[lttng-dev] Unable to make lttng run for multiple instances in parallel

Chidhu R chid1989 at gmail.com
Wed Mar 18 12:30:10 EDT 2015


When I try to execute the following code, I always run into errors. Can
someone help me.


int lttng_init() {
        int err;
        int l_fd = -1;

        if(0 != system("mkdir /tmp/mk_lttng")) {
                printf("Directory exists\n");

        setenv("LTTNG_HOME", "/tmp/mk_lttng", 1);
        fprintf(stderr, "LTTNG_HOME is %s\n",getenv("LTTNG_HOME"));

        l_fd = open("/tmp/lttng_test.lck", O_CREAT | O_WRONLY | O_EXCL,
        err = errno;

        if(l_fd != -1) {
                fprintf(stderr, "Creating lock file l_fd = %d\n", l_fd);
                if(0 != system("lttng destroy -a")) {
                        return -1;

                if(0 != system("lttng create")) {
                        return -1;

                if(0 != system("lttng enable-event -u -a")) {
                        return -1;

                if(0 != system("lttng start")) {
                        return -1;

        else {
                fprintf(stderr, "Unable to get lock err = %d\n",err);
                // Someone has already created a session. We just dump into
their buffer

int main() {
        if( -1 == lttng_init())

When I compile and run the above code, I am getting these errors.

cycl01:~/hello-tp% ./hello
mkdir: cannot create directory `/tmp/mk_lttng': File exists
Directory exists
LTTNG_HOME is /tmp/mk_lttng
Creating lock file l_fd = 4
Spawning a session daemon
I/O warning : failed to load external entity
XML Error: Failed to locate the main schema resource at
Error: XSD parsing failed
Error: Session load failed: Invalid session configuration
No session found, nothing to do.
*PERROR - 09:20:36.889067 [7142/7150]: bind inet: Address already in use
(in lttcomm_bind_inet_sock() at inet.c:109)*
*Warning: Another session daemon is using this JUL port. JUL support will
be deactivated to prevent interfering with the tracing. *

*I am trying to run multiple of these programs in parallel*. So I am trying
to incorporate a locking mechanism so that only one instance succeeds and
creates the session, and other instances just dump into the existing

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