cfc with no var scoping

BadObject.cfc

component output="false"{

	function loop1(){
		x = 1;
		for( x = 1; x LTE 100; x++ ){
			writeLog("x is #x#");
			loop2();
		}
		return x;
	}
	function loop2 (){
		x = 1;
		for( x = 1; x LTE 5; x++ ){
		}
	}

}

runThisToKillYourServer.cfm

<cfset obj = new BadObject()>
<cfoutput>
#obj.loop1()#
</cfoutput>

Why does this kill your server even though it's run in a single thread, even when you do this in a non-shared (i.e. application/server) scope?

loop1 sets X = 1. Because it's not var scoped, this creates "x" in the variables scope.

It starts the loop, then runs the loop2() function.

Loop 2 sets X = 1... again, since it's not var scoped it overwrites X in the variables scope.

It then loops 5 times. When the method exits, variables.X will == 6 (5++).

After loop2() exits the first time, loop1() will finish its first loop, incrementing X at the end. Thus, variables.X will now be 7.

The second iteration of Loop1() will start, with variables.x == 7 because loop2() overwrote X.

This entire cycle will continue, with X never exceeding 7. Since it never exceeds 7, the loop1() loop's termination condition is never met.