Apparent DEADLOCK!!! Error resolution process

1. Project Environment
   

   Database: Oracle

   Middleware: Was

2. Description of the problem

2015.05.21 (a good day), found in the morning was backstage error as follows:

[15-5-21 7:31:01:171 CST] 00000027 systemerr R com[email protected]498e498e--apparent DEADLOCK!!! Creating Emergency threads for unassigned pending tasks!

3. Problem solving Process

Baidu from the Internet under this error, the analysis is as follows:

The reason is that hibernate does not release after using C3P0 to connect Orcale data, c3p0 the maximum number of connections is 100, but obviously c3p0 has a bug, resulting in insufficient database connection pool, causing the process to deadlock.

After changing Proxool, observe normal.

Reference URL:http://blog.csdn.net/chinesesword/article/details/7902702

http://blog.sina.com.cn/s/blog_5491164b0100sxtc.html

http://myzee.blog.163.com/blog/static/2088712420121110139423/

http://www.blogjava.net/liuyimx/articles/296849.html

For a comprehensive reference site, the number of connections to Oracle has been modified as follows:

1. Ways to modify the maximum number of connections for Oracle

   
A, landing in SYSDBA status of PL/SQL or Worksheet
B, query the current number of connections
show parameter processes;
C, change the number of system connections
alter system set processes=1000 Scope=spfile;
d. Create Pfile
create Pfile from SPFile;
E. Restart the Oracle service or restart the Oracle server

after the change, the error point is c3p0 setting parameters, no reported apparent DEADLOCK!!! Wrong, but after a few hours the apparent DEADLOCK was reported!!! Error

Contact developer developers to inform:

in \web-inf\classes\ hibernate.cfg.xml file to remove the relevant configuration

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<!--<property name= "Hibernate.c3p0.min_size" >5</property>-->

<!--<property name= "Hibernate.c3p0.max_size" >500</property>-->

<!--<property name= "Hibernate.c3p0.timeout" >1800</property>-->

<!--<property name= "hibernate.c3p0.max_statements" >50</property>-

650) this.width=650; "src="/e/u261/themes/default/images/spacer.gif "style=" Background:url ("/e/u261/lang/zh-cn/ Images/localimage.png ") no-repeat center;border:1px solid #ddd;" alt= "spacer.gif"/>--- Comment out the C3P0 configuration parameters in the Hibernate configuration file

Restarting was, and then running an ETL task test, did not find that the error was reported again.

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Apparent DEADLOCK!!! Error resolution process