What every DBA needs to know about JDBC connection pools * Bridging the language barrier between DBA and Middleware Administrators

Transcription

1

2 Presented at What every DBA needs to know about JDBC connection pools * Bridging the language barrier between DBA and Middleware Administrators Jacco H. Landlust Platform Architect Director Oracle Consulting NL, Core Technology March, 2015

3 Safe Harbor 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. 3

4 Program Agenda Terminology Connection Pool configuration Perhaps some other helpful topics Q&A 4

5 Terminology Ensure you are talking the same language as your middleware friends 5

6 WebLogic Terminology Domain Machine A Machine B AdminServer Managed Server Cluster Managed Server Managed Server Node Manager Node Manager 6

7 Resources and Services within a Domain Can be target at One or Multiple Managed Servers Examples: application components, such as EJBs security providers resource adapters diagnostics and monitoring services JDBC data sources JMS servers or other messaging resources persistent store 7

8 Data source A Data Source object is the representation of a data source in the Java programming language. In basic terms, a data source is a facility for storing data An object that implements the Data Source interface will typically be registered with a naming service based on the Java Naming and Directory Interface (JNDI) API The Data Source interface is implemented by a driver vendor (in this presentation examples are based on Oracle s driver) 8

9 Data source; 3 types of implementations Basic implementation produces a standard Connection object Connection pooling implementation produces a Connection object that will automatically participate in connection pooling. This implementation works with a middle-tier connection pooling manager Distributed transaction implementation produces a Connection object that may be used for distributed transactions and almost always participates in connection pooling. This implementation works with a middle-tier transaction manager and almost always with a connection pooling manager. 9

10 Distributed transactions (XA) extended Architecture, An X/Open group standard For executing a "global transaction" that accesses more than one back-end data-store, thus XA is a type of transaction coordination over more than one resource (JDBC, JMS, other resource adapters) Two-phase commit (2PC) 10

11 Be alarmed if your developer calls every transaction distributed 11

12 Java Transaction API (JTA) Enables distributed transactions to be done across multiple XA resources Can even be cross domain (warning: sometimes a complicated setup!) Configuration settings for JTA are applicable at the domain level. This means that configuration attribute settings (e.g. timeout) apply to all servers within a domain Monitoring and logging tasks for JTA are performed at the server level Configuration settings for participating resources (such as JDBC data sources) are per configured object 12

13 Data sources in Oracle WebLogic Server Generic Multi-Data source GridLink 13

14 Generic Data source Provide connection management processes that help keep your system running efficiently Connects to a specific database (service) Contains a pool of database connections that are created when the data source is created and at server startup WLS Generic DS RDBMS 14

15 Multi-Data source Abstraction around a group of generic data sources WLS The multi data source determines which data source to use to satisfy the request depending on the algorithm selected in the multi data source configuration: load balancing or failover Generic DS Multi DS Generic DS INST1 RAC INST2 15

16 GridLink Data source Event-based data source that adaptively responds to state changes in an Oracle RAC instance WLS Key foundation for providing deeper integration with Oracle RAC GridLink DS Responds to FAN events to provide Fast Connection Failover (FCF), Runtime Connection Load-Balancing (RCLB), and RAC instance graceful shutdown XA and Websession affinity is supported at the global transaction ID level INST1 RAC INST2 16

17 A GridLink data source uses Fast Connection Failover to: Provides rapid failure detection Abort and remove invalid connections from the connection pool Perform graceful shutdown for planned and unplanned Oracle RAC node outages Adapt to changes in topology, such as adding or removing a node without changes in the datasource configuration Distribute runtime work requests to all active Oracle RAC instances, including those rejoining a cluster 17

18 Runtime Connection Load Balancing allows WebLogic Server to: Adjust the distribution of work based on back end node capacities such as CPU, availability, and current workload React to changes in Oracle RAC topology Manage pooled connections for high performance and scalability 18

19 XA affinity with GridLink Performance feature that ensures that all database operations performed on a RAC cluster within the context of a global transaction are directed to the same RAC instance. Do not confuse this with DTP services! Will be established based on the global transaction id (=context), instead of by individual data source, to ensure that connections obtained from different data sources that are configured for the same RAC cluster are all associated with the same RAC instance.. 19

20 Use GridLink whenever using RAC* : GridLink provides performance improvements because of RLB, XA and WebSession affinity 20

21 When to use what? 21

22 When to use what? 22

23 Connection pools Cache of database connections maintained so connections can be reused when future requests to the database are required 23

24 Connection properties: JDBC URL @(DESCRIPTION=(ADDRESS_LIST=( (ADDRESS=(PROTOCOL=TCP)(HOST=cluster-scan)(PORT=1521))) (CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=service))) 24

25 Connection properties: JDBC URL & SCAN usage Requires JDBC Driver Included in WebLogic version and newer If FAN is not used (and therefore RLB is not used) all connections are initiated to first SCAN IP Caused by ordered reply in InetAddress.getAllByName Workaround: set oracle.jdbc.thinforcednsloadbalancing =true 25

26 Connection Properties: Using SDP with Exadata Add Weblogic startup options: JAVA_OPTIONS="${JAVA_OPTIONS} -Djava.net.preferIPv4Stack=true -Doracle.net.SDP=true Use PROTOCOL=SDP X.XX.XX)(PORT=1522))(CONNECT_DATA=(SERVICE_NAME=myservice))) 26

27 Connection Pool: Capacity Settings are per managed server Available settings: Initial, Min, Max Direct link to processes parameter configured per database instance: PROCESSES = ( #ManagedServers * MAX) + 30* Test what happens if your application runs out of connections! 27

28 Consider using a value of 5000 operating system processes to be connected to Oracle concurrently Fusion Middleware Performance and Tuning Guide 11g Release 1 28

29 Connection Pool: Capacity Management Set Shrink frequency to manage aggressive capacity management (default 900 seconds) Set Inactive Connection Timeout to return unused connections (default 0 = disabled) Set Login Delay to prevent logon storm (default 0) 29

30 Connection Pool: Pinned to Thread Minimize the time it takes for an application to reserve a database connection from a data source Eliminates contention between threads for a database connection Do not use in combination with Multi Data Sources Maximum Capacity is ignored Shrinking does not apply When you Reset a connection pool, the reset connections from the connection pool are marked as Test Needed. 30

31 Connection Pool: Row Prefetching Every time an application asks the driver to retrieve a row from the database, several rows are prefetched with it and stored in client-side memory. In this way, several subsequent requests do not have to execute database calls to fetch data Default disabled at data source level Some memory structures are pre-initialise to hold the full prefetch size. 31

32 Configure prefetch size at per-query basis 32

33 Connection Pool: Statement Cache Size of cache is 1:1 related to OPEN_CURSORS database parameter Can be mistaken for cursor Leaking Type [LRU Fixed]: LRU: After the Statement Cache Size is met, the Least Recently Used statement is removed when a new statement is used Fixed: The first Statement Cache Size number of statements is stored and stay fixed in the cache. No new statements are cached unless the cache is manually cleared or the cache size is increased. 33

34 Connection Pool: Test Connections on Reserve Test each connection before giving to a client Adds slight delay to the request Seconds to Trust an Idle Pool Connection setting to minimize delay If tested via a query instead of API: only use dual for test SQL table to minimize unnecessary LIO 34

35 Connection Pool: Statement Timeout The time after which a statement currently being executed will time out. A value of -1 disables this feature A value of 0 means that statements will not time out Statement Timeout <= JTA This will not kill the database session/transaction! So load on database server will remain. 35

36 Connection Pool: XA transaction timeout Whenever the timeout has been reached, an error will be thrown at the client starting the transaction. The actual transaction will be rolled back. The actual error is: ORA timeout: distributed transaction waiting for lock JTA timeout <= XA Transaction Timeout <= DISTRIBUTED_LOCK_TIMEOUT Extra privileges required for monitoring: dba_2pc_pending, dba_2pc_neighbors dba_pending_transactions v$global_transactions 36

37 Other helpful topics Some semi-random topics that might be helpful when working with WebLogic and JDBC 37

38 Use jnettrace.jar to Debug Connectivity issues java -jar jnettrace.jar <Database Server Host> <Database Server Port> <JavaNet_Port> 38

39 JDBC persistent stores You can configure a persistency store to use JDBC for TLOGs and JMS, which provides the following benefits: Leverages replication and HA characteristics of the underlying database. Simplifies disaster recovery by allowing the easy synchronization of the state of the database and JMS/TLOGs. Improved Transaction Recovery service migration as the JMS mssages / Transaction Logs to do not need to be migrated (copied) to a new location. 39

40 Hints when configuring JDBC persistent stores Default store used long raw data type, have your MW admin configure Create Tables from DLL file to oracle_blob_securefile.ddl Configure WorkerCount (a.k.a. I/O multithreading) Setup hash partition on persistent store table Persistent stores for JMS tables should use MDS instead of GridLink. 40

41 WebLogic in HA and DR scenario s: use JDBC based persistent stores 41

42 Rolling Upgrades at Database level Data source must run against service 11gR2 Database service must have q=true to pass HA events via ONS 12c Database service must have notification=true to pass HA events via ONS Failover activities: Failover service to other instance(s) before shutdown of instance Let connection dry out (= wait) Stop instance, patch and start instance Repeat for other instances 42

43 Wrap data types If something like this shows up in the log file of WebLogic: java.lang.classcastexception: WebLogic.jdbc.wrapper.Blob_oracle_sql_BLOB at oracle.ifs.server.s_librarysession.gettokencredentialblob(s_librarysess ion.java:23888) You do not have a database issue, you have a WebLogic issue: Disable wrap data types 43

44 WLS provides the ability to disable wrapping Although WLS generates a dynamic proxy for vendor methods that implement an interface to show through the wrapper, some data types do not implement an interface. For example, Oracle data types Array, Blob, Clob, NClob, Ref, SQLXML, and Struct are classes that do not implement interfaces. Disabling wrapping allows applications to use native driver objects directly. Eliminating wrapping overhead can provide a significant performance improvement. 44

45 Ignore in use connections upon shutdown Default enabled Can kill in-flight transactions, and therefore jeopardize RPO=0 theories When disabled shutdown can take (very) long time. 45

46 Currently, Oracle Fusion Middleware does not support configuring Oracle Active Data Guard for the database repositories that are a part of the Fusion Middleware topology. From: Disaster Recovery for Oracle Exalogic Elastic Cloud 46

47 Oracle Fusion Middleware SOA does not support Oracle Active Data Guard because the SOA components execute and update information regarding SOA composite instances in the database as soon as they are started. From: Best Practices for Oracle Fusion Middleware SOA 11g Multi Data Center Active-Active Deployment 47

48 Exadata / Exalogic Pass startup options to Managed Server: -Djava.net.preferIPv4Stack=true -Doracle.net.SDP=true Change protocol from TCP to SDP in JDBC_URL No SCAN on SDP Monitoring SDP Sockets Using sdpnetstat on Oracle Linux Stay away from com.sum.sdp.conf when using Weblogic 48

49 Application Continuity New 12.1 feature allowing for replay of in flight transactions Requires 12.1 datasource replay datasource=oracle.jdbc.replay.oracledatasourceimpl 49

50 Questions? and hopefully also some answers 50

51 51

52