Problems with recursion

[Jason Durham]

We're in the process of tooling up to roll out Lucee 4.5.3 to production with code that is currently running on ACF8.  We have a couple of areas in our application where we use recursion and Lucee appears to be having a tough time with a method calling itself.  I created a test bit of code to demonstrate the issue.  You can run this on CFLive.net for both ACF and Lucee and you'll notice ACF doesn't hiccup while Lucee throws a stack overflow. Is there an issue in my code?  If not, is this a known bug?

<cfscript>

variables.times = 10;

function recurse( source, stop) {

out = [source];

if(variables.times > 0) {

variables.times--;

arrayAppend(out, recurse(out, true));

}

return out;

};

source = [1];

start = getTickCount();

result = recurse(source, false);

end = getTickCount();

</cfscript>

<cfdump var="#result#" />

<cfdump var="#end-start# ms" />

[Jason Durham]

I've attached a cleaner version of the code snippet.  This works on ACF8, ACF10, ACF11, ACF16 and times out on Railo 4.2, Lucee 4.5 or Lucee 5.

<cfscript>

times = 10;

function recurse( source ) {

        var out = source;

if(times > 0) {

times--;

arrayAppend(out, recurse(out));

}

return out;

};

source = [1];

start = getTickCount();

result = recurse(source);

end = getTickCount();

</cfscript>

<cfdump var="#result#" />

<cfdump var="#end-start# ms" />

Jason Durham

--
Get 10% off of the regular price for this years CFCamp in Munich, Germany (Oct. 20th & 21st) with the Lucee discount code Lucee@cfcamp. 189€ instead of 210€. Visit https://ti.to/cfcamp/cfcamp-2016/discount/Lucee@cfcamp
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[Jon Clausen]

Jason,

It’s probably an issue with concurrent modifications to the reference object. Lucee is strict about array references. If you use duplicate on the source argument the loop completes just fine in Lucee:

<cfscript>
times = 10;

function recurse( source ) {
    var out = duplicate(source);
    if(times > 0) {
        times--;
        arrayAppend(out, recurse(out));
    }
    return out;
};

source = [1];
start = getTickCount();
result = recurse(source);
end = getTickCount();

writeDump(var=result);
writeDump("#end-start# ms");
abort;

</cfscript>

[Jason Durham]

Thanks Jon.  Brad Wood told me that moments before you sent this and I was coming here to share it when my doorbell rang. 

Jason Durham

--

Get 10% off of the regular price for this years CFCamp in Munich, Germany (Oct. 20th & 21st) with the Lucee discount code Lucee@cfcamp. 189€ instead of 210€. Visit https://ti.to/cfcamp/cfcamp-2016/discount/Lucee@cfcamp
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Jason Durham