The dbx and libumem utilities are pretty slow in finding leaks. in my experience I didnt get callstacks for memory leaks. so I used Dtrace tool which can print malloc/free callstacks and size to outputfile. From the output file we can extract malloc addresses which are not present in free ptr address. these addresses and callstacks will be memory leaked ones.
Step 1 ) use this dtrace script to print malloc/free statistics . usage is ./memleak.d pid > output.txt
#!/usr/sbin/dtrace -s
#echo " usage ./memleak.d pid "
pid$1:libc.so.1:malloc:entry
{
self->trace = 1;
self->size = arg0;
}
pid$1:libc.so.1:malloc:return
/self->trace == 1/
{
printf("Ptr=0x%p Size=%d", arg1, self->size);
ustack();
self->trace = 0;
self->size = 0;
}
pid$1:libc.so.1:free:entry
{
printf("Ptr=0x%p ", arg0);
}
for example if the process id is 1234 then
/memleak.d 1234 > output.txt
step 2 )
copy this python script to showleaks.py and run python ./showleaks.py output.txt 6 > leaks.txt
output.txt is the output file you got from dtrace
6 is the depth of callstack. make sure your output.txt has minimum of callstack depth 6.
#showleaks.py
import sys
import re
if (len(sys.argv) > 1 ):
allocsfile = open(sys.argv[1],'r')
allocs_lines=list(allocsfile.readlines())
linenums=len(allocs_lines)
i=0
poin_size=" "
''' str1='12 66201 malloc:return Ptr=0x10244cb30 Size=73' '''
allocs_map={}
stacks_map={}
final_map={}
depth=int(sys.argv[2])
malloc_set=set(" ")
free_set=set(" ")
while i < linenums:
malloc_match=re.search(r"malloc:return Ptr=\b0[xX][0-9a-fA-F]+\b Size=[0-9]*", allocs_lines[i])
free_match=re.search(r"free:entry Ptr=\b0[xX][0-9a-fA-F]+\b",allocs_lines[i])
if malloc_match:
malloc_line=str(malloc_match.group())
pos_ptr=malloc_line.find('=')
ptr_address=str(malloc_line[pos_ptr+1:pos_ptr+12])
malloc_set.add(ptr_address)
allocs_map[ptr_address]=i # store ptr addr and line number
elif free_match:
free_line=str(free_match.group())
pos_ptr=free_line.find('=')
freeptr_address=str(free_line[pos_ptr+1::])
free_set.add(freeptr_address)
i=i+1
else:
print("usage: ./showleaks.py ")
leak_set=malloc_set - free_set
for i in leak_set:
j=allocs_map[i]
formatstr="malloc:return Ptr=%s Size=[0-9]*" % i
malloc_match=re.search(formatstr,allocs_lines[j])
if malloc_match:
malloc_line=str(malloc_match.group())
pos_ptr=malloc_line.find('=')
rest_of_line=str(malloc_line[pos_ptr+1::])
pos_Size=rest_of_line.find('=')
Size = int(rest_of_line[pos_Size+1::])
callstack=str(allocs_lines[j+1:j+depth])
if callstack in stacks_map:
value=stacks_map[callstack]
stacks_map[callstack] = value + Size
else:
stacks_map[callstack] = Size
keys=stacks_map.keys()
for k in keys:
print("leaked bytes: %d" %stacks_map[k])
stacks=str(k)
stacks1=stacks.split(r'\n')
for sts in stacks1:
print(sts)
print("\n DONE ")
for any queries, pls do post here. I will respond to it .
