On Tue, Jun 21, 2011 at 6:33 PM, Tom Phillips <tphill0...@gmail.com> wrote:
> Hi Jon,
>
> I raised issue http://code.google.com/p/googleappengine/issues/detail?id=5214
> on the non-loading requests resulting in instance deaths with
> threadsafe on. It was a bit more verbose than it probably needs to be,
> but it describes the problem.
Thanks! It's very helpful.
>
> If anyone knows another way to detect loading requests that works with
> threadsafe on, let me know. There is no guarantee that the servlet
> context is loaded during the loading request, so that's out for now,
> but if anyone knows another trick it will create options to work
> around the problem until a fix is available.
>
> Otherwise, I can disable threadsafe for now. But I'm reluctant - the
> efficiency is strangely reassuring..
Of course, you've got another workaround so that's better than turning
off threadsafe. Makes sense.
>
> /Tom
>
>
>
> On Jun 21, 1:25 pm, Jon McAlister <jon...@google.com> wrote:
>> Hi Tom,
>>
>> I'm not sure about the servlet context listener code.
>>
>> However, thanks for pointing out the behavior of the interaction of
>> loading requests and threadsafe apps. We are indeed sending down
>> non-loading-requests while the instance is still processing the
>> loading request. This is problematic (for the reasons you list) and
>> something we didn't anticipate. We'll try to get a fix in to one of
>> the next releases. If you file it as an external issue we can use that
>> to notify when its closed. Until then your suggested workaround is
>> good, the other known workaround being to turn off threadsafe.
>>
>> Thanks for bringing this to our attention.
>>
>> On Sun, Jun 19, 2011 at 5:11 PM, Tom Phillips <tphill0...@gmail.com> wrote:
>> > The GAE documentation says you can detect loading requests like this:
>>
>> > // web.xml snippet
>> > <listener>
>> > <listener-class>
>> > com.example.LogLoadingRequest
>> > </listener-class>
>> > </listener>
>>
>> > // LogLoadingRequest.java
>> > public class LogLoadingRequest implements ServletContextListener {
>> > private static final Logger logger =
>> > Logger.getLogger(LogLoadingRequest.class.getName());
>> > public void contextInitialized(ServletContextEvent sce) {
>> > logger.log(Level.INFO, "Loading request occuring.");
>> > }
>>
>> > public void contextDestroyed(ServletContextEvent sce) {
>> > }
>> > }
>>
>> > But I'm finding from my logs that what GAE thinks is a loading request
>> > (identified in log as loading_request=1) and which is given longer
>> > deadline, does NOT always match the request that logs the above
>> > "Loading request occuring." when Threadsafe is on.
>>
>> > Should it, or is this method obsolete for threadsafe instances? Is
>> > there some other way I can detect loading vs non-loading requests with
>> > threadsafe on?
>>
>> > With threadsafe on, non-loading requests are being assigned by GAE to
>> > instances while the loading request is still happening, resulting in
>> > all sort of (Hard)DeadlineExceeded issues in the non-loading requests.
>> > Reason is, loading requests are showing huge slow down and variance in
>> > loading times lately, often exceeding the 30 seconds that non-loading
>> > request are allowed - even though in my case loading should only take
>> > about 4 seconds (jaxb,PMF) plus whatever classloading and jvm startup
>> > takes. Worst thing is, these exceptions bring down the instance before
>> > loading can even finish, requiring multiple startup attempts. I'm
>> > trying to work around it by detecting loading vs. non-loading requests
>> > and in non-loading either doing a no-op if not critical, or proxying
>> > via urlfetch through to a backend until the loading request is
>> > complete.
>>
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>>
>
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