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Bug #13276
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Dir.glob returns empty array when OS has no more file handles (expected exception)
Description
The following terminal session demonstrates how Dir.glob returns an empty array when the OS has run out of file handles; whereas File.new raises a Errno::EMFILE exception.
I would expect Dir.glob to fail fast in a similar way to File.new.
$ mkdir /tmp/ruby-dir-glob-returns-empty-array-when-too-many-open-files
$ cd /tmp/ruby-dir-glob-returns-empty-array-when-too-many-open-files
$ touch foo
$ ulimit -n 16
$ ruby -e "1.upto(16).map { |i| p [i, Dir.glob('*')]; File.new('foo') }"
[1, ["foo"]]
[2, ["foo"]]
[3, ["foo"]]
[4, ["foo"]]
[5, ["foo"]]
[6, ["foo"]]
[7, ["foo"]]
[8, ["foo"]]
[9, ["foo"]]
[10, []] # Dir.glob returns empty array and does not raise exception
-e:1:in `initialize': Too many open files @ rb_sysopen - foo (Errno::EMFILE)
from -e:1:in `new'
from -e:1:in `block in <main>'
from -e:1:in `upto'
from -e:1:in `each'
from -e:1:in `map'
from -e:1:in `<main>'
The following is a counter example which shows how Dir.new raises an exception under the same conditions.
$ mkdir /tmp/ruby-dir-new-raises-exception-when-too-many-files-open
$ cd /tmp/ruby-dir-new-raises-exception-when-too-many-files-open
$ touch foo
$ mkdir bar
$ ulimit -n 16
$ ruby -e "1.upto(16).map { |i| p [i, Dir.new('bar')]; File.new('foo') }"
[1, #<Dir:bar>]
[2, #<Dir:bar>]
[3, #<Dir:bar>]
[4, #<Dir:bar>]
[5, #<Dir:bar>]
[6, #<Dir:bar>]
[7, #<Dir:bar>]
[8, #<Dir:bar>]
[9, #<Dir:bar>]
-e:1:in `initialize': Too many open files @ dir_initialize - bar (Errno::EMFILE)
from -e:1:in `new'
from -e:1:in `block in <main>'
from -e:1:in `upto'
from -e:1:in `each'
from -e:1:in `map'
from -e:1:in `<main>'
This is what I would expect for Dir.glob, i.e. I would expect an exception like this: Too many open files @ dir_s_glob (Errno::EMFILE) in the first example.
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