PH45868: REXX EDITOR - POOR PERFORMANCE WHEN PARSING LARGE OR COMPLEX FILES

APAR status

• Closed as program error.

Error description

• The following rexx exec illustrates the problem -
  
  /* REXX - nested IF statements - slow response from
  Content-Assist */
  IF x=1 THEN DO
     IF x=2 THEN DO
       select
         when x = 0 then do
           if 1=2 then do
             if 1=2 then do
               if 1=2 then do
                 if 1=2 then do
                   if 1=2 then do
                      if 1=2 then do
                      end
                   end
                 end
               end
             end
           end
         end
         otherwise do
         end
       end
     END
  END
  
  It doesn't do anything useful, but the syntax is perfectly
  valid, and it runs to completion with RC=0
  
  In the IDz client, open the above rexx using the rexx editor,
  then place the cursor anywhere and press CTRL-SPACEBAR to invoke
  content-assist.  With 7 or 8 levels of nested IF statements,
  response from content-assist takes about 20 to 30 seconds.
  Adding more levels of nesting degrades performance even more.
  Removing some levels of nesting improves performance which
  becomes acceptable at about 4 or 5 levels.
  
  The slow response happens the first time you press CTRL-SPACEBAR
  after opening the rexx.  It also happens if you type some
  characters into the rexx and press CTRL-SPACEBAR again.
  

Local fix

• keep nested IFs to no more than 4 or 5 levels
  

Problem summary

• See error description.
  

Problem conclusion

• Removed ambiguities from the REXX grammar, allowing the parser
  to efficiently parse files.
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

Fix information

• Fixed component name

  DEV FOR Z/OS

• Fixed component ID

  5724T0700

Applicable component levels