为什么结果是这样的啊该如何解决

#include<pthread.h>
#include<stdlib.h>
#include<stdio.h>
#include<errno.h>

pthread_cond_t taxiCond=PTHREAD_COND_INITIALIZER;

pthread_mutex_t taxiMutex=PTHREAD_MUTEX_INITIALIZER;
void * traveler_arrive(void *name)
{
    int ret;
    printf("Traveler %s needs a taxi now1\n",name);
    ret=pthread_mutex_lock(&taxiMutex);
    if (ret==0) printf("cond is locked\n");
    pthread_cond_wait(&taxiCond,&taxiMutex);
    printf("test\n");
    pthread_mutex_unlock(&taxiMutex);
    printf("%s got a taxi\n",name);
    printf("traver thread sucess and exit\n");
    pthread_exit((void *)0);
}

void * taxi_arrive(void * name)
{
    int ret;
    printf("taxi %s arrive \n",name);

    pthread_mutex_unlock(&taxiMutex);
    ret=pthread_cond_signal(&taxiCond);
    if(ret==0) printf("cond is lived\n");
    
    pthread_mutex_unlock(&taxiMutex);
    printf("taxi thread sucess and exit\n");
    pthread_exit((void *)0);
}

void main()
{
    pthread_t thread;
    pthread_attr_t threadAttr;
    pthread_attr_init(&threadAttr);

    pthread_create(&thread,&threadAttr,taxi_arrive,(void *)("Jack"));
    sleep(10);

    pthread_create(&thread,&threadAttr,traveler_arrive,(void *)("Susan"));
    sleep(10);

    pthread_create(&thread,&threadAttr,taxi_arrive,(void *)("Mike"));
    sleep(10);

    return ;

}