Shutting down Ebean

[Alex]

Hi,

A quick newbie question: how do we shutdown Ebean? After the main
thread has finished I have following threads:

BackgroundThread
H2 File Lock Watchdog
H2 Log Writer
TransactionManager.0
Timer-0
Timer-1
DestroyJavaVM

I've tryed calling ShutdownManager.shutdown() but I still have

Timer-0
Timer-1
DestroyJavaVM

running in background.

Thanks in advance

alx

P.S.1: My system

Ebean 2.1.0
DB: H2 Version 1.2.121
java version "1.6.0_16"
Java(TM) SE Runtime Environment (build 1.6.0_16-b01)
Java HotSpot(TM) Server VM (build 14.2-b01, mixed mode)
OS: Ubuntu 8.0.4 LTS


P.S.2: By the way, I'm very new to Ebean, and its ORM approach seems
very interesting to me, but I'm having some trouble starting using it.
I've found the User Guide very good, but it would be very nice to have
very simple ready to run examples (yes, I've downloaded
EbeanExampleApp and I'm currently getting acquainted to it) such as:

Howto 1 - Hello World (with DDL)
Howto 2 - Saving / Retrieving objects (simple queries)
Howto 3 - ...

[edge]

some if not all of those threads might belong to H2 so you probably
need to shout down H2 to get rid of them

If you download the Ebean source code from SVN you will see lots of
tests - they are pretty good example of how to use Ebean - lots of
queries, saves etc
Hope that helps
Eddie

[Alex]

Thanks for the hint.

> some if not all of those threads might belong to H2 so you probably
> need to shout down H2 to get rid of them

So, does anybody knows how can we get a reference to the underlying
database object (in this case I think it is an instance of
org.h2.engine.Database) ? By the way, isn't it something that Ebean
should take care of? I didn't initialize the db, so I shouldn't be
required to shut it down myself.

[Rob Bygrave]

When running the example application you should not need to shutdown H2.

It's actually not clear to me what you are doing and what your issue is ... but I'll guess and say you are running the example application ... one of the classes with a main method... and it is hanging / not terminating? 

I haven't come across any problem like that... is this your issue or am I misunderstanding?

Note that Ebean registers with the JVM shutdown hook ... and uses that to close it's resources such as thread pools and Connection pools. It also can trigger a GC to collection profiling information for Autofetch (with a small wait of 100ms from memory).

Thanks, Rob.

[Alex]

Hi,
no, I'm not running the example application. Well, I've decided to
write a minimalistic howto on start using Ebean, please have a look
at http://alxa.wikidot.com/ebean-howto-1 for the complete setup.

Below the main code:

public class HelloWorld {
public static void main(String[] args) {
// ### Configuration Objects ###
ServerConfig serverConfig = new ServerConfig();
DataSourceConfig dataSourceConfig = new DataSourceConfig();

// ### Configuration Settings ###
// -> data source
dataSourceConfig.setDriver("org.h2.Driver");
dataSourceConfig.setUsername("howtouser");
dataSourceConfig.setPassword("");
dataSourceConfig.setUrl("jdbc:h2:db/howto1");

// -> server
serverConfig.setName("default");
serverConfig.setDataSourceConfig(dataSourceConfig);

// auto create db if it does not exist
if(!(new File("db/howto1.h2.db")).exists() ){
serverConfig.setDdlGenerate(true);
serverConfig.setDdlRun(true);
serverConfig.addClass(Hello.class);
}

EbeanServer eServer = EbeanServerFactory.create(serverConfig);

long id = 3;
Hello data = eServer.find(Hello.class, id);
if (data == null) {
System.out.println("This is the first run, saving
data..");
eServer.save(new Hello(id, "Hello World!"));
} else {
System.out.println(String.format("############\n%s
\n############", data.getMessage()));
}
ShutdownManager.shutdown();
}
}

Thanks in advance

alx

On 18 Okt., 02:50, Rob Bygrave <robin.bygr...@gmail.com> wrote:
> When running the example application you should not need to shutdown H2.
>
> It's actually not clear to me what you are doing and what your issue is ...
> but I'll guess and say you are running the example application ... one of
> the classes with a main method... and it is hanging / not terminating?
>
> I haven't come across any problem like that... is this your issue or am I
> misunderstanding?
>
> Note that Ebean registers with the JVM shutdown hook ... and uses that to
> close it's resources such as thread pools and Connection pools. It also can
> trigger a GC to collection profiling information for Autofetch (with a small
> wait of 100ms from memory).
>
> Thanks, Rob.
>

[edge]

I tried this out and you have to wait a while (1 min exactly as far as
I can tell) for the app to shutdown but it does shutdown cleanly (I
tried this in mvn, java command line and eclipse)
... so I wondering why it takes so long - none of our test cases show
this behaviour - why it takes so long in this case is strange
seem like there is a wait of 1 min somewhere
so a few things I ruled out
1. Its not specific to H2 - I tried MySQL and it also took 1 min
2. Placing the data access code in an extra method @Transactional in
case the app was waiting on a connection to close didn't help either

must be one of the daemon threads that is waiting ... any ideas Rob?

On Oct 18, 5:13 pm, Alex <alxa...@googlemail.com> wrote:
> Hi,
> no, I'm not running the example application. Well, I've decided to
> write a minimalistic howto on start using Ebean, please have a look

> at  http://alxa.wikidot.com/ebean-howto-1for the complete setup.

[Rob Bygrave]

I haven't tried this yet.  The code looks fine ... the line "serverConfig.addClass(Hello.

class);" ... should probably be outside that if statement (you always register the bean even if you don't run the DDL).

You don't (shouldn't) need that explicit call to ShutdownManager.shutdown();  Ebean registers a shutdown hook ... we should never need to code that ourselves. I'm pretty sure you added that after you got this issue.

I think we are running different JVM's (Linux, MacOS and I'm using Windows mostly).

So yeah, I'll give it a go tonight. A ~1min wait/hang at shutdown ... I'll probably look to use MySql so as to discount H2 background threads from the issue.

[Alex]

Hi

> I haven't tried this yet. The code looks fine ... the line

> "serverConfig.addClass(Hello.class);" ... should probably be outside that if

> statement (you always register the bean even if you don't run the DDL).

ok

> You don't (shouldn't) need that explicit call to
> ShutdownManager.shutdown(); Ebean registers a shutdown hook ... we should
> never need to code that ourselves. I'm pretty sure you added that after you
> got this issue.

yes, that was the reason why I've added that.

> I think we are running different JVM's (Linux, MacOS and I'm using Windows
> mostly).

> So yeah, I'll give it a go tonight. A ~1min wait/hang at shutdown ... I'll
> probably look to use MySql so as to discount H2 background threads from the
> issue.

great, thanks, alx

[Rob Bygrave]

Hmmm. Well, I wasn't able to reproduce... in that it terminated in about 1 second or so.

I wonder if it is specific to a particular JDK/JVM. 

[Rob Bygrave]

Ok, I reproduced it and found the problem with Ebean not shutting down
in a timely fashion.

Logged as BUG 176 : Shutdown taking 30 secs or so ... should be
immediate

http://www.avaje.org/bugdetail-176.html

The problem was there is optionally a Timer that is used to warm the
Ebean server cache. That Timer was not a daemon ... so effectively
stopped the JVM from shutting down - hence hanging for 30 secs or so.
The fix was to make the Timer a daemon - I also made the thread names
a bit more meaningful.


Fixed in HEAD.


Cheers, Rob.

On Oct 19, 7:38 pm, Rob Bygrave <robin.bygr...@gmail.com> wrote:
> Hmmm. Well, I wasn't able to reproduce... in that it terminated in about 1
> second or so.
>
> I wonder if it is specific to a particular JDK/JVM.
>

[Alex]

Thanks, with ebean 2.2.0 it works fine now. By the way, where can I get
the artifact com.oracle-oracle:10.2.0.2.0 from? I've created a dummy
oracle jdbc in order to compile ebean, but it would be nice if it were
possible to have references of closed source software out of
ebean-core. Maybe an ebean-oracle artifact?

Cheers, alx

2009/11/17 Rob Bygrave <robin....@gmail.com>

[Rob Bygrave]

> where can I get the artifact com.oracle-oracle:10.2.0.2.0 from?

I'm keen to put the non-maven dependencies (aka like the oracle jdbc driver) into svn so that people don't have to find it. Mario had a mechanism to do that with maven via 'system dependencies' I believe so I think (if I understood correctly) so I think we just need to re-instate that.

Yes, at the moment it's a PITA for anyone as they have to track down the Oracle jdbc drivers to compile from source.

Mario, if you have time you can re-instate that 'system dependency' thing you did and stick the oracle jdbc jar into svn.

NB: Just as a reminder ... the reason why we have a dependency on the Oracle jdbc drivers is that they don't fully support JDBC statement batching via the standard api (PreparedStatement.executeBatch()) - specifically it doesn't currently return the row counts from the batched statement execution (which we need for optimistic concurrency control). So for Oracle we need to use the OraclePreparedStatement - joy.