Bug #3290: File descriptors not closed when all IO objects are collected

• Status: Rejected
• Assignee: -
• Target version: -
• ruby -v: ruby 1.9.1p129 (2009-05-12 revision 23412) [i386-mswin32]

[tmat (Tomas Matousek)]

=begin
The following script should raise an exception (invalid descriptor) on line [2] since the file object that allocated it should have been collected on line [1]. The script actually writes "hello" to the file so it seems that Ruby is leaking file descriptors.

def foo
f = File.open("a.txt", "w+")
fd = f.to_i
f = nil
fd
end

fd = foo
10.times { GC.start } # [1]

g = IO.new(fd, "w+") # [2]
g.write('hello')
g.close

---

The behavior is same in 1.8.6.
=end

[mame (Yusuke Endoh)]

• Status changed from Open to Rejected

=begin
Hi,

2010/5/14 Tomas Matousek [e-mail]:

def foo
f = File.open("a.txt", "w+")
fd = f.to_i
f = nil
fd
end

fd = foo
10.times { GC.start } ? ? ?# [1]

This is not a bug. The IO has been not collected yet.
MRI's GC is not exact. In other words, MRI does not guarantee
that an object is collected as soon as it becomes unreachable.

You can see the IO closed if you open many files:

def foo(f)
f = File.open("#{ f }.txt", "w+")
fd = f.to_i
f = nil
fd
end

fds = ("a".."z").map {|f| foo(f) }
GC.start

fds.each do |fd|
g = IO.new(fd, "w+") #=> Bad file descriptor (Errno::EBADF)
end

--
Yusuke Endoh [e-mail]
=end