#10295: Upgrading pexpect
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Reporter: SimonKing | Owner: was
Type: enhancement | Status: needs_work
Priority: major | Milestone: sage-6.10
Component: interfaces | Resolution:
Keywords: pexpect upgrade | Merged in:
Authors: François Bissey, | Reviewers: Jeroen Demeyer
Bill Page | Work issues:
Report Upstream: N/A | Commit:
Branch: | de71ef81f8acac4c3dd2219d87de897c965fc11a
u/jdemeyer/pexpect3.3 | Stopgaps:
Dependencies: |
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Comment (by fbissey):
I asked upstream for guidance, this is what they have to say so far:
When the `PtyProcess` instance (`self.ptyproc` on a `Pexpect` spawn
instance) is garbage collected, it will indeed close the file descriptor.
But I don't see how that could have happened when you're still calling
`E.sendline()` - clearly there is still a reference to the object, so it
shouldn't be garbage collected.
Could something else be closing an fd explicitly? I have run into odd
effects before because the numbers representing fds are readily reused. If
one fd gets closed while its corresponding 'handle' object (e.g. a
`PtyProcess` instance) still exists, when the handle object is garbage
collected, it may close an unrelated file which has been opened in the
meantime:
{{{
A = open('foo')
# handle A with fd=5
os.close(5)
B = open('bar')
# handle A with fd=5
# handle B with fd=5
del A
# handle A is garbage collected, closing fd 5
B.read()
# Bad fd!
}}}
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Ticket URL: <http://trac.sagemath.org/ticket/10295#comment:119>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
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