create a thread from a returning function


 
Thread Tools Search this Thread
Top Forums Programming create a thread from a returning function
# 1  
Old 05-08-2008
create a thread from a returning function

hi all,
my requirement is to create a thread by calling another function.
i.e i dont call pthread_create directly from main, but by calling another function (createThd - below ), from main.
Example:
[CODE]

void *thread_function(void *arg) { /* thread function */
int i;
rc = pthread_detach(pthread_self());
for ( ; ; ) {
printf("Thread says hi!\n");
sleep(1);
}
pthread_exit(NULL);
}

int main(void) {

int i;
i = createThd(); /* call to thread creating function */

return (0);

}

int createThd()
{
int rc = 0;
pthread_t mythread;

if ( pthread_create( &mythread, NULL, thread_function, NULL) ) {
printf("error creating thread.");
return(-1);
}
return 0;
}
[\CODE]
this creates the thread but doesnt run it, thread terminates as soon as the function createThd() returns.
is there a way to overcome this problem.

any help is appreciated, thankx in advanced.
wolwy.
# 2  
Old 05-08-2008
The reason this is not working is that your main function doesn't have an event loop and/or doesn't block on the created thread.
An easy way out is to return the created thread tid, do not detach, and call pthread_join in main.

HTH.
# 3  
Old 05-08-2008
Quote:
Originally Posted by wolwy_pete
hi all,
my requirement is to create a thread by calling another function.
i.e i dont call pthread_create directly from main, but by calling another function (createThd - below ), from main.
Example:
Code:
void *thread_function(void *arg) {  /* thread function */
	int i;
	rc = pthread_detach(pthread_self());
	for ( ; ; )  {
		printf("Thread says hi!\n");
		sleep(1);
	}
	pthread_exit(NULL);
}

int main(void) {

	int i;
	i = createThd();  /* call to thread creating function */

	return (0);

}

int createThd()
{
	int rc = 0;
	pthread_t mythread;

	if ( pthread_create( &mythread, NULL, thread_function, NULL) ) {
		printf("error creating thread.");
		return(-1);
	}
	return 0;
}

this creates the thread but doesnt run it, thread terminates as soon as the function createThd() returns.
is there a way to overcome this problem.

any help is appreciated, thankx in advanced.
wolwy.
Hi,
You could wait on createThd() until thread_function() has done his job by means of pthread_cond_wait/pthread_cond_signal & mutexes, just like a parent process would wait (with wait/waitpid) for its child to terminate...
# 4  
Old 05-08-2008
thankx ramen_noodle & andryk Smilie
ramen_noodle was actually correct, sorry abt my lack of knowledge.
i put a loop in my main program and it was ok.
wolwy.
Login or Register to Ask a Question

Previous Thread | Next Thread

10 More Discussions You Might Find Interesting

1. Programming

Malloc function returning NULL

Hi All, I am using malloc function for allocating dynamic memory. When I am using below code on Linux server its working fine, but When I am trying the same code on HP UNIX server its returning NULL. below is a fragment of code in which it is giving problem. tmp = (format_tree... (4 Replies)
Discussion started by: Taher Saifuddin
4 Replies

2. Programming

Returning local string value from a function in C

Hi, If I have a code like this, what are the potential problems do you see? const char* const retString() { return "hello"; /* string literal */ } My questions are: a) Since the string literal which is already a constant read only data (cannot be... (4 Replies)
Discussion started by: royalibrahim
4 Replies

3. Programming

Function Returning Pointer

Hi guys. how a functions such fdopen, ... can return pointer? are these functions use static memory(variables)? (6 Replies)
Discussion started by: majid.merkava
6 Replies

4. Programming

segmentation fault while returning from function.

I am working on the application in which I have to fetch values from the database and paste in url and send it to portal. table=get_result("SELECT serialno,cas,Mode,FLC,TLC,location,CompName,CompCode,FG,FC,DispNo,TruckNo,LWbill,RRGPN,INVNO,DCN,RQTY,DQTY,SQTY,DDATE,RDATE,SDATE,TTIME FROM... (1 Reply)
Discussion started by: er.rohan88
1 Replies

5. Programming

Function Returning Value w/o return stmt

I am working on a C/Unix application from last 2 years which communicates with other systems using proprietary format of my client. We have a function written in C which returns integer, which is response from other system to the request message initiated by my system. This return value is then... (1 Reply)
Discussion started by: dpmore
1 Replies

6. Shell Programming and Scripting

Returning the name of function used

Hi All In my script, I can call on several functions. I have a logging function that is called by any of these functions. What I would like is some way of identifying which function I am using and pass this to the log function as some parameter. Is there some built in command or way of... (3 Replies)
Discussion started by: kingpin2502
3 Replies

7. Programming

returning multiple values from a function in C

hi how can I return multiple values from a C function. I tried the following: #include <stdio.h> void foo(int id, char *first_name, char *last_name) { /* this is just an example to illustrate my problem... real code makes use of the "id" parameter. */ first_name = (char... (8 Replies)
Discussion started by: Andrewkl
8 Replies

8. Shell Programming and Scripting

returning from a function

Hi all, I am very new to BASH shell programming. I need to return an integer from a function to the caller function. I did this: but it keeps giving me wrong return: Can someone help me out here, please? Thanks (2 Replies)
Discussion started by: alirezan
2 Replies

9. Programming

string returning function

I have two string returning function in ESQL/C char *segment_name(lbuffer) char *lbuffer; {..... and char *get_bpdvalue(f_name) char *f_name; {...... both declared above main() char *get_bpdvalue(); char *segment_name(); my problem is segment_name works on sprintf and strcpy... (5 Replies)
Discussion started by: jisc
5 Replies

10. HP-UX

create thread C with JNI function with JAVA

Hello, J create a thread C with a JNI function via JAVA. J have the following message (but not in each time): Someone has an idea ? Thank. Unexpected Signal : 4 occurred at PC=0x78C103E0 Function= Library=(N/A) NOTE: We are unable to locate the function name... (0 Replies)
Discussion started by: AUBERT
0 Replies
Login or Register to Ask a Question