> Does ctypes, when using restype, frees allocated memory?
>
> For example, will the memory allocated by "strdup" be freed after the "del"
> statement? If not, how can I free it?
I've tried the following program and I'm more confused now :) Can anyone
explain the output?
---
import ctypes
import gc
import resource
def mem_usage():
return resource.getrusage(resource.RUSAGE_SELF).ru_maxrss
libc = ctypes.cdll.LoadLibrary('libc.so.6')
strdup = libc.strdup
strdup.argtypes = [ctypes.c_char_p]
strdup.restype = ctypes.c_char_p
size = 1 << 20
print(f'size: {size:,}')
data = b'x' * size # 1MB
mb = mem_usage()
print(f'memory before: {mb:,}')
n = 1000
print(f'n: {n:,}')
for _ in range(n):
strdup(data)
gc.collect()
ma = mem_usage()
diff = ma - mb
print(f'memory after: {ma:,}')
print(f'diff: {diff:,}')
print(f'diff/size: {diff/size:.2f}')
---
Which prints
---
size: 1,048,576
memory before: 21,556
n: 1,000
memory after: 1,035,180
diff: 1,013,624
diff/size: 0.97
---
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