Groovy JsonOutput failing example

gistfile1.groovy

// Groovy's JsonOutput is using a static SimpleDateFormat. This is not threadsafe.

import java.text.SimpleDateFormat
import java.util.concurrent.LinkedBlockingQueue
import java.util.concurrent.ThreadPoolExecutor
import java.util.concurrent.TimeUnit

ThreadPoolExecutor executor = new ThreadPoolExecutor(4, 4, 500, TimeUnit.MILLISECONDS, new LinkedBlockingQueue<Runnable>(1000))
    1000.times {executor.execute(new KillJsonOutput())}
    while (true) {
        sleep(5000)
    }

class KillJsonOutput implements Runnable {
        private SimpleDateFormat formatterLocal = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssZ", Locale.US)

        @Override
        void run() {
            formatterLocal.timeZone = TimeZone.getTimeZone('GMT')
            def date = new Date()

            sleep(new Random().nextInt(1000))
            date.setHours(new Random().nextInt(24))
            assert "\"${formatterLocal.format(date)}\"" == groovy.json.JsonOutput.toJson(date)
        }
    }

Krufty example of the 'ol static SimpleDateFormat not being threadsafe problem. Would love to see Oracle actually make this threadsafe some time in the future.