How do I close Krati store?

[Daniel Canas]

I took the sample code in quickstart section of the web page and tried
a quick test.
This simple program starts up Krati but never exits.
How do I shutdown Krati?
I am using Krati 0.3.5

public class KratiSimpleTest {

public static void main(String[] args) throws Exception {
File storeHome = new File("/tmp/krati.store",
"kratiSimpleTest");
DataStore<byte[], byte[]> ds = new
DynamicDataStore(storeHome, new MappedSegmentFactory());
}

Log file produced:

INFO main krati.core.array.entry.EntryPool - Entry 0 created:
PreFillEntryLong
INFO main krati.core.array.entry.EntryPool - Entry 0 serviceId 0
INFO main krati.core.array.entry.EntryPool - Entry 1 created:
PreFillEntryLong
INFO main krati.core.array.entry.EntryPool - Entry 1 serviceId 1
INFO main krati.core.array.basic.ArrayEntryManager - arrayLength=65536
maxEntries=5 maxEntrySize=10000
INFO main krati.core.array.basic.ArrayFile - indexes.dat header:
version=0 lwmScn=0 hwmScn=0 arrayLength=65536 elementSize=8
INFO main krati.core.array.basic.ArrayFile - indexes.dat loaded in
Time: 362 ms
INFO main krati.core.array.basic.RecoverableArray - length:65536
entrySize:10000 maxEntries:5 directory:/tmp/krati.store/
kratiSimpleTest arrayFile:indexes.dat
INFO main krati.core.segment.SegmentManager - init segHomePath=/tmp/
krati.store/kratiSimpleTest/segs segFileSizeMB=256
INFO main krati.core.segment.SegmentMeta - /tmp/krati.store/
kratiSimpleTest/segs/.meta created
INFO main krati.core.segment.SegmentMeta - workingGeneration=0
liveSegmentCount=0
INFO main krati.core.array.SimpleDataArrayCompactor -
CompactionUpdateBatch 0
INFO main krati.core.segment.MappedSegment - Segment 0 forced:
loadSize=0 appendPosition=16 channelPosition=0 lastForcedTime=Mon Dec
06 12:12:26 CST 2010
INFO main krati.core.segment.MappedSegment - Segment 0 initialized:
loadSize=0 appendPosition=128 channelPosition=128 lastForcedTime=Mon
Dec 06 12:12:26 CST 2010
INFO main krati.core.array.SimpleDataArray - Segment 0 online:
loadSize=0 appendPosition=128 channelPosition=128 lastForcedTime=Mon
Dec 06 12:12:26 CST 2010
INFO main krati.store.DynamicDataStore - level=0 split=0
capacity=65536 loadCount=0 loadFactor=0.0
INFO pool-1-thread-1 krati.core.array.SimpleDataArrayCompactor - cycle
started
INFO pool-1-thread-1 krati.core.array.SimpleDataArrayCompactor - cycle
ended

[Jingwei]

You can add the following at the end of your main method.

ds.sync();
System.exit(0);

-jingwei

[Daniel Canas]

Yes, that works for this specific example if Krati does not throw an
exception.

I want to use Krati and be able to close it without exiting the whole
program. Is that possible?

Daniel

[Jingwei]

In Krati 0.3.5, compactor runs as a non-daemon thread. This prevents
JVM from shutting down cleanly.

The latest dev from https://github.com/jingwei/krati makes compactor
run as a daemon thread so JVM can shutdown nicely.

We are thinking to extend DataStore with open/close methods in the
next release. So the store can be closed before JVM shutdown.

Thanks.

-jingwei

[Tatu Saloranta]

On Mon, Dec 13, 2010 at 10:18 PM, Jingwei <jingw...@gmail.com> wrote:
> In Krati 0.3.5, compactor runs as a non-daemon thread. This prevents
> JVM from shutting down cleanly.
>
> The latest dev from https://github.com/jingwei/krati makes compactor
> run as a daemon thread so JVM can shutdown nicely.
>
> We are thinking to extend DataStore with open/close methods in the
> next release. So the store can be closed before JVM shutdown.

I think this would be an excellent idea. Life-cycle of a store may
well be shorter than that of the system that uses it.

-+ Tatu +-

[Rodolfo M. Raya]

Hi Jingwei,

 

I got the latest source code from the repository and the option for cosing databases is working fine. Thanks for implementing it.

 

I have two questions regarding the new feature:

 

Do I need to call sync() before close()?

 

close() can take a while, normally more than the end user would wait. Can the closing operation be done in a background thread?

 

Regards,

Rodolfo

[Rodolfo Raya]

On Tue, Jun 7, 2011 at 10:27 AM, Rodolfo M. Raya <rmr...@gmail.com> wrote:

 

close() can take a while, normally more than the end user would wait. Can the closing operation be done in a background thread?

 

I placed the call to close() in its own thread for testing and it is fast enough; end users will not notice a delay.

Now I'd like to know if it is safe to do what I did.

Regards,

Rodolfo
--
Rodolfo M. Raya <rmr...@maxprograms.com>
http://www.maxprograms.com

[Jingwei]

Hi Rodolfo,

You do not need to call sync() before close() since the latter
internally calls the former.
In addition, you can delegate call to close() to a background thread.

Thanks.

-jingwei

[Jingwei]

Hi Rodolfo,

It is safe to call close() in a background thread. However, calls to
methods get/set/put etc will be impacted and exceptions (such as
NullPointerException) may be thrown.

Thanks.

-jingwei

[Rodolfo Raya]

On Tue, Jun 7, 2011 at 3:21 PM, Jingwei <jingw...@gmail.com> wrote:

Hi Rodolfo,

It is safe to call close() in a background thread. However, calls to
methods get/set/put etc will be impacted and exceptions (such as
NullPointerException) may be thrown.

 

Many thanks for the feedback, Jinwei.

 

Best regards,