Hey Maxim, Batch calls can reduce your latency allowing your app to service requests much faster -- so batching is still going to be a good idea. Also, be sure to check out the async db methods, they can help reduce latency even further.
Robert On Wed, May 18, 2011 at 02:54, Maxim Lacrima <[email protected]> wrote: > Hi! > > Under the new model for the Datastore API calls, does it mean that I don't > care anymore about performing operations in batches? So in terms of costs > db.get(key1); db.get(key2) is essentially the same as db.get([key1, key2])? > > Thank you! > > On 18 May 2011 07:49, 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 only planning on having one size of Frontend Instance. >> >> Q: Do Frontend instances handle Task Queues and Cron? >> A: Yes. >> >> Q: Can the experimental Go Runtime handle concurrent requests? >> A: Not currently. >> >> Costs >> Q: Is the $9/app/month a fee or a minimum spend? >> A: Based on the feedback we’ve received we are changing this $9 fee to be >> a minimum spend rather than a fee a originally listed. In other words you >> will still have to spend $9/month in order to scale but you won’t pay an >> additional $9 for your first $9 worth of usage each month. The >> $500/account/month will still be a fee as it covers the cost of operational >> support. >> >> Q: Will most customers have to move to Paid Apps? >> A: No, we expect the majority of current active apps will still fall under >> the free quota. >> >> Q: Will existing apps be grandfathered in and continue under today’s >> billing model? >> A: No, existing apps will fall under the new billing model once App Engine >> is out of preview. >> >> Q: Will most customers’ bills increase? If so, why is Google increasing >> the price for App Engine? >> A: Yes, most paying customers will see higher bills. During the preview >> phase of App Engine we have been able to observe what it costs to run the >> product as well as what typical use patterns have been. We are changing the >> prices now because GAE is going to be a full product for Google and >> therefore needs to have a sustainable revenue model for years to come. >> >> APIs >> Q: How were the APIs priced? >> A: For the most part the APIs are priced similarly to what they cost >> today, but rather than charging for CPU hours we are charging for >> operations. For instance the Channel API is $0.01/100 channels. This is >> approximately what users pay today (although it would be paid as a fraction >> of a CPU hour). The datastore API is the most significantly changed and is >> described below. >> >> Q: For the items under APIs on the pricing page that just have a check, >> what does that mean? >> A: Those items come free with using App Engine. >> >> Q: For XMPP, how does the new model work? How much do presence messages >> cost? >> A: For XMPP we will only be charging an operation fee for outgoing >> stanzas. Incoming stanzas are just considered requests similar to any other >> request and so we’ll charge for the bandwidth used as well as whatever it >> takes to process the request in terms of Instance Hours. We don’t charge >> for presence messages other than the bandwidth it consumes. This is almost >> exactly how it works today with the exception that your bill would show CPU >> hours as opposed to Stanzas. >> >> Q: For Email, how much do incoming emails cost? >> A: Incoming emails will just be considered requests similar to any other >> request and so we’ll charge for the bandwidth used as well as whatever it >> takes to process the request in terms of Instance Hours. This is in essence >> how it works today. >> >> Q: Will the Front End Cache feature ever be formalized as an expected, >> documented part of the service offering? >> A: We are currently looking at various options, but don’t yet have any >> plans for when this would happen. >> >> Q: What is being charged for in terms of Datastore operations? What do >> you expect the ratio to be between the new pricing metric and the Datastore >> API calls metric we have today? >> A: Today we charge for the CPU consumed per entity written, index written, >> entity read, query index scanned, and query result read. Under the new >> model we will charge per operation rather than CPU, and we will no longer >> charge for query index scans. This means the cost of your queries will be >> tied exclusively to the size of your result set. We expect the cost of >> these operations will be approximately 4x the cost of the equivalent CPU >> under today’s model, but for apps that make heavy use of indexes, this will >> be somewhat offset by the fact that we will no longer be charging for query >> index scans. The admin console today shows total Datastore API Calls, but >> this is not a good gauge of how many operations you will be charged for >> under the new model. Your costs will be highly dependent on the types and >> contents of your API calls, not the number of calls themselves, which is >> what we currently display. For example a single get() API call may retrieve >> 1 Entity or 100 Entities, and a beginTransaction() API call doesn’t consume >> any billable resources. >> >> Q: Could emails sent to admins be cheaper or free? >> A: That’s a possibility that we can look into. >> >> Usage Types >> Q: What does the Premier cost of "$500/account" mean? Per Google Apps >> Account? Per Developer Account, Per Application Owner Account? >> A: It is per Organization (which would translate into per Google Apps >> account if you are currently a Google Apps customer). So, for instance if >> you are working at gregco.com and you signed up for a Premier account, >> gregco.com users will be able to create apps which are billed to the >> gregco.com account. >> >> Q: Will there be special programs for non-profit usage? >> A: Possibly, we are currently looking into this. >> >> Q: Will there be special programs for educational usage? >> A: Possibly, we are currently looking into this. >> >> Q: Will there be special programs for open-source projects? >> A: Possibly, we are currently looking into this. >> >> Usage Limits >> Q: If I migrate to HR Datastore, does that mean I have a "newly created" >> application, and will get the new, lower, free quota for email? Could you >> grandfather in migrated apps at the old 2000 limit? >> A: Yes, we can grandfather in the email quota for HRD apps that are >> migrating from M/S apps. >> >> -- >> 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. > > > > -- > with regards, > Maxim > > -- > 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. > -- You received this message because you are subscribed to the Google Groups "Google App Engine" group. 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