pthread_mutex_trylock和pthread_mutex_lock问题（没有加锁？？？）

#include<iostream>
#include<pthread.h>
#include<string.h>
#include<stdio.h>

using namespace std;
pthread_mutex_t q_lock=PTHREAD_MUTEX_INITIALIZER;
void *read(void *arg)
{
  int err=0;
  while((err=pthread_mutex_trylock(&q_lock))!=0)
  {
  cout <<"read :"<< strerror(err) << endl;
  }

  /*err=pthread_mutex_lock(&q_lock);
  if(err!=0)
  {
  cout << "error " << endl;
  };
  */
  cout << "first " << endl;
  for(int i = 0;i<=5;i++)
  cout << " " << i << endl;
  err=pthread_mutex_unlock(&q_lock);
  if(err!=0)
  {
  cout << "wrong " <<endl;
  }
};
void *read1(void *arg)
{ int err=0;
  while((err=pthread_mutex_trylock(&q_lock))!=0)
  {
  cout <<"read1:"<< strerror(err) <<endl;
  }
  /* err = pthread_mutex_trylock(&q_lock);
  if(err == EBUSY)
  {
  cout << "busy " << endl;
  }
  */
  cout << "second " << endl;
  for(int i = 0;i<=5;i++)
  cout << " " << i << endl;
  err=pthread_mutex_unlock(&q_lock);
  if(err!=0)
  {
  cout << "wrong " <<endl;
  }
}
int main()
{
  pthread_t id1,id2;
  int ret;

  ret=pthread_create(&id1,NULL,read, NULL);
  if(ret!=0)perror("pthread cread1");


  ret=pthread_create(&id2,NULL,read1, NULL);
  if(ret!=0)perror("pthread cread2");

  pthread_join(id1,NULL);
  pthread_join(id2,NULL);


return 0;

}
输出结果为：
first read1:Device or resource busy

read1:Device or resource busy
read1:Device or resource busy
....
..
..
..

read1:Device or resource busy
read1:Device or resource busy
read1:Device or resource busy
read1:Device or resource busy
read1:Device or resource busy
read1:Device or resource busy
read1:Device or resource busy  
0
  1
  2
  3
  4
read1: 5
Device or resource busy
second 
  0
  1
  2
  3
  4
  5
输出的结果有点诡异，像是没有加锁，求解释。。。

改用write替代cout试一试把.

这个说明已经加锁了，

first输出这个的时候以前是第一线程在运行，这时候跳到第二个线程 read1:Device or resource busy

read1:Device or resource busy
read1:Device or resource busy
....
..
..
..

read1:Device or resource busy
read1:Device or resource busy
read1:Device or resource busy
read1:Device or resource busy
read1:Device or resource busy
read1:Device or resource busy
read1:Device or resource busy //这时候第二个线程运行结束，跳到第一个线程
0
  1
  2
  3
  4
read1: 5//第一个线程释放锁
Device or resource busy//第二个线程运行
//获得锁second  
  0
  1
  2
  3
  4
  5
运行结束。

结果看来是正常的啊，first先锁了，0-5输出完了以后释放锁，然后second才往下跑，很正常啊