@Size without max attribute causes a java.lang.OutOfMemoryError: Java heap space

[Redid]

Hi random-beans Team,

@Size on String is causing java.lang.OutOfMemoryError: Java heap space.
This bug is not always happening, but during debugging there are always problems.

Example:

public class TestString {
    @Size(min = 2)
    public String str1;
}

Also it is not working at all with validation-api pre 2.0, even if Java heap space doesn't appear @Size is just ignored.

Best regards,
Redid

[fmbenhassine]

This bug is not always happening

Yeah, with random beans, we have random bugs 😄 Sorry, I couldn't resist on this..

Anyway, thank you for pointing this out!
Will take a look at this and get back to you asap

[fmbenhassine]

Hi,

The issue does not happen when both min and max attributes are specified.
But I do confirm there is a OOM error when the max attribute is not specified.

Thank you for pointing this out! Let me try to fix that for v3.8.0.

Kr
Mahmoud

[fmbenhassine]

Hi,

When the max attribute is not specified, the default max value is Integer.MAX_VALUE and the generated random string length can be too high and causes the OOM (The reason for that is the arrays copy at java.util.Arrays.copyOf(Arrays.java:3332)).

When I first analysed this issue, I thought that the cause of the OOM is the string concatenation in StringRandomizer#getRandomValue:

@Override
public String getRandomValue() {
   StringBuilder stringBuilder = new StringBuilder();
   int length = minLength + random.nextInt(maxLength - minLength + 1);
   for (int i = 0; i < length; i++) {
      stringBuilder.append(characterRandomizer.getRandomValue());
   }
   return stringBuilder.toString();
}

I changed the above code to:

@Override
public String getRandomValue() {
    int length = minLength + random.nextInt(maxLength - minLength + 1);
    char[] chars = new char[length];
    for (int i = 0; i < length; i++) {
        chars[i] = characterRandomizer.getRandomValue();
    }
    return new String(chars);
}

which is better but the OOM still happens for a large length.

Random Beans can do nothing in this case. We need to:

• either allocate more memory to the JVM (with a -Xmx512m, I tired to dump the value of the string to a text file when the generated length was 374668018 and it worked, the file size was 374m)
• or specify a reasonable value for the max size of the string

BTW, here is the exact same code outside of Random Beans which also causes an OOM with a high length value:

import java.util.Random;

class Scratch {
    public static void main(String[] args) {
        Random random = new Random();
        int length = 374668018; 
        char[] chars = new char[length];
        for (int i = 0; i < length; i++) {
            chars[i] = (char) random.nextInt(127);
        }
        String value = new String(chars); // java.lang.OutOfMemoryError: Java heap space at java.util.Arrays.copyOf(Arrays.java:3332)
        System.out.println("value = " + value);
    }
}

That said, I'm closing this issue.

Kr,
Mahmoud