Deploying a new version has no effect on data stored in the datastore.
What do you mean by "initialize" your app. If you are referring to
loading data into memory then that needs to be done for every instance
of your app that is loaded. Not just once per deployment.
On 19 Mar 2010, at 19:10, Ali Ok wrote:
Ok, I understood this one. However, I think you should warn the
developers not to use static variables at all, in a large and red
styled documentation paragraph.
In this case, assume that every static variable is converted, and they
all being set from Datastore.
However, this does not solve the problem.
Let me explain an example:
* After deployment, at the first request, let me put a flag,
"initialized=true", into datastore
* On later requests, my app does not need to be initialized, since I
get initialized=true from Datastore. Everything is cool.
* Let's make a new deployment to App Engine at this stage.
* After deployment of a new version, my app needs to be intialized
again
* In the code, once again I check my "initialized" flag from Datastore
is "true", since a new deployment doesn't clear the stored data,
right?
* How to determine that a new deployment is made, and the
initialization needs to be run again?
What are the effects of a new deployment to the Datastore?
Thanks for your replies,
Ali
On 18 Mart, 22:34, Don Schwarz <[email protected]> wrote:
Unlike most Java hosting providers, we load and unload your code on
JVMs as
your load patterns change. This will result in static variable
static being
lost, and as a result you should only expect durability of data
stored in
the datastore. Transient data should generally be stored in
memcache,
although data may be evicted from memcache as well.
For more information, see:
http://code.google.com/appengine/kb/
java.html#What_Causes_Loading_Req...
On Thu, Mar 18, 2010 at 9:34 AM, Ali Ok <[email protected]> wrote:
Hi,
I am trying to implement Google App Engine support for Myfaces 2.
You
can see the work [1] [2].
At the moment, I am making some trials to identify the problem at
[2].
I am experiencing an interesting problem. My filter's static
variable
is lost after some time(ie. 3 minutes)
I have a filter like this:
public class TestFilter implements Filter
{
...
private static String myStaticVariable;
public void doFilter(ServletRequest arg0, ServletResponse arg1,
FilterChain arg2) throws IOException, ServletException
{
log.warning("myStaticVariable" + myStaticVariable);
if(myStaticVariable==null)
myStaticVariable = "someValue";
arg2.doFilter(arg0, arg1);
}
...
}
When I make the first request, "myStaticVariable" is set to
"someValue". If I make a request in a short period (ie. 20
seconds), I
see that value of "myStaticVariable" is still "someValue".
However, after 3 minutes, when I make another request, I see that
"myStaticVariable" is set to its default value (null).
Why are my static variables are gone? Am I doing something wrong?
I can understand that the reconstruction of the filter and loss of
instance variables; we are trying to run our application on cloud.
But loss of static variables are completely weird.
I couldn't find an issue on Google Code project, thus wanted to ask
you before opening an issue.
Thanks,
Ali
[1]https://issues.apache.org/jira/browse/MYFACES-2559
[2]https://issues.apache.org/jira/browse/MYFACES-2606
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