FileDB gets corrupted after Thread.interrupt

[vadimzv]

My application consumes data from external source and writes it to mapdb, this process happens in a separate thread and looks like this:

void run()
{
    while (isAlive)
    {
        Data data = retrieveData();
        if (data.isEmpty())
        {
            Thread.sleep(timeout);
        }
        else if (data.isExternalSystemUnavailable())
        {
            Thread.sleep(data.tillExternalSystemIsAvailable);
        }
        else
        {
            writeToMapDB(data);
        }
    }
}

When user stops application I'm calling thread.interrupt to interrupt all possible sleeps. But if in that moment writing to mapdb was in progress, I get the exception:

Caused by: java.io.IOError: java.nio.channels.ClosedByInterruptException
    at org.mapdb.Volume$FileChannelVol.getDataInput(Volume.java:784)[214:mapdb:0.9.7.SNAPSHOT]
    at org.mapdb.StoreDirect.get2(StoreDirect.java:381)[214:mapdb:0.9.7.SNAPSHOT]
    at org.mapdb.StoreDirect.get(StoreDirect.java:364)[214:mapdb:0.9.7.SNAPSHOT]
    at org.mapdb.EngineWrapper.get(EngineWrapper.java:60)[214:mapdb:0.9.7.SNAPSHOT]
    at org.mapdb.AsyncWriteEngine.get(AsyncWriteEngine.java:361)[214:mapdb:0.9.7.SNAPSHOT]
    at org.mapdb.Caches$HashTable.get(Caches.java:213)[214:mapdb:0.9.7.SNAPSHOT]
    at org.mapdb.BTreeMap.remove2(BTreeMap.java:906)[214:mapdb:0.9.7.SNAPSHOT]
    at org.mapdb.BTreeMap.remove(BTreeMap.java:897)[214:mapdb:0.9.7.SNAPSHOT]
    at mhubdb.TableDB.put(TableDB.java:107)[197:mhubDB.mhubDB:1.0.0.SNAPSHOT]
Caused by: java.nio.channels.ClosedByInterruptException
    at java.nio.channels.spi.AbstractInterruptibleChannel.end(AbstractInterruptibleChannel.java:202)[:1.7.0_25]
    at sun.nio.ch.FileChannelImpl.read(FileChannelImpl.java:679)[:1.7.0_25]
    at org.mapdb.Volume$FileChannelVol.readFully(Volume.java:719)[214:mapdb:0.9.7.SNAPSHOT]
    at org.mapdb.Volume$FileChannelVol.getDataInput(Volume.java:781)[214:mapdb:0.9.7.SNAPSHOT]
    ... 61 more

And the whole data file gets corrupted. That's the error when I'm trying to read data file just after ClosedByInterruptException:

java.lang.RuntimeException: Writer thread failed
        at org.mapdb.AsyncWriteEngine.checkState(AsyncWriteEngine.java:290)[214:mapdb:0.9.7.SNAPSHOT]
        at org.mapdb.AsyncWriteEngine.get(AsyncWriteEngine.java:354)[214:mapdb:0.9.7.SNAPSHOT]
        at org.mapdb.Caches$HashTable.get(Caches.java:213)[214:mapdb:0.9.7.SNAPSHOT]
        at org.mapdb.BTreeMap.lastEntryRecur(BTreeMap.java:1319)[214:mapdb:0.9.7.SNAPSHOT]
        at org.mapdb.BTreeMap.lastEntryRecur(BTreeMap.java:1320)[214:mapdb:0.9.7.SNAPSHOT]
        at org.mapdb.BTreeMap.lastEntryRecur(BTreeMap.java:1320)[214:mapdb:0.9.7.SNAPSHOT]
        at org.mapdb.BTreeMap.lastEntry(BTreeMap.java:1293)[214:mapdb:0.9.7.SNAPSHOT]
        at mhubdb.TableDB.getLastRecord(TableDB.java:172)[197:mhubDB.mhubDB:1.0.0.SNAPSHOT]
Caused by: java.io.IOError: java.nio.channels.ClosedChannelException
        at org.mapdb.Volume$FileChannelVol.putData(Volume.java:703)[214:mapdb:0.9.7.SNAPSHOT]
        at org.mapdb.StoreDirect.update2(StoreDirect.java:443)[214:mapdb:0.9.7.SNAPSHOT]
        at org.mapdb.StoreDirect.update(StoreDirect.java:424)[214:mapdb:0.9.7.SNAPSHOT]
        at org.mapdb.EngineWrapper.update(EngineWrapper.java:66)[214:mapdb:0.9.7.SNAPSHOT]
        at org.mapdb.AsyncWriteEngine.access$101(AsyncWriteEngine.java:72)[214:mapdb:0.9.7.SNAPSHOT]
        at org.mapdb.AsyncWriteEngine.runWriter(AsyncWriteEngine.java:206)[214:mapdb:0.9.7.SNAPSHOT]
        at org.mapdb.AsyncWriteEngine$WriterRunnable.run(AsyncWriteEngine.java:156)[214:mapdb:0.9.7.SNAPSHOT]
        at java.lang.Thread.run(Thread.java:724)[:1.7.0_25]
Caused by: java.nio.channels.ClosedChannelException
        at sun.nio.ch.FileChannelImpl.ensureOpen(FileChannelImpl.java:94)[:1.7.0_25]
        at sun.nio.ch.FileChannelImpl.write(FileChannelImpl.java:691)[:1.7.0_25]
        at org.mapdb.Volume$FileChannelVol.writeFully(Volume.java:638)[214:mapdb:0.9.7.SNAPSHOT]
        at org.mapdb.Volume$FileChannelVol.putData(Volume.java:701)[214:mapdb:0.9.7.SNAPSHOT]
        ... 7 more

And this is the error after I reinitialized db and tried to call BTreeMap.lastKey:

Caused by: java.lang.NullPointerException
        at org.mapdb.BTreeMap.lastEntryRecur(BTreeMap.java:1300)[214:mapdb:0.9.7.SNAPSHOT]
        at org.mapdb.BTreeMap.lastEntryRecur(BTreeMap.java:1320)[214:mapdb:0.9.7.SNAPSHOT]
        at org.mapdb.BTreeMap.lastEntryRecur(BTreeMap.java:1320)[214:mapdb:0.9.7.SNAPSHOT]
        at org.mapdb.BTreeMap.lastEntry(BTreeMap.java:1293)[214:mapdb:0.9.7.SNAPSHOT]
        at org.mapdb.BTreeMap.lastKey(BTreeMap.java:1469)[214:mapdb:0.9.7.SNAPSHOT]

Of course I can apply some synchronization trick on writeToMapDB to prevent simultaneous writeToMapDB and thread.interrupt. But is this behaviour of mapdb normal?

[jankotek]

Yes, it is expectable. FileChannel is closed if thread is interrupted during IO. First exception actually happened during read.

I could in theory check and reopen closed channels, but it seems like big performance overhead for narrow corner case.

It seems you use RAF mode, memory-mapped-files could perhaps handle interrupts, but I have no idea.