It isn't bad only for write operations. Get operations have same CPU time in both storage type. http://code.google.com/intl/en/appengine/docs/java/datastore/hr/
On May 18, 7:47 pm, "Gregory D'alesandre" <[email protected]> wrote: > On Tue, May 17, 2011 at 10:13 PM, Robert Kluin <[email protected]>wrote: > > > Hi Greg, > > I'm looking forward to seeing the scheduler improvements in the > > coming weeks. Overall this looks promising, I'm actually pretty happy > > to see that the API calls 'with checks' will be included and just > > billed by time consumed. Is the 4x cost relative to a master-slave > > (M/S) or high-replication (HR) apps? Certainly if that is relative to > > M/S then it is not that bad, HR is totally worth it. ;) > > Good point! It is relative to M/S. > > > Thanks for listening to and addressing the community's feedback. > > We're trying our best, thanks for hanging in there :) > > > > > > > > > > > Robert > > > On Wed, May 18, 2011 at 00:49, Gregory D'alesandre <[email protected]> > > wrote: > > > Hello All! > > > As you've likely heard, when Google App Engine leaves Preview in the > > second > > > half of 2011, the pricing model will change. Prices are listed here: > > >http://www.google.com/enterprise/appengine/appengine_pricing.html. But > > that > > > leaves a lot of questions unanswered, this FAQ is intended to help answer > > > some of the frequently asked questions about the new model. We are > > > interested in hearing additional thoughts and comments you have based on > > > this. Once it is relatively stable I'll add it to our official docs. If > > > you find there is something you want to know but it is not yet answered, > > > just ask and I'll try to answer it as clearly as possible. We've made > > some > > > changes based on the feedback we've gotten (from this group in > > particular), > > > they are bolded below but not updated on the external pages yet. There > > are > > > still blanks to fill in and I will be sending that information to this > > group > > > first in order as it is available. Finally, thank you for your questions > > > and bearing with us as we are ironing out details, I and the whole App > > > Engine team very much appreciate it. > > > Greg D'Alesandre > > > Senior Product Manager, Google App Engine > > > > ------------------- > > > Definitions > > > Instance: A small virtual environment to run your code with a reserved > > > amount of CPU and Memory. > > > Frontend Instance: An Instance running your code and scaling dynamically > > > based on the incoming requests but limited in how long a request can run. > > > Backend Instance: An Instance running your code with limited scaling > > based > > > on your settings and potentially starting and stopping based on your > > > actions. > > > Scheduler: Part of the App Engine infrastructure that determines which > > > Instance should serve a request including whether or not a new Instance > > is > > > needed. > > > > Serving Infrastructure > > > Q: What’s an Instance? > > > A: When App Engine starts running your code it creates a small virtual > > > environment to run your code with a reserved amount of CPU and Memory. > > For > > > example if you are running a Java app, we will start a new JVM for you > > and > > > load your code into it. > > > > Q: Is an App Engine Instance similar to a VM from infrastructure > > providers? > > > A: Yes and no, they both have a set amount of CPU and Memory allocated to > > > them, but GAE instances don’t have the overhead of operating systems or > > > other applications running, so a much larger percentage of the CPU and > > > memory is considered “usable.” They also operate against high-level APIs > > and > > > not down through layers of code to virtual device drivers, so it’s more > > > efficient, and allows all the services to be fully managed. > > > > Q: How does GAE determine the number of Frontend Instances to run? > > > A: For each new request, the Scheduler decides whether there is an > > available > > > Instance for the request, the request should wait, or a new Instance > > should > > > be created to service the request. It looks at the number of Instances, > > the > > > throughput of the Instances, and the number of requests waiting. Based > > on > > > that it predicts how long it will take before it can serve the request > > (aka > > > the Pending Latency). If it predicts the delay will be over 1 second, a > > new > > > Instance is created. If it looks like an Instance is no longer needed, > > it > > > will take that Instance down. > > > > Q: Should I assume I will be charged for the number of Instances > > currently > > > being shown in the Admin console? > > > A: No, we are working to change the Scheduler to optimize the utilization > > of > > > instances, so that number should go down somewhat. If you are using > > Java, > > > you can also make your app threadsafe and take advantage of handling > > > concurrent requests. You can look at that as an upper bound on how many > > > Instances you will be charged for. > > > > Q: How can I control the number of instances running? > > > A: With the new Scheduler you’ll have the ability to choose a set of > > > parameters that will help you specify how many instances are spun up to > > > serve your traffic. More information about the specific parameters and > > how > > > they will affect the Scheduler will be available on this within a few > > weeks. > > > > Q: What can I control in terms of how many requests an Instance can > > handle? > > > A: The single largest factor is your application’s latency in handling > > the > > > request. If you service requests quickly, a single instance can handle a > > > lot of requests. Also, Java apps support concurrent requests, so it can > > > handle additional requests while waiting for other requests to complete. > > > This can significantly lower the number of Instances your app requires. > > > > Q: Will there be a solution for Python concurrency? Will this require > > any > > > code changes? > > > Python concurrency will be handled by our release of Python 2.7 on App > > > Engine. We’ve heard a lot of feedback from our Python users who are > > worried > > > that the incentive is to move to Java because of its support for > > concurrent > > > requests, so we’ve made a change to the new pricing to account for that. > > > While Python 2.7 support is currently in progress it is not yet done so > > we > > > will be providing a half-sized instance for Python (at half the price) > > until > > > Python 2.7 is released. > > > > Q: How many requests can an average instance handle? > > > A: Single-threaded Instances (python or java) can currently handle 1 > > > concurrent request. Single-threaded Instances (python or java) can > > > currently handle 1 concurrent request. Therefore there is a direct > > > relationship between the latency and number of requests which can be > > handled > > > on the instance per second, for instance: 10ms latency = 100 > > > request/second/Instance, 100ms latency = 10 request/second/Instance, etc. > > > Multi-Threaded Instances can handle many concurrent requests. Therefore > > > there is a direct relationship between the cpu consumed and the number of > > > requests/second. For instance, for a B4 (approx 2.4GHz) instance: > > consuming > > > 10 Mcycles/request = 240 request/second/Instance, 100 Mcycles/request = > > 24 > > > request/second/Instance, etc. These numbers are the ideal case but they > > are > > > pretty close to what you should be able to accomplish on an Instance. > > > Multi-Threaded instances are currently only supported for Java; we are > > > planning support for Python later this year. > > > > Q: Why is Google charging for instances rather than CPU as in the old > > model? > > > Were customers really asking for this? > > > A: CPU time only accounts for a portion of the resources used by App > > Engine. > > > When App Engine runs your code it creates an Instance, this is a maximum > > > amount of CPU and Memory that can be used for running a set of your code. > > > Even if the CPU is not currently working due to waiting for responses, > > the > > > instance is still resident and considered “in use” so, essentially, it > > still > > > costs Google money. Under the current model, apps that have high latency > > > (or in other words stay resident for long periods of time without doing > > > anything) are not able to scale because it would be cost-prohibitive to > > > Google. So, this change is designed to allow developers to run any sort > > of > > > application they would like but pay for all of the resources that are > > being > > > used. > > > > Q: What does this mean for existing customers? > > > A: Many customers have optimized for low CPU usage to keep bills low, but > > in > > > turn are often using a large amount of memory (by having high latency > > > applications). This new model will encourage low latency applications > > even > > > if it means using larger amounts of CPU. > > > > Q: How will always-on work under the new model? > > > A: Still determining how this will work, answer coming very soon (no > > > seriously, we are almost done). > > > > Q: What is the difference between On-demand Instances and Reserved > > > Instances? > > > A: On-demand Instances have no pre-commitment in terms of the number that > > > will be used. You pay for them as you use them. Reserved Instances are > > > pre-commitment to a certain number of Instance Hours in a week. They are > > > cheaper but you must pay for all the Instance Hours that you have > > > pre-committed to whether you use them or not. This does not mean they > > have > > > to be running the whole time. > > > > Q: Wait, so Reserved instances don’t mean you have to keep them running > > the > > > whole time? > > > A: No, it is just a way to get cheaper instance-hours by pre-committing > > to > > > them. > > > > Q: What is the time granularity of the instance pricing? ie if I have an > > > instance up for 5 minutes, what am I charged, $0.08 / 60*5? > > > A: Instances are charged for their uptime and until they are idle for 15 > > > minutes (when the scheduler takes them down). So if you have an > > on-demand > > > Instance only serving traffic for 5 minutes, you will pay for 5+15 > > minutes, > > > or $0.08 / 60 * 20 = 2.6 cents. > > > > Q: You seem to be trying to account for RAM in the new model. Will I be > > > able to purchase Frontend Instances that use different amounts of memory? > > > A: We are... > > read more » -- You received this message because you are subscribed to the Google Groups "Google App Engine" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en.
