- 浏览: 277763 次
- 性别:
- 来自: 北京
文章分类
最新评论
-
somefuture:
为何有文章说asyncAppdender不支持J2ee容器ht ...
log4j 日志异步化AsyncAppender 大幅提升系统性能 -
model2012:
你用adt跑的吧,android里面是不能直接运行main方法 ...
JVM崩溃:Current thread JavaThread "CompilerThread1" daemon [_thre -
di1984HIT:
不错。学习了啊
.rmi.ConnectException: Connection refused to host: 127.0.0.1来龙去脉 -
gygwoaini:
还有可能是第3个问号没给值
索引中丢失 IN 或 OUT 参数:: 3 -
fool2011:
多谢
索引中丢失 IN 或 OUT 参数:: 3
http://yong321.freeshell.org/computer/deadlocks.txt
There're two common deadlocks. ORA-60, enqueue deadlocks; ORA-4020, library cache deadlocks. ********** ORA-60 ********** Reproduction: This is very easy to reproduce. Just follow this procedure: In sessionA, update tb set col = 'x' where pk = 'aa' In sessionB, update tb set col = 'x' where pk = 'bb' In sessionA, update tb set col = 'x' where pk = 'bb' In sessionB, update tb set col = 'x' where pk = 'aa' If neither session commits, 3 seconds after the last statement shown above is issued, sessionA will throw error ORA-60, with the corresponding deadlock graph generated in the udump trace file: ---------Blocker(s)-------- ---------Waiter(s)--------- Resource Name process session holds waits process session holds waits TX-00010017-000000ba 8 7 X 9 8 X TX-00020012-000000af 9 8 X 8 7 X session 7: DID 0001-0008-00000002 session 8: DID 0001-0009-00000002 session 8: DID 0001-0009-00000002 session 7: DID 0001-0008-00000002 Rows waited on: Session 8: obj - rowid = 00000CBB - AAAAzjAADAAAAFDAAA Session 7: obj - rowid = 00000CBB - AAAAzjAADAAAAFDAAB Interpretation: Resource here simply means lock as in v$resource (technically it should be the locked resource). TX stands for transaction, usually row lock. The numbers that follow are v$lock.id1, v$lock.id2, respectively, in hex radix for TX enqueue. E.g., 20012[hex] is 131090; ba[hex] is 175. Anjo Kolk's Wait Event paper (Description of Oracle7 Wait Events and Enqueues, used to be at www.dbatoolbox.com/WP2001/dbamisc/events.pdf) tells us that id1 is "undo segment number << 16 | slot". Indeed we find v$transaction.xidusn = 2 and x$transaction.xidslot = 18. So 10[bin] left shifted 16 bits ORed with 18 equals 131090. id2 should be "sequence"; v$transaction.xidsqn = 175. Process is Oracle process ID (not to be confused with the OS level process ID in UNIX or thread ID in Windows); it is v$process.pid where v$process.addr matches v$session.paddr. Session is v$session.sid. X means it's holding or waiting for an exclusive lock. DID is deadlock ID (see Note:6145177.8); the first number is always 1; second number is Oracle process ID; I don't know the third number. For sessions waiting for row locks, additional information about the rows is given. CBB[hex] is dba_objects.object_id from which you'll know the table. Then the rowid is given so that you can quickly find the row by SELECT * FROM thetable WHERE ROWID = 'rowid'. If the "Rows waited on" is followed by "no rows", then it's waiting on a table lock, not a row lock, like in this case: ---------Blocker(s)-------- ---------Waiter(s)--------- Resource Name process session holds waits process session holds waits TX-00060004-00003155 41 45 X 15 26 S TX-0012000b-00002802 15 26 X 41 45 S session 45: DID 0001-0029-00000002 session 26: DID 0001-000F-00000002 session 26: DID 0001-000F-00000002 session 45: DID 0001-0029-00000002 Rows waited on: Session 26: no row Session 45: no row Following the deadlock graph is process state dump, which shows state object (SO) hierarchy in properly indented form, with the root being a process SO. Remedy: If the "Session <SID>" line gives row IDs, simply wait and rerun the application later. And consider application design to see if you have two programs updating the same table but in different order. [note1] If the Session line says "no row", the error could be triggered when multiple sessions try to update the same block while the free space for the block is already too small for Oracle to automatically increase ITLs (interested transaction lists), regardless the value of MAXTRANS. You can try rebuilding the table with a higher INITRANS (initial ITL entries) and setting a higher value of PCTFREE. Beginning with 8i, the easiest way to do this is ALTER TABLE yourtable MOVE STORAGE (INITRANS xxx). Another scenario which does happen often is that you don't have indexes on child table foreign key columns and multiple sessions are updating the parent table primary key columns or deleting rows from the parent table. Both sessions will attempt to acquire a shared table lock on the child table and if they already hold row locks (on different rows), a deadlock results. In this case, you may build indexes on foreign keys in the child table. Numerous sites provide scripts to find foreign keys that are missing indexes (osi.oracle.com/~tkyte/unindex/ and www.jlcomp.demon.co.uk/faq/fk_ind.html). If you don't do this (possibly for legitimate reason such as child table DML performance), make sure you never or rarely delete rows from the parent table (updating parent table primary keys is very rare). Or as Steve Adams suggested, ALTER TABLE childtable DISABLE TABLE LOCK. Further reading: Metalink Note:62365.1 ********** ORA-4020 ********** Reproduction: SQL> create procedure p1 as begin p2; end; 2 / Warning: Procedure created with compilation errors. SQL> create procedure p2 as begin p1; end; 2 / Warning: Procedure created with compilation errors. SQL> alter procedure p1 compile; alter procedure p1 compile * ERROR at line 1: ORA-04020: deadlock detected while trying to lock object YONG.P1 The above case is modified from an example in Connor McDonald's "Mastering Oracle PL/SQL: Practical Solutions". Obviously, you can't have mutual library cache locks in each other's code. More commonly, this error is thrown due to invalid objects especially triggers, or due to Oracle bugs. E.g., Jonathan Lewis in "Practical Oracle8i" reported that query throws ORA-4020 if partitioned IOT maintenance is going on. An ORA-4020 deadlock graph looks like the following: ORA-04020: deadlock detected while trying to lock object YONG.P1 -------------------------------------------------------- object waiting waiting blocking blocking handle session lock mode session lock mode -------- -------- -------- ---- -------- -------- ---- 797992F8 7AA06C48 79FA5554 X 7AA06C48 79F8B3D0 X -------------------------------------------------------- Note that in this case, the waiting session is the same as the blocking session because they have the same session address. Remedy: If the deadlock is caused by the same session that experiences the deadlock, make sure you don't have any invalid objects on the table reported in the deadlock trace file, such as invalid triggers. If you do, manually compile them. With this deadlock, it's helpful to get more insight by tracing the event 4020 as follows: alter session set events '4020 trace name processstate forever, level 10'; or if you don't know or can't access the session, put event='4020 trace name processstate forever, level 10' in init.ora file and bounce the database. The trace file thus created when the deadlock occurs next time may have strings like "status=INVL". Look at the corresponding object name after "name=". If you do experience ORA-4020 and it happens fairly often, search on Metalink or open a tar. ********** Deadlocks in RAC ********** There's no error number reported but both ORA-60 and ORA-4020 are possible. In alert.log, we only see "Global Enqueue Services Deadlock detected. More info in filen /home/oracle/admin/<SID>/bdump/<SID>_lmd0_<pid>.trc." ["filen" is not typo; it means "file name".] LMD trace file has: user session for deadlock lock 0x7553ab14 pid=33 serial=37657 audsid=6450105 user: 246/<LinuxUsername> O/S info: user: <WindowsUsername>, term: MISFBB10-54, ospid: 4148:5156, machine: <NTdomain>\<PCname> program: sqlplus.exe application name: SQL*Plus, hash value=3669949024 Current SQL Statement: update test set a = :"SYS_B_0" where a = :"SYS_B_1" Global Wait-For-Graph(WFG) at ddTS[0.28] : BLOCKED 0x7553ab14 5 [0xf001d][0x8353],[TX] [2162689,7995] 0 BLOCKER 0x69cabb5c 5 [0xf001d][0x8353],[TX] [1769474,4478] 1 BLOCKED 0x69cabc30 5 [0x70014][0xe908],[TX] [1769474,4478] 1 BLOCKER 0x7e1424e8 5 [0x70014][0xe908],[TX] [2162689,7995] 0 That was Oracle 9.2.0.7.0 on Linux accessed from a Windows PC. According to Note:262226.1, the first process in instance 0 (on the first line) requested for a TX lock in mode 5 or exclusive [note2] and was blocked by the second process in instance 1 (on the second line), which requested for another TX lock (third line) and was blocked by the first process (fourth line). The note interprets the numbers after the lock name, e.g. [2162689,7995], as process ID. But if there're two numbers in square brackets, those two numbers are transaction_id0 and transaction_id1 of v$ges_blocking_enqueue, respectively, or equivalently the same columns in v$dlm_locks. (But I don't know what the transaction number means; it doesn't seem to be concatenation of xidusn.xidslot.xidsqn of v$transaction.) In addition, the hex numbers following "BLOCKED" or "BLOCKER" are handles (lock pointers) of v$ges_blocking_enqueue, and the two hex numbers after lock mode are id1 and id2 in v$lock (refer to http://yong321.freeshell.org/oranotes/LocksWhere2FindMoreInfo.txt on how to find their meanings). The above trace shows the SQL involved in the deadlock. But in some cases, the SQL is missing,[note3] as in this example: Global Wait-For-Graph(WFG) at ddTS[0.15] : BLOCKED 0x70d17058 5 [0xf4dd2a46][0x57e4077],[LB] 30268 0 BLOCKER 0x70d16594 5 [0xf4dd2a46][0x57e4077],[LB] 30268 0 This deadlock was caused by B-namespace library cache lock requested and blocked by itself. The process PID is 30268 (a single number, not in brackets). Unfortunately it's missing the SQL. Note:262226.1 acknowledges that it would be more helpful to add the SQL to the WFG trace. In the meantime, if the deadlock can be reproduced with one instance (as in this case because the last column, instance number, is the same number), then do so by setting cluster_database to false; a deadlock graph in a non-cluster database is much more useful than a global WFG, which is created even if all involved processes are on one node. Yong Huang yong321@yahoo.com ________________________ [note1] It's often suggested that applications should be written in a way to ensure the same order in running DMLs on the table. This means ProgramI should update tblX then tblY and ProgramII should also update them in this order. But there're many other cases than this rule should apply. Consider this case: if conditionA, update tblX if conditionB, update tblY if conditionC, update tblX if conditionD, update tblY If this single program (no ProgramII) is run by multiple processes, depending on the conditions met in each process, a deadlock could occur. [note2] According to http://www.rachelp.nl/index_kb.php?menu=articles&actie=show&id=15 these mode numbers start with 0. So mode 5 here means exclusive, which would be mode 6 in non-RAC lock mode. [note3] According to Dusan Bolek (message 10 of http://groups.google.com/group/comp.databases.oracle.server/browse_frm/thread/a1e9aacfc4e16e25/), the SQL is present if the deadlock occurs between instances and missing if on the same instance. ORA-12829 ORA-99 12345678901234567890123456789012345678901234567890123456789012345678901234567890
发表评论
-
转:概述 java 数据库连接 3.0 规范的新功能和改进之处
2010-06-02 22:55 1042概述 java 数据库连接 3.0 规范的新功能和 ... -
转:如何利用连接和语句池特性来提高 Oracle 驱动的 JDBC 程序的性能
2010-06-02 22:45 1837开发人员:JDBC ... -
Java用OCI驱连Oracle数据库的实现方法
2009-12-09 22:46 1551Java程序连接oracle数据库时,用oci驱动要比用thi ... -
JDBC OCI——不同平台安装oracle client 配置不同环境变量
2009-12-09 11:17 2477以下内容适用Oracle client安装版: ... -
JDBC OCI的调用过程
2009-12-09 11:13 1625原文:http://hzcaixiao.ite ... -
JBOSS下的OCI配置
2009-12-06 16:25 1059原文:http://hzcaixiao.iteye.com ... -
转载:RAC 专题(英文)
2009-06-11 09:02 991http://www.dba-oracle.com/real_ ... -
转:RAC的TAF简单测试(一)
2009-06-12 01:51 1085http://yangtingkun.itpub.net/po ... -
ASH AWRX相关内容
2009-06-12 05:41 1113ASH AWRX相关内容 -
转:解决Oracle数据库死锁
2009-06-16 09:45 981http://blog.oracle.com.cn/index ... -
转:Oracle性能误区--MTS,RAC,分区,并行查询
2009-06-12 02:11 953http://www.cnblogs.com/zyk/arch ... -
转:死锁的头号原因:不加索引的外键(第6章.锁)
2009-06-16 09:24 1059http://blog.oracle.com.cn/index ... -
Deadlocks
2009-06-26 02:29 1116http://www.oratechinfo.co.uk/ ... -
查找没有索引的外键
2009-06-26 03:17 753http://asktom.oracle.com/tkyte/ ...
相关推荐
Oracle数据库的Library Cache Lock等待事件是数据库性能优化中常见的问题之一,主要涉及到Oracle数据库的缓存管理和并发控制机制。在Oracle中,Library Cache是存储PL/SQL代码、SQL语句及其解析结果的地方,用于减少...
enqueue_sidekiq_job RSpec块匹配器 安装 # Gemfile group :test do gem 'rspec-enqueue_sidekiq_job' end 用法 检查某个作业是否已排入队列。 expect { AwesomeWorker . perform_async } . to enqueue_sidekiq_...
3. **Library Cache Locks**:当执行SQL语句时,Oracle会尝试从库缓存中找到已编译的执行计划,如果没有则需要创建新的执行计划,并对其进行锁定。 4. **DML Locks (数据锁定)**:包括行锁、表锁等,用于保护数据行...
priority-navigation, Priority 导航—的Javascript实现无相关性 PriorityNavigation.js如果你的菜单项不适合它的父项,那么PriorityNav是一个纯javascript插件,它将移动你的菜单项。 我们将查看网站的收费。...
.enqueue(new Callback() { @Override public void onFailure(Call call, IOException e) { // 处理失败情况 e.printStackTrace(); } @Override .public void onResponse(Call call, Response response) ...
在 RAC 环境中,Cache Fusion 机制主要包括三个部分:Global Cache Service (GCS)、Global Enqueue Service (GES) 和 Dynamic Remastering (DRM)。 1. Global Cache Service (GCS) GCS 负责管理数据库中的块,包括...
call.enqueue(new Callback() { /* 回调处理 */ }); // 或者 Response<User> response = call.execute(); // 同步调用 ``` 4. **OkHttp集成**:Retrofit2默认使用OkHttp作为网络堆栈,提供了强大的网络请求功能,如...
Enqueue ( " one " ); numbers . Enqueue ( " two " ); numbers . Enqueue ( " three " ); numbers . Enqueue ( " four " ); numbers . Enqueue ( " five " ); numbers . Enqueue ( " six " ); Obtener y eliminar...
3. **发送请求**:通过OkHttpClient的newCall(Request)方法获取Call对象,然后调用execute()或enqueue()发送同步或异步请求。 4. **处理响应**:同步请求返回Response对象,异步请求则在Callback中接收结果。 在...
也可以使用Swift的泛型队列(Queue)库,通过enqueue(入队)和dequeue(出队)实现。 4. 队列(Queue): 队列是一种先进先出(FIFO)的数据结构。Swift的Array或CollectionType可以实现简单的队列操作。Swift标准...
在编写网络请求代码时,可以创建OkHttpClient实例,定义Request对象,最后通过client的execute或enqueue方法发起请求。对于Okio,你可以使用它来优化文件读写或数据处理的性能。 总之,OkHttp和Okio是Java和Android...
2. **自定义缓存策略**:可以实现`CacheControl`接口,自定义缓存策略。 3. **自定义Cookie管理**:通过实现`CookieJar`接口,实现自定义的Cookie管理策略。 4. **自定义证书**:对于HTTPS请求,可以配置SSL证书,...
如果某个节点的cache被修改,更改会通过集群软件传播到其他节点,最后写入磁盘以保持一致性。 四、ClusterWare组件 1. CRSd:集群资源服务,管理集群资源的启动、停止和监控。 2. Cssd:集群同步服务,保证集群节点...
在链队列中,我们通常有两个关键操作:入队(enqueue)和出队(dequeue)。入队操作是在队尾添加新元素,而出队操作则是移除队首元素。在链队列实现中,队头和队尾通常用两个指针来标识,分别是front和rear。当front...
队列的基本操作包括入队(enqueue)、出队(dequeue)、查看队首元素(front)和检查队列是否为空(isEmpty)。 1. **入队操作**:在队尾添加新的元素。如果队列满,可以考虑使用循环队列来避免溢出问题。在C语言中...
// Enqueue and return future.auto result = pool.enqueue([]( int x) { return x; }, 42 );// Get result from future.std::cout << result.get() << std::endl; 另外, riften::Thiefpool提供了分离...
为了在ListView中显示结果,我们需要在主线程之外处理这个请求,可以使用`enqueue()`方法: ```java service.getData().enqueue(new Callback<List<DataModel>>() { @Override public void onResponse(Call...
Resque::延迟Resque 的作业排队延迟。 将仅在指定延迟后或将来特定时间出现以供处理的作业入队。... 调用Resque.enqueue_in或Resque.enqueue_at而不是Resque.enqueue例如: class User after_create :send_call_to
def enqueue(self, item): self.q.append(item) def dequeue(self): # if self.q != []: if len(self.q)>0: return self.q.pop(0) else: return None def length(self): return len(self.q) def ...