Tomcat vs. DRMAA

[Stefan Metzlaff <st...@gmx.de>]

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Hi,

I'm developing a drmaa application which should run on the tomcat
application server with axis. The web front end accesses the application
through web services (wsdl).
The application works pretty fine, if it is started from command line.
But if I'm using the web services the following error occurs frequently:

java.lang.UnsatisfiedLinkError: Native Library
/opt/SGE/lib/lx26-amd64/libdrmaa.so already loaded in another classloader
java.lang.ClassLoader.loadLibrary0(ClassLoader.java:1716)
java.lang.ClassLoader.loadLibrary(ClassLoader.java:1676)
java.lang.Runtime.loadLibrary0(Runtime.java:822)
java.lang.System.loadLibrary(System.java:992)
com.sun.grid.drmaa.SessionImpl$1.run(SessionImpl.java:58)
java.security.AccessController.doPrivileged(Native Method)
com.sun.grid.drmaa.SessionImpl.(SessionImpl.java:56)
com.sun.grid.drmaa.SessionFactoryImpl.getSession(SessionFactoryImpl.java:59)
cef.VirtualJob.startDRMAAJob(VirtualJob.java:591)
cef.VirtualBlastJob.startJob(VirtualBlastJob.java:212)
cef.ClusterMaster.startNewJob(ClusterMaster.java:91)
cef.BlastAllWebService.startNewJob(BlastAllWebService.java:47)
org.apache.jsp.sampleBlastAllWebService.Result_jsp._jspService(Result_jsp.java:81)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:332)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)

After this error every other drmaa web service call results the
following error:

java.lang.NoClassDefFoundError
com.sun.grid.drmaa.SessionFactoryImpl.getSession(SessionFactoryImpl.java:59)
cef.VirtualJob.startDRMAAJob(VirtualJob.java:591)
cef.VirtualBlastJob.startJob(VirtualBlastJob.java:212)
cef.ClusterMaster.startNewJob(ClusterMaster.java:91)
cef.BlastAllWebService.startNewJob(BlastAllWebService.java:47)
org.apache.jsp.sampleBlastAllWebService.Result_jsp._jspService(Result_jsp.java:81)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:332)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)

After restarting the tomcat and the grid engine the application is
working for some web service calls, until the UnsatisfiedLinkError occurs.

I'm using the following environment:
Linux
Sun Grid Engine SGE 6.0u4
6.0u4 DRMAA.JAR
jdk1.5.0_06
Tomcat 5.5
Axis 1.3

I think something is going wrong the the factory.getSession() call, but
I dont't know why. All my sessions are closed (via session.exit()) on
exit of the application. So there should be no conflict with the drmaa
library.
Is it possible that tomcat tries to load the libdrmaa.so more than once,
if one user calls different methods of the web service or multiple users
using the web services?


Best regards
Stefan Metzlaff
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