I have a parallel program that sometimes runs, and sometimes just gives a segmentation error. The executable when it starts with three threads works fine (basically it also starts with a single thread that is only sequential), but it gives a segmentation error when it is forced to work with any other thread value. Here is the scenario:
From main.cinside the main function:
cilk_for ( line_count = 0; line_count != no_of_lines ; ++line_count )
{
for ( j=line_count+1; j<no_of_lines; ++j )
{
final_result[line_count][j] = bf_dup_eleminate ( table_bloom[line_count], file_names[j], j );
}
}
bf_dup_eleminatefunction from file bloom-filter.c:
int bf_dup_eleminate ( const bloom_filter *bf, const char *file_name, int j )
{
int count=-1;
FILE *fp = fopen (file_name, "rb" );
if (fp)
{
count = bf_dup_eleminate_read ( bf, fp, j);
fclose ( fp );
}
else
{
printf ( "Could not open file\n" );
}
return count;
}
bf_dup_eleminate_readfrom bloom-filter.cfile:
int bf_dup_eleminate_read ( const bloom_filter *bf, FILE *fp, int j )
{
printf ( "before while loop. j is %d ** workder id: **********%d***********\n", j, __cilkrts_get_worker_number());
while ()
{}
}
I reported this error from intel inspector:
ID | Problem | Sources
P1 | Unhandled application exception | bloom-filter.c
and the call stack:
exec!bf_dup_eleminate_read - bloom-filter.c:550
exec!bf_dup_eleminate - bloom-filter.c:653
exec!__cilk_for_001.10209 - main.c:341
It is similarly gdbalso reporting an error in the same place, and this:
Now gdbtells me that you have the following error
0x0000000000406fc4 in bf_dup_eleminate_read (bf=<error reading variable: Cannot access memory at address 0x7ffff7edba58>,
fp=<error reading variable: Cannot access memory at address 0x7ffff7edba50>,
j=<error reading variable: Cannot access memory at address 0x7ffff7edba4c>) at bloom-filter.c:536
Line 536 is an int bf_dup_eleminate_read ( const bloom_filter *bf, FILE *fp, int j )
Additional Information:
bloomfilter ,
struct bloom_filter
{
int64_t m;
int32_t k;
uint8_t *array;
int64_t no_of_elements_added;
int64_t expected_no_of_elements;
};
:
bloom_filter *bf = (bloom_filter *)malloc( sizeof(bloom_filter));
if ( bf != NULL )
{
bf->m = filter_size*8;
bf->k = num_hashes;
bf->expected_no_of_elements = expected_no_of_elements;
bf->no_of_elements_added = (int64_t)0;
bf->array = (uint8_t *)malloc(filter_size);
if ( bf->array == NULL )
{
free(bf);
return NULL;
}
}
bloom_filter, ( ).
- , 4 , . , 3 !!!
: cilk_for - cilk.