cfthread in cfloop, all variables passed in on the thread, intermittent java.util.concurrentmodificationexception. cfloop is a query loop and each thread calls cfquery. How do I find the error?

Code

Below is the script, the queries in the thread only use the variables on the cfthread call. The process works about 80% of the time and then I receive Java.util.concurrentmodificationexception on one of the threads, occasionally more than one.  Using CF 9,0,0,251028, but have tested with 9,0,2,282541 with the same issue.

Any hekp is appreciated

<cfquery name = "variables.Dts" datasource="#mydsn#">

select 

to_char(next_day(to_date('#selDate#','mm/dd/yyyy')-56,'sat')+(level-1)*7-2,'mm/dd/yyyy') as thu,

to_char(next_day(to_date('#selDate#','mm/dd/yyyy')-56,'sat')+(level-1)*7-1,'mm/dd/yyyy') as fri,

to_char(next_day(to_date('#selDate#','mm/dd/yyyy')-56,'sat')+(level-1)*7,'mm/dd/yyyy') as sat

from dual

connect by  level <  9

</cfquery>

<!--- test --->

<cfset qtr = 0>

<cfset tname = ''>

<cfloop query="variables.dts" >

<cfset qtr += 1>

<cfthread name="t#qtr#" action="run" sat2='#variables.dts.sat#' thu2='#variables.dts.thu#' selarea2='#selArea#' selDistrict2='#seldistrict#' qtr2='#qtr#' dsn="#mydsn#" >

<cfquery name="variables.m#qtr2#" datasource="#dsn#" >

...

</cfquery>

</cfthread>

<cfset tname &= 't#qtr#' & ','>

</cfloop>

<cfloop query="variables.dts" >

<cfset qtr += 1>

<cfthread name="t#qtr#" action="run" sat1='#variables.dts.sat#' fri1='#variables.dts.fri#' selarea1='#selArea#' selDistrict1='#seldistrict#' qtr1='#qtr#' dsn="#mydsn#">

<cfquery name="variables.m#qtr1#" datasource="#dsn#" >

...

</cfquery>

</cfthread>

<cfset tname &= 't#qtr#' & ','>

</cfloop>

<cfset tname = left(tname,len(tname)-1)>

<cfthread action="join" name="#tname#" />