# Runtime.getRuntime().exec() not working in a module **URL:** \ **Category:** Wowza Developer Dojo\ **Tags:** wowza-streaming-server-java-api\ **Created:** [March 20, 2014, 5:18pm UTC](https://community.wowza.com/t/runtime-getruntime-exec-not-working-in-a-module/41423 "2014-03-20T17:18:15Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![krishna\_mohan](https://avatars.discourse-cdn.com/v4/letter/k/5f9b8f/32.png) [@krishna\_mohan](https://community.wowza.com/u/krishna_mohan)\ **Post date:** [March 20, 2014, 5:18pm UTC](https://community.wowza.com/t/runtime-getruntime-exec-not-working-in-a-module/41423/1 "2014-03-20T17:18:15Z")
Hi, I need to run a process using java’s Runtime.getRuntime().exec() when a stream gets unPublished. So I implemented IMediaStreamActionNotify3 on my Module and registered the notifier with the stream. In onUnPublish(), I tried to execute Runtime.getRuntime().exec(). As i can see, it starts the process, but execution of the created process just **hangs** (i can see process name in my taskmanager with 0% cpu and no change in memory). If I close the instance of the server, the created process executes and gives me desired output. **Note : Am running wowza in windows 8/64 bit. Behaviour is same if i run server instance from eclipse or as standalone application(startup.bat) . If i execute the same command through simple java class with a main() method, it just works fine.** Command i was executing was: "ffmpeg -y -i in.mp4 -i in2.mp4 -filter\_complex “[0] trim=start=40:end=70:duration=30, setpts=PTS-STARTPTS, scale=512:288 [v2] ;[0] trim=start=60:end=80:duration=20, setpts=PTS-STARTPTS, scale=512:288 [v1] ; [1] trim=start=0:end=30:duration=30, setpts=PTS-STARTPTS, scale=512:288 [v4] ; [1] trim=start=20:end=40:duration=20, setpts=PTS-STARTPTS, scale=512:288 [v3] ; [v2][v4][v1][v3] concat=n=4:v=1:a=0 [outv]; [0] atrim=start=40:end=70:duration=30, asetpts=PTS-STARTPTS [a2] ;[0] atrim=start=60:end=80:duration=20, asetpts=PTS-STARTPTS [a1] ; [1] atrim=start=0:end=30:duration=30, asetpts=PTS-STARTPTS [a4] ; [1] atrim=start=20:end=40:duration=20, asetpts=PTS-STARTPTS [a3]; [a2][a4][a1][a3] concat=n=4:v=0:a=1 [outa] " -map [outv] -map [outa] -profile:v main -level 3.1 -b:v 440k -ar 48000 -ab 128k -s 720x400 -vcodec h264 -acodec libvo\_aacenc test.mp4” ffmpeg with 2 input files(usage of -i twice): **ffmpeg hangs till i close server instance and once i close server, works fine** Other command(works fine): "ffmpeg -y -i in.mp4 -filter\_complex “[0] trim=start=40:end=70:duration=30, setpts=PTS-STARTPTS, scale=512:288 [v2] ;[0] trim=start=60:end=80:duration=20, setpts=PTS-STARTPTS, scale=512:288 [v1] ; movie=in2.mp4, trim=start=0:end=30:duration=30, setpts=PTS-STARTPTS, scale=512:288 [v4] ; movie=in2.mp4, trim=start=20:end=40:duration=20, setpts=PTS-STARTPTS, scale=512:288 [v3] ; [v2][v4][v1][v3] concat=n=4:v=1:a=0 [outv]; [0] atrim=start=40:end=70:duration=30, asetpts=PTS-STARTPTS [a2] ;[0] atrim=start=60:end=80:duration=20, asetpts=PTS-STARTPTS [a1] ; amovie=in2.mp4, atrim=start=0:end=30:duration=30, asetpts=PTS-STARTPTS [a4] ; amovie=in2.mp4, atrim=start=20:end=40:duration=20, asetpts=PTS-STARTPTS [a3]; [a2][a4][a1][a3] concat=n=4:v=0:a=1 [outa] " -map [outv] -map [outa] -profile:v main -level 3.1 -b:v 440k -ar 48000 -ab 128k -s 720x400 -vcodec h264 -acodec libvo\_aacenc test.mp4” ffmpeg with 1 input file(usage of -i once. 2nd input is used with movie/amovie filter option, a work around to replace usage of -i option): **ffmpeg executes normal** Both commands works fine from a simple java class with main() method(as module is java class too i expect both the commands to work on wowza module too). What difference it makes to execution if i supply ffmpeg 2 inputs(-i twice) through wowza module? Can there be any memory/cpu usage contrains on my newly created process by the instance of wowza server? Krishna ---
**Author:** ![Roger\_Littin1](https://avatars.discourse-cdn.com/v4/letter/r/c89c15/32.png) [@Roger\_Littin1](https://community.wowza.com/u/Roger_Littin1)\ **Post date:** [March 21, 2014, 11:35am UTC](https://community.wowza.com/t/runtime-getruntime-exec-not-working-in-a-module/41423/2 "2014-03-21T11:35:34Z")
Hi Krishna, I’m not really sure why it is working in some cases but not others but this appropriately named article, [When Runtime.exec() won’t](http://www.javaworld.com/article/2071275/core-java/when-runtime-exec---won-t.html), may indicate why. In the past, I have used ProcessBuilder instead of Runtime.exec() in a separate thread to run external processes from within Wowza. The following is a class that I have used previously to write a series of timestamped images out to an mp4 file. It was run every 24 hours on a timer thread to process the images. I know it is different to what you are doing but it does show how to invoke ffmpeg from within wowza using ProcessBuilder. ```auto private class TimeLapseWriter extends Thread { Calendar cal; File filePath; private TimeLapseWriter(File filePath) { cal = Calendar.getInstance(); this.filePath = filePath; cal.add(Calendar.DATE, -1); } public void run() { String yesterday = dateFormat.format(cal.getTime()); File yesterdaysFolder = new File(filePath.getAbsolutePath() + File.separator + yesterday); if (yesterdaysFolder.exists()) { try { File outFolder = new File(appInstance .getStreamStoragePath() + File.separator + yesterday); if (!outFolder.exists()) outFolder.mkdirs(); String[] parts = fileName.split("\\."); String ffmpegPath = props.getPropertyStr("ffmpegPath", "/usr/bin/ffmpeg"); String[] execStr = { ffmpegPath, "-f", "image2", "-r", "10", "-i", yesterdaysFolder.getAbsolutePath() + File.separator + parts[0] + "%04d." + parts[1], "-vcodec", "libx264", "-vpre", "default", "-vpre", "baseline", "-s", "512x288", outFolder.getAbsolutePath() + File.separator + streamName + ".mp4" }; for (String arg : execStr) System.out.println(arg); ProcessBuilder pb = new ProcessBuilder(execStr); // pb.environment().put("LD_LIBRARY_PATH", // "/usr/local/av/lib:/usr/lib:/lib"); // pb // .environment() // .put("PATH", // "/usr/local/av/bin:/usr/kerberos/bin:/usr/bin:/bin:/usr/sbin:/sbin"); pb.redirectErrorStream(true); Process p = pb.start(); BufferedReader in = new BufferedReader( new InputStreamReader(p.getInputStream())); String line = null; while ((line = in.readLine()) != null) { System.out.println(line); } if (p.waitFor() == 0) { logger.info("File " + outFolder + File.separator + streamName + ".mp4 Written Successfully."); } else { logger.error("File " + outFolder + File.separator + streamName + ".mp4 Write Error."); } } catch (IOException e) { e.printStackTrace(); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } } ``` Hope this helps. Roger. ---
**Author:** ![Roger\_Littin1](https://avatars.discourse-cdn.com/v4/letter/r/c89c15/32.png) [@Roger\_Littin1](https://community.wowza.com/u/Roger_Littin1)\ **Post date:** [March 22, 2014, 8:35am UTC](https://community.wowza.com/t/runtime-getruntime-exec-not-working-in-a-module/41423/3 "2014-03-22T08:35:24Z")
Hi, Good to hear it is working. It’s a long time since I did anything with this and I do recall having similar issues with Runtime.exec. Roger. ---
**Author:** ![krishna\_mohan](https://avatars.discourse-cdn.com/v4/letter/k/5f9b8f/32.png) [@krishna\_mohan](https://community.wowza.com/u/krishna_mohan)\ **Post date:** [March 21, 2014, 11:29am UTC](https://community.wowza.com/t/runtime-getruntime-exec-not-working-in-a-module/41423/4 "2014-03-21T11:29:20Z")
Hi Roger, Appreciate ur reply. The [link](http://www.javaworld.com/article/2071275/core-java/when-runtime-exec---won-t.html) provided by u is very detailed. Applying the measures described(handling error and input streams of process) in that post helped me to fix my ‘process blocking’ problem. Thanx man. Krishna