Know if a pthread thread is Alive in a safe way
I made a multithread application that generates/destroy 100 threads continuously:
//Here is the thread class (one by every thread
struct s_control
{
data_in[D_BUFFER_SIZE];//data in to thread
data_out[D_BUFFER_SIZE];//data generated by the thread
//I use volatile in order to status data is avaiable in and out of the thread:
volatile __int16 status;//thread state 0=empty,1=full,2=filling (thread running)
}*control;
//Here is the thread main function
static void* F_pull(void* vv)//=pull_one_curl()
{
s_control* cc = (s_control* ) vv;
//use of cc->data_in and filling of cc->data out
cc->status=1; //Here advises that thread is finished and data out is filled
return NULL;
}
void main()
{
initialization();
control=new s_control[D_TAREAS];
pthread_t *tid=new pthread_t[D_TAREAS];
for (th=0;th<D_TAREAS;th++)
{ //Access to status of thread at the beginning
//(to avoid if it changes in the middle):
long status1=control[th].status
if (status1==0) //Thread finished and data_out of thread is empty
{ control[i2].status=2; //Filling in (thread initiated)status LLENANDO
error = pthread_create(&tid[th开发者_如何学Go],NULL,F_pull,(void *) &control[th]);
}
else if (status1==1) //Thread finished and data_out of thread is full
{
//do things with control[th].data_out;
//and fill in control[th].data_in with data to pass to next thread
control[th].status=0; //Thread is finished and now its data_out is empty
}
else
{
//printf("\nThread#%li:filling",i2);
}
}while(!_kbhit());
finish();
}
Then as you can see, at the end of the thread, I used the variable volatile to advise that thread is about to exit:
begin of thread{ ....
cc->status=1; //Here advises that thread is finished and data out is filled
return NULL;
}//END OF THREAD
But after cc->status is set to 1 thread is not finished yet (it exist one more line)
So I do not like set status inside the thread. I tried pthread_kill, but it didn´t work, because it does not work until thread is alive, as can be seen at: pthread_kill
I am not sure if this answers your question, but you can use pthread_join() to wait for a thread to terminate. In conjunction with some (properly synchronized) status variables, you should be able to achieve what you need.
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