my debug statements (removed for readability) showed the script going all the way back to the select statement and then never coming back,

It ought to be fairly easy to tell if the timeout is failing to trigger. Just bracket the select line with 

warn "before select: " . time;
select...
warn "after select: " . time;

[download]

And if it is, then that to me indicates that something is very broken. But I don;t know enough about it to say what.

I'd suggest that you confirm your suspicion, and then post a new SoPW with "select timeout failng on Ubunto vxxx & Perl vx.x.x". With as much logging from the period immediately preceding the failure--perhaps a tcp trace--as you can gather.

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.
"I'd rather go naked than blow up my ass"

In reply to Re^5: socket select hangs after client restarts by BrowserUk
in thread socket select hangs after client restarts by planetjeff

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