The LOG_ARCHIVE_MAX_PROCESSES initialization parameter specifies the number of ARCn processes that the database initially invokes.See Also: Oracle Database Concepts and Oracle Database Administrator's GuideDatabase instance
ASMBASM Background ProcessCommunicates with the ASM instance, managing storage and providing statisticsASMB runs in ASM instances when the ASMCMD cp command runs or when the database instance first starts if the server parameter file is stored in ASM. ASMB also runs with Oracle Cluster Registry on ASM.Database and ASM instances
ASnnLogical Standby / Streams Apply Process Reader Server or Apply Server· Computes dependencies between logical change records (LCRs) and assembles messages into transactions (Reader Server)· Applies LCRs to database objects or passes LCRs and user messages to their appropriate apply handlers (Apply Server)When the reader server finishes computing dependencies between LCRs and assembling transactions, it returns the assembled transactions to the coordinator process. Query V$STREAMS_APPLY_READER for information about the reader server background process.An apply server receives the transactions from the coordinator background process, and either applies database changes in LCRs or sends LCRs or messages to apply handlers. Apply servers can also enqueue a queue. If an apply server encounters an error, then it then tries to resolve the error with a user-specified conflict handler or error handler. If an apply server cannot resolve an error, then it rolls back the transaction and places the entire transaction, including all of its messages, in the error queue. When an apply server commits a completed transaction, this transaction has been applied. When an apply server places a transaction in the error queue and commits, this transaction also has been applied. Query V$STREAMS_APPLY_SERVER for information about the apply server background process.The coordinator process name is ASnn, where nn can include letters and numbers.Database instance
BMRnAutomatic Block Media Recovery Slave Pool ProcessFetches blocks from a real-time readable standby databaseWhen a process submits a block media recovery request to ABMR, it dynamically spawns slave processes (BMRn) to perform the recovery. BMRn processes fetch blocks from a real-time readable standby database. ABMR and BMRn terminate after being idle for a long time.See Also: Oracle Database Backup and Recovery User's GuideDatabase instance
BnnnASM Blocking Slave Process for GMONPerforms maintenance actions on ASM disk groupsBnnn performs actions that require waiting for resources on behalf of GMON. GMON must be highly available and cannot wait.A Bnnn slave is spawned when a disk is taken offline in an ASM disk group. Offline timer processing and drop of the disk are performed in this slave. Up to five process (B000 to B004) can exist depending on the load.ASM instance
CJQ0Job Queue Coordinator ProcessSelects jobs that need to be run from the data dictionary and spawns job queue slave processes (Jnnn) to run the jobsCJQ0 is automatically started and stopped as needed by Oracle Scheduler.The JOB_QUEUE_PROCESSES initialization parameter specifies the maximum number of processes that can be created for the execution of jobs. CJQ0 starts only as many job queue processes as required by the number of jobs to run and available resources.See Also: Oracle Database Concepts and Oracle Database Administrator's GuideDatabase instance
CKPTCheckpoint ProcessSignals DBWn at checkpoints and updates all the data files and control files of the database to indicate the most recent checkpointAt specific times CKPT starts a checkpoint request by messaging DBWnto begin writing dirty buffers. On completion of individual checkpoint requests, CKPT updates data file headers and control files to record most recent checkpoint.See Also: Oracle Database ConceptsDatabase and ASM instances
CPnnStreams Capture ProcessCaptures database changes from the redo log by using the infrastructure of LogMinerThe capture process name is CPnn, where nn can include letters and numbers. The underlying LogMiner process name is MSnn, where nn can include letters and numbers. The capture process includes one reader server that reads the redo log and divides it into regions, one or more preparer servers that scan the redo log, and one builder server that merges redo records from the preparer servers. Each reader server, preparer server, and builder server is a process. Query theV$STREAMS_CAPTURE view for information about this background process.See Also: Oracle Streams Concepts and AdministrationDatabase instance, Oracle Streams
CSnnStreams Propagation Sender ProcessSends LCRs to a propagation receiverThe propagation sender process name is CSnn, where nn can include letters and numbers. In an Oracle Streams combined capture and apply optimization, the propagation sender sends LCRs directly to the propagation receiver to improve performance. The propagation receiver passes the LCRs to an apply process. Query V$PROPAGATION_SENDER for information about a propagation sender.Database instance, Oracle Streams
CSnnI/O Calibration ProcessIssues I/Os to storage as part of storage calibration.CSnn slave processes are started on execution of theDBMS_RESOURCE_MANAGER.CALIBRATE_IO() procedure. There is one slave process per CPU on each node of the database.Database instance, Oracle RAC
CTWRChange Tracking Writer ProcessTracks changed data blocks as part of the Recovery Manager block change tracking featureCTWR tracks changed blocks as redo is generated at a primary database and as redo is applied at a standby database. The process is slightly different depending on the type of database.See Also: Oracle Database Backup and Recovery User's GuideDatabase instance
DBRMDatabase Resource Manager ProcessSets resource plans and performs other tasks related to the Database Resource ManagerIf a resource plan is not enabled, then this process is idle.See Also: Oracle Database Administrator's GuideDatabase instance
DBWnDatabase Writer ProcessWrites modified blocks from the database buffer cache to the data filesThe primary responsibility of DBWn is to write data blocks to disk. DBWnalso handles checkpoints, file open synchronization, and logging of Block Written records.In many cases the blocks that DBWn writes are scattered throughout the disk. Thus, the writes tend to be slower than the sequential writes performed by LGWR. DBWn performs multiblock writes when possible to improve efficiency. The number of blocks written in a multiblock write varies by operating system.The DB_WRITER_PROCESSES initialization parameter specifies the number of DBWn processes (DBW0-DBW9 and DBWa-DBWz). The database selects an appropriate default setting for this parameter or adjusts a user-specified setting based on the number of CPUs and processor groups.See Also: Oracle Database Concepts and Oracle Database Performance Tuning GuideDatabase instance
DIA0Diagnostic Process
Detects and resolves hangs and deadlocks ASM and Database instances
DIAGDiagnostic Capture Process
Performs diagnostic dumps
DIAG performs diagnostic dumps requested by other processes and dumps triggered by process or instance termination. In Oracle RAC, DIAG performs global diagnostic dumps requested by remote instances.ASM and Database instances
DMnnData Pump Master ProcessCoordinates the Data Pump job tasks performed by Data Pump worker processes and handles client interactionsThe Data Pump master (control) process is started during job creation and coordinates all tasks performed by the Data Pump job. It handles all client interactions and communication, establishes all job contexts, and coordinates all worker process activities on behalf of the job.Database instance, Data Pump
DMONData Guard Broker Monitor ProcessManages and monitors a database that is part of a Data Guard broker configurationWhen you start the Data Guard broker, a DMON process is created. DMON runs for every database instance that is managed by the broker. DMON interacts with the local database and the DMON processes of the other databases to perform the requested function. DMON also monitors the health of the broker configuration and ensures that every database has a consistent description of the configuration.DMON maintains profiles about all database objects in the broker configuration in a binary configuration file. A copy of this file is maintained by the DMON process for each of the databases that belong to the broker configuration. The process is created when theDG_BROKER_START initialization parameter is set to true.See Also: Oracle Data Guard BrokerDatabase instance, Data Guard
DnnnDispatcher ProcessPerforms network communication in the shared server architectureIn the shared server architecture, clients connect to a dispatcher process, which creates a virtual circuit for each connection. When the client sends data to the server, the dispatcher receives the data into the virtual circuit and places the active circuit on the common queue to be picked up by an idle shared server. The shared server then reads the data from the virtual circuit and performs the database work necessary to complete the request. When the shared server must send data to the client, the server writes the data back into the virtual circuit and the dispatcher sends the data to the client. After the shared server completes the client request, the server releases the virtual circuit back to the dispatcher and is free to handle other clients.Several initialization parameters relate to shared servers. The principal parameters are: DISPATCHERS, SHARED_SERVERS, MAX_SHARED_SERVERS,LOCAL_LISTENER, REMOTE_LISTENER.See Also: Oracle Database ConceptsDatabase instance, shared servers
DRnnASM Disk Resynchronization Slave ProcessResynchronizes the contents of an offline diskWhen a disk online SQL command is issued on a disk or disks that are offline, ASM spawns DRnn. Depending on the load, more than one slave may be spawned.ASM Instance
DSKMSlave Diskmon ProcessActs as the conduit between the database, ASM instances, and the Master Diskmon daemon to communicate information to Exadata storageThis process is active only if Exadata Storage is used. DSKM performs operations related to Exadata I/O fencing and Exadata cell failure handling.ASM instance, Exadata
DWnnData Pump Worker ProcessPerforms Data Pump tasks as assigned by the Data Pump master processThe Data Pump worker process is responsible for performing tasks that are assigned by the Data Pump master process, such as the loading and unloading of metadata and data.Database instance
EMNCEMON Coordinator ProcessCoordinates database event management and notificationsEMNC coordinates event management and notification activity in the database, including Streams Event Notifications, Continuous Query Notifications, and Fast Application Notifications.Database and ASM instances
EnnnEMON Slave ProcessPerforms database event management and notificationsThe database event management and notification load is distributed among the EMON slave processes. These processes work on the system notifications in parallel, offering a capability to process a larger volume of notifications, a faster response time, and a lower shared memory use for staging notifications.Database and ASM instances
FBDAFlashback Data Archiver ProcessArchives historical rows for tracked tables into flashback data archives and manages archive space, organization, and retentionWhen a transaction that modifies a tracked table commits, FBDA stores the pre-image of the rows in the archive. FDBA maintains metadata on the current rows and tracks how much data has been archived.FBDA is also responsible for automatically managing the flashback data archive for space, organization (partitioning tablespaces), and retention. FBDA also keeps track of how far the archiving of tracked transactions has progressed.See Also: Oracle Database Advanced Application Developer's GuideDatabase and ASM instances
FMONFile Mapping Monitor ProcessManages mapping information for the Oracle Database file mapping interfaceThe DBMS_STORAGE_MAP package enables you to control the mapping operations. When instructed by the user, FMON builds mapping information and stores it in the SGA, refreshes the information when a change occurs, saves the information to the data dictionary, and restores it to the SGA at instance startup.FMON is started by the database whenever the FILE_MAPPING initialization parameter is set to true.Database and ASM instances
FSFPData Guard Broker Fast Start Failover Pinger ProcessMaintains fast-start failover state between the primary and target standby databasesFSFP is created when fast-start failover is enabled.Database instance, Data Guard
GCRn href="#sthref4494" Foot 1 Global Conflict Resolution Slave ProcessPerforms synchronous tasks on behalf of LMHBGCRn processes are transient slaves that are started and stopped as required by LMHB to perform synchronous or resource intensive tasks.Database and ASM instances, Oracle RAC
GEN0General Task Execution ProcessPerforms required tasks including SQL and DML Database and ASM instances
GMONASM Disk Group Monitor ProcessMonitors all mounted ASM disk groupsGMON monitors all the disk groups mounted in an ASM instance and is responsible for maintaining consistent disk membership and status information. Membership changes result from adding and dropping disks, whereas disk status changes result from taking disks offline or bringing them online.ASM instance
GTXnGlobal Transaction ProcessProvides transparent support for XA global transactions in an Oracle RAC environmentThese processes help maintain the global information about XA global transactions throughout the cluster. Also, the processes help perform two-phase commit for global transactions anywhere in the cluster so that an Oracle RAC database behaves as a single system to the externally coordinated distributed transactions.The GLOBAL_TXN_PROCESSES initialization parameter specifies the number of GTXn processes, where n is 0-9 or a-j. The database automatically tunes the number of these processes based on the workload of XA global transactions. You can disable these processes by setting the parameter to 0. If you try to run XA global transactions with these process disabled, an error is returned.See Also: Oracle Real Application Clusters Administration and Deployment GuideDatabase instance, Oracle RAC
InnnDisk and Tape I/O Slave ProcessServes as an I/O slave process spawned on behalf of DBWR, LGWR, or an RMAN backup sessionI/O slave process can be configured on platforms where asynchronous I/O support is not available. These slaves are started by setting the corresponding slave enable parameter in the server parameter file. The I/O slaves simulate the asynchronous I/O behavior when the underlying platform does not have native support for asynchronous I/O.Database instance
INSVData Guard Broker Instance Slave ProcessPerforms Data Guard broker communication among instances in an Oracle RAC environmentINSV is created when the DG_BROKER_START initialization parameter is set to true.Database instance, Data Guard
JnnnJob Queue Slave ProcessExecutes jobs assigned by the job coordinatorJob slave processes are created or awakened by the job coordinator when it is time for a job to be executed.Job slaves gather all the metadata required to run the job from the data dictionary. The slave processes start a database session as the owner of the job, execute triggers, and then execute the job. After the job is complete, the slave processes commit and then execute appropriate triggers and close the session. The slave can repeat this operation in case additional jobs need to be run.Database instance
LCK0Instance Enqueue Background ProcessManages global enqueue requests and cross-instance broadcastsThe process handles all requests for resources other than data blocks. For examples, LCK0 manages library and row cache requests.Database and ASM instances, Oracle RAC
LGWRLog Writer ProcessWrites redo entries to the online redo logRedo log entries are generated in the redo log buffer of the system global area (SGA). LGWR writes the redo log entries sequentially into a redo log file. If the database has a multiplexed redo log, then LGWR writes the redo log entries to a group of redo log files.See Also: Oracle Database Concepts and Oracle Database Administrator's GuideDatabase and ASM instances
LMD0Global Enqueue Service Daemon 0 ProcessManages incoming remote resource requests from other instancesLMD0 processes enqueue resources managed under Global Enqueue Service. In particular, LMD0 processes incoming enqueue request messages and controls access to global enqueues. It also performs distributed deadlock detections.Database and ASM instances, Oracle RAC
LMHBGlobal Cache/Enqueue Service Heartbeat MonitorMonitor the heartbeat of LMON, LMD, and LMSn processesLMHB monitors LMON, LMD, and LMSn processes to ensure they are running normally without blocking or spinning.Database and ASM instances, Oracle RAC
LMONGlobal Enqueue Service Monitor ProcessMonitors an Oracle RAC cluster to manage global resourcesLMON maintains instance membership within Oracle RAC. The process detects instance transitions and performs reconfiguration of GES and GCS resources.See Also: Oracle Real Application Clusters Administration and Deployment GuideDatabase and ASM instances, Oracle RAC
LMSnGlobal Cache Service ProcessManages resources and provides resource control among Oracle RAC instancesLMS, where n is 0-9 or a-z, maintains a lock database for Global Cache Service (GCS) and buffer cache resources. This process receives, processes, and sends GCS requests, block transfers, and other GCS-related messages.See Also: Oracle Real Application Clusters Administration and Deployment GuideDatabase and ASM instances, Oracle RAC
LSP0Logical Standby Coordinator ProcessSchedules transactions for Data Guard SQL ApplyLSP0 is the initial process created upon startup of Data Guard SQL Apply. In addition to managing LogMiner and Apply processes, LSP0 is responsible for maintaining inter-transaction dependencies and appropriately scheduling transactions with applier processes. LSP0 is also responsible for detecting and enabling runtime parameter changes for the SQL Apply product as a whole.Database instance, Data Guard
LSP1Logical Standby Dictionary Build ProcessPerforms a logical standby dictionary build on a primary databaseThe LSP1 process is spawned on a logical standby database that is intended to become the new primary database. A logical standby database becomes a primary database by means of switchover or failover. The dictionary is necessary for logical standby databases to interpret the redo of the new primary database.Database instance, Data Guard
LSP2Logical Standby Set Guard ProcessDetermines which database objects will be protected by the database guardThe LSP2 process is created as needed during startup of SQL Apply to update the list of objects that are protected by the database guard.Database instance, Data Guard
LnnnPooled Server ProcessHandles client requests in Database Resident Connection PoolingIn Database Resident Connection Pooling, clients connect to a connection broker process. When a connection becomes active, the connection broker hands off the connection to a compatible pooled server process. The pooled server process performs network communication directly on the client connection and processes requests until the client releases the server. After being released, the connection is returned to the broker for monitoring, leaving the server free to handle other clients.See Also: Oracle Database ConceptsDatabase instance, Database Resident Connection Pooling
MARKMark AU for Resynchronization Coordinator ProcessMarks ASM allocation units as stale following a missed write to an offline diskMARK essentially tracks which extents require resynchronization for offline disks. This process runs in the database instance and is started when the database instance first begins using the ASM instance. If required, MARK can also be started on demand when disks go offline in the ASM redundancy disk group.Database and ASM instances
MMANMemory Manager ProcessServes as the instance memory managerThis process performs the resizing of memory components on the instance.Database and ASM instances
MMNLManageability Monitor Lite ProcessPerforms tasks relating to manageability, including active session history sampling and metrics computationMMNL performs many tasks relating to manageability, including session history capture and metrics computation.Database and ASM instances
MMONManageability Monitor ProcessPerforms or schedules many manageability tasksMMON performs many tasks related to manageability, including taking Automatic Workload Repository snapshots and performing Automatic Database Diagnostic Monitor analysis.Database and ASM instances
MnnnMMON Slave ProcessPerforms manageability tasks on behalf of MMONMnnn performs manageability tasks dispatched to them by MMON. Tasks performed include taking Automatic Workload Repository snapshots and Automatic Database Diagnostic Monitor analysis.Database and ASM instances
MRP0Managed Standby Recovery ProcessCoordinates the application of redo on a physical standby databaseMRP0 is spawned at the start of redo apply on a physical standby database. This process handles the extraction of redo and coordinates the application of that redo on a physical standby database.See Also: Oracle Data Guard Concepts and AdministrationDatabase instance, Data Guard
MSnnLogMiner Worker ProcessReads redo log files and translates and assembles into transactionsMultiple MSnn processes can exists, where n is 0-9 or a-Z. A minimum of three MSnn processes work as a group to provide transactions to a LogMiner client, for example, a logical standby database. There may be more than one such group, for example, Downstream Capture sessions.Database instance, Logical Standby, Oracle Streams
NnnnConnection Broker ProcessMonitors idle connections and hands off active connections in Database Resident Connection PoolingIn Database Resident Connection Pooling, clients connect to a connection broker process. When a connection becomes active, the connection broker hands off the connection to a compatible pooled server process. The pooled server process performs network communication directly on the client connection and processes requests until the client releases the server. After being released, the connection is returned to the broker for monitoring, leaving the server free to handle other clients.See Also: Oracle Database ConceptsDatabase instance, Database Resident Connection Pooling
NSAnRedo Transport NSA1 ProcessShips redo from current online redo logs to remote standby destinations configured for ASYNC transportNSAn can run as multiple processes, where n is 1-9 or A-V.See Also: Oracle Data Guard Concepts and AdministrationDatabase instance, Data Guard
NSSnRedo Transport NSS1 ProcessActs as a slave for LGWR when SYNC transport is configured for a remote standby destinationNSSn can run as multiple processes, where n is 1-9 or A-V.See Also: Oracle Data Guard Concepts and AdministrationDatabase instance, Data Guard
NSVnData Guard Broker NetSlave ProcessPerforms broker network communications between databases in a Data Guard environmentNSVn is created when a Data Guard broker configuration is enabled. There can be as many NSVn processes (where n is 0- 9 and A-U) created as there are databases in the Data Guard broker configuration.Database instance, Data Guard
OCFnASM CF Connection Pool ProcessMaintains a connection to the ASM instance for metadata operations Database and ASM instances
OnnnASM Connection Pool ProcessMaintains a connection to the ASM instance for metadata operationsOnnn slave processes are spawned on demand. These processes communicate with the ASM instance.Database and ASM instances
PINGInterconnect Latency Measurement ProcessAssesses latencies associated with communications for each pair of cluster instancesEvery few seconds, the process in one instance sends messages to each instance. The message is received by PING on the target instance. The time for the round trip is measured and collected.Database and ASM instances, Oracle RAC
PMONProcess MonitorMonitors the other background processes and performs process recovery when a server or dispatcher process terminates abnormallyPMON periodically performs cleanup of all the following:· Processes that died abnormally· Sessions that were killed· Detached transactions that have exceeded their idle timeout· Detached network connections which have exceeded their idle timeoutIn addition, PMON monitors, spawns, and stops the following as needed:· Dispatcher and shared server processes· Job queue processes· Pooled server processes for database resident connection pooling· Restartable background processesPMON is also responsible for registering information about the instance and dispatcher processes with the network listener.See Also: Oracle Database Concepts and Oracle Database Net Services Administrator's GuideDatabase and ASM instances
PnnnParallel Query Slave ProcessPerform parallel execution of a SQL statement (query, DML, or DDL)Parallel Query has two components: a foreground process that acts as query coordinator and a set of parallel slaves (Pnnn) that are background processes. These background processes are spawned or reused during the start of a parallel statement. They receive and carry out units of work sent from the query coordinator.The maximum number of Pnnn processes is controlled by the initialization parameter PARALLEL_MAX_SERVERS. Slave processes are numbered from 0 to the PARALLEL_MAX_SERVERS setting. If the query is aGV$ query, then these background processes are numbered backward, starting from PZ99.Database and ASM instances
PRnnParallel Recovery ProcessPerforms tasks assigned by the coordinator process performing parallel recoveryPRnn serves as a slave process for the coordinator process performing parallel media recovery and carries out tasks assigned by the coordinator. The default number of these processes is based on number of CPUs.Database instance
PSP0Process Spawner ProcessSpawns Oracle background processes after initial instance startup Database and ASM instances
QMNCAQ Coordinator ProcessMonitors AQQMNC is responsible for facilitating various background activities required by AQ and Oracle Streams: time management of messages, management of nonpersistent queues, cleanup of resources, and so on. QMNC dynamically spawns Qnnn processes as needed for performing these tasks.Note that if the AQ_TM_PROCESSES initialization parameter is set to 0, this process will not start. The database writes the following message to the alert log: WARNING: AQ_TM_PROCESSES is set to 0. System might be adversely affected.Database instance, Advanced Queuing
QnnnAQ Server Class ProcessPerforms various AQ-related background task for QMNCQnnn acts as a slave process for QMNC and carry out tasks assigned by QMNC. The number of these processes is dynamically managed by QMNC based on load.Database instance
RBALASM Rebalance Master ProcessCoordinates rebalance activityIn an ASM instance, it coordinates rebalance activity for disk groups. In a database instances, it manages ASM disk groups.Database and ASM instances
RCBGResult Cache Background ProcessHandles result cache messagesThis process is used for handling invalidation and other messages generated by server processes attached to other instances in Oracle RAC.Database instance, Oracle RAC
RECORecoverer ProcessResolves distributed transactions that are pending because of a network or system failure in a distributed databaseRECO uses the information in the pending transaction table to finalize the status of in-doubt transactions. At timed intervals, the local RECO attempts to connect to remote databases and automatically complete the commit or rollback of the local portion of any pending distributed transactions. All transactions automatically resolved by RECO are removed from the pending transaction table.See Also: Oracle Database Concepts and Oracle Database Net Services Administrator's GuideDatabase instance
RMSnOracle RAC Management ProcessPerforms manageability tasks for Oracle RACRMSn performs a variety of tasks, including creating resources related to Oracle RAC when new instances are added to a cluster.See Also: Oracle Real Application Clusters Administration and Deployment GuideDatabase instance, Oracle RAC
RnnnASM Block Remap Slave ProcessRemaps a block with a read errorA database instance reading from an ASM disk group can encounter an error during a read. If possible, ASM asynchronously schedules a Rnnnslave process to remap this bad block from a mirror copy.ASM instance
RPnnCapture Processing Worker ProcessProcesses a set of workload capture filesRPnn are worker processes spawned by callingDBMS_WORKLOAD_REPLAY.PROCESS_CAPTURE(capture_dir,parallel_level). Each worker process is assigned a set of workload capture files to process.Worker processes execute in parallel without needing to communicate with each other. After each process is finished processing its assigned files, it exits and informs its parent process.The number of worker processes is controlled by the parallel_levelparameter of DBMS_WORKLOAD_REPLAY.PROCESS_CAPTURE. By default,parallel_level is null. Then, the number of worker processes is computed as follows:SELECT VALUE FROM V$PARAMETER WHERENAME='cpu_count';When parallel_level is 1, no worker processes are spawned.Database instance
RSM0Data Guard Broker Worker ProcessPerforms monitoring management tasks related to Data Guard on behalf of DMONThe process is created when a Data Guard broker configuration is enabled.Database instance, Data Guard
RSMNRemote Slave Monitor ProcessManages background slave process creation and communication on remote instances in Oracle RACThis background process manages the creation of slave processes and the communication with their coordinators and peers. These background slave processes perform tasks on behalf of a coordinating process running in another cluster instance.Database instance, Oracle RAC
RVWRRecovery Writer ProcessWrites flashback data to the flashback logs in the fast recovery areaRVWR writes flashback data from the flashback buffer in the SGA to the flashback logs. RVWR also creates flashback logs and performs some tasks for flashback log automatic management.Database instance, Flashback Database
SMCOSpace Management Coordinator ProcessCoordinates the execution of various space management tasksThis background process coordinates the execution of various space management tasks, including proactive space allocation and space reclamation. SMCO dynamically spawns slave processes (Wnnn) to implement these tasks.Database instance
SMONSystem Monitor ProcessPerforms critical tasks such as instance recovery and dead transaction recovery, and maintenance tasks such as temporary space reclamation, data dictionary cleanup, and undo tablespace managementSMON performs many database maintenance tasks, including the following:· Creates and manages the temporary tablespace metadata· Reclaims space used by orphaned temporary segments· Maintains the undo tablespace by onlining, offlining, and shrinking the undo segments based on undo space usage statistics· Cleans up the data dictionary when it is in a transient and inconsistent state· Maintains the SCN to time mapping table used to support Oracle Flashback featuresIn an Oracle RAC database, the SMON process of one instance can perform instance recovery for other instances that have failed.SMON is resilient to internal and external errors raised during background activities.See Also: Oracle Database ConceptsDatabase instance
SnnnShared Server ProcessHandles client requests in the shared server architectureIn the shared server architecture, clients connect to a dispatcher process, which creates a virtual circuit for each connection. When the client sends data to the server, the dispatcher receives the data into the virtual circuit and places the active circuit on the common queue to be picked up by an idle shared server. The shared server then reads the data from the virtual circuit and performs the database work necessary to complete the request. When the shared server must send data to the client, the server writes the data back into the virtual circuit and the dispatcher sends the data to the client. After the shared server completes the client request, the server releases the virtual circuit back to the dispatcher and is free to handle other clients.Several initialization parameters relate to shared servers. The principal parameters are: DISPATCHERS, SHARED_SERVERS, MAX_SHARED_SERVERS,LOCAL_LISTENER, REMOTE_LISTENER.See Also: Oracle Database ConceptsDatabase instance, shared servers
TEMnASM disk Test Error Emulation ProcessEmulates I/O errors on ASM disks through named eventsI/O errors can be emulated on ASM disk I/O through named events. The scope can be the process, instance, or even cluster. Optionally, a set of AUs can be chosen for error emulation.ASM instance
VBGnVolume Background ProcessCommunicates between the ASM instance and the operating system volume driverVBGn handles messages originating from the volume driver in the operating system and sends them to the ASM instance.VBGn can run as multiple processes, where n is 0-9.ASM instance
VDBGVolume Driver ProcessForwards ASM requests to perform various volume-related tasksVDBG handles requests to lock or unlock an extent for rebalancing, volume resize, disk offline, add or drop a disk, force and dismount disk group to the Dynamic Volume Manager driver.ASM instance
VKRMVirtual Scheduler for Resource Manager ProcessServes as centralized scheduler for Resource Manager activityVKRM manages the CPU scheduling for all managed Oracle processes. The process schedules managed processes in accordance with an active resource plan.Database instance
VKTMVirtual Keeper of Time ProcessProvides a wall clock time and reference time for time interval measurementsVKTM acts as a time publisher for an Oracle instance. VKTM publishes two sets of time: a wall clock time using a seconds interval and a higher resolution time (which is not wall clock time) for interval measurements. The VKTM timer service centralizes time tracking and offloads multiple timer calls from other clients.Database and ASM instances
VMB0Volume Membership ProcessMaintains cluster membership on behalf of the ASM volume driverThis process membership in the cluster as an I/O-capable client on behalf of the ASM volume driver.ASM instance
VnnnASM Volume I/O Slave ProcessInitializes ASM volume contents during creationThis process is responsible for initializing the ASM volume during creation.ASM instance
WnnnSpace Management Slave ProcessPerforms various background space management tasks, including proactive space allocation and space reclamationWnnn processes are slave processes dynamically spawned by SMCO to perform space management tasks in the background. These tasks include preallocating space into locally managed tablespace and SecureFiles segments based on space usage growth analysis, and reclaiming space from dropped segments. At most 10 Wnnn slaves can run on one database instance. After being started, the slave acts as an autonomous agent. After it finishes task execution, it automatically picks up another task from the queue. The process terminates itself after being idle for a long time.Database instance
XDMGExadata Automation ManagerInitiates automation tasks involved in managing Exadata storageXDMG monitors all configured Exadata cells for state changes, such as a bad disk getting replaced, and performs the required tasks for such events. Its primary tasks are to watch for inaccessible disks and cells and when they become accessible again, and to initiate the ASM ONLINE operation. The ONLINE operation is handled by XDWK.ASM instance, Exadata
XDWKExadata Automation ManagerPerforms automation tasks requested by XDMGXDWK gets started when asynchronous actions such as ONLINE, DROP, and ADD an ASM disk are requested by XDMG. After a 5 minute period of inactivity, this process will shut itself down.ASM instance, Exadata
XnnnASM Disk Expel Slave ProcessPerforms ASM post-rebalance activitiesThis process expels dropped disks at the end of an ASM rebalance.ASM instance
*ACMS (atomic controlfile to memory service) per-instance process is an agent that contributes to ensuring a distributed SGA memory update is either globally committed on success or globally aborted in the event of a failure in an Oracle RAC environment.
*DBRM (database resource manager) process is responsible for setting resource plans and other resource manager related tasks.
*DIA0 (diagnosability process 0) (only 0 is currently being used) is responsible for hang detection and deadlock resolution. *DIAG (diagnosability) process performs diagnostic dumps and executes global oradebug commands.*EMNC (event monitor coordinator) is the background server process used for database event management and notifications. *FBDA (flashback data archiver process) archives the historical rows of tracked tables into flashback data archives. Tracked tables are tables which are enabled for flashback archive. When a transaction containing DML on a tracked table commits, this process stores the pre-image of the rows into the flashback archive. It also keeps metadata on the current rows.
FBDA is also responsible for automatically managing the flashback data archive for space, organization, and retention and keeps track of how far the archiving of tracked transactions has occurred.
*GTX0-j (global transaction) processes provide transparent support for XA global transactions in an Oracle RAC environment. The database autotunes the number of these processes based on the workload of XA global transactions. Global transaction processes are only seen in an Oracle RAC environment. *KATE performs proxy I/O to an ASM metafile when a disk goes offline. *MARK marks ASM allocation units as stale following a missed write to an offline disk. *SMCO (space management coordinator) process coordinates the execution of various space management related tasks, such as proactive space allocation and space reclamation. It dynamically spawns slave processes (Wnnn) to implement the task.
*VKTM (virtual keeper of time) is responsible for providing a wall-clock time (updated every second) and reference-time counter (updated every 20 ms and available only when running at elevated priority) * PZ (PQ slaves used for global Views) are RAC Parallel Server Slave processes, but they are not normal parallel slave processes, PZnn processes (starting at 99) are used to query GV$ views which is done using Parallel Execution on all instances, if more than one PZ process is needed, then PZ98, PZ97,... (in that order) are created automatically. * O00 (ASM slave processes) A group of slave processes establish connections to the ASM instance. Through this connection pool database processes can send messages to the ASM instance. For example opening a file sends the open request to the ASM instance via a slave. However slaves are not used for long running operations such as creating a file. The use slave (pool) connections eliminate the overhead oflogging into the ASM instance for short requests * x000 - Slave used to expell disks after diskgroup reconfiguration
参考附件
xifenfei 发表于 2014-10-23 16:53
除了少数user进程job相关进程，其他都是属于oracle 后台进程，属于正常情况
Oracle常见后台进程及其功能汇 ...
谢谢飞总 雁过留声
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