Shulou(Shulou.com)06/01 Report--

Project environment

Database: oracle

Middleware: WAS

two。 Problem description

On May 21, 2015 (a good day), the was backend reported an error in the morning as follows:

[15-5-21 7 com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@498e498e 31 Freight 01 Freight 171 CST] 00000027 SystemErr R com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@498e498e-- APPARENT DEADLOCKOKBY! Creating emergency threads for unassigned pending tasks!

3. Problem solving process

From the online Baidu under this error, the analysis is roughly as follows:

The reason is that hibernate will not be released after using c3p0 to connect orcale data, and the maximum number of connections in c3p0 is 100. however, it is obvious that c3p0 has Bug, which leads to insufficient database connection pool and process lock.

After changing Proxool, the observation was normal.

Reference website: 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

Comprehensive reference website, the number of modified oracle connections is as follows:

1. The method of modifying the maximum number of connections in Oracle

A. Log in to PL/SQL or Worksheet as sysdba

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

Restart the Oracle service or restart the Oracle server

After the modification, the error was directed to the setting parameter of c3p0, but not APPARENT Deadlock warning! Error, but after a few hours began to report APPARENT DEADLOCKOKBY! Error

Contact the developer to inform the developer:

Remove the relevant configuration from the\ WEB-INF\ classes\ hibernate.cfg.xml file

-comment out the c3p0 configuration parameters in the hibernate configuration file

Restart was, and then run an etl task test, did not find this error reported again.

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