JNI_CreateJavaVM fails in Multithreaded app.

Question

Hello,
when i call JNI_CreateJavaVM in a multithreaded application, I ll get the error:
"ERROR: Could not find the pthread library (2). Are you running a supported Linux
distribution?"
So, given the following program, everyhing works okay:
----code---
#include "jni.h"
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
void jnicall()
JNIEnv *env;
JavaVM *jvm;
jint res;
jclass cls;
jmethodID mid;
jstring jstr;
jclass stringClass;
jobjectArray args;
JavaVMInitArgs vm_args;
JavaVMOption options[1];
options[0].optionString = "-Djava.class.path=.";
vm_args.version = 0x00010002;
vm_args.options = options;
vm_args.nOptions = 1;
vm_args.ignoreUnrecognized = JNI_TRUE;
res = JNI_CreateJavaVM(&jvm, (void**)&env, &vm_args);
if (res < 0) {
fprintf(stderr, "Can't create Java VM\n");
exit(1);
cls = env->FindClass("Hello");
if (cls == NULL) {
goto destroy;
mid = env->GetStaticMethodID(cls, "main", "([Ljava/lang/String;)V");
if (mid == NULL) {
goto destroy;
jstr = env->NewStringUTF(" from C!");
if (jstr == NULL) {
goto destroy;
stringClass = env->FindClass("java/lang/String");
args = env->NewObjectArray(1, stringClass, jstr);
if (args == NULL) {
goto destroy;
env->CallStaticVoidMethod(cls, mid, args);
destroy:
if (env->ExceptionOccurred()) {
env->ExceptionDescribe();
jvm->DestroyJavaVM();
int main()
jnicall();
---code---
But when I replace main with something like
---code---
int main()
pthread_t thread;
if (0 != pthread_create(&thread, NULL, (void*(*)(void*))jnicall, NULL))
fprintf(stderr, "Cannot create thread");
exit(1);
---code---
Really strange is that is does not matter, how i use pthread functions: even if
i call the jnicall function directly from main but start a different thread using
pthread_create, i get this method too:
---code---
int main()
pthread_t thread;
jnicall();
if (0 != pthread_create(&thread, NULL, (void*(*)(void*))some_other_thread_without_jni,
NULL))
fprintf(stderr, "Cannot create thread");
exit(1);
---code---
My system is a Suse Linux Enterprise Server 8.0 (wth United Linux 1.0) (kernel
2.4.19, glibc is 2.2.5); the Jrockit stuff is JRockit 8.1 SP 2
Any ideas?
TIA,
Johannes

Answer 1

Try checking that the environment variable LD_ASSUME_KERNEL=2.2.5 is not
set.
From the release notes at:
http://edocs.bea.com/wljrockit/docs81/relnotes/relnotes.html#1041981
Best Regards,
Josefin Hallberg
BEA WebLogic JRockit
Customer Centric Engineering
"Johannes Hampel" <[email protected]> wrote in message
news:[email protected]...
>
Hello,
when i call JNI_CreateJavaVM in a multithreaded application, I ll getthe error:
"ERROR: Could not find the pthread library (2). Are you running asupported Linux
distribution?"
So, given the following program, everyhing works okay:
----code---
#include "jni.h"
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
void jnicall()
JNIEnv *env;
JavaVM *jvm;
jint res;
jclass cls;
jmethodID mid;
jstring jstr;
jclass stringClass;
jobjectArray args;
JavaVMInitArgs vm_args;
JavaVMOption options[1];
options[0].optionString = "-Djava.class.path=.";
vm_args.version = 0x00010002;
vm_args.options = options;
vm_args.nOptions = 1;
vm_args.ignoreUnrecognized = JNI_TRUE;
res = JNI_CreateJavaVM(&jvm, (void**)&env, &vm_args);
if (res < 0) {
fprintf(stderr, "Can't create Java VM\n");
exit(1);
cls = env->FindClass("Hello");
if (cls == NULL) {
goto destroy;
mid = env->GetStaticMethodID(cls, "main", "([Ljava/lang/String;)V");
if (mid == NULL) {
goto destroy;
jstr = env->NewStringUTF(" from C!");
if (jstr == NULL) {
goto destroy;
stringClass = env->FindClass("java/lang/String");
args = env->NewObjectArray(1, stringClass, jstr);
if (args == NULL) {
goto destroy;
env->CallStaticVoidMethod(cls, mid, args);
destroy:
if (env->ExceptionOccurred()) {
env->ExceptionDescribe();
jvm->DestroyJavaVM();
int main()
jnicall();
---code---
But when I replace main with something like
---code---
int main()
pthread_t thread;
if (0 != pthread_create(&thread, NULL, (void*(*)(void*))jnicall,NULL))
fprintf(stderr, "Cannot create thread");
exit(1);
---code---
Really strange is that is does not matter, how i use pthread functions:even if
i call the jnicall function directly from main but start a differentthread using
pthread_create, i get this method too:
---code---
int main()
pthread_t thread;
jnicall();
if (0 != pthread_create(&thread, NULL,(void*(*)(void*))some_other_thread_without_jni,
NULL))
fprintf(stderr, "Cannot create thread");
exit(1);
---code---
My system is a Suse Linux Enterprise Server 8.0 (wth United Linux 1.0)(kernel
2.4.19, glibc is 2.2.5); the Jrockit stuff is JRockit 8.1 SP 2
Any ideas?
TIA,
Johannes