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# This script renders a graph of the MicroPython heap at the given point it was dumped.
# It takes three files, the binary dump of ram, the binary for CircuitPython and the linker map file.
# To dump ram do this in GDB: dump binary memory ram.bin &_srelocate &_estack
import binascii
import struct
import sys
import pygraphviz as pgv
import io
import html
import os.path
import string
import click
from analyze_mpy import Prelude
BITS_PER_BYTE = 8
BLOCKS_PER_ATB = 4
BLOCKS_PER_FTB = 8
BYTES_PER_BLOCK = 16
AT_FREE = 0
AT_HEAD = 1
AT_TAIL = 2
AT_MARK = 3
MICROPY_QSTR_BYTES_IN_HASH = 1
MICROPY_QSTR_BYTES_IN_LEN = 1
MP_OBJ_NULL = 0
MP_OBJ_SENTINEL = 4
READLINE_HIST_SIZE = 8
SKIP_SYMBOLS = [".debug_ranges", ".debug_frame", ".debug_loc", ".comment", ".debug_str", ".debug_line", ".debug_abbrev", ".debug_info", "COMMON"]
@click.command()
@click.argument("ram_filename")
@click.argument("bin_filename")
@click.argument("map_filename")
@click.option("--print_block_contents", default=False,
help="Prints the contents of each allocated block")
@click.option("--print_unknown_types", default=False,
help="Prints the micropython base type if we don't understand it.")
@click.option("--print_block_state", default=False,
help="Prints the heap block states (allocated or free)")
@click.option("--print_conflicting_symbols", default=False,
help="Prints conflicting symbols from the map")
@click.option("--print-heap-structure/--no-print-heap-structure", default=False,
help="Print heap structure")
@click.option("--output_directory", default="heapvis",
help="Destination for rendered output")
@click.option("--draw-heap-layout/--no-draw-heap-layout", default=True,
help="Draw the heap layout")
@click.option("--draw-heap-ownership/--no-draw-heap-ownership", default=False,
help="Draw the ownership graph of blocks on the heap")
@click.option("--analyze-snapshots", default="last", type=click.Choice(['all', 'last']))
def do_all_the_things(ram_filename, bin_filename, map_filename, print_block_contents,
print_unknown_types, print_block_state, print_conflicting_symbols,
print_heap_structure, output_directory, draw_heap_layout,
draw_heap_ownership, analyze_snapshots):
with open(ram_filename, "rb") as f:
ram_dump = f.read()
with open(bin_filename, "rb") as f:
rom = f.read()
symbols = {} # name -> address, size
symbol_lookup = {} # address -> name
manual_symbol_map = {} # autoname -> name
def add_symbol(name, address=None, size=None):
if "lto_priv" in name:
name = name.split(".")[0]
if address:
address = int(address, 0)
if size:
size = int(size, 0)
if name in symbols:
if address and symbols[name][0] and symbols[name][0] != address:
if print_conflicting_symbols:
print("Conflicting symbol: {} at addresses 0x{:08x} and 0x{:08x}".format(name, address, symbols[name][0]))
return
if not address:
address = symbols[name][0]
if not size:
size = symbols[name][1]
symbols[name] = (address, size)
if address:
if not size:
size = 4
for offset in range(0, size, 4):
symbol_lookup[address + offset] = "{}+{}".format(name, offset)
with open(map_filename, "r") as f:
common_symbols = False
name = None
for line in f:
line = line.strip()
parts = line.split()
if line.startswith("Common symbol"):
common_symbols = True
if line == "Discarded input sections":
common_symbols = False
if common_symbols:
if len(parts) == 1:
name = parts[0]
elif len(parts) == 2 and name:
add_symbol(name, size=parts[0])
name = None
elif len(parts) == 3:
add_symbol(parts[0], size=parts[1])
name = None
else:
if len(parts) == 1 and parts[0].startswith((".text", ".rodata", ".bss")) and parts[0].count(".") > 1 and not parts[0].isnumeric() and ".str" not in parts[0]:
name = parts[0].split(".")[2]
if len(parts) == 3 and parts[0].startswith("0x") and parts[1].startswith("0x") and name:
add_symbol(name, parts[0], parts[1])
name = None
if len(parts) == 2 and parts[0].startswith("0x") and not parts[1].startswith("0x"):
add_symbol(parts[1], parts[0])
if len(parts) == 4 and parts[0] not in SKIP_SYMBOLS and parts[1].startswith("0x") and parts[2].startswith("0x"):
name, address, size, source = parts
if name.startswith((".text", ".rodata", ".bss")) and name.count(".") > 1:
name = name.split(".")[-1]
add_symbol(name, address, size)
name = None
# Linker symbols
if len(parts) >= 4 and parts[0].startswith("0x") and parts[2] == "=" and parts[1] != ".":
add_symbol(parts[1], parts[0])
rom_start = symbols["_sfixed"][0]
ram_start = symbols["_srelocate"][0]
ram_end = symbols["_estack"][0]
ram_length = ram_end - ram_start
# print(ram_length, "ram length")
# print(len(ram_dump) // ram_length, "snapshots")
if analyze_snapshots == "all":
snapshots = range(len(ram_dump) // ram_length - 1, -1, -1)
#snapshots = range(4576, -1, -1)
elif analyze_snapshots == "last":
snapshots = range(len(ram_dump) // ram_length - 1, len(ram_dump) // ram_length - 2, -1)
for snapshot_num in snapshots:
ram = ram_dump[ram_length*snapshot_num:ram_length*(snapshot_num + 1)]
ownership_graph = pgv.AGraph(directed=True)
def load(address, size=4):
if size is None:
raise ValueError("You must provide a size")
if address > ram_start:
ram_address = address - ram_start
if (ram_address + size) > len(ram):
raise ValueError("Unable to read 0x{:08x} from ram.".format(address))
return ram[ram_address:ram_address+size]
elif address < len(rom):
if (address + size) > len(rom):
raise ValueError("Unable to read 0x{:08x} from rom.".format(address))
return rom[address:address+size]
def load_pointer(address):
return struct.unpack("<I", load(address))[0]
if "heap" in symbols:
heap_start, heap_size = symbols["heap"]
else:
print("no static heap")
allocations_start, allocations_size = symbols["allocations"]
allocations = load(allocations_start, allocations_size)
first_zero = True
potential_heap = None
# The heap is the last left hand allocated section that should span all the way to the
# right side list.
for address, size in struct.iter_unpack("<II", allocations):
print(address, size)
if address == 0 and first_zero:
first_zero = False
if first_zero:
potential_heap = (address, size)
if not first_zero and address != 0:
if address != potential_heap[0] + potential_heap[1]:
print("no active heap")
return
else:
heap_start, heap_size = potential_heap
break
print("found heap", heap_start, heap_size)
heap = load(heap_start, heap_size)
total_byte_len = len(heap)
# These change every run so we load them from the symbol table
mp_state_ctx = symbols["mp_state_ctx"][0]
manual_symbol_map["mp_state_ctx+20"] = "mp_state_ctx.vm.last_pool"
last_pool = load_pointer(mp_state_ctx + 20) # (gdb) p &mp_state_ctx.vm.last_pool
manual_symbol_map["mp_state_ctx+108"] = "mp_state_ctx.vm.dict_main.map.table"
dict_main_table = load_pointer(mp_state_ctx + 108) # (gdb) p &mp_state_ctx.vm.dict_main.map.table
manual_symbol_map["mp_state_ctx+84"] = "mp_state_ctx.vm.mp_loaded_modules_dict.map.table"
imports_table = load_pointer(mp_state_ctx + 84) # (gdb) p &mp_state_ctx.vm.mp_loaded_modules_dict.map.table
manual_symbol_map["mp_state_ctx+124"] = "mp_state_ctx.vm.mp_sys_path_obj.items"
manual_symbol_map["mp_state_ctx+140"] = "mp_state_ctx.vm.mp_sys_argv_obj.items"
manual_symbol_map["mp_state_ctx+96"] = "mp_state_ctx.vm.dict_main"
manual_symbol_map["0x200015e0"] = "mp_state_ctx.vm.dict_main"
for i in range(READLINE_HIST_SIZE):
manual_symbol_map["mp_state_ctx+{}".format(148 + i * 4)] = "mp_state_ctx.vm.readline_hist[{}]".format(i)
tuple_type = symbols["mp_type_tuple"][0]
type_type = symbols["mp_type_type"][0]
map_type = symbols["mp_type_map"][0]
dict_type = symbols["mp_type_dict"][0]
property_type = symbols["mp_type_property"][0]
str_type = symbols["mp_type_str"][0]
function_types = [symbols["mp_type_fun_" + x][0] for x in ["bc", "builtin_0", "builtin_1", "builtin_2", "builtin_3", "builtin_var"]]
bytearray_type = symbols["mp_type_bytearray"][0]
dynamic_type = 0x40000000 # placeholder, doesn't match any memory
long_lived_start = load_pointer(mp_state_ctx + 272) # (gdb) p &mp_state_ctx.mem.gc_lowest_long_lived_ptr
type_colors = {
dict_type: "red",
property_type: "yellow",
map_type: "blue",
type_type: "orange",
tuple_type: "skyblue",
str_type: "pink",
bytearray_type: "purple"
}
pool_shift = heap_start % BYTES_PER_BLOCK
atb_length = total_byte_len * BITS_PER_BYTE // (BITS_PER_BYTE + BITS_PER_BYTE * BLOCKS_PER_ATB // BLOCKS_PER_FTB + BITS_PER_BYTE * BLOCKS_PER_ATB * BYTES_PER_BLOCK)
pool_length = atb_length * BLOCKS_PER_ATB * BYTES_PER_BLOCK
gc_finaliser_table_byte_len = (atb_length * BLOCKS_PER_ATB + BLOCKS_PER_FTB - 1) // BLOCKS_PER_FTB
if print_heap_structure:
print("mp_state_ctx at 0x{:08x} and length {}".format(*symbols["mp_state_ctx"]))
print("Total heap length:", total_byte_len)
print("ATB length:", atb_length)
print("Total allocatable:", pool_length)
print("FTB length:", gc_finaliser_table_byte_len)
pool_start = heap_start + total_byte_len - pool_length - pool_shift
pool = heap[-pool_length-pool_shift:]
total_height = 128 * 18
total_width = (pool_length // (128 * 16)) * 85
map_element_blocks = [dict_main_table, imports_table]
string_blocks = []
bytecode_blocks = []
qstr_pools = []
qstr_chunks = []
block_data = {}
# Find all the qtr pool addresses.
prev_pool = last_pool
while prev_pool > ram_start:
qstr_pools.append(prev_pool)
prev_pool = load_pointer(prev_pool)
def save_allocated_block(end, current_allocation):
allocation_length = current_allocation * BYTES_PER_BLOCK
start = end - allocation_length
address = pool_start + start
data = pool[start:end]
if print_block_state:
print("0x{:x} {} bytes allocated".format(address, allocation_length))
if print_block_contents:
print(data)
rows = ""
for k in range(current_allocation - 1):
rows += "<tr>"
for l in range(4):
rows += "<td port=\"{}\" height=\"18\" width=\"20\"></td>".format(4 * (k + 1) + l)
rows += "</tr>"
table = "<<table bgcolor=\"gray\" border=\"1\" cellpadding=\"0\" cellspacing=\"0\"><tr><td colspan=\"4\" port=\"0\" height=\"18\" width=\"80\">0x{:08x}</td></tr>{}</table>>".format(address, rows)
ownership_graph.add_node(address, label=table, style="invisible", shape="plaintext")
print("add 0x{:08x}".format(address))
potential_type = None
node = ownership_graph.get_node(address)
node.attr["height"] = 0.25 * current_allocation
if address >= long_lived_start:
node.attr["fontcolor"] = "hotpink"
else:
node.attr["fontcolor"] = "black"
block_data[address] = data
for k in range(len(data) // 4):
word = struct.unpack_from("<I", data, offset=(k * 4))[0]
if word < len(rom) and k == 0 or address in qstr_pools:
potential_type = word
bgcolor = "gray"
if address in qstr_pools:
#print(address, len(data))
bgcolor = "tomato"
elif potential_type in function_types:
bgcolor = "green"
elif potential_type in type_colors:
bgcolor = type_colors[potential_type]
elif print_unknown_types:
print("unknown type", hex(potential_type))
node.attr["label"] = "<" + node.attr["label"].replace("\"gray\"", "\"" + bgcolor + "\"") + ">"
if potential_type == str_type and k == 3:
string_blocks.append(word)
if potential_type == dict_type:
if k == 3:
map_element_blocks.append(word)
if ram_start < word < (ram_start + len(ram)) and word % 16 == 0:
port = k
if k < 4:
port = 0
ownership_graph.add_edge(address, word, tailport=str(port)+":_")
print(" 0x{:08x}".format(word))
if address in qstr_pools:
if k > 0:
qstr_chunks.append(word)
if k == 0:
potential_type = dynamic_type
if potential_type == dynamic_type:
if k == 0:
node.attr["fillcolor"] = "plum"
if k == 3 and ram_start < word < ram_end:
map_element_blocks.append(word)
if potential_type in function_types:
if k == 2 and ram_start < word < ram_end:
bytecode_blocks.append(word)
longest_free = 0
current_free = 0
current_allocation = 0
total_free = 0
for i in range(atb_length):
# Each atb byte is four blocks worth of info
atb = heap[i]
for j in range(4):
block_state = (atb >> (j * 2)) & 0x3
if block_state != AT_FREE and current_free > 0:
if print_block_state:
print("{} bytes free".format(current_free * BYTES_PER_BLOCK))
current_free = 0
if block_state != AT_TAIL and current_allocation > 0:
save_allocated_block((i * BLOCKS_PER_ATB + j) * BYTES_PER_BLOCK, current_allocation)
current_allocation = 0
if block_state == AT_FREE:
current_free += 1
total_free += 1
elif block_state == AT_HEAD or block_state == AT_MARK:
current_allocation = 1
elif block_state == AT_TAIL and current_allocation > 0:
# In gc_free the logging happens before the tail is freed. So checking
# current_allocation > 0 ensures we only extend an allocation thats started.
current_allocation += 1
longest_free = max(longest_free, current_free)
#if current_free > 0:
# print("{} bytes free".format(current_free * BYTES_PER_BLOCK))
if current_allocation > 0:
save_allocated_block(pool_length, current_allocation)
def is_qstr(obj):
return obj & 0xff800007 == 0x00000006
def find_qstr(qstr_index):
pool_ptr = last_pool
if not is_qstr(qstr_index):
return "object"
pool = block_data[pool_ptr]
prev, total_prev_len, alloc, length = struct.unpack_from("<IIII", pool)
qstr_index >>= 3
if qstr_index > total_prev_len + alloc:
return "invalid"
while pool_ptr != 0:
if pool_ptr > ram_start:
if pool_ptr in block_data:
pool = block_data[pool_ptr]
prev, total_prev_len, alloc, length = struct.unpack_from("<IIII", pool)
else:
print("missing qstr pool: {:08x}".format(pool_ptr))
return "missing"
else:
rom_offset = pool_ptr - rom_start
prev, total_prev_len, alloc, length = struct.unpack_from("<IIII", rom[rom_offset:rom_offset+32])
pool = rom[rom_offset:rom_offset + 32 + length * 4]
if qstr_index >= total_prev_len:
offset = (qstr_index - total_prev_len) * 4 + 16
start = struct.unpack_from("<I", pool, offset=offset)[0]
if start < heap_start:
start -= rom_start
if start > len(rom):
return "more than rom: {:x}".format(start + rom_start)
qstr_hash, qstr_len = struct.unpack("<BB", rom[start:start+2])
return rom[start+2:start+2+qstr_len].decode("utf-8")
else:
if start > heap_start + len(heap):
return "out of range: {:x}".format(start)
local = start - heap_start
qstr_hash, qstr_len = struct.unpack("<BB", heap[local:local+2])
return heap[local+2:local+2+qstr_len].decode("utf-8")
pool_ptr = prev
return "unknown"
def format(obj):
if obj & 1 != 0:
return obj >> 1
if is_qstr(obj):
return find_qstr(obj)
else:
return "0x{:08x}".format(obj)
for block in sorted(map_element_blocks):
if block == 0:
continue
try:
node = ownership_graph.get_node(block)
except KeyError:
print("Unable to find memory block for 0x{:08x}. Is there something running?".format(block))
continue
if block not in block_data:
continue
data = block_data[block]
cells = []
for i in range(len(data) // 8):
key, value = struct.unpack_from("<II", data, offset=(i * 8))
if key == MP_OBJ_NULL or key == MP_OBJ_SENTINEL:
cells.append(("", " "))
else:
cells.append((key, format(key)))
if value in block_data:
edge = ownership_graph.get_edge(block, value)
edge.attr["tailport"] = str(key)
rows = ""
for i in range(len(cells) // 2):
rows += "<tr><td port=\"{}\">{}</td><td port=\"{}\">{}</td></tr>".format(
cells[2*i][0],
cells[2*i][1],
cells[2*i+1][0],
cells[2*i+1][1])
node.attr["shape"] = "plaintext"
node.attr["style"] = "invisible"
node.attr["label"] = "<<table bgcolor=\"gold\" border=\"1\" cellpadding=\"0\" cellspacing=\"0\"><tr><td colspan=\"2\">0x{:08x}</td></tr>{}</table>>".format(block, rows)
for node, degree in ownership_graph.in_degree_iter():
print(node, degree)
if degree == 0:
address_bytes = struct.pack("<I", int(node))
location = -1
for _ in range(ram.count(address_bytes)):
location = ram.find(address_bytes, location + 1)
pointer_location = ram_start + location
source = "0x{:08x}".format(pointer_location)
if pointer_location in symbol_lookup:
source = symbol_lookup[pointer_location]
if source in manual_symbol_map:
source = manual_symbol_map[source]
if "readline_hist" in source:
string_blocks.append(int(node))
if pointer_location > heap_start + heap_size:
source = "stack " + source
ownership_graph.add_edge(source, node)
for block in string_blocks:
if block == 0:
continue
node = ownership_graph.get_node(block)
node.attr["fillcolor"] = "hotpink"
if block in block_data:
raw_string = block_data[block]
else:
print("Unable to find memory block for string at 0x{:08x}.".format(block))
continue
try:
raw_string = block_data[block].decode('utf-8')
except:
raw_string = str(block_data[block])
wrapped = []
for i in range(0, len(raw_string), 16):
wrapped.append(raw_string[i:i+16])
node.attr["label"] = "\n".join(wrapped)
node.attr["style"] = "filled"
node.attr["fontname"] = "FiraCode-Medium"
node.attr["fontpath"] = "/Users/tannewt/Library/Fonts/"
node.attr["fontsize"] = 8
node.attr["height"] = len(wrapped) * 0.25
for block in bytecode_blocks:
node = ownership_graph.get_node(block)
node.attr["fillcolor"] = "lightseagreen"
if block in block_data:
data = block_data[block]
else:
print("Unable to find memory block for bytecode at 0x{:08x}.".format(block))
continue
prelude = Prelude(io.BufferedReader(io.BytesIO(data)))
node.attr["shape"] = "plaintext"
node.attr["style"] = "invisible"
code_info_size = prelude.code_info_size
rows = ""
remaining_bytecode = len(data) - 16
while code_info_size >= 16:
rows += "<tr><td colspan=\"16\" bgcolor=\"palegreen\" height=\"18\" width=\"80\"></td></tr>"
code_info_size -= 16
remaining_bytecode -= 16
if code_info_size > 0:
rows += ("<tr><td colspan=\"{}\" bgcolor=\"palegreen\" height=\"18\" width=\"{}\"></td>"
"<td colspan=\"{}\" bgcolor=\"seagreen\" height=\"18\" width=\"{}\"></td></tr>"
).format(code_info_size, code_info_size * (80 / 16), (16 - code_info_size), (80 / 16) * (16 - code_info_size))
remaining_bytecode -= 16
for i in range(remaining_bytecode // 16):
rows += "<tr><td colspan=\"16\" bgcolor=\"seagreen\" height=\"18\" width=\"80\"></td></tr>"
node.attr["label"] = "<<table border=\"1\" cellspacing=\"0\"><tr><td colspan=\"16\" bgcolor=\"lightseagreen\" height=\"18\" width=\"80\">0x{:08x}</td></tr>{}</table>>".format(block, rows)
for block in qstr_chunks:
if block not in block_data:
ownership_graph.delete_node(block)
continue
data = block_data[block]
qstrs_in_chunk = ""
offset = 0
while offset < len(data) - 1:
qstr_hash, qstr_len = struct.unpack_from("<BB", data, offset=offset)
if qstr_hash == 0:
qstrs_in_chunk += " " * (len(data) - offset)
offset = len(data)
continue
offset += 2 + qstr_len + 1
try:
qstrs_in_chunk += " " + data[offset - qstr_len - 1: offset - 1].decode("utf-8")
except UnicodeDecodeError:
qstrs_in_chunk += " " + ""*qstr_len
printable_qstrs = ""
for i in range(len(qstrs_in_chunk)):
c = qstrs_in_chunk[i]
if c not in string.printable or c in "\v\f":
printable_qstrs += ""
else:
printable_qstrs += qstrs_in_chunk[i]
wrapped = []
for i in range(0, len(printable_qstrs), 16):
wrapped.append(html.escape(printable_qstrs[i:i+16]))
node = ownership_graph.get_node(block)
node.attr["label"] = "<<table border=\"1\" cellspacing=\"0\" bgcolor=\"lightsalmon\" width=\"80\"><tr><td height=\"18\" >0x{:08x}</td></tr><tr><td height=\"{}\" >{}</td></tr></table>>".format(block, 18 * (len(wrapped) - 1), "<br/>".join(wrapped))
node.attr["fontname"] = "FiraCode-Bold"
if block >= long_lived_start:
node.attr["fontcolor"] = "hotpink"
else:
node.attr["fontcolor"] = "black"
node.attr["fontpath"] = "/Users/tannewt/Library/Fonts/"
node.attr["fontsize"] = 8
print("Total free space:", BYTES_PER_BLOCK * total_free)
print("Longest free space:", BYTES_PER_BLOCK * longest_free)
# First render the graph of objects on the heap.
if draw_heap_ownership:
ownership_graph.layout(prog="dot")
fn = os.path.join(output_directory, "heap_ownership{:04d}.svg".format(snapshot_num))
print(fn)
ownership_graph.draw(fn)
# Clear edge positioning from ownership graph layout.
if draw_heap_ownership:
for edge in ownership_graph.iteredges():
del edge.attr["pos"]
else:
for edge in ownership_graph.edges():
ownership_graph.delete_edge(edge)
# Second, render the heap layout in memory order.
for node in ownership_graph.nodes():
try:
address = int(node.name)
except ValueError:
ownership_graph.remove_node(node.name)
continue
block = (address - pool_start) // 16
x = block // 128
y = 128 - block % 128
try:
height = float(node.attr["height"])
except:
height = 0.25
#print(hex(address), "height", height, y)
#if address in block_data:
# print(hex(address), block, len(block_data[address]), x, y, height)
node.attr["pos"] = "{},{}".format(x * 80, (y - (height - 0.25) * 2) * 18) # in inches
# Reformat block nodes so they are the correct size and do not have keys in them.
for block in sorted(map_element_blocks):
try:
node = ownership_graph.get_node(block)
except KeyError:
if block != 0:
print("Unable to find memory block for 0x{:08x}. Is there something running?".format(block))
continue
#node.attr["fillcolor"] = "gold"
if block not in block_data:
continue
data = block_data[block]
#print("0x{:08x}".format(block))
cells = []
for i in range(len(data) // 8):
key, value = struct.unpack_from("<II", data, offset=(i * 8))
if key == MP_OBJ_NULL or key == MP_OBJ_SENTINEL:
#print(" <empty slot>")
cells.append(("", " "))
else:
#print(" {}, {}".format(format(key), format(value)))
cells.append((key, ""))
# if value in block_data:
# edge = ownership_graph.get_edge(block, value)
# edge.attr["tailport"] = str(key)
rows = ""
for i in range(len(cells) // 2):
rows += "<tr><td port=\"{}\" height=\"18\" width=\"40\">{}</td><td port=\"{}\" height=\"18\" width=\"40\">{}</td></tr>".format(
cells[2*i][0],
cells[2*i][1],
cells[2*i+1][0],
cells[2*i+1][1])
node.attr["label"] = "<<table bgcolor=\"gold\" border=\"1\" cellpadding=\"0\" cellspacing=\"0\">{}</table>>".format(rows)
ownership_graph.add_node("center", pos="{},{}".format(total_width // 2 - 40, total_height // 2), shape="plaintext", label=" ")
ownership_graph.graph_attr["viewport"] = "{},{},1,{}".format(total_width, total_height, "center")
ownership_graph.has_layout = True
if draw_heap_layout:
fn = os.path.join(output_directory, "heap_layout{:04d}.png".format(snapshot_num))
print(fn)
#ownership_graph.write(fn+".dot")
ownership_graph.draw(fn)
if __name__ == "__main__":
do_all_the_things()