Groovy I/O performance issue - performance

Question

I'm not a groovy expert, just use it from time to time. One of the latest goals was to generate a very simple file containing some random data. I created the following script:
out = new File('sampledata.txt')
Random random = new Random();
java.util.Date dt = new java.util.Date();
for (int i=0; i<100000; ++i) {
dt = new java.util.Date();
out << dt.format('yyyMMdd HH:mm:ss.SSS') + '|box|process|||java.lang.Long|' + random.nextInt(100) + '|name\n'
}
Now, I'm really puzzled with its performance. It takes around 1.5 minutes to complete whilst the same code written in Java or Ruby takes less than a second.
Similar code in Ruby (takes around 1 second to execute):
require "time"
File.open("output.txt", "w") do |file|
100000.times do
line = Time.now.strftime("%Y%m%d %H:%M:%S.%L") + '|box|process|||java.lang.Long|' + rand(100).to_s + '|name'
file.puts line
end
end
Any ideas how groovy's processing speed could be improved?

Answer 1

The left shift operator opens the file, jumps to the end, appends the text, and closes the file again...
Instead, try:
Random random = new Random();
// Open the file and append to it.
// If you want a new file each time, use withWriter instead of withWriterAppend
new File('sampledata.txt').withWriterAppend { w ->
100000.times {
w.writeLine "${new Date().format('yyyMMdd HH:mm:ss.SSS')}|box|process|||java.lang.Long|${random.nextInt(100)}|name"
}
}
(this is also much more like what the Ruby code is doing)