I ran a test to see the maximum number of elements swift could handle before
crashing and the numbers are
swift 2.2: 1213
swift 3-dev (mar 16 snapshot): 976
I don't know why swift 3 is lower than swift 2.2, but I'm guessing its due to
the same underlying cause, which is running out of stack space. If the swift 3
snapshot was compiled with different flags than 2.2 then swift 3 could have
different stack usage properties, and thus run out of stack space quicker.
Here is a python script that generates a dictionary literal with some number of
elements and runs swift on it, then does binary search to find the maximum
number of elements before swift crashes.
#!/usr/bin/env python
def make_swift(n):
def element(x):
return '"x%d": "0"' % x
data = "let n = [";
data += ',\n'.join([element(x) for x in xrange(0, n)])
data += "]"
path = 'test-%d.swift' % n
file = open(path, 'w')
file.write(data)
file.write('\n')
file.close()
return path
def translate(path):
print "Testing %s" % path
import subprocess
out = subprocess.call(['swift', path])
if out == 0:
print " ok"
else:
print " failed"
return out == 0
def test(n):
path = make_swift(n)
return translate(path)
def binary_search(low, high):
while low < high:
middle = (low + high) / 2
if middle == low:
low = high
middle = high
if test(middle):
low = middle
else:
high = middle
return middle
#test(5000)
low = 1
high = 10
while test(high):
low = high
high *= 2
last_failed = binary_search(low, high)
print "Failed at %d" % last_failed
On 03/22/2016 09:03 PM, Kyle Jessup via swift-dev wrote:
Ok I will test with swift 3, but just to avoid any confusion I am not a
developer on PerfectLib.
I am! Admittedly, that dictionary contains many obsolete mime type mappings
which could be pruned (anyone serving Lotus 1-2-3 files?). However, 816 items
is not an absurdly large number so it’s likely someone else would have run into
this in the near future.
The code does successfully compile for me using the release 2.2 version on my
VMWare based Ubuntu 15 system. It also compiles using 3.0.
-Kyle
I was just using that file as a test case for my application that is based on
the swiftc code base. My application is designed to consume arbitrary swift 2.2
code. If there is a problem with swift 3 then I suppose it can be fixed, but if
swift 3 has no issues then it looks like I have few options for remediation.
On 03/22/2016 12:56 PM, Dmitri Gribenko wrote:
On Tue, Mar 22, 2016 at 12:17 PM, Rafkind, Jon via swift-dev
<[email protected]><mailto:[email protected]><mailto:[email protected]><mailto:[email protected]>wrote:
I have to support swift 2.2 for the time being because I have to support the
current release of xcode. I will upgrade to swift 3 when it is released.
I understand your motivation, but I would still recommend trying to
update your code (on a branch) to Swift 3. This way you will get a
preview of the changes, would be able to provide feedback, and maybe
even find issues with the changes that we are making before Swift 3 is
finalized in a release. There is benefit for both your library and
the Swift community.
Dmitri
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