Java - Memory Allocation Difficulties (GC_FOR_ALLOC)

Question

My Android app crash when I start this Thread.

This Thread should restart the phone. When I start it it don't restart the phone and I have the following text in the LOG :

08-25 09:12:00.946 26029-26813/com.datasulting.chris.smsgateway D/dalvikvm: GC_FOR_ALLOC freed 1279K (30823), 55% free 4485K/9968K, paused 53ms, total 53ms 08-25 09:12:01.294 26029-26813/com.datasulting.chris.smsgateway D/dalvikvm: between the previous GC alloc 1280K 08-25 09:12:01.346 26029-26813/com.datasulting.chris.smsgateway D/dalvikvm: GC_FOR_ALLOC freed 1280K (30820), 55% free 4485K/9968K, paused 52ms, total 52ms 08-25 09:12:01.713 26029-26813/com.datasulting.chris.smsgateway D/dalvikvm: between the previous GC alloc 1279K 08-25 09:12:01.768 26029-26813/com.datasulting.chris.smsgateway D/dalvikvm: GC_FOR_ALLOC freed 1279K (30813), 55% free 4486K/9968K, paused 55ms, total 55ms 08-25 09:12:02.111 26029-26813/com.datasulting.chris.smsgateway D/dalvikvm: between the previous GC alloc 1279K 08-25 09:12:02.164 26029-26813/com.datasulting.chris.smsgateway D/dalvikvm: GC_FOR_ALLOC freed 1280K (30819), 55% free 4486K/9968K, paused 53ms, total 53ms 08-25 09:12:02.504 26029-26813/com.datas ulting.chris.smsgateway D/dalvikvm: between the previous GC alloc 1279K 08-25 09:12:02.557 26029-26813/com.datasulting.chris.smsgateway D/dalvikvm: GC_FOR_ALLOC freed 1280K (30823), 55% free 4485K/9968K, paused 53ms, total 53ms 08-25 09:12:02.901 26029-26813/com.datasulting.chris.smsgateway D/dalvikvm: between the previous GC alloc 1279K 08-25 09:12:02.956 26029-26813/com.datasulting.chris.smsgateway D/dalvikvm: GC_FOR_ALLOC freed 1279K (30818), 55% free 4485K/9968K, paused 55ms, total 55ms 08-25 09:12:03.298 26029-26813/com.datasulting.chris.smsgateway D/dalvikvm: between the previous GC alloc 1280K

This is my Thread.

class Reboot implements Runnable {

    private volatile boolean cancelled;
    Boolean checkRebootHeb;
    Boolean checkRebootQuo;
    int jourDemandeeInt;
    String jourDemandeeString;
    String weekDay;
    int dayOfWeek;
    SimpleDateFormat df;
    String heure;
    String dayOfWeekString;
    String heureDemandee;
    Calendar c;

    public Reboot(Boolean VARcheckReboot, Boolean VARcheckRebootQuo, int VARjour, String VARtextReboot) {
        checkRebootHeb = VARcheckReboot;
        checkRebootQuo = VARcheckRebootQuo;
        jourDemandeeInt = VARjour;
        heureDemandee = VARtextReboot;
    }


    @Override
    public void run() {

        while (!cancelled) {

            if (jourDemandeeInt == 0){
                jourDemandeeString = "Lundi";
            }
            if (jourDemandeeInt == 1){
                jourDemandeeString = "Mardi";
            }
            if (jourDemandeeInt == 2){
                jourDemandeeString = "Mercredi";
            }
            if (jourDemandeeInt == 3){
                jourDemandeeString = "Jeudi";
            }
            if (jourDemandeeInt == 4){
                jourDemandeeString = "Vendredi";
            }
            if (jourDemandeeInt == 5){
                jourDemandeeString = "Samedi";
            }
            if (jourDemandeeInt == 6){
                jourDemandeeString = "Dimanche";
            }

            c = Calendar.getInstance();
            dayOfWeek = c.get(Calendar.DAY_OF_WEEK);
            df = new SimpleDateFormat("HH:mm");
            heure = df.format(c.getTime());


            if (Calendar.MONDAY == dayOfWeek) weekDay = "Lundi";
            else if (Calendar.TUESDAY == dayOfWeek) weekDay = "Mardi";
            else if (Calendar.WEDNESDAY == dayOfWeek) weekDay = "Mercredi";
            else if (Calendar.THURSDAY == dayOfWeek) weekDay = "Jeudi";
            else if (Calendar.FRIDAY == dayOfWeek) weekDay = "Vendredi";
            else if (Calendar.SATURDAY == dayOfWeek) weekDay = "Samedi";
            else if (Calendar.SUNDAY == dayOfWeek) weekDay = "Dimanche";


            dayOfWeekString = String.valueOf(dayOfWeek);

            if (checkRebootQuo == true) {
                if (heure.equals(heureDemandee)) {
                    try {

                        Process proc = Runtime.getRuntime().exec(new String[]{"su", "-c", "reboot"});
                        proc.waitFor();
                    } catch (Exception ex) {
                        ex.printStackTrace();
                    }
                }
            }

            if (checkRebootHeb == true) {
                if (dayOfWeekString.equals(jourDemandeeString)) {
                    if (heure.equals(heureDemandee)) {
                        try {

                            Process proc = Runtime.getRuntime().exec(new String[]{"su", "-c", "reboot"});
                            proc.waitFor();
                        } catch (Exception ex) {
                            ex.printStackTrace();
                        }
                    }
                }
            }

        }


    }

    public void cancel() {
        cancelled = true;
    }
}

Answer 1

Lots of things wrong with that code.

Your main problem - your thread is doing "active" waiting. This means: it just loops and creates a new Calendar object each iteration . Then you immediately throw away that object, and create a new one.

And you are surprised that the garbage collector has a hard time with your code? And just to be sure that my sarcasm doesn't prevent people from understanding the issue: no garbage collector in the world is designed to allow for a "hot" loop that only creates garbage objects; especially in the "mobile" world.

So, the obvious answer: add some Thread.sleep() statement in the body of your loop; like:

• check if its the hour to reboot
• if yes: reboot
• if no: sleep for a minute
• repeat

Your code does: - check if its the hour to reboot - if yes: reboot - repeat

Then, some general feedback on your (sorry) horrible code:

• It is absolutely crazy that you turn weekdays in to french strings in order to compare them. You already got an int that says 0 for Monday. Then just ask the calendar object for the week day as int. You are converting 0 to "Lundi" so that you can convert 0 to "Lundi" again to make a string match. Crazy that is.
• Your naming is terrible, too. Really - stick with one language. I guess "checkRebootQuo" is about "hourly rebooting"; whereas "checkRebootHeb" is about weekly reboots somehow. If you would rename your variables to "rebootHourly" vs "rebootWeekly" ... that would be much clearer.
• Finally: dont use multiple boolean parameters to then have multiple IFs in your methods. Instead: use polymorphism. Have base class that knows to loop and reboot; and then have two subclasses; one that knows how to reboot on the next hour, and another one that reboots on the specified day of the week.