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Posted to users@tomcat.apache.org by Nick Holmes <Ni...@investis.com> on 2004/03/17 11:37:58 UTC

Native libraries configuration under tomcat.

Hi,

I am trying to get the JMagick library working under Tomcat to do some image
translation following an upload.  

My platform is Apache 2, Mod_jk2 and Tomcat 4.1.27 I have several .jar
extensions installed, including postgres, so basic external libraries do
work.

JMagick comes as a semi-stub library .jar archive and a native library
libJMagick.so - under the command line my code works (following "ldconfig"),
but I get errors in the catalina.out complaining about being unable to find
the library (details at the end of this message). the key clause being:

"Caused by: java.lang.RuntimeException: Can't load MagickLoader (class not
found)
        at magick.Magick.<clinit>(Magick.java:25)"

Essentially, having trawled through the various documentation, I haven't
worked out how to direct Tomcat to find/use the .so library, so any pointers
to how to do this would be great.

Any help on this would be very much appreciated.

Nick


the catalina.out says.... 

java.lang.ExceptionInInitializerError
        at org.apache.jsp.test_jsp._jspService(test_jsp.java:86)
        at
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:137)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
        at
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:2
10)
        at
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:295)
        at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:241)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
        at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Application
FilterChain.java:247)
        at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterCh
ain.java:193)
        at
org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.ja
va:256)
        at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invok
eNext(StandardPipeline.java:643)
        at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
        at
org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
        at
org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.ja
va:191)
        at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invok
eNext(StandardPipeline.java:643)
        at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
        at
org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
        at
org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2416)
        at
org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180
)
        at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invok
eNext(StandardPipeline.java:643)
        at
org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.
java:171)
        at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invok
eNext(StandardPipeline.java:641)
        at
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:172
)
        at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invok
eNext(StandardPipeline.java:641)
        at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
        at
org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
        at
org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java
:174)
        at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invok
eNext(StandardPipeline.java:643)
        at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
        at
org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
        at
org.apache.coyote.tomcat4.CoyoteAdapter.service(CoyoteAdapter.java:223)
        at
org.apache.jk.server.JkCoyoteHandler.invoke(JkCoyoteHandler.java:263)
        at
org.apache.jk.common.HandlerRequest.invoke(HandlerRequest.java:360)
        at org.apache.jk.common.ChannelSocket.invoke(ChannelSocket.java:604)
        at
org.apache.jk.common.ChannelSocket.processConnection(ChannelSocket.java:562)
        at
org.apache.jk.common.SocketConnection.runIt(ChannelSocket.java:679)
        at
org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.jav
a:619)
        at java.lang.Thread.run(Thread.java:534)
Caused by: java.lang.RuntimeException: Can't load MagickLoader (class not
found)
        at magick.Magick.<clinit>(Magick.java:25)
        ... 38 more
java.lang.NoClassDefFoundError
        at org.apache.jsp.test_jsp._jspService(test_jsp.java:86)
        at
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:137)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
        at
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:2
10)
        at
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:295)
        at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:241)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
        at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Application
FilterChain.java:247)
        at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterCh
ain.java:193)
        at
org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.ja
va:256)
        at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invok
eNext(StandardPipeline.java:643)
        at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
        at
org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
        at
org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.ja
va:191)
        at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invok
eNext(StandardPipeline.java:643)
        at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
        at
org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
        at
org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2416)
        at
org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180
)
        at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invok
eNext(StandardPipeline.java:643)
        at
org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.
java:171)
        at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invok
eNext(StandardPipeline.java:641)
        at
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:172
)
        at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invok
eNext(StandardPipeline.java:641)
        at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
        at
org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
        at
org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java
:174)
        at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invok
eNext(StandardPipeline.java:643)
        at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
        at
org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
        at
org.apache.coyote.tomcat4.CoyoteAdapter.service(CoyoteAdapter.java:223)
        at
org.apache.jk.server.JkCoyoteHandler.invoke(JkCoyoteHandler.java:263)
        at
org.apache.jk.common.HandlerRequest.invoke(HandlerRequest.java:360)
        at org.apache.jk.common.ChannelSocket.invoke(ChannelSocket.java:604)
        at
org.apache.jk.common.ChannelSocket.processConnection(ChannelSocket.java:562)
        at
org.apache.jk.common.SocketConnection.runIt(ChannelSocket.java:679)
        at
org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.jav
a:619)
        at java.lang.Thread.run(Thread.java:534)


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Re: Native libraries configuration under tomcat.

Posted by Christopher Schultz <ch...@comcast.net>.
Nick,

> JMagick comes as a semi-stub library .jar archive and a native library
> libJMagick.so - under the command line my code works (following "ldconfig"),
> but I get errors in the catalina.out complaining about being unable to find
> the library (details at the end of this message). the key clause being:
> 
> "Caused by: java.lang.RuntimeException: Can't load MagickLoader (class not
> found)
>         at magick.Magick.<clinit>(Magick.java:25)"
> 
> Essentially, having trawled through the various documentation, I haven't
> worked out how to direct Tomcat to find/use the .so library, so any pointers
> to how to do this would be great.

I'm not sure where it is, but I'm sure that Tomcat has a directory 
that's specified as a search path for shared libs. Your JMagick class's 
<clinit> (public static { }) method is bombing probably because a call 
to System.loadLibrary() can't find the shared lib.

Can anyone say if Tomcat itself provides 'another' directory where 
shared objects can go?

You can put it in the SDK somewhere, but that's ugly.

Finally, let me issue a word of warning: using native code from a webapp 
is pretty dangerous: if the native code, say, segfaults, then Tomcat 
will go down along with all your webapps. Also, you have to be careful: 
the JVM gets very upset if you call System.loadLibrary() more than once 
for a given library. So, you should take care to have your JMagick 
library sitting in a common area, rather than your webapp's WEB-INF/lib 
directory. (Unless you promose never to re-start your webapp without 
re-starting Tomcat ;)

-chris