Bug #4040: SystemStackError with Hash[*a] for Large _a_

• Status: Assigned
• Priority: Normal
• Assignee: ko1 (Koichi Sasada)
• Target version: -
• ruby -v: ruby 1.9.3dev (2010-11-09 trunk 29737) [x86_64-linux]
• Backport: 2.2: UNKNOWN, 2.3: UNKNOWN, 2.4: UNKNOWN
• Tags: core

[runpaint (Run Paint Run Run)]

=begin
I've been hesitating over whether to file a ticket about this, so please feel free to close if I've made the wrong choice.

I often use Hash[*array.flatten] in IRB to convert arrays of arrays into hashes. Today I noticed that if the array is big enough, this would raise a SystemStackError. Puzzled, I looked deeper. I assumed I was hitting the maximum number of arguments a method's argc can hold, but realised that the minimum size of the array needed to trigger this exception differed depending on whether I used IRB or not. So, presumably this is indeed exhausting the stack...

In IRB, the following is the minimal reproduction of this problem:

Hash[*130648.times.map{ 1 }]; true

I haven't looked for the minimum value needed with ruby -e, but the following reproduces:

ruby -e 'Hash[*1380888.times.map{ 1 }]'

I suppose this isn't technically a bug, but maybe it offers another argument for either #666 or an extension of #3131.
=end

[duerst (Martin Dürst)]

=begin
This bug may be related to bug #982.
=end

[naruse (Yui NARUSE)]

• Status changed from Open to Assigned
• Assignee set to ko1 (Koichi Sasada)

[nahi (Hiroshi Nakamura)]

• Target version set to 1.9.3

[ko1 (Koichi Sasada)]

• Target version changed from 1.9.3 to 2.0.0

Let us pending it to next version....

[ko1 (Koichi Sasada)]

• Target version changed from 2.0.0 to 2.6

We need re-consideration about method invocation to support such cases.
I want to challenge at next version.

[ko1 (Koichi Sasada)]

Current implementation: now splatting huge parameters (and receive rest arguments) for Ruby methods are fine. However, C methods doesn't support this pattern. It should be fixed.

[ko1 (Koichi Sasada)]

• Related to Bug #5719: Hash::[] can't handle 100000+ args added

[naruse (Yui NARUSE)]

• Target version deleted (2.6)

[jeremyevans0 (Jeremy Evans)]

I submitted a pull request to fix this: https://github.com/ruby/ruby/pull/6816