We are facing an unusual problem, our JNI lib crashes at load time.
we use CentOS 5.4/G++ and VS2005 for development.
scenario:
we are currently working on an enhancement in our product and wanted to pass the new information back to the Java server code using JNI.
our C/C++ code works fine and we have tested it by running for around 6 hours or so in our dev environment. we have updated two result structure(which were already present) with one long value each to pass on the result of our new enhancement.
when we updated the JNI code to pass on the result to Java code, we found that Java server is crashing while loading JNI, we did debugging and found that JNI lib crashes, even, when we do not have our changes in JNI lib code base.
in our further debugging we found that, JNI Makefile includes a .c file(aa.c), which has a couple of our changes for the new enhancement; we started with commenting our changes in this aa.c file one by one and found that the crash happens only when we have BBB.cpp::method1() call(which we have added, as part of our new enhancement).
The unusual part is, this .c file(aa.c) is not needed in the JNI lib and we do not have any methods of aa.c called from JNI lib;
Now we have removed aa.c from the JNI Makefile and compile just fine, but still crashes when we have BBB.cpp::method1() call, if we remove this method1() call then it works fine.
we are not sure, why/how it is linking to a file which is not included, in the Makefile and crashing.
this is the error log we see
AgentServer#0 started: OK
12750 [Connection#Cnx:#0.0.1026:0 – Session#c0s1] ERROR com.xx.xxx.xxxx – Unable to load JNI BBBController Library
java.lang.UnsatisfiedLinkError: /opt/XXXXX/lib/libjnixxx.so: Can’t load IA 32-bit .so on a IA 32-bit platform
at java.lang.ClassLoader$NativeLibrary.load(Native Method)
at java.lang.ClassLoader.loadLibrary0(ClassLoader.java:1751)
at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1676)
at java.lang.Runtime.loadLibrary0(Runtime.java:822)
at java.lang.System.loadLibrary(System.java:993)
Please suggest, any idea’s would be appreciated.
Thanks in advance,
Aqura
finally, we are able to solve this issue.
We were seeing this issue because the Makefile we used to build the JNI lib had a lot of .o files which were not needed by the build.
one of the file happened to be the one, we were modifying, but other dependent files were not included in the Makefile and this was causing the crash at load time as it was not able to resolve the references.
to find and fix the issue, we created a simple Java class which just loads the libjni.so, this gave us undefined references to method, which we searched and started fixing the ones not needed.
I know this was a crude method and it will take some time to find and fix the original issue.
This worked for us, so I thought I would share this with others.
Aqura