A: 

I would guess that you have 2 threads accessing the same JNIEnv object.

See:

jlstrecker  2009-12-24 22:14:04
That's exactly what it means. Note this is a Dalvik VM error, emitted when CheckJNI is enabled.
fadden  2010-07-29 20:54:16

related questions

Calling a JNI modal dialog disables taskbar icon.
How do I redirect terminal output from a C program to System.out with JNI?
How to automatically copy data to new RMI threads ?
Anyone know how to use WMI with C instead of C++ ?
Swing transparency using JNI
Best way to throw exceptions in JNI code?
Why does my JNI code not successfully find a jthrowable's getMessage method?
JNI memory management using the Invocation API
How to create a JNIEnv mock in C/C++
How do I create a symlink in Windows Vista?
Open CDialog from Java using JNI
Accessing RPG on iSeries from Java
Monitoring memory usage for a C DLL called with Java via JNI?
How can I expose a C ODBC connection to a JVM using JNI?
How to determine if a JNI (jogl) is available at runtime?
Autoconf test for JNI include dir
UnsatisfiedLinkError: The specified procedure could not be found
Memory footprint issues with JAVA, JNI, and C application
Way to read Windows EventLog with Java
How do I convert jstring to wchar_t *
faster Math.exp() via JNI?
Calling C# code from Java?
JNI and Java: ant calling make or make calling ant?
Getting Java and TWAIN to play together nicely
How can I Java webstart multiple, dependent, native libraries?