Thanks for digging into this!
I’m seeing the same thing you are - in Swift 3, we’ve solved the problem for
array literals, but dictionary literals are still susceptible. I’ll take a look
to see why the current round of optimizations aren’t being applied to them.
- Joe
> On Mar 23, 2016, at 11:56 AM, Rafkind, Jon via swift-dev
> <swift-dev@swift.org> wrote:
>
> 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
> <swift-dev@swift.org <mailto:swift-dev@swift.org>><mailto:swift-dev@swift.org
> <mailto:swift-dev@swift.org>><mailto:swift-dev@swift.org
> <mailto:swift-dev@swift.org>><mailto:swift-dev@swift.org
> <mailto:swift-dev@swift.org>>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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>
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