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  • Theory: "Lexical Encoding"

    - by _ande_turner_
    I am using the term "Lexical Encoding" for my lack of a better one. A Word is arguably the fundamental unit of communication as opposed to a Letter. Unicode tries to assign a numeric value to each Letter of all known Alphabets. What is a Letter to one language, is a Glyph to another. Unicode 5.1 assigns more than 100,000 values to these Glyphs currently. Out of the approximately 180,000 Words being used in Modern English, it is said that with a vocabulary of about 2,000 Words, you should be able to converse in general terms. A "Lexical Encoding" would encode each Word not each Letter, and encapsulate them within a Sentence. // An simplified example of a "Lexical Encoding" String sentence = "How are you today?"; int[] sentence = { 93, 22, 14, 330, QUERY }; In this example each Token in the String was encoded as an Integer. The Encoding Scheme here simply assigned an int value based on generalised statistical ranking of word usage, and assigned a constant to the question mark. Ultimately, a Word has both a Spelling & Meaning though. Any "Lexical Encoding" would preserve the meaning and intent of the Sentence as a whole, and not be language specific. An English sentence would be encoded into "...language-neutral atomic elements of meaning ..." which could then be reconstituted into any language with a structured Syntactic Form and Grammatical Structure. What are other examples of "Lexical Encoding" techniques? If you were interested in where the word-usage statistics come from : http://www.wordcount.org

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  • Is there a way to toggle bluetooth and/or wifi on and off programatically in iOS?

    - by Andy W
    I am looking for an easy way to toggle both bluetooth and wifi between on and off states on iOS 4.x devices (iPhone and iPad). I am constantly toggling these functions as I move between different locations and usage scenarios, and right now it takes multiple taps and visits to the Settings App. I am looking to create a simple App, that lives on Springboard, that I can just tap and it will turn off the wifi if it's on, and vice versa, then immediately quit. Similarly with an App for toggling bluetooth’s state. I have the developer SDK, and am comfortable in Xcode and with iOS development, so am happy to write the required Xcode to create the App. I am just at a loss as to which API, private or not, has the required functionality to simply toggle the state of these facilities. Because this is scratching a very personal itch, I have no intent to try and sell the App or get it up on the App store, so conforming with App guidelines on API usage is a non-issue. What I don’t want to do is jailbreak the devices, as I want to keep the core software as shipped. Can anyone point me at some sample code or more info on achieving this goal, as my Google-fu is letting me down, and if the information is out there for 4.x devices I just can’t find it.

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  • Using memory-based cache together with conventional cache

    - by Industrial
    Hi! Here's the deal. We would have taken the complete static html road to solve performance issues, but since the site will be partially dynamic, this won't work out for us. What we have thought of instead is using memcache + eAccelerator to speed up PHP and take care of caching for the most used data. Here's our two approaches that we have thought of right now: Using memcache on all<< major queries and leaving it alone to do what it does best. Usinc memcache for most commonly retrieved data, and combining with a standard harddrive-stored cache for further usage. The major advantage of only using memcache is of course the performance, but as users increases, the memory usage gets heavy. Combining the two sounds like a more natural approach to us, even though the theoretical compromize in performance. Memcached appears to have some replication features available as well, which may come handy when it's time to increase the nodes. What approach should we use? - Is it stupid to compromize and combine the two methods? Should we insted be focusing on utilizing memcache and instead focusing on upgrading the memory as the load increases with the number of users? Thanks a lot!

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  • Swig C++ Lua Pass class by reference

    - by Jeremy
    I don't know why I'm having a hard time with this. All I want to do is this: class foo { public: foo(){} ~foo(){} float a,b; }; class foo2 { public: foo2(){} foo2(const foo &f){*this = f;} ~foo2(){} void operator=(const foo& f){ x = f.a; y = f.b; } float x,y; }; /* Usage(cpp): foo f; foo2 f2(f); //or using the = operator f2 = f; */ The problem I'm having is that, after swigging this code, I can't figure out how to make the lua script play nice. /* Usage(lua) f = example.foo() f2 = example.foo2(f) --error */ The error I get is "Wrong arguments for overloaded function 'new_Foo2'": Possible c/c++ prototypes are: foo2() foo2(foo const &) The same thing happens if I try and use do f2 = f. As I understand it everything is stored as a pointer so I did try adding an additional constructor that took a pointer to foo but to no avail.

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  • A commercial software but open and free for personal/edu. How to license?

    - by Ivan
    I am developing a software to sell for business use but am willing to make it free and open-source for personal and educational use. Actually I can see the flowing requirements I would like the license to set: Personal and educational usage of the program and its source codes is to be free. In case of publishing of derivative works the original work and author (me) must be mentioned (incl. textual link to my website in a not-very-far-hidden place) and the derivative work must have different name. A derivative work can be closed-source. In every case of commercial (when the end-user is a commercial body (as a company (expect of non-profit organizations), an individual entrepreneur or government office)) usage of my work or any of derivative works made by anyone, the end-user, service provider or the derivative author must buy a commercial license from me. I mean no guarantees or responsibilities, whether expressed or implied... (except the case when one explicitly purchases a support service contract from me and the particular contract specifies a responsibility). Is there a known common license for this case? As far as I can see now it can not be OSI-approved as it does not comply to the §6. of OSI definition of open source. But there still can be an a common known reusable license for this case as it looks quite natural, I think.

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  • Upload using python script takes very long on one laptop as compared to another

    - by Engr Am
    I have a python 2.7 code which uses STORBINARY function for uploading files to an ftp server and RETRBINARY for downloading from this server. However, the issue is the upload is taking a very long time on three laptops from different brands as compared to a Dell laptop. The strange part is when I manually upload any file, it takes the same time on all the systems. The manual upload rate and upload rate with the python script is the same on the Dell Laptop. However, on every other brand of laptop (I have tried with IBM, Toshiba, Fujitsu-Siemens) the python script has a very low upload rate than the manual attempt. Also, on all these other laptops, the upload rate using the python script is the same (1Mbit/s) while the manual upload rate is approx. 8 Mbit/s. I have tried to vary the filesize for the upload to no avail. TCP Optimizer improved the download rate on all the systems but had no effect on the upload rate. Download rate using this script on all the systems is fine and same as the manual download rate. I have checked the server and it has more than 90% free space. The network connection is the same for all the laptops, and I try uploading only with one laptop at a time. All the laptops have almost the same system configurations, same operating system and approximately the same free drive space. If anything the Dell laptop is a little less in terms of processing power and RAM than 2 of the others, but I suppose this has no effect as I have checked many times to see how much was the CPU usage and network usage during these uploads and downloads, and I am sure that no other virus or program has been eating up my bandwidth. Here is the code ('ftp' and 'file_path' are inputs to the function): path,filename=os.path.split(file_path) filesize=os.path.getsize(file_path) deffilesize=(filesize/1024)/1024 f = open(file_path, "rb") upstart = time.clock() print ftp.storbinary("STOR "+filename, f) upende = time.clock()-upstart outname="Upload " f.close() return upende, deffilesize, outname

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  • Array of templated structs

    - by Jakub Mertlik
    I have structs templated by int derived from a Base struct. struct Base { int i; double d; }; template< int N > struct Derv : base { static const int mN = N; }; I need to make an array of Derv< N where N can vary for each struct in that array. I know C/C++ does not allow arrays of objects of different types, but is there a way around this? I was thinking of separating the type information somehow (hints like pointers to Base struct or usage of union spring to my mind, but with all of these I don't know how to store the type information of each array element for usage DURING COMPILE TIME). As you can see, the memory pattern of each Derv< N is the same. I need to access the type of each array element for template specialization later in my code. The general aim of this all is to have a compile-time dispatch mechanism without the need to do a runtime "type switch" somewhere in the code. Thank you.

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  • What is the purpose of the s==NULL case for mbrtowc?

    - by R..
    mbrtowc is specified to handle a NULL pointer for the s (multibyte character pointer) argument as follows: If s is a null pointer, the mbrtowc() function shall be equivalent to the call: mbrtowc(NULL, "", 1, ps) In this case, the values of the arguments pwc and n are ignored. As far as I can tell, this usage is largely useless. If ps is not storing any partially-converted character, the call will simply return 0 with no side effects. If ps is storing a partially-converted character, then since '\0' is not valid as the next byte in a multibyte sequence ('\0' can only be a string terminator), the call will return (size_t)-1 with errno==EILSEQ. and leave ps in an undefined state. The intended usage seems to have been to reset the state variable, particularly when NULL is passed for ps and the internal state has been used, analogous to mbtowc's behavior with stateful encodings, but this is not specified anywhere as far as I can tell, and it conflicts with the semantics for mbrtowc's storage of partially-converted characters (if mbrtowc were to reset state when encountering a 0 byte after a potentially-valid initial subsequence, it would be unable to detect this dangerous invalid sequence). If mbrtowc were specified to reset the state variable only when s is NULL, but not when it points to a 0 byte, a desirable state-reset behavior would be possible, but such behavior would violate the standard as written. Is this a defect in the standard? As far as I can tell, there is absolutely no way to reset the internal state (used when ps is NULL) once an illegal sequence has been encountered, and thus no correct program can use mbrtowc with ps==NULL.

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  • Using memcache together with conventional cache

    - by Industrial
    Hi! Here's the deal. We would have taken the complete static html road to solve performance issues, but since the site will be partially dynamic, this won't work out for us. What we have thought of instead is using memcache + eAccelerator to speed up PHP and take care of caching for the most used data. Here's our two approaches that we have thought of right now: Using memcache on all<< major queries and leaving it alone to do what it does best. Usinc memcache for most commonly retrieved data, and combining with a standard harddrive-stored cache for further usage. The major advantage of only using memcache is of course the performance, but as users increases, the memory usage gets heavy. Combining the two sounds like a more natural approach to us, even though the theoretical compromize in performance. Memcached appears to have some replication features available as well, which may come handy when it's time to increase the nodes. What approach should we use? - Is it stupid to compromize and combine the two methods? Should we insted be focusing on utilizing memcache and instead focusing on upgrading the memory as the load increases with the number of users? Thanks a lot!

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  • Why does Hibernate 2nd level cache only cache queries within a session?

    - by Synesso
    Using a named query in our application and with ehcache as the provider, it seems that the query results are tied to the session within the cache. Any attempt to access the value from the cache for a second time results in a LazyInitializationException We have set lazy = true for the following mapping because this object is also used by another part of the system which does not require the reference... and we want to keep it lean. <class name="domain.ReferenceAdPoint" table="ad_point" mutable="false" lazy="false"> <cache usage="read-only"/> <id name="code" type="long" column="ad_point_id"> <generator class="assigned" /> </id> <property name="name" column="ad_point_description" type="string"/> <set name="synonyms" table="ad_point_synonym" cascade="all-delete-orphan" lazy="true"> <cache usage="read-only"/> <key column="ad_point_id" /> <element type="string" column="synonym_description" /> </set> </class> <query name="find.adpoints.by.heading">from ReferenceAdPoint adpoint left outer join fetch adpoint.synonyms where adpoint.adPointField.headingCode = ?</query> Here's a snippet from our hibernate.cfg.xml <property name="hibernate.cache.provider_class">net.sf.ehcache.hibernate.SingletonEhCacheProvider</property> <property name="hibernate.cache.use_query_cache">true</property> It doesn't seem to make sense that the cache would be constrained to the session. Why are the cached queries not usable outside of the (relatively short-lived) sessions?

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  • x509 certificate Information

    - by sid
    Certificate: Data: Version: 3 (0x2) Serial Number: 95 (0x5f) Signature Algorithm: sha1WithRSAEncryption Issuer: C=, O=, CN= Validity Not Before: Apr 22 16:42:11 2008 GMT Not After : Apr 22 16:42:11 2009 GMT Subject: C=, O=, CN=, L=, ST= Subject Public Key Info: Public Key Algorithm: rsaEncryption RSA Public Key: (1024 bit) Modulus (1024 bit): ... ... ... Exponent: 65537 (0x10001) X509v3 extensions: X509v3 Key Usage: critical Digital Signature, Key Encipherment X509v3 Extended Key Usage: critical Code Signing X509v3 Authority Key Identifier: keyid: ... Signature Algorithm: sha1WithRSAEncryption a9:55:56:9b:9e:60:7a:57:fd:7:6b:1e:c0:79:1c:50:62:8f: ... ... -----BEGIN CERTIFICATE----- ... ... ... -----END CERTIFICATE----- In This Certificate, Which is the public key? is Modulus? what does the Signature Algorithm, a9:55:56:... represent (is it message digest)? And what is between -----BEGIN CERTIFICATE----- & -----END CERTIFICATE-----, is That the whole certificate? As I am novice, little bit confusing between the message digest and public key? Thanks in Advance-opensid

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  • Any useful suggestions to figure out where memory is being free'd in a Win32 process?

    - by LeopardSkinPillBoxHat
    An application I am working with is exhibiting the following behaviour: During a particular high-memory operation, the memory usage of the process under Task Manager (Mem Usage stat) reaches a peak of approximately 2.5GB (Note: A registry key has been set to allow this, as usually there is a maximum of 2GB for a process under 32-bit Windows) After the operation is complete, the process size slowly starts decreasing at a rate of 1MB per second. I am trying to figure out the easiest way to quickly determine who is freeing this memory, and where it is being free'd. I am having trouble attaching a memory profiler to my code, and I don't particularly want to override the new/delete operators to track the allocations/deallocations (IOW, I want to do this without re-compiling my code). Can anyone offer any useful suggestions of how I could do this via the Visual Studio debugger? Update I should also mention that it's a multi-threaded application, so pausing the application and analysing the call stack through the debugger is not the most desirable option. I considered freezing different threads one at a time to see if the memory stops reducing, but I'm fairly certain this will cause the application to crash.

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  • How to perform Rails model validation checks within model but outside of filters using ledermann-rails-settings and extensions

    - by user1277160
    Background I'm using ledermann-rails-settings (https://github.com/ledermann/rails-settings) on a Rails 2/3 project to extend virtually the model with certain attributes that don't necessarily need to be placed into the DB in a wide table and it's working out swimmingly for our needs. An additional reason I chose this Gem is because of the post How to create a form for the rails-settings plugin which ties ledermann-rails-settings more closely to the model for the purpose of clean form_for usage for administrator GUI support. It's a perfect solution for addressing form_for support although... Something that I'm running into now though is properly validating the dynamic getters/setters before being passed to the ledermann-rails-settings module. At the moment they are saved immediately, regardless if the model validation has actually fired - I can see through script/console that validation errors are being raised. Example For instance I would like to validate that the attribute :foo is within the range of 0..100 for decimal usage (or even a regex). I've found that with the previous post that I can use standard Rails validators (surprise, surprise) but I want to halt on actually saving any values until those are addressed - ensure that the user of the GUI has given 61.43 as a numerical value. The following code has been borrowed from the quoted post. class User < ActiveRecord::Base has_settings validates_inclusion_of :foo, :in => 0..100 def self.settings_attr_accessor(*args) >>SOME SORT OF UNLESS MODEL.VALID? CHECK HERE args.each do |method_name| eval " def #{method_name} self.settings.send(:#{method_name}) end def #{method_name}=(value) self.settings.send(:#{method_name}=, value) end " end >>END UNLESS end settings_attr_accessor :foo end Anyone have any thoughts here on pulling the state of the model at this point outside of having to put this into a before filter? The goal here is to be able to use the standard validations and avoid rolling custom validation checks for each new settings_attr_accessor that is added. Thanks!

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  • Memory leaks while using array of double

    - by Gacek
    I have a part of code that operates on large arrays of double (containing about 6000 elements at least) and executes several hundred times (usually 800) . When I use standard loop, like that: double[] singleRow = new double[6000]; int maxI = 800; for(int i=0; i<maxI; i++) { singleRow = someObject.producesOutput(); //... // do something with singleRow // ... } The memory usage rises for about 40MB (from 40MB at the beggining of the loop, to the 80MB at the end). When I force to use the garbage collector to execute at every iteration, the memory usage stays at the level of 40MB (the rise is unsignificant). double[] singleRow = new double[6000]; int maxI = 800; for(int i=0; i<maxI; i++) { singleRow = someObject.producesOutput(); //... // do something with singleRow // ... GC.Collect() } But the execution time is 3 times longer! (it is crucial) How can I force the C# to use the same area of memory instead of allocating new ones? Note: I have the access to the code of someObject class, so if it would be needed, I can change it.

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  • Interpolating data points in Excel

    - by Niels Basjes
    Hi, I'm sure this is the kind of problem other have solved many times before. A group of people are going to do measurements (Home energy usage to be exact). All of them will do that at different times and in different intervals. So what I'll get from each person is a set of {date, value} pairs where there are dates missing in the set. What I need is a complete set of {date, value} pairs where for each date withing the range a value is known (either measured or calculated). I expect that a simple linear interpolation would suffice for this project. If I assume that it must be done in Excel. What is the best way to interpolate in such a dataset (so I have a value for every day) ? Thanks. NOTE: When these datasets are complete I'll determine the slope (i.e. usage per day) and from that we can start doing home-to-home comparisons. ADDITIONAL INFO After first few suggestions: I do not want to manually figure out where the holes are in my measurement set (too many incomplete measurement sets!!). I'm looking for something (existing) automatic to do that for me. So if my input is {2009-06-01, 10} {2009-06-03, 20} {2009-06-06, 110} Then I expect to automatically get {2009-06-01, 10} {2009-06-02, 15} {2009-06-03, 20} {2009-06-04, 50} {2009-06-05, 80} {2009-06-06, 110} Yes, I can write software that does this. I am just hoping that someone already has a "ready to run" software (Excel) feature for this (rather generic) problem.

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  • When should we use Views, Temporary Tables and Direct Queries ? What are the Performance issues in a

    - by Shantanu Gupta
    I want to know the performance of using Views, Temp Tables and Direct Queries Usage in a Stored Procedure. I have a table that gets created every time when a trigger gets fired. I know this trigger will be fired very rare and only once at the time of setup. Now I have to use that created table from triggers at many places for fetching data and I confirms it that no one make any changes in that table. i.e ReadOnly Table. I have to use this tables data along with multiple tables to join and fetch result for further queries say select * from triggertable By Using temp table select ... into #tx from triggertable join t2 join t3 and so on select a,b, c from #tx --do something select d,e,f from #tx ---do somethign --and so on --around 6-7 queries in a row in a stored procedure. By Using Views create view viewname ( select ... from triggertable join t2 join t3 and so on ) select a,b, c from viewname --do something select d,e,f from viewname ---do somethign --and so on --around 6-7 queries in a row in a stored procedure. This View can be used in other places as well. So I will be creating at database rather than at sp By Using Direct Query select a,b, c from select ... into #tx from triggertable join t2 join t3 join ... --do something select a,b, c from select ... into #tx from triggertable join t2 join t3 join ... --do something . . --and so on --around 6-7 queries in a row in a stored procedure. Now I can create a view/temporary table/ directly query usage in all upcoming queries. What would be the best to use in this case.

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  • How to keep windows from paging block of memory

    - by photo_tom
    We are working on a Vista/Windows 7 applicaiton that will be running in 64 bit mode using VS2008/C++. We will be needing to cache hundreds of 2-3 mb blobs of data in RAM for performance reasons up to some memory limit. Our usage profile is such that we cannot read the data in fast enough if it is all on the the disk. Cached Memory usage will be larger than 1gb memory used. For this to work well, we need to ensure that Windows does not page this memory out as it will defeat the purpose of why we are doing this. I've done a fair amount of research and cannot find documenation that states exactly how to do this. I've seen several references that infer memory mapped files work this way. Is there an expert who can clarify this for me? I'm aware there are other programs that we could adapt to do this, for example, splitting the blobs and loading into memcache or inmemory databases, but they all have too many problems with performance or code complexity. Suggestions?

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  • Preallocating memory with C++ in realtime environment

    - by Elazar Leibovich
    I'm having a function which gets an input buffer of n bytes, and needs an auxillary buffer of n bytes in order to process the given input buffer. (I know vector is allocating memory at runtime, let's say that I'm using a vector which uses static preallocated memory. Imagine this is NOT an STL vector.) The usual approach is void processData(vector<T> &vec) { vector<T> &aux = new vector<T>(vec.size()); //dynamically allocate memory // process data } //usage: processData(v) Since I'm working in a real time environment, I wish to preallocate all the memory I'll ever need in advance. The buffer is allocated only once at startup. I want that whenever I'm allocating a vector, I'll automatically allocate auxillary buffer for my processData function. I can do something similar with a template function static void _processData(vector<T> &vec,vector<T> &aux) { // process data } template<size_t sz> void processData(vector<T> &vec) { static aux_buffer[sz]; vector aux(vec.size(),aux_buffer); // use aux_buffer for the vector _processData(vec,aux); } // usage: processData<V_MAX_SIZE>(v); However working alot with templates is not much fun (now let's recompile everything since I changed a comment!), and it forces me to do some bookkeeping whenever I use this function. Are there any nicer designs around this problem?

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  • What should I use to increase performance. View/Query/Temporary Table

    - by Shantanu Gupta
    I want to know the performance of using Views, Temp Tables and Direct Queries Usage in a Stored Procedure. I have a table that gets created every time when a trigger gets fired. I know this trigger will be fired very rare and only once at the time of setup. Now I have to use that created table from triggers at many places for fetching data and I confirms it that no one make any changes in that table. i.e ReadOnly Table. I have to use this tables data along with multiple tables to join and fetch result for further queries say select * from triggertable By Using temp table select ... into #tx from triggertable join t2 join t3 and so on select a,b, c from #tx --do something select d,e,f from #tx ---do somethign --and so on --around 6-7 queries in a row in a stored procedure. By Using Views create view viewname ( select ... from triggertable join t2 join t3 and so on ) select a,b, c from viewname --do something select d,e,f from viewname ---do somethign --and so on --around 6-7 queries in a row in a stored procedure. This View can be used in other places as well. So I will be creating at database rather than at sp By Using Direct Query select a,b, c from select ... into #tx from triggertable join t2 join t3 join ... --do something select a,b, c from select ... into #tx from triggertable join t2 join t3 join ... --do something . . --and so on --around 6-7 queries in a row in a stored procedure. Now I can create a view/temporary table/ directly query usage in all upcoming queries. What would be the best to use in this case.

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  • one-to-many with criteria question

    - by brnzn
    enter code hereI want to apply restrictions on the list of items, so only items from a given dates will be retrieved. Here are my mappings: <class name="MyClass" table="MyTable" mutable="false" > <cache usage="read-only"/> <id name="myId" column="myId" type="integer"/> <property name="myProp" type="string" column="prop"/> <list name="items" inverse="true" cascade="none"> <key column="myId"/> <list-index column="itemVersion"/> <one-to-many class="Item"/> </list> </class> <class name="Item" table="Items" mutable="false" > <cache usage="read-only"/> <id name="myId" column="myId" type="integer"/> <property name="itemVersion" type="string" column="version"/> <property name="startDate" type="date" column="startDate"/> </class> I tried this code: Criteria crit = session.createCriteria(MyClass.class); crit.add( Restrictions.eq("myId", new Integer(1))); crit = crit.createCriteria("items").add( Restrictions.le("startDate", new Date()) ); which result the following quires: select ... from MyTable this_ inner join Items items1_ on this_.myId=items1_.myId where this_.myId=? and items1_.startDate<=? followed by select ... from Items items0_ where items0_.myId=? But what I need is something like: select ... from MyTable this_ where this_.myId=? followed by select ... from Items items0_ where items0_.myId=? and items0_.startDate<=? Any idea how I can apply a criteria on the list of items?

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  • Can you dynamically combine multiple conditional functions into one in Python?

    - by erich
    I'm curious if it's possible to take several conditional functions and create one function that checks them all (e.g. the way a generator takes a procedure for iterating through a series and creates an iterator). The basic usage case would be when you have a large number of conditional parameters (e.g. "max_a", "min_a", "max_b", "min_b", etc.), many of which could be blank. They would all be passed to this "function creating" function, which would then return one function that checked them all. Below is an example of a naive way of doing what I'm asking: def combining_function(max_a, min_a, max_b, min_b, ...): f_array = [] if max_a is not None: f_array.append( lambda x: x.a < max_a ) if min_a is not None: f_array.append( lambda x: x.a > min_a ) ... return lambda x: all( [ f(x) for f in f_array ] ) What I'm wondering is what is the most efficient to achieve what's being done above? It seems like executing a function call for every function in f_array would create a decent amount of overhead, but perhaps I'm engaging in premature/unnecessary optimization. Regardless, I'd be interested to see if anyone else has come across usage cases like this and how they proceeded. Also, if this isn't possible in Python, is it possible in other (perhaps more functional) languages?

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  • Many users, many cpus, no delays. Good for cloud?

    - by Eric
    I wish to set up a CPU-intensive time-important query service for users on the internet. A usage scenario is described below. Is cloud computing the right way to go for such an implementation? If so, what cloud vendor(s) cater to this type of application? I ask specifically, in terms of: 1) pricing 2) latency resulting from: - slow CPUs, instance creations, JIT compiles, etc.. - internal management and communication of processes inside the cloud (e.g. a queuing process and a calculation process) - communication between cloud and end user 3) ease of deployment A usage scenario I am expecting is: - A typical user sends a query (XML of size around 1K) once every 30 seconds on average. - Each query requires a numerical computation of average time 0.2 sec and max time 1 sec on a 1 GHz Pentium. The computation requires no data other than the query itself and is performed by the same piece of code each time. - The delay a user experiences between sending a query and receiving a response should be on average no more than 2 seconds and in general no more than 5 seconds. - A background save to a DB of the response should occur (not time critical) - There can be up to 30000 simultaneous users - i.e., on average 1000 queries a second, each requiring an average 0.2 sec calculation, so that would necessitate around 200 CPUs. Currently I'm look at GAE Java (for quicker deployment and less IT hassle) and EC2 (Speed and price optimization) as options. Where can I learn more about the right way to set ups such a system? past threads, different blogs, books, etc.. BTW, if my terminology is wrong or confusing, please let me know. I'd greatly appreciate any help.

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  • Testing paginated UIScrollView on iPad

    - by Piotr Czapla
    I'm creating a magazine reader (something like iGizmo on iPad). I have two scrollviews one that paginate over articles and second to paginate inside of an article through pages. I'd like to check memory usage of my app after scrolling through 20 pages. To do so I decided to create an automated ui test that scrolls 20 times right and the check the memory foot print at the end of the test. I need that info to have some metrics before I start optimizing the memory usage And Here is the thing: I can't make the ui automation to pass to the second page. My automation code looks like that: var window = UIATarget.localTarget().frontMostApp().mainWindow(); var articleScrollView = window.scrollViews()[0]; articleScrollView.scrollRight(); // do you know any command to wait until first scrolls ends? articleScrollView.scrollRight(); // this one doesn't work I guess that I need to wait for the first scorlling to end before I can run another one, but I don't know how to do that as each page is just an image. (I don't have anything else on pages yet) Any idea?

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  • When to use reinterpret_cast?

    - by HeretoLearn
    I am little confused with the applicability of reinterpret_cast vs static_cast. From what I have read the general rules are to use static cast when the types can be interpreted at compile time hence the word static. This is the cast the C++ compiler uses internally for implicit casts also. reinterpret_cast are applicable in two scenarios, convert integer types to pointer types and vice versa or to convert one pointer type to another. The general idea I get is this is unportable and should be avoided. Where I am a little confused is one usage which I need, I am calling C++ from C and the C code needs to hold on to the C++ object so basically it holds a void*. What cast should be used to convert between the void * and the Class type? I have seen usage of both static_cast and reinterpret_cast? Though from what I have been reading it appears static is better as the cast can happen at compile time? Though it says to use reinterpret_cast to convert from one pointer type to another?

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  • How to debug JBoss out of memory problem?

    - by user561733
    Hello, I am trying to debug a JBoss out of memory problem. When JBoss starts up and runs for a while, it seems to use memory as intended by the startup configuration. However, it seems that when some unknown user action is taken (or the log file grows to a certain size) using the sole web application JBoss is serving up, memory increases dramatically and JBoss freezes. When JBoss freezes, it is difficult to kill the process or do anything because of low memory. When the process is finally killed via a -9 argument and the server is restarted, the log file is very small and only contains outputs from the startup of the newly started process and not any information on why the memory increased so much. This is why it is so hard to debug: server.log does not have information from the killed process. The log is set to grow to 2 GB and the log file for the new process is only about 300 Kb though it grows properly during normal memory circumstances. This is information on the JBoss configuration: JBoss (MX MicroKernel) 4.0.3 JDK 1.6.0 update 22 PermSize=512m MaxPermSize=512m Xms=1024m Xmx=6144m This is basic info on the system: Operating system: CentOS Linux 5.5 Kernel and CPU: Linux 2.6.18-194.26.1.el5 on x86_64 Processor information: Intel(R) Xeon(R) CPU E5420 @ 2.50GHz, 8 cores This is good example information on the system during normal pre-freeze conditions a few minutes after the jboss service startup: Running processes: 183 CPU load averages: 0.16 (1 min) 0.06 (5 mins) 0.09 (15 mins) CPU usage: 0% user, 0% kernel, 1% IO, 99% idle Real memory: 17.38 GB total, 2.46 GB used Virtual memory: 19.59 GB total, 0 bytes used Local disk space: 113.37 GB total, 11.89 GB used When JBoss freezes, system information looks like this: Running processes: 225 CPU load averages: 4.66 (1 min) 1.84 (5 mins) 0.93 (15 mins) CPU usage: 0% user, 12% kernel, 73% IO, 15% idle Real memory: 17.38 GB total, 17.18 GB used Virtual memory: 19.59 GB total, 706.29 MB used Local disk space: 113.37 GB total, 11.89 GB used

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