CFFILE creating a file with APPEND or WRITE - coldfusion

Question

I'm having an issue with a coldfusion11 website, under certain conditions my attempt to create and send a report file is failing, apparently due to permission issues. I can't recreate the issue on in my test/dev environment so I need to understand what is happening for a live fix, I can't just start arbitrarily changing code on production. The current code creates the file using an APPEND action like this:
<cfset f_dir = EXCEL_PATH >
<cfset f_name = CreateUUID() & ".csv">
<cffile action="APPEND" file="#f_dir##f_name#" output="My Report "
addnewline="Yes">
<cffile action="APPEND" file="#f_dir##f_name#"
output="Title,#attributes.title#" addnewline="Yes">
Elsewhere in the code are similar functions that use WRITE as the first cffile action, like this:
<cfset f_dir = EXCEL_PATH >
<cfset f_name = CreateUUID() & ".csv">
<cffile action="WRITE" file="#f_dir##f_name#" output="My Report "
addnewline="Yes">
<cffile action="APPEND" file="#f_dir##f_name#"
output="Title,#attributes.title#" addnewline="Yes">
The code that uses WRITE first is not failing, this leads to my question:
Is there a difference between creating a file with action="APPEND" and action="WRITE" in coldfusion 11?

Answer 1

Ron - Write is "create" - it makes a new file. Append is used to add data to an existing file on the disk. They are different actions.
Try modifying your code as follows:
<cflock name="#f_name#">
<cfif NOT fileexists(f_dir & f_name)>
... do your WRITE action>
</cfif>
</cflock>
<cflock name="#f_name#">
.... do your APPEND action - you can be sure your file exists at this point.
</cflock>
Note, I usually use a named lock to serialize these two actions. Sometimes your code trips over file handles not quite released. Not typical but if your disk is ever thrashing it can happen.