csvReader.close() potential memory leak

[tttzach]

Food for thought: if the code which processes the file throws an exception, then you will never call csvReader.close(). This can cause your code to leak file handles and other resources, which would be problematic in a real application with a high volume of requests.

Normally you would handle this by writing something like:

CSVReaderHeaderAware csvReader = null;
try {
  csvReader = ...
  // process the file
} catch (IOException ..) {
  // file doesn't exist (although it could be another error like access denied)
} catch (/* other errors thrown by CSV library */) {
} finally {
  if (csvReader != null) {
    csvReader.Close();
  }
}

Fortunately, modern Java has better syntax for it, but I don't know what version app engine uses. See this article: https://www.infoq.com/news/2010/08/arm-blocks/

try(CSVReaderHeaderAware csvReader = new CSVReaderHeaderAware(new FileReader(filePath))) {
  // process the file
  // no need to close it manually
} catch (IOException /* or whatever */) {
  // ...
}

Originally posted by @antmar in #48