Cannot Open Shared Object file - C++ library in Java

Question

I am trying to use a C++ compiled library in my Java code. I set java.library.path to /usr/local/lib/ and I have all the .so files for the libraries installed there.

However, when I try to run the Java application I see the following:

Native code library failed to load. 
java.lang.UnsatisfiedLinkError: /usr/local/lib/libA.so: libB.so.2.4: cannot open shared object file: No such file or directory

However the file seems to be there:

ls /usr/local/lib/libB.so.2.4
lrwxrwxrwx 1 root root 20 Jan 24 16:33 /usr/local/lib/libB.so.2.4 -> libB.so.2.4.5

The symlinked file also exists. Any idea why this library can't be found?

Worth checking the file permissions. Or you can use strace to see what it is trying to do. You could also as a test System.load() the exact filename and see if/how that fails, possibly under strace again. — Chris Stratton, Jan 24 '15 at 23:24
@ElliottFrisch Ok so I added `/usr/local/lib` to the `/etc/ld.so.conf` and then reran this and it seems to have fixed the problem. — Oleksi, Jan 24 '15 at 23:48
If someone could explain the details how this fixed the issue, I'd love to accept that answer — Oleksi, Jan 24 '15 at 23:49
Did you try to replace the symbol name with the real file? `cp libB.so.2.4.5 libB.so.2.4` — alijandro, Jan 26 '15 at 02:56

score 4 · Accepted Answer · edited May 23 '17 at 12:33

Java was able to load the native code for library A (libA.so) and when it ran that native code there was a dependency on libB.so (however, it's in native code at that point - outside of the JVMs control). At that point, you must use the native libraries on the system. The usual mechanism is to set the LD_LIBRARY_PATH environment variable or use ldconfig (per the man page) which says in part

ldconfig creates the necessary links and cache to the most recent shared libraries found in the directories specified on the command line, in the file /etc/ld.so.conf, and in the trusted directories (/lib and /usr/lib). The cache is used by the run-time linker, ld.so or ld-linux.so.

score 1 · Answer 2 · edited Oct 15 '18 at 19:40

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If you are using WebLogic: make sure you have a system variable called USTART_LD_LIB in the wlstart-script of weblogic that overwrites LD_LIBRARY_PATH variable. So you need to set this variable also append the lib to this variable and also simultaneously set LD_LIBRARY_PATH.

The reason is you cannot keep on exporting the variables before start of your app manually..

edited Oct 15 '18 at 19:40

Peanut

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answered Oct 15 '18 at 19:34

Mark Jones

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Cannot Open Shared Object file - C++ library in Java

2 Answers2