On Thu, Jun 9, 2016 at 6:50 PM, YuRen Lin <yuren...@gmail.com> wrote:
> Hi, Nicholas > > Thanks for your explanation. Very nice. I think the most simple and > fastest way is to store all these constants in resource file and then load > them to instance memory. Do you know how much instance memory a Java App > Engine can hold? > Depends on your instance class -- per the intro at https://cloud.google.com/appengine/docs/java/an-overview-of-app-engine , you can get up to a GB by configuring your instance class as F4_1G (if you choose the default scaling mode, automatic scaling; with manual or basic scaling, B4_1G) though defaults are way smaller. Alex > 'Nicholas (Google Cloud Support)' via Google App Engine < > google-appengine@googlegroups.com> 於 2016年6月10日 星期五寫道： > >> Thanks for sharing your question and situation here. >> >> From what I understand of your scenario, accessing a large array of >> integers from memcache and occasionally Datastore is not quite as fast as >> is needed for your implementation. >> >> The fastest as you suggested would be to have all constants loaded within >> instance memory. There would be a few different points to consider if >> using this route that regard performance: >> >> - Compile time >> - Start-up time >> - Read time >> >> Compile time >> This cost is only paid once and is not incurred by your end users which I >> believe is your main concern. >> >> Start-up time >> This may be longer if hard-coding all your constants into your Java >> code. This would still only be paid when starting instances and may not be >> all that significant. I might suggest testing start-up times with some >> logging to really know what the time cost would be. This time however, >> will not affect too many end-users barring the occasional ones to be >> waiting for instance to be available. >> >> Read time >> This should be very fast with an *int* >> <https://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html> >> array and still quite fast with a *HashMap* >> <https://docs.oracle.com/javase/7/docs/api/java/util/HashMap.html>. >> Both of these would have a negligible memory footprint if existing once per >> instance (as opposed to once per request). >> >> If you noticed start-up time being a problem, you could instead store the >> constants in a file accessible to your App Engine service using >> *<resource-files>* >> <https://cloud.google.com/appengine/docs/java/config/appref#resource_files> >> or a Cloud Storage bucket >> <https://cloud.google.com/appengine/docs/java/googlecloudstorageclient/read-write-to-cloud-storage#reading_from_cloud_storage> >> and only load it upon the first request. For example in pseudo-code: >> HashMap constants = null; >> >> >> private void loadConstants() { >> // retrieve values from constants.json >> // and set to constants HashMap >> } >> >> >> public void doGet(...) { >> if (constants == null) { >> loadConstants(); >> } >> // serve response >> } >> >> The trade off here is that the time cost of getting the constants into >> instance memory is only paid during the first request. You should also >> consider deferring it to a warm-up request >> <https://cloud.google.com/appengine/docs/java/warmup-requests/> as they >> are excellent for these sorts of tasks. >> >> Hope this helps! >> >> On Wednesday, June 8, 2016 at 11:20:03 PM UTC-4, YuRen Lin wrote: >>> >>> Hi, all >>> >>> I am in the game industry and use Google App Engine as my backend >>> server. My problem is we do the game logic calculation in the server side >>> and use thousands of Constants which read from csv files. Our current >>> solution is to read CSV files and store them into the datastore. Then when >>> a request comes, the servlet checks memcache first, if miss read from >>> datastore. This is done automatically by Objectify. I am wondering if there >>> is other more effective way to do this. >>> >>> Other solutions include: >>> 1. store all constants in the servlet as int array. But I think the >>> launch overhead may be a lot, since there are thousands more constants. >>> 2. read constant from csv files each time the servlet needs it. I don't >>> think this is a good idea. >>> >>> >>> Thanks in advance. First time to post here. >>> >> -- >> You received this message because you are subscribed to a topic in the >> Google Groups "Google App Engine" group. >> To unsubscribe from this topic, visit >> https://groups.google.com/d/topic/google-appengine/Ap8z5OsgiFg/unsubscribe >> . >> To unsubscribe from this group and all its topics, send an email to >> google-appengine+unsubscr...@googlegroups.com. >> To post to this group, send email to google-appengine@googlegroups.com. >> Visit this group at https://groups.google.com/group/google-appengine. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/google-appengine/addc1755-0d84-4018-bec3-faae4f3f18c9%40googlegroups.com >> <https://groups.google.com/d/msgid/google-appengine/addc1755-0d84-4018-bec3-faae4f3f18c9%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> For more options, visit https://groups.google.com/d/optout. >> > > > -- > ---- > YuRen Lin > Skype: yuren892 > QQ: 2254642234 > > -- > You received this message because you are subscribed to the Google Groups > "Google App Engine" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to google-appengine+unsubscr...@googlegroups.com. > To post to this group, send email to google-appengine@googlegroups.com. > Visit this group at https://groups.google.com/group/google-appengine. > To view this discussion on the web visit > https://groups.google.com/d/msgid/google-appengine/CADQfWyZkYJVTHVbBObeKfCFMp5K6dLZaFdt8LN%2Bs6EXM8xKCQA%40mail.gmail.com > <https://groups.google.com/d/msgid/google-appengine/CADQfWyZkYJVTHVbBObeKfCFMp5K6dLZaFdt8LN%2Bs6EXM8xKCQA%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "Google App Engine" group. 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