[appengine-java] Re: DEPLOYMENT FAILING AGAIN
Hi, I don't know why the pre-compilation has to be turned off - as far as I understand it, this activity occurs on the Google servers and it's there that the problem occurs. In one of the other deployment issue threads, Ikai mentioned that you can get around this issue by turning the pre-compilation off, so I'm just repeating that information! On Dec 14, 10:25 pm, J Handal jhand...@gmail.com wrote: Simon I have exactly the same problem.I upgraded de JRE and JDK to version 6 build 23(Last one) Why the jsp file don't compile? If you get the solution please let me know. -- You received this message because you are subscribed to the Google Groups Google App Engine for Java group. To post to this group, send email to google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
[appengine-java] Multiple Async get vs one Sync batch get?
Should I expect the similar performance? or the batch will always be better? -- You received this message because you are subscribed to the Google Groups Google App Engine for Java group. To post to this group, send email to google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
[appengine-java] Re: Synchronized reads/writes on a memcache variable
Hi,
I think the following should work with the following caveats:
- there's a small danger that if the server blows up before it
releases the lock, that no threads would be able to update your cache,
but since it's only a cache of data. This is easily mitigated by
introducing a task which periodically resets the lock.
- I still believe that there's the possibility that separate instances
will get a non-updated object, even if you use the locking, since I'm
assuming it takes x-amount of time for the changes in MemCache to
propagate throughout the instances. I may be wrong in this assumption
however.
Anyway, your code would go something like:
boolean lockAcquired = false;
try {
lockAcquired = acquireLock();
doStuff();
} finally {
if (lockAcquired) {
releaseLock();
}
}
With the locking code being:
public static boolean acquireLock() {
boolean lockAcquired = true;
try {
while (increment() != 1) {
decrement();
Thread.sleep(500);
}
} catch (Throwable t) {
// Log error
lockAcquired = false;
}
return lockAcquired;
}
public static void releaseLock() {
decrement();
}
private static void decrement() {
MemcacheServiceFactory.getMemcacheService().increment(LOCK,
-1, 0L);
}
private static Long increment() {
return
MemcacheServiceFactory.getMemcacheService().increment(LOCK, 1, 0L);
}
On Dec 14, 9:56 pm, Jay Young jaydevfollo...@gmail.com wrote:
Grr. Just noticed another issue. The cache item that you get the
index is not the same item as the lock, so really you need two
different cache items, one to make sure you have a unique value for
the lock, and the lock itself. The code above is correct, you just
need different keys for the first two cache reads.
If you can generate a guaranteed-unique name (maybe the thread ID +
time?), you can drop the first cache item and use that as the lock
value. This would also prevent the issue with the code above if the
lockIndex item is ever evicted and re-read at the same time (thus
returning 0 for both), or if it overflows the long.
(I honestly don't know if this is iron-clad, but intuitively it seems
like it would work with only very minor edge cases.)
On Dec 14, 4:08 pm, Andrei Cosmin Fifiiþã andrei.fifi...@gmail.com
wrote:
H, super...
I was thinking of smth like (val mod 2) == 0/1 (true/false), but the lock
reading wasn't safe.
Thanks!
On 14 December 2010 20:57, Jay Young jaydevfollo...@gmail.com wrote:
Except return lockIndex should just be return true.
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Re: [appengine-java] JavaMail Multipart message with inline images
Voted and added a comment. It really is amazing that this simple feature is not supported. -- You received this message because you are subscribed to the Google Groups Google App Engine for Java group. To post to this group, send email to google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
Re: [appengine-java] JSF: sudden ViewExpiredException on GAE
I'm currently looking at MemcacheService.SetPolicyhttp://code.google.com/appengine/docs/java/javadoc/com/google/appengine/api/memcache/MemcacheService.SetPolicy.html trying to find out what can be causing the problem. Can please anyone shed some light on: 1. Are changes of HttpSession attributes propagated into memcache first? If 'yes', what is the default SetPolicy then? 2. How data store service is involved in HttpSession handling? -- You received this message because you are subscribed to the Google Groups Google App Engine for Java group. To post to this group, send email to google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
Re: [appengine-java] Re: UserService functionality when run via cron
The bug reference would be nice. If only to vote it up. On Wed, Dec 15, 2010 at 2:10 AM, andrew aute...@gmail.com wrote: I submitted a bug on the subject, and it was accepted. If you want the bug reference I can find it. Andrew -- You received this message because you are subscribed to the Google Groups Google App Engine for Java group. To post to this group, send email to google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.comgoogle-appengine-java%2bunsubscr...@googlegroups.com . For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en. -- You received this message because you are subscribed to the Google Groups Google App Engine for Java group. To post to this group, send email to google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
[appengine-java] Re: Synchronized reads/writes on a memcache variable
On Dec 15, 8:23 am, Simon qila...@gmail.com wrote: since I'm assuming it takes x-amount of time for the changes in MemCache to propagate throughout the instances. I may be wrong in this assumption however. I don't think cache data is propagated to the various app instances. It resides in its own central (distributed) system and all handlers/ tasks/cron/whatever make RPC calls into the cache. -- You received this message because you are subscribed to the Google Groups Google App Engine for Java group. To post to this group, send email to google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
[appengine-java] Re: Synchronized reads/writes on a memcache variable
I considered the increment decrement approach, but it creates a race
condition with the counter. Having many different threads/tasks
trying to grab the lock at the same time could increment the number
above one, even when no one has the lock because there is still a
period of time between the increment() and decrement(). Remember,
these are RPC calls going over the network. If any part of that
interaction is slow, there will be even longer periods between the +1
and -1. I think this method errs on the side of accidentally locking
when there isn't a lock. The only negatives I see would apply to any
lock that's implemented in a cache.
On Dec 15, 8:23 am, Simon qila...@gmail.com wrote:
Hi,
I think the following should work with the following caveats:
- there's a small danger that if the server blows up before it
releases the lock, that no threads would be able to update your cache,
but since it's only a cache of data. This is easily mitigated by
introducing a task which periodically resets the lock.
- I still believe that there's the possibility that separate instances
will get a non-updated object, even if you use the locking, since I'm
assuming it takes x-amount of time for the changes in MemCache to
propagate throughout the instances. I may be wrong in this assumption
however.
Anyway, your code would go something like:
boolean lockAcquired = false;
try {
lockAcquired = acquireLock();
doStuff();} finally {
if (lockAcquired) {
releaseLock();
}
}
With the locking code being:
public static boolean acquireLock() {
boolean lockAcquired = true;
try {
while (increment() != 1) {
decrement();
Thread.sleep(500);
}
} catch (Throwable t) {
// Log error
lockAcquired = false;
}
return lockAcquired;
}
public static void releaseLock() {
decrement();
}
private static void decrement() {
MemcacheServiceFactory.getMemcacheService().increment(LOCK,
-1, 0L);
}
private static Long increment() {
return
MemcacheServiceFactory.getMemcacheService().increment(LOCK, 1, 0L);
}
On Dec 14, 9:56 pm, Jay Young jaydevfollo...@gmail.com wrote:
Grr. Just noticed another issue. The cache item that you get the
index is not the same item as the lock, so really you need two
different cache items, one to make sure you have a unique value for
the lock, and the lock itself. The code above is correct, you just
need different keys for the first two cache reads.
If you can generate a guaranteed-unique name (maybe the thread ID +
time?), you can drop the first cache item and use that as the lock
value. This would also prevent the issue with the code above if the
lockIndex item is ever evicted and re-read at the same time (thus
returning 0 for both), or if it overflows the long.
(I honestly don't know if this is iron-clad, but intuitively it seems
like it would work with only very minor edge cases.)
On Dec 14, 4:08 pm, Andrei Cosmin Fifiiþã andrei.fifi...@gmail.com
wrote:
H, super...
I was thinking of smth like (val mod 2) == 0/1 (true/false), but the lock
reading wasn't safe.
Thanks!
On 14 December 2010 20:57, Jay Young jaydevfollo...@gmail.com wrote:
Except return lockIndex should just be return true.
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[appengine-java] Re: Synchronized reads/writes on a memcache variable
I guess it depends on how much throughput you're expecting through the
bit of the system which requires the lock - I agree that if there is
huge contention then this isn't the way to go, although I'd argue that
you should be changing your design anyway since synchronizing across a
distributed architecture for a lot of threads is just unadvisable.
Memcache API calls currently take ~3ms according to the status page -
running a quick (and dirty ;) ) test with 100 threads attempting to
lock using the above method averages out at ~40ms for one of the
threads to obtain the lock. If the API call times increase from 3 to
10ms, the time taken for one of the threads to obtain the lock
actually decreases to ~30ms! The biggest risk you run is that because
it isn't FIFO, there may be a large portion of time before a
particular thread obtains the lock and so it may time out.
On Dec 15, 3:06 pm, Jay Young jaydevfollo...@gmail.com wrote:
I considered the increment decrement approach, but it creates a race
condition with the counter. Having many different threads/tasks
trying to grab the lock at the same time could increment the number
above one, even when no one has the lock because there is still a
period of time between the increment() and decrement(). Remember,
these are RPC calls going over the network. If any part of that
interaction is slow, there will be even longer periods between the +1
and -1. I think this method errs on the side of accidentally locking
when there isn't a lock. The only negatives I see would apply to any
lock that's implemented in a cache.
On Dec 15, 8:23 am, Simon qila...@gmail.com wrote:
Hi,
I think the following should work with the following caveats:
- there's a small danger that if the server blows up before it
releases the lock, that no threads would be able to update your cache,
but since it's only a cache of data. This is easily mitigated by
introducing a task which periodically resets the lock.
- I still believe that there's the possibility that separate instances
will get a non-updated object, even if you use the locking, since I'm
assuming it takes x-amount of time for the changes in MemCache to
propagate throughout the instances. I may be wrong in this assumption
however.
Anyway, your code would go something like:
boolean lockAcquired = false;
try {
lockAcquired = acquireLock();
doStuff();} finally {
if (lockAcquired) {
releaseLock();
}
}
With the locking code being:
public static boolean acquireLock() {
boolean lockAcquired = true;
try {
while (increment() != 1) {
decrement();
Thread.sleep(500);
}
} catch (Throwable t) {
// Log error
lockAcquired = false;
}
return lockAcquired;
}
public static void releaseLock() {
decrement();
}
private static void decrement() {
MemcacheServiceFactory.getMemcacheService().increment(LOCK,
-1, 0L);
}
private static Long increment() {
return
MemcacheServiceFactory.getMemcacheService().increment(LOCK, 1, 0L);
}
On Dec 14, 9:56 pm, Jay Young jaydevfollo...@gmail.com wrote:
Grr. Just noticed another issue. The cache item that you get the
index is not the same item as the lock, so really you need two
different cache items, one to make sure you have a unique value for
the lock, and the lock itself. The code above is correct, you just
need different keys for the first two cache reads.
If you can generate a guaranteed-unique name (maybe the thread ID +
time?), you can drop the first cache item and use that as the lock
value. This would also prevent the issue with the code above if the
lockIndex item is ever evicted and re-read at the same time (thus
returning 0 for both), or if it overflows the long.
(I honestly don't know if this is iron-clad, but intuitively it seems
like it would work with only very minor edge cases.)
On Dec 14, 4:08 pm, Andrei Cosmin Fifiiþã andrei.fifi...@gmail.com
wrote:
H, super...
I was thinking of smth like (val mod 2) == 0/1 (true/false), but the
lock
reading wasn't safe.
Thanks!
On 14 December 2010 20:57, Jay Young jaydevfollo...@gmail.com wrote:
Except return lockIndex should just be return true.
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[appengine-java] storing unowned objects(one to many) in datastore
Can we store two unowned objects(one to many) in datastore in a single
transaction.
For example - We have
public class Person {
@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
private Long id;
@Persistent
private String name;
@Persistent
private ListKey mobileIds = new ArrayListKey();
//
//.
}
public class Mobile {
@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
private Key mobileId;
// ...
//
}
I want to store these two objects in datastore in single transaction so that
relation can be made in between both objects.
Tell me if any other solution is there ?
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[appengine-java] Re: Does the local unit test framework use the same datastore-indexes.xml file as the app?
Also, a coworker was able to consistently generate a missing index exception from a local unit test, but I couldn't reproduce using the same code, so it doesn't seem we can rely on this mechanism to test our indexes until we figure out what's happening here. -- You received this message because you are subscribed to the Google Groups Google App Engine for Java group. To post to this group, send email to google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
[appengine-java] GWT and GAE debugging problem
Hey. Im starting with GAE, and im making an RCP program (a book address), on the server side I've got all the methods for manipulating the datastore (I'm using JPA), and on the client side I'm using GWT as a framework. When debugging it turns out, that I can only see the server side, and program never stops in any breakpoint on the client side. Is there any way that I can debug on both side sas the program runs. Because, just debugging on the server side is not very helpful. Thank you in advanced for your recomendation. Kido. -- You received this message because you are subscribed to the Google Groups Google App Engine for Java group. To post to this group, send email to google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
[appengine-java] Re: Synchronized reads/writes on a memcache variable
On Dec 15, 10:50 am, Simon qila...@gmail.com wrote: although I'd argue that you should be changing your design anyway since synchronizing across a distributed architecture for a lot of threads is just unadvisable. No doubt. I was simply commenting on the method in question. -- You received this message because you are subscribed to the Google Groups Google App Engine for Java group. To post to this group, send email to google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
[appengine-java] Re: Memcache entries - available how soon after entry?
So using UUID's class scope static variables I can now tell which JVM services each request. What I've confirmed is that at least when using reserved instances (Always On), Memcache entries are only found within the same JVM instance that created the cache entry. So I only get a cache hit if the next request goes to that same JVM. Is this expected behavior from Memcache, or should I raise a bug report? I pictured a highly-distributed memory cache available to the entire application. If it's per-JVM, I'm not sure why one wouldn't just use a Singleton or something to cache data, or why GAE RPC would be required when invoking the Memcache API. Thanks, Tom On Dec 14, 11:33 pm, Tom Phillips tphill0...@gmail.com wrote: I'm seeing unexpected (to me) Memcache behavior in my app ever since I enabled reserved instances (which I did first thing after 1.4.0). When one request adds a cache entry, subsequent requests anywhere from 10-60 seconds after are only able to find the entry sporadically. The cache is very lightly used and no expiry is set. I know that the correct key is being used by the writer and readers. The followup requests could be being handled by different JVM instances than the writer, but I wouldn't think this would make a difference. I'm not sure how to tell which instance services which request, I just now the request sequence. For all I know, the times it does find the cache entry might be only when serviced by the same JVM as the writer. Shouldn't Memcache entries be available to readers immediately after addition, and presumably available to all JVM instances? If not immediately for some reason, shouldn't they be available with 60 seconds? Thanks for any insight, Tom -- You received this message because you are subscribed to the Google Groups Google App Engine for Java group. To post to this group, send email to google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
[appengine-java] GWT Designer for NetBeans
Hey, is there any gwt designer for NetBeans out there?. It would be nice to place all the design and receive automatically the code for it. I have read theres a plugin for Eclipse but I can't find anything for NetBeans. Any sugestion?. Cheers. Kido. -- You received this message because you are subscribed to the Google Groups Google App Engine for Java group. To post to this group, send email to google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
[appengine-java] url fetch quota: ResponseTooLargeException
Hello, I got a ResponseTooLargeException when using the url fetch service. I checked the quota ( http://code.google.com/appengine/docs/java/urlfetch/overview.html#Quotas_and_Limits) and my request and response are within these quotas. Here is the response header when fetching the url in a browser: Date Wed, 15 Dec 2010 23:45:05 GMT Server Microsoft-IIS/6.0 X-Powered-By ASP.NET X-AspNet-Version 2.0.50727 Cache-Control private Content-Type text/xml; charset=utf-8 Content-Length 1141487 My app is not deployed on app engine, so I just tested locally. I am using app engine 1.4.0 Thanks -- You received this message because you are subscribed to the Google Groups Google App Engine for Java group. To post to this group, send email to google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
[appengine-java] Re: GWT Designer for NetBeans
Hi, A more appropriate place to post this question is http://groups.google.com/group/google-web-toolkit regards didier On Dec 15, 8:03 pm, kidowell crui...@gmail.com wrote: Hey, is there any gwt designer for NetBeans out there?. It would be nice to place all the design and receive automatically the code for it. I have read theres a plugin for Eclipse but I can't find anything for NetBeans. Any sugestion?. Cheers. Kido. -- You received this message because you are subscribed to the Google Groups Google App Engine for Java group. To post to this group, send email to google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
[appengine-java] Re: url fetch quota: ResponseTooLargeException
Hi, According to http://code.google.com/appengine/docs/java/tools/devserver.html#Using_URL_Fetch, there may be differences between dev server and real infrastructure. So, if I were you, I would quickly upload and make a test from the live env and see what happens. Let us know regards didier On Dec 16, 1:07 am, Sydney sydney.henr...@gmail.com wrote: Hello, I got a ResponseTooLargeException when using the url fetch service. I checked the quota (http://code.google.com/appengine/docs/java/urlfetch/overview.html#Quo...) and my request and response are within these quotas. Here is the response header when fetching the url in a browser: Date Wed, 15 Dec 2010 23:45:05 GMT Server Microsoft-IIS/6.0 X-Powered-By ASP.NET X-AspNet-Version 2.0.50727 Cache-Control private Content-Type text/xml; charset=utf-8 Content-Length 1141487 My app is not deployed on app engine, so I just tested locally. I am using app engine 1.4.0 Thanks -- You received this message because you are subscribed to the Google Groups Google App Engine for Java group. To post to this group, send email to google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
[appengine-java] Re: storing unowned objects(one to many) in datastore
Hi,
If they don't belong to the same entity group, you will raise an
exception by trying to store 2 objects in a single transaction.
2 ways to handle that:
a) you make Mobile belong to same entity group as Person so you'll
be able to store both in a single transaction. I understand in your
question that you can't go this way.
b) you store one let's say Person in first transaction and during
this transaction, you start a task as part of the transaction: You
can enqueue a task as part of a datastore transaction, such that the
task is only enqueued—and guaranteed to be enqueued—if the transaction
is committed successfully. Tasks added within a transaction are
considered to be a part of it and have the same level of isolation and
consistency. as said in
http://code.google.com/appengine/docs/java/taskqueue/overview.html#Tasks_Within_Transactions
Hope it helps
didier
On Dec 15, 8:26 am, kartik kudada kartik.kud...@gmail.com wrote:
Can we store two unowned objects(one to many) in datastore in a single
transaction.
For example - We have
public class Person {
@PrimaryKey
�...@persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
private Long id;
@Persistent
private String name;
@Persistent
private ListKey mobileIds = new ArrayListKey();
//
//.
}
public class Mobile {
�...@primarykey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
private Key mobileId;
// ...
//
}
I want to store these two objects in datastore in single transaction so that
relation can be made in between both objects.
Tell me if any other solution is there ?
--
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[appengine-java] Re: how to open an instance of a class
Hi, What you are trying to achieve is based on the reflection capabilities of Java and mainly the class java.lang.Class. (See http://download.oracle.com/javase/1.5.0/docs/api/java/lang/Class.html) To describe it shortly: a) use static method forName: Class.forName(yourClassName) b) then use reflection on the object of class Class that will be returned: class.getConstructors() to get the constructor you need c) read http://download.oracle.com/javase/tutorial/reflect/class/index.html and http://download.oracle.com/javase/tutorial/reflect/member/index.html to discover the next steps. This is fully possible as App Engine gives access to the reflection API of Java. I personnally use this API on GAE. regards didier On Dec 14, 10:41 pm, Abdel_eid a.eid.1...@gmail.com wrote: Dear All , I am working on a project in which the user enters the class name and data that he needs to add to the data store but i faced a big problem , i had successfully read the data from the user and checked it's correctness but i am trying to open a new instance of the class send by the user in the form of String for example String class_name = Student; String final_class_name = package_name + class_name; so how can i open an object of that sent class and also send the caught variables to it's constructor N.B i don't know how many classes i had or there name to check it with ( instance of ) Thanks for your attention -- You received this message because you are subscribed to the Google Groups Google App Engine for Java group. To post to this group, send email to google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
[appengine-java] Re: JSP compiling fails after upgrade from 1.3.8 to 1.4.0
Note that the previous post only applies to my local development environment. I just tried using the new version of the SDK on the production server, and it has no problems. -- You received this message because you are subscribed to the Google Groups Google App Engine for Java group. To post to this group, send email to google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
