web service returns 500 when concurrent access

Description of problem:
web service returns 500 when concurrent access. It works fine with a single access.

Version-Release number of selected component (if applicable):

How reproducible:

Please find the attached reproducer kit reproducer.tar.gz which contains

reproducer
├── accounts.csv // data source
├── command.log // test result
├── SampleJDV.zip // project source code
├── server.log // test result
├── SOAP_TEST2.jmx // config file for JMeter
├── WSTest.vdb // VDB which contains web service model
└── WSTest.war // generated JBossWS-CXF War

Steps to Reproduce:
0. add user/user in teiid-security-users.properties
1. add datasource in standalone.xml

<datasource jndi-name="java:/WSTest" pool-name="WSTest" enabled="true">
<connection-url>jdbc:teiid:WSTest</connection-url>
<driver>teiid</driver>
<pool>
<min-pool-size>100</min-pool-size>
<max-pool-size>100</max-pool-size>
<use-strict-min>true</use-strict-min>
</pool>
<security>
<user-name>user</user-name>
<password>user</password>
</security>

2. unjar WSTest.vdb, change the path to accounts.csv in SampleJDV/sandbox/WSTest_Source.xmi, rejar WSTest.vdb.
3. deploy WSTest.vdb
4. deploy WSTest.war
5. run jmeter, and open SOAP_TEST2.jmx
6. run test on jmeter

Actual results:

Expected results:

Additional info: