4 Replies Latest reply on Apr 10, 2013 12:40 PM by gkaiseril

    JavaScript Performance Slow – Not Utilizing Full CPU?


      Hello all. I have a script performance question I was hoping someone could help with.


      I’ve developed a folder level JavaScript for Acrobat that does a great detail of linking and annotation for a certain kind of PDF book that we produce where I work.   The script works, however the performance is quite slower than I would expect.  On some of the larger books I run the script on it takes hours to complete.    I did suspect my code for a while and optimized it as much as possible.  I noticed later though that while the script is running Acrobat only utilizes a maximum of about 12 percent of the CPU (12 percent of one core).   I would think this number would be much higher.  Has anyone else experienced this? Is there a way around it?  




        • 1. Re: JavaScript Performance Slow – Not Utilizing Full CPU?
          try67 MVP & Adobe Community Professional

          Acrobat does a very bad job in handling the CPU and memory of the computer

          when running complex scripts. It happened to me many times that it got

          stuck when processing large files or large number of files.

          My only advice is to try to optimize the code as much as possible, run it

          in batches (if possible), and try to avoid a lot of nested loops that do

          many things.

          For example, if you want to add an annotation to a piece of text, use one

          loop to look for the text you want to add the annotation to, save that

          information in a variable, and then use a separate loop to actually add the

          annotations themselves. That proves less likely to get stuck than doing

          everything in a single loop.

          1 person found this helpful
          • 2. Re: JavaScript Performance Slow – Not Utilizing Full CPU?
            Test Screen Name Most Valuable Participant

            Not a solution or even a suggestion... just observations. Where we can influence performance (and it isn't often), there is a way of looking at performance tuning. Essentially, a program will go as fast as it can until it reaches one of its limits. A limit might be

            * User. Waiting for you. Probably not the case here.

            * CPU. Once it's using all of your CPU (or all of one CPU) that's it.How to test? Performance monitors.

            * Disk. If a program needs to read or write disk, then it will usually stop what it is doing until that is finished. CPU drops. It isn't as simple as it seems, since disk cacheing means many things can be found back in memory if read or written recently. How to test? Performance monitors. A program which seems not to need disk can become mysteriously disk bound if, for example, it is writing a lot of logs.

            * Memory. If there isn't enough free RAM there will be paging. That is, disk reads/writes. Now you become disk bound. How to test? Performance monitors; close down other programs especially all browsers.

            * Other external resource (e.g. network).

            * Inter process or inter thread communication. Where a program wastes most of its time talking to another process or another part of itself. How to test: virtually impossible to monitor, but high SYSTEM CPU is a clue. Virtually impossible to improve.

            * Waiting for the system to do something. In this case the system is going to hit one of the things above.

            • 3. Re: JavaScript Performance Slow – Not Utilizing Full CPU?
              Craig8876 Level 1

              Thank you both for your replies.  I have many acrobat scripts and none of them can seem to break that 12 percent CPU mark when running.  I wonder if it's just a limitation that Adobe set so that a bad JavaScript in a document won't crash or slowdown a computer.  If someone gets a chance and could test to see if they get higher CPU usage by acrobat during a script run (acrobat 9 or higher), I'd appreciate it. 

              • 4. Re: JavaScript Performance Slow – Not Utilizing Full CPU?
                gkaiseril MVP & Adobe Community Professional

                JavaScript is an interpretive language or each line of  code is reprocessed each time it is asked to be rerun. When a PDF form is opened all of the JavaScript is processed from plain text through a syntax check, and common actions being converted into tokens for faster running. Also functions are converted into tokens for reuse.


                So gains in processing times are achieved by determining the best place to place code like using the on blur action for processing a field process that only has to occur when a field value changes  like testing a value and issuing a waring versus running a full calculation for that same action.


                When any field used within a calculation is modified, all calculations are reprocessed when ever one of those fields is changed. Another way to improve performance is to create a function  or a predefined process that may have some input values, performs a specific task. and may return a result. So if I have a calculation like computing elapsed time between 2 time values on a time sheet rather than coding the conversion of the time strings to a number, performing calculation and formatting the result for each day, I could define a function that uses the 2 time values, computes the difference and returns the formatted result. Since the function has been syntax checked and tokenized it will run faster on each call for each day.


                It is also possible to combine the calculation for many fields into one larger calculation in one form field and it is even possible to call a user defined function within another user defined function so one eliminates the repeated initialization for the code for each field.


                If one is adding fields with JavaScript and adding calculation actions, it is best to turn off the the doc's calculate property while adding the fields since each new added field will trigger a recalculation as each field is added. Just remember to turn it back on at the end. This should have no affect when adding annotations or searching for words.


                If you are having to search through the PDF for each word, then there is a lot of overhead. I have noticed with such scripts that the first use takes significantly longer than the next call as long as Acrobat is not closed. This maybe due to the use of virtual memory by the computer and the code I use is in the RAM from the first call and not the virtual swap file for the second call of the process.


                You might also get faster processing by using the Action/Batch processing of Acrobat Professional.