FlightMemory

A java flight recording helper

Helper class for production profiling using java flight recorder (JFR)

FlightMemory.recordingAsZip(Duration.ofSeconds(10));

Returns a CompletableFuture<InputStream> to a zipfile which contains:

• profile-XXX.jfr
  • A java flight recorder file, open in jdk mission control (JMC)
• stacks-XXX.folded
  • A folded stacktrace file, can be visualized with Flame graph tools like Brendan Greggs flame graph tools
• _coroutinesDump.txt
  • A kotlin coroutines dump. Debug probes must be installed beforehand (at start), with DebugProbes.install() available in . If debug probes are not installed the file is empty.

Requires the app to run in a JVM with flight recorder classes available (jdk.jfr package), for example java8u262 or higher (jdk not jre) or java11

Depend on it in gradle or maven

repositories {
    ...
    maven { url 'https://jitpack.io' }
}

implementation 'com.github.rrva:flightmemory:0.1.0'

Example usage in a spring boot application:

Here we do a ten second profiling, so we record and return the recording synchronously. For long recordings you might get a HTTP timeout so it might be better to return immediately with a link where the finished recording can be fetched.

Java usage:

import org.springframework.core.io.InputStreamResource;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import io.github.rrva.flightmemory.FlightMemory;
import java.time.LocalDateTime;
import java.time.Duration;
import java.util.concurrent.ExecutionException;


@RestController
public class FlightRecordingController {

    @GetMapping("/profile.jfr.zip")
    public ResponseEntity<InputStreamResource> flightRecorder() throws ExecutionException, InterruptedException {
        LocalDateTime now = LocalDateTime.now();
        InputStreamResource inputStreamResource = 
                new InputStreamResource(FlightMemory.recordingAsZip(Duration.ofSeconds(10)).get());
        HttpHeaders httpHeaders = new HttpHeaders();
        httpHeaders.setContentType(MediaType.APPLICATION_OCTET_STREAM);

        httpHeaders.set("Content-Disposition", "attachment; filename=index-profile-"+now+".zip");

        return new ResponseEntity<InputStreamResource>(inputStreamResource, httpHeaders, HttpStatus.OK);
    }
}