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Date: Thu, 26 Jun 2003 10:32:02 -0700
From: Alex Boisvert <boisvert@intalio.com>
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Subject: libkse / libthr bugs?
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Hi,

I written a small test case (see source below), which I've run against 
both libkse and libthr.  I'm using -CURRENT as of last Tuesday and 
running on a Dual Athlon MP 1.2 GHz (Tyan Thunder K7 motherboard).

With libkse, the program runs most of the time (say, about 9 times out 
of 10) but sometimes hang and, interestingly, prints an "F" character to 
the console -- but that "F" character is never printed by the 
application itself! (see source)

Here are two examples of when it hangs:

bipolar:boisvert:~/prog/pthread:48 gcc -g -lkse -o foo2 foo2.c
bipolar:boisvert:~/prog/pthread:49 ./foo2 1000
Using 1000 threads (parameter)
bar 0
bar 1
bar 2
Fbar 3
^C
bipolar:boisvert:~/prog/pthread:50

(Notice the "F" on  the last line, before I had to use CTRL-C to 
terminate the application).

Also, sometimes I get:

bipolar:boisvert:~/prog/pthread:65 ./foo2 1000
Using 1000 threads (parameter)
F
^C
bipolar:boisvert:~/prog/pthread:66


I also tried the same test case with libthr and got a different behavior:

bipolar:boisvert:~/prog/pthread:141 gcc -g -lthr -o foo2 foo2.c
bipolar:boisvert:~/prog/pthread:142 ./foo2 1000
Using 1000 threads (parameter)
bar 0
foo2: Unknown error: 0
bipolar:boisvert:~/prog/pthread:143

In this case, the behavior is more easily reproductible.

So, maybe you can help me figure out if my test case is somehow invalid 
or these are genuine problems within the threading libraries...

cheers,
alex

----------- foo2.c

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

void *foo(void *);

typedef struct
{
	int number;
} arg_t;


/**
  * Simple test case for the thread system.  Start "n" threads,
  * and join them afterwards.
  */
int
main( int argc, char** argv)
{
	pthread_t* threads;
	arg_t* args;
	void* ret;
	int n;
	int i;
	
	if ( argc > 1 ) {
		n = strtoimax( argv[1], NULL, 10 );
		printf( "Using %d threads (parameter)\n", n );
	} else {
		n = 5;
		printf( "Using %d threads (default)\n", n );
	}

	// initialize random number generator
	srandomdev();

	threads = (pthread_t*) malloc( sizeof(pthread_t) * n );
	args = (arg_t*) malloc( sizeof(arg_t) * n );
	
	// start n threads
	for ( i=0; i<n; i++ ) {
		args[i].number = i;
		if (pthread_create(&threads[i], NULL, foo, &args[i]) != 0) {
			err(1, NULL);
		}
	}

	// join threads
	for ( i=0; i<n; i++ ) {
		if (pthread_join(threads[i], &ret) != 0) {
			err(1, NULL);
		}
	}

	free( threads );

	return (0);
}

void *
foo(void *v)
{
	int i;
	arg_t arg;

	arg = *(arg_t*)v;

	// simulate some CPU-intensive calculations
         int loops = ( ( random() % 100 ) + 1 ) * 100;
	for (i=1;i<loops;i++) {
		int a = i * (random() % 11);
		int b = a * (random() % 13);
		int c = b * (random() % 17);
		int d = c * (random() % 23);
	}

	printf("bar %d\n", arg.number);

	return (NULL);

}