Found setting where I lose part of a List value 'silently'

[reuschling]

I store LinkedList values with String keys and sadly, more or less by accident, I recognized that jdbm loses a single entry from a LinkedList that I stored. I tried to reproduce this in a small snippet which was not so easy, because most of the times everything worked well - but now I have a stable setting (see below). The snippet runs on a linux 64 bit jdk 1.7.0_09-b05. I started with the jdbm3-alpha4, tried 5, and now I use the current snapshot. No difference.
I guess it could be something with the serialization, because the behaviour is only seen after writing a certain amount of entries. Here is the according snippet:

    DB jdbmDB = DBMaker.openFile("testDB").disableTransactions().disableLocking().deleteFilesAfterClose().closeOnExit().make();
    Map<String, LinkedList<String>> map = jdbmDB.createTreeMap("testMap");

    int iLoops = 2000000;
    for (int i = 0; i < iLoops; i++)
    {
        String strRandomKey = String.valueOf(Math.random());
        LinkedList<String> llVals4RandomKey = map.get(strRandomKey);
        if(llVals4RandomKey == null)
        {
            llVals4RandomKey = new LinkedList<String>();
            map.put(strRandomKey, llVals4RandomKey);
        }
        llVals4RandomKey.add(UUID.randomUUID().toString());


        if(i == (int) (iLoops * 0.9))
        {
            System.out.println("insert first");
            LinkedList<String> llFirstValue = new LinkedList<String>();
            map.put("ourKey", llFirstValue);
            llFirstValue.add("firstValue");
        }
        if(i == (int) (iLoops * 0.97))
        {
            System.out.println("insert second");
            LinkedList<String> llValues = map.get("ourKey");
            llValues.add("secondValue");
        }


        if(i % 100000 == 0) System.out.println(i);
    }


    System.out.println(map.get("ourKey"));
    if(map.get("ourKey").size() < 2)
        System.err.println("second value is lost :(");
    else
        System.out.println("everything seems to be fine...");

    jdbmDB.close();

[jankotek]

JDBM3 is no longer supported. Please migrate to MapDB (aka JDBM4)

On Thursday 31 January 2013 09:52:39 reuschling wrote:

I store LinkedList values with String keys and sadly, more or less by
accident, I recognized that jdbm loses a single entry from a LinkedList that I
stored. I tried to reproduce this in a small snippet which was not so easy,
because most of the times everything worked well - but now I have a stable
setting (see below). The snippet runs on a linux 64 bit jdk 1.7.0_09-b05. I
started with the jdbm3-alpha4, tried 5, and now I use the current snapshot. No
difference.
I guess it could be something with the serialization, because the behaviour is
only seen after writing a certain amount of entries. Here is the according
snippet:
DB jdbmDB = DBMaker.openFile("testDB").disableTransactions().disableLocking().deleteFilesAfterClose().closeOnExit().make();
Map<String, LinkedList> map = jdbmDB.createTreeMap("testMap");

int iLoops = 1500000;
for (int i = 0; i < iLoops; i++)
{
    String strRandomKey = String.valueOf(Math.random());
    LinkedList<String> llVals4RandomKey = map.get(strRandomKey);
    if(llVals4RandomKey == null)
    {
        llVals4RandomKey = new LinkedList<String>();
        map.put(strRandomKey, llVals4RandomKey);
    }
    llVals4RandomKey.add(UUID.randomUUID().toString());


    if(i == (int) (iLoops * 0.9))
    {
        System.out.println("insert first");
        LinkedList<String> llFirstValue = new LinkedList<String>();
        map.put("ourKey", llFirstValue);
        llFirstValue.add("firstValue");
    }
    if(i == (int) (iLoops * 0.97))
    {
        System.out.println("insert second");
        LinkedList<String> llValues = map.get("ourKey");
        llValues.add("secondValue");
    }


    if(i % 100000 == 0) System.out.println(i);
}


System.out.println(map.get("ourKey"));
if(map.get("ourKey").size() < 2)
    System.err.println("second value is lost :(");
else
    System.out.println("everything seems to be fine...");

jdbmDB.close();

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