The hidden trap in this suggestion is 
    if(scalar keys %HASH <= $keep) {

[download]
The risk is that if %HASH really does hold 10 million entries, and you haven't yet blown memory and started thrashing badly, loading all of the keys into a new temporary array will push you over the edge. (Unless Perl is clever enough to optimize this case, which I don't believe it is. Does anyone know otherwise?) See update.

Virtual memory is a real nuisance. A lot of schemes that work fast on paper collapse entirely once you start having to start swapping memory to disk.

Update: BrowserUk has graciously pointed out that keys in scalar context returns the number of keys.

In reply to Re: Re: Re: *Fastest* way to print a hash sorted by value by dws
in thread *Fastest* way to print a hash sorted by value by smellysocks

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