Breakpoints

A breakpoint makes your program stop whenever a certain point in the program is reached.

You can set breakpoints with the break command to specify the place where your program should stop in the kernel. Define breakpoints by line numbers or function names.

You have several ways to set breakpoints:

  • break <function>

  • break <filename>:<linenumber>

  • break <filename>:<function>

  • break … if <condition>

See also:

Consider the following numba-dpex kernel code (refer numba_dpex/examples/debug/simple_sum.py for full example):

15
16
17global_size = 10
18N = global_size
19
20a = np.array(np.random.random(N), dtype=np.float32)
21b = np.array(np.random.random(N), dtype=np.float32)
22c = np.ones_like(a)
23
24data_parallel_sum[ndpx.Range(global_size)](a, b, c)
25
26print("Done...")

break function

The debugger output:

$ NUMBA_OPT=0 gdb-oneapi -q python
(gdb) set breakpoint pending on
(gdb) break data_parallel_sum
(gdb) run simple_sum.py
...
Thread 2.2 hit Breakpoint 1, with SIMD lanes [0-7], __main__::data_parallel_sum () at simple_sum.py:20
20          @dpex.kernel(debug=True)
(gdb) continue
Thread 2.3 hit Breakpoint 1, with SIMD lanes [0-1], __main__::data_parallel_sum () at simple_sum.py:20
20          @dpex.kernel(debug=True)
(gdb) continue
...
Done...

break filename:linenumber

The debugger output:

$ NUMBA_OPT=0 gdb-oneapi -q python
(gdb) set breakpoint pending on
(gdb) break simple_sum.py:20
(gdb) run simple_sum.py
...
Thread 2.2 hit Breakpoint 1, with SIMD lanes [0-7], __main__::data_parallel_sum () at simple_sum.py:20
20          @dpex.kernel(debug=True)
(gdb) continue
Thread 2.3 hit Breakpoint 1, with SIMD lanes [0-1], __main__::data_parallel_sum () at simple_sum.py:20
20          @dpex.kernel(debug=True)
(gdb) continue
...
Done...

break filename:function

The debugger output:

$ NUMBA_OPT=0 gdb-oneapi -q python
(gdb) set breakpoint pending on
(gdb) break simple_sum.py:data_parallel_sum
(gdb) run simple_sum.py
...
Thread 2.2 hit Breakpoint 1, with SIMD lanes [0-7], __main__::data_parallel_sum () at simple_sum.py:20
20          @dpex.kernel(debug=True)
(gdb) continue
Thread 2.3 hit Breakpoint 1, with SIMD lanes [0-1], __main__::data_parallel_sum () at simple_sum.py:20
20          @dpex.kernel(debug=True)
(gdb) continue
...
Done...

break … if cond

The debugger output:

$ NUMBA_OPT=0 gdb-oneapi -q python
(gdb) set breakpoint pending on
(gdb) break simple_sum.py:23 if i == 1
(gdb) run simple_sum.py
...
Thread 2.2 hit Breakpoint 1, with SIMD lane 1, __main__::data_parallel_sum () at simple_sum.py:23
23          c[i] = a[i] + b[i]
(gdb) print i
$1 = 1
(gdb) continue
...
Done...

Breakpoints with nested functions

Consider numba-dpex kernel code. See the source file numba_dpex/examples/debug/simple_dpex_func.py:

15
16@ndpx.kernel(debug=True)
17def kernel_sum(a_in_kernel, b_in_kernel, c_in_kernel):
18    i = ndpx.get_global_id(0)
19    c_in_kernel[i] = func_sum(a_in_kernel[i], b_in_kernel[i])
20
21
22global_size = 10
23a = np.arange(global_size, dtype=np.float32)
24b = np.arange(global_size, dtype=np.float32)
25c = np.empty_like(a)
26
27kernel_sum[ndpx.Range(global_size)](a, b, c)
28
29print("Done...")

The debugger output:

$ NUMBA_OPT=0 gdb-oneapi -q python
(gdb) set breakpoint pending on
(gdb) break simple_dpex_func.py:func_sum
(gdb) run simple_dpex_func.py
...
Thread 2.2 hit Breakpoint 1, with SIMD lanes [0-7], __main__::func_sum () at simple_dpex_func.py:22
22          result = a_in_func + b_in_func
(gdb) continue
Thread 2.3 hit Breakpoint 1, with SIMD lanes [0-1], __main__::func_sum () at simple_dpex_func.py:22
22          result = a_in_func + b_in_func
(gdb) continue
...
Done...