5 min with serial monitor results in OutOfMemoryException

[willie68]

I have to debug some longer running tasks. But after some minutes i get an OutOfMEmoryException than the IDE is not resonding. I think it's the buffer for the serial monitor text area.
As a workaround: Is there a possibility to clear the text area? Maybe an autoclear on low memory would help.
Setting the memory params of the IDE doesn't help, because this would only postpone the problem. And without the autosave feature this bug is more serious. I have again lost some code because of this.
Arduino IDE 1.5.7, SerialMOnitor with 57600 Baud.

[ffissore]

Wow! How much RAM does your computer have? If it's the serial monitor, you should have printed an amount of text almost equal to the amount of free ram
+1 with limiting the number of rows displayed in the serial monitor

[willie68]

8GB. But i have try only 1GB for the JavaVM. Because than you get the next issue. If your vm is blown up to 1GB the garbage collector needs huge time to work. So the IDE freezes sometimes.
As i see in the source the serial monitor is an JTextArea. And so it uses the Document model from swing which uses an double buffer algo. for the presentation. So every char in the textarea will use more than 1 bytes (i think, i have readed, that it will use up to 6 Bytes (2 Buffers and the displaybuffer with 2 Bytes))

[ffissore]

It seems you know java swing quite well: mind to provide some code that limits the number of rows to a given value? :)

[willie68]

You have two mails from me with attached source...

[ffissore]

Read. I'll try and report back asap

[PaulStoffregen]

This problem happens with Teensy, if a sketch uses Serial.print() in loop() without any delay. At best speed, Teensy can send about 1 Mbyte/sec. In just a few minutes, the JVM reports an out of memory exception and pretty much nothing works until Arduino is started. I use 64 bit Linux and "top" reports the process has allocated 10 GB of virtual memory.

If this were only the text stored by the window, it should take at least 2 hours to send that much data over 12 Mbit/sec USB. The out of memory condition happens in only a matter of minutes.

[PaulStoffregen]

If anyone tries testing this, I'd recommend using Arduino Due with the native port, running this sketch:

void setup() {
SerialUSB.begin(9600);
while (!SerialUSB) ; // wait
delay(250);
}
unsigned long count=1;
void loop() {
SerialUSB.print("Printing simple text, count # ");
SerialUSB.println(count++);
}

[PaulStoffregen]

Here's a quick screenshot showing Arduino 1.5.7 has allocated 5.9 gigabytes of RAM after 7805055 lines have printed. Each line is 39 bytes, which should be approx 0.29 Gbyte, not 5.9 Gbyte.

[ffissore]

I've tried implementing a limit to the amount of output shown in the serial monitor. Unfortunately, after minute or so spent looking at the output of an endless Asciitable example, it starts slowing down until it blocks. I still don't know the cause and will investigate further.
Anyone wishing to give a hand is welcome: branch is this, commit is 3ae7aa7

[willie68]

Hi,

i have tried this with a LimitLinesDocumentFilter and it worked perfectly.
Maybe the lines will be stored anywhere else?

    plainDocument.setDocumentFilter(new LimitLinesDocumentFilter(maxLineCount));

import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.Document;
import javax.swing.text.DocumentFilter;
import javax.swing.text.DocumentFilter.FilterBypass;
import javax.swing.text.Element;

/**
 * 
 */

/**
 * @author w.klaas
 *
 */
public class LimitLinesDocumentFilter extends DocumentFilter {
    private int maxLineCount;

    public LimitLinesDocumentFilter(int maxLineCount) {
        this.maxLineCount = maxLineCount;
    }

    @Override
    public void insertString(FilterBypass fb, int offset, String string,
            AttributeSet attr) throws BadLocationException {
        super.insertString(fb, offset, string, attr);

        removeFromStart(fb);
    }

    @Override
    public void replace(FilterBypass fb, int offset, int length, String text,
            AttributeSet attrs) throws BadLocationException {
        super.replace(fb, offset, length, text, attrs);

        removeFromStart(fb);
    }

    private void removeFromStart(FilterBypass fb) {
        Document doc = fb.getDocument();
        Element root = doc.getDefaultRootElement();
        while (root.getElementCount() > maxLineCount) {
            removeLineFromStart(doc, root);
        }
    }

    private void removeLineFromStart(Document document, Element root) {
        Element line = root.getElement(0);
        int end = line.getEndOffset();

        try {
            document.remove(0, end);
        } catch (BadLocationException ble) {
            ble.printStackTrace();
        }
    }
}

[ffissore]

Which number did you set for maxLineCount ?

[willie68]

1000 lines.