Dec 2, 2013

Linx 4: Writing large files

We recently had an issue reported that Linx 4 takes a long time to build strings. The problem showed up when trying to write a large file in Linx 4 took a lot longer than it used to in Linx 2. The process to prove it was

  1. Create a string variable.
  2. Read a database table with 1 million records.
  3. Loop through the records and add to the string variable i.e. for each record string = string + record data.
  4. Write the string to file.

The problem turned out to be the creation of a very large string by appending to the same string in a loop. We have improved the performance to Linx 2 levels by using a different string concatenation mechanism when we detect the process wants to append to a string. Even though this solves the speed problem it does not mean that building large strings in memory is a good idea.

To illustrate the problem I built a small application that writes 500 character long rows to build 3 different file sizes. One method uses the string concatenation method and the other writes directly to file. There was not much difference in speed but memory usage was drastically different:

So be careful when building very large strings in memory, especially if they can happen simultaneously. At least now you won't have to wait very long for the crash...


  1. Thanks for this update guys. We've recently discovered the same issue on of our solutions and are glad it has been addressed.

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