1 //------------------------------------------------------------------------------
2 // GraphBLAS/Demo/Program/openmp_demo: example of user multithreading
3 //------------------------------------------------------------------------------
4
5 // SuiteSparse:GraphBLAS, Timothy A. Davis, (c) 2017-2021, All Rights Reserved.
6 // SPDX-License-Identifier: Apache-2.0
7
8 //------------------------------------------------------------------------------
9
10 // This demo uses OpenMP, and illustrates how GraphBLAS can be called from
11 // a multi-threaded user program.
12
13 #include "GraphBLAS.h"
14
15 #ifdef _OPENMP
16 #include <omp.h>
17 #endif
18
19 #if defined __INTEL_COMPILER
20 #pragma warning (disable: 58 167 144 177 181 186 188 589 593 869 981 1418 1419 1572 1599 2259 2282 2557 2547 3280 )
21 #elif defined __GNUC__
22 #pragma GCC diagnostic ignored "-Wunknown-pragmas"
23 #pragma GCC diagnostic ignored "-Wunused-parameter"
24 #if !defined ( __cplusplus )
25 #pragma GCC diagnostic ignored "-Wincompatible-pointer-types"
26 #endif
27 #endif
28
29 #define NTHREADS 8
30 #define NTRIALS 10
31 #define N 6
32
33 #define OK(method) \
34 { \
35 GrB_Info info = method ; \
36 if (! (info == GrB_SUCCESS || info == GrB_NO_VALUE)) \
37 { \
38 printf ("Failure (id: %d, info: %d):\n", id, info) ; \
39 /* return to caller (do not use inside critical section) */ \
40 return (0) ; \
41 } \
42 }
43
44 //------------------------------------------------------------------------------
45 // worker
46 //------------------------------------------------------------------------------
47
worker(GrB_Matrix * Ahandle,int id)48 int worker (GrB_Matrix *Ahandle, int id)
49 {
50
51 printf ("\n================= worker %d starts:\n", id) ;
52 fprintf (stderr, "worker %d\n", id) ;
53
54 OK (GrB_Matrix_new (Ahandle, GrB_FP64, N, N)) ;
55 GrB_Matrix A = *Ahandle ;
56
57 // worker generates an intentional error message
58 GrB_Matrix_setElement_INT32 (A, 42, 1000+id, 1000+id) ;
59
60 // print the intentional error generated when the worker started
61 #pragma omp critical
62 {
63 // critical section
64 printf ("\n----------------- worker %d intentional error:\n", id) ;
65 const char *s ;
66 GrB_Matrix_error (&s, A) ;
67 printf ("%s\n", s) ;
68 }
69
70 for (int hammer_hard = 0 ; hammer_hard < NTRIALS ; hammer_hard++)
71 {
72 for (int i = 0 ; i < N ; i++)
73 {
74 for (int j = 0 ; j < N ; j++)
75 {
76 double x = (i+1)*100000 + (j+1)*1000 + id ;
77 OK (GrB_Matrix_setElement_FP64 (A, x, i, j)) ;
78 }
79 }
80
81 // force completion
82 OK (GrB_Matrix_wait (&A)) ;
83 }
84
85 // Printing is done in a critical section, just so it is not overly
86 // jumbled. Each matrix and error will print in a single body of text,
87 // but the order of the matrices and errors printed will be out of order
88 // because the critical section does not enforce the order that the
89 // threads enter.
90
91 GrB_Info info2 ;
92 #pragma omp critical
93 {
94 // critical section
95 printf ("\n----------------- worker %d is done:\n", id) ;
96 info2 = GxB_Matrix_fprint (A, "A", GxB_SHORT, stdout) ;
97 }
98 OK (info2) ;
99
100 // worker generates an intentional error message
101 GrB_Matrix_setElement_INT32 (A, 42, 1000+id, 1000+id) ;
102
103 // print the intentional error generated when the worker started
104 // It should be unchanged.
105 #pragma omp critical
106 {
107 // critical section
108 printf ("\n----------------- worker %d error should be same:\n", id) ;
109 const char *s ;
110 GrB_Matrix_error (&s, A) ;
111 printf ("%s\n", s) ;
112 }
113 return (0) ;
114 }
115
116 //------------------------------------------------------------------------------
117 // openmp_demo main program
118 //------------------------------------------------------------------------------
119
main(int argc,char ** argv)120 int main (int argc, char **argv)
121 {
122 fprintf (stderr, "Demo: %s:\n", argv [0]) ;
123 printf ("Demo: %s:\n", argv [0]) ;
124
125 // initialize the mutex
126 int id = -1 ;
127
128 // start GraphBLAS
129 OK (GrB_init (GrB_NONBLOCKING)) ;
130 int nthreads ;
131 OK (GxB_Global_Option_get (GxB_GLOBAL_NTHREADS, &nthreads)) ;
132 fprintf (stderr, "openmp demo, nthreads %d\n", nthreads) ;
133
134 // Determine which user-threading model is being used.
135 #ifdef _OPENMP
136 printf ("User threads in this program are OpenMP threads.\n") ;
137 #else
138 printf ("This user program is single threaded.\n") ;
139 #endif
140
141 GrB_Matrix Aarray [NTHREADS] ;
142
143 // create the threads
144 #pragma omp parallel for num_threads(NTHREADS)
145 for (id = 0 ; id < NTHREADS ; id++)
146 {
147 worker (&Aarray [id], id) ;
148 }
149
150 // the leader thread prints them again, and frees them
151 for (int id = 0 ; id < NTHREADS ; id++)
152 {
153 GrB_Matrix A = Aarray [id] ;
154 printf ("\n---- Leader prints matrix %d\n", id) ;
155 OK (GxB_Matrix_fprint (A, "A", GxB_SHORT, stdout)) ;
156 GrB_Matrix_free (&A) ;
157 }
158
159 // finish GraphBLAS
160 GrB_finalize ( ) ;
161
162 // finish OpenMP
163 exit (0) ;
164 }
165
166