donn wrote:
> On 28/08/2010 12:03, Peter Otten wrote:
>> But be warned that if you set the limit too high instead of giving you a
>> RuntimeError your program will segfault.
> Silly question: is there any way to tell the future in this case? I
> mean, ask for X recursion limit, and catch an error (or something) if
> that won't fly.
I don't think it's a silly question, and I don't think there is an exact
answer, even for a given platform. You'll want to stay well below the
number calculated by the following script:
import os
import subprocess
SCRIPT = "tmp_check.py"
def ok(n):
return subprocess.call(["python", SCRIPT, str(n)]) == 0
if __name__ == "__main__":
if not os.path.exists(SCRIPT):
with open(SCRIPT, "w") as out:
out.write("""\
import sys
def f():
return f()
if __name__ == "__main__":
n = int(sys.argv[1])
sys.setrecursionlimit(n)
try:
f()
except RuntimeError:
pass
""")
low = 1000
while True:
new_low = 2*low
if not ok(new_low):
high = new_low
break
low = new_low
while high - low > 1:
mid = (low + high) // 2
if ok(mid):
low = mid
else:
high = mid
print "max recursion limit", low, high
BTW, I didn't expect it but I get different results on different runs.
Peter
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