Append to a file in Groovy in Jmeter

Question

To log the total time of a test scenario I use Groovy scripts in JSR223 PostProcessors to capture the timestamp before and after the script.

Script to capture the scenario start timestamp:

def scenario_start = System.currentTimeMillis().toString();
vars.put("scenario_start", scenario_start);

When I want to append the results for one Customer I want to append the results to an output file using a second groovy script:

def scenario_end = System.currentTimeMillis().toString();
def scenario_start = vars.get("scenario_start");
def cm = vars.get("CUSTOMER_NUMBER");

log.debug("scenario_start = " + scenario_start);
log.debug("scenario_end = " + scenario_end);
log.debug("CUSTOMER_NUMBER = " + cm);

File file = new File("logs/output/scenario_times_idtv.txt").newOutputStream().withWriter { out ->
    out.append(cm + ";" + scenario_start + ";" + scenario_end);
}

The actual results is the first line in my log: scenario_times_idtv.txt is overwritten each time.

I've used out.append, out.println, new File("...").withWriter {...}, new File("...").newOutputStream().withWriter {...} but I get ONE line of data each time in my log.

I can't find how to properly APPEND new results to the log file.

Thanks for your experienced input!

Answer 1

I'm not very Groovy expert, but recall answering something similar at JMeter soap response - data analysis

using Beanshell.

I guess that if you change your code line

File file = new File("logs/output/scenario_times_idtv.txt").newOutputStream().withWriter { out ->
out.append(cm + ";" + scenario_start + ";" + scenario_end);

to something like:

FileOutputStream file = new FileOutputStream("logs/output/scenario_times_idtv.txt", true);
file.append((cm + ";" + scenario_start + ";" + scenario_end).getBytes());
file.flush();
file.close();

your script will behave as expected. Mind the true parameter of FileOutputStream. It tells the stream to append existing file. Perhaps there is a Groovy analogue, but this bit should work as well.

Answer 2

What worked best for me was to set up the output file in a setUp thread group as a property (so it will be global across all thread groups), then use it within my main thread group, and close it out in a tearDown thread group.

setUp:

def fileName = vars.get("CSVFileName");

def currDate = new Date().format("_yyy-MM-dd_HH.mm.ss")
fileName = fileName.replace(".csv",  currDate + ".csv");
FileOutputStream fileLOG = new FileOutputStream(fileName, true);
fileps = new PrintStream( fileLOG );
fileps.println("user,otherCSV headers...");

props.put("MYLOGPRINTSTREAM", fileps);  // Properties are global to JMeter, so can be used to communicate between threads and thread groups

then in the main thread group:

def fileps = props.get("MYLOGPRINTSTREAM");
fileps.println(vars.get("user") + "," + other CSV fields ...);

and in the tearDown:

def fileps = props.get("MYLOGPRINTSTREAM");
fileps.close();
log.info("***TEARDOWN DONE*** ");