Having seen the pattern, and the description you give of the problem, I suspect that when the program appears to hang, it's actually really really busy trying to match the pattern. It probably won't match, but if it does (after a long time), it's likely to not match what you intended.

You're match is sprinkled with .* and .+. That's usually fine if you know it's going to match. But if it doesn't (and the optimizer hasn't determined this already - but clearly in your case, it hasn't) perl will try every possible length. I count 11 uses of .* and .+, which means your match is running in O(n11) time, where n is the length of the HTML document.

That will take a while. You'd be much better off in making your .* and .+ much more restrictive. For instance, 

    id="market-watch-(.+?)"

[download]
can probably be written as 
    id="market-watch-([^"]++)"   # Lose one + if you don't use 5.10

[download]

In reply to Re^5: Regex infinite loop? by JavaFan
in thread Regex infinite loop? by Ninth Prince

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