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• Is it correct to fix bugs without adding new features when releasing software for system testing?

  - by Pratik

  This question is to experienced testers or test leads. This is a scenario from a software project: Say the dev team have completed the first iteration of 10 features and released it to system testing. The test team has created test cases for these 10 features and estimated 5 days for testing. The dev team of course cannot sit idle for 5 days and they start creating 10 new features for next iteration. During this time the test team found defects and raised some bugs. The bugs are prioritised and some of them have to be fixed before next iteration. The catch is that they would not accept the new release with any new features or changes to existing features until all those bugs fixed. The test team says that's how can we guarantee a stable release for testing if we also introduce new features along with the bug fix. They also cannot do regression tests of all their test cases each iteration. Apparently this is proper testing process according to ISQTB. This means the dev team has to create a branch of code solely for bug fixing and another branch where they continue development. There is more merging overhead specially with refactoring and architectural changes. Can you agree if this is a common testing principle. Is the test team's concern valid. Have you encountered this in practice in your project.

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• Is "White-Board-Coding" inappropriate during interviews?

  - by Eoin Campbell

  This is a somewhat subjective quesiton but I'd love to hear feedback/opinions from either interviewers/interviewees on the topic. We split our technical part into 4 parts. Write Code, Read & Analyse Code, Design Session & Code on the white board. For the last part what we ask interviewees to do is write a small code snippet (4-5 lines) on the whiteboard and explain as they go through it. Let me be clear the purpose is not to catch people out. We're not looking for perfect syntax. Hell it can even be pseudo-code. but the point is to give them a very simple problem and see if their brain can communicate the solution to us. By simple problems I mean "Reverse a string", "FizzBuzz" etc... EDIT Just with regards the comment about Pseudo-Code. We always ask for an explicit language first. We;re a .NET C# house. we've only said "pseudo-code" where someone has been blanking/really struggling with the code. My question is "Is it innappropriate / unreasonable to expect a programmer to write a code snippet on a whiteboard during an interview ?"

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• Trying to use OpenGL in Java on Netbeans but getting an error. Please help [migrated]

  - by Steven Rogers

  I am on a Mac running Netbeans 6.9. I downloaded and installed LWJGL using this tutorial down to the letter: http://lwjgl.org/wiki/index.php?title=Setting_Up_LWJGL_with_NetBeans I finished the installation and copied sample code to see if my system is working. I got a bug, and was not sure if it was because of faulty code or i was doing something wrong. So i shortened down the code to this little simple bit: package javaopengl; import org.lwjgl.Sys; import org.lwjgl.opengl.Display; //Testing public class Main { public static void main(String[] args) { boolean fullscreen = (args.length == 1 && args[0].equals("-fullscreen")); try { Display.create(); Display.destroy(); } catch (Exception e) { e.printStackTrace(System.err); } System.exit(0); } } But i still get the same error, this is the error that i get: run: Exception in thread "main" java.lang.NoClassDefFoundError: = Caused by: java.lang.ClassNotFoundException: = at java.net.URLClassLoader$1.run(URLClassLoader.java:202) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:190) at java.lang.ClassLoader.loadClass(ClassLoader.java:306) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301) at java.lang.ClassLoader.loadClass(ClassLoader.java:247) Java Result: 1 BUILD SUCCESSFUL (total time: 0 seconds) I am not sure what exactly is going on, Would you please tell me what is going on and how to fix it? It would be greatly appreciated, and thank you. Note: When i am looking at the text in the development environment, it does not show those red lines indicating there are any errors.

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• Using PDO with MVC

  - by mister martin

  I asked this question at stackoverflow and received no response (closed as duplicate with no answer). I'm experimenting with OOP and I have the following basic MVC layout: class Model { // do database stuff } class View { public function load($filename, $data = array()) { if(!empty($data)) { extract($data); } require_once('views/header.php'); require_once("views/$filename"); require_once('views/footer.php'); } } class Controller { public $model; public $view; function __construct() { $this->model = new Model(); $this->view = new View(); // determine what page we're on $page = isset($_GET['view']) ? $_GET['view'] : 'home'; $this->display($page); } public function display($page) { switch($page) { case 'home': $this->view->load('home.php'); break; } } } These classes are brought together in my setup file: // start session session_start(); require_once('Model.php'); require_once('View.php'); require_once('Controller.php'); new Controller(); Now where do I place my database connection code and how do I pass the connection onto the model? try { $db = new PDO('mysql:host='.DB_HOST.';dbname='.DB_DATABASE.'', DB_USERNAME, DB_PASSWORD); $db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION); } catch(PDOException $err) { die($err->getMessage()); } I've read about Dependency Injection, factories and miscellaneous other design patterns talking about keeping SQL out of the model, but it's all over my head using abstract examples. Can someone please just show me a straight-forward practical example?

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• Developing Schema Compare for Oracle (Part 2): Dependencies

  - by Simon Cooper

  In developing Schema Compare for Oracle, one of the issues we came across was the size of the databases. As detailed in my last blog post, we had to allow schema pre-filtering due to the number of objects in a standard Oracle database. Unfortunately, this leads to some quite tricky situations regarding object dependencies. This post explains how we deal with these dependencies. 1. Cross-schema dependencies Say, in the following database, you're populating SchemaA, and synchronizing SchemaA.Table1: SOURCE   TARGET CREATE TABLE SchemaA.Table1 ( Col1 NUMBER REFERENCES SchemaB.Table1(Col1));   CREATE TABLE SchemaA.Table1 ( Col1 VARCHAR2(100) REFERENCES SchemaB.Table1(Col1)); CREATE TABLE SchemaB.Table1 ( Col1 NUMBER PRIMARY KEY);   CREATE TABLE SchemaB.Table1 ( Col1 VARCHAR2(100) PRIMARY KEY); We need to do a rebuild of SchemaA.Table1 to change Col1 from a VARCHAR2(100) to a NUMBER. This consists of: Creating a table with the new schema Inserting data from the old table to the new table, with appropriate conversion functions (in this case, TO_NUMBER) Dropping the old table Rename new table to same name as old table Unfortunately, in this situation, the rebuild will fail at step 1, as we're trying to create a NUMBER column with a foreign key reference to a VARCHAR2(100) column. As we're only populating SchemaA, the naive implementation of the object population prefiltering (sticking a WHERE owner = 'SCHEMAA' on all the data dictionary queries) will generate an incorrect sync script. What we actually have to do is: Drop foreign key constraint on SchemaA.Table1 Rebuild SchemaB.Table1 Rebuild SchemaA.Table1, adding the foreign key constraint to the new table This means that in order to generate a correct synchronization script for SchemaA.Table1 we have to know what SchemaB.Table1 is, and that it also needs to be rebuilt to successfully rebuild SchemaA.Table1. SchemaB isn't the schema that the user wants to synchronize, but we still have to load the table and column information for SchemaB.Table1 the same way as any table in SchemaA. Fortunately, Oracle provides (mostly) complete dependency information in the dictionary views. Before we actually read the information on all the tables and columns in the database, we can get dependency information on all the objects that are either pointed at by objects in the schemas we’re populating, or point to objects in the schemas we’re populating (think about what would happen if SchemaB was being explicitly populated instead), with a suitable query on all_constraints (for foreign key relationships) and all_dependencies (for most other types of dependencies eg a function using another function). The extra objects found can then be included in the actual object population, and the sync wizard then has enough information to figure out the right thing to do when we get to actually synchronize the objects. Unfortunately, this isn’t enough. 2. Dependency chains The solution above will only get the immediate dependencies of objects in populated schemas. What if there’s a chain of dependencies? A.tbl1 -> B.tbl1 -> C.tbl1 -> D.tbl1 If we’re only populating SchemaA, the implementation above will only include B.tbl1 in the dependent objects list, whereas we might need to know about C.tbl1 and D.tbl1 as well, in order to ensure a modification on A.tbl1 can succeed. What we actually need is a graph traversal on the dependency graph that all_dependencies represents. Fortunately, we don’t have to read all the database dependency information from the server and run the graph traversal on the client computer, as Oracle provides a method of doing this in SQL – CONNECT BY. So, we can put all the dependencies we want to include together in big bag with UNION ALL, then run a SELECT ... CONNECT BY on it, starting with objects in the schema we’re populating. We should end up with all the objects that might be affected by modifications in the initial schema we’re populating. Good solution? Well, no. For one thing, it’s sloooooow. all_dependencies, on my test databases, has got over 110,000 rows in it, and the entire query, for which Oracle was creating a temporary table to hold the big bag of graph edges, was often taking upwards of two minutes. This is too long, and would only get worse for large databases. But it had some more fundamental problems than just performance. 3. Comparison dependencies Consider the following schema: SOURCE   TARGET CREATE TABLE SchemaA.Table1 ( Col1 NUMBER REFERENCES SchemaB.Table1(col1));   CREATE TABLE SchemaA.Table1 ( Col1 VARCHAR2(100)); CREATE TABLE SchemaB.Table1 ( Col1 NUMBER PRIMARY KEY);   CREATE TABLE SchemaB.Table1 ( Col1 VARCHAR2(100)); What will happen if we used the dependency algorithm above on the source & target database? Well, SchemaA.Table1 has a foreign key reference to SchemaB.Table1, so that will be included in the source database population. On the target, SchemaA.Table1 has no such reference. Therefore SchemaB.Table1 will not be included in the target database population. In the resulting comparison of the two objects models, what you will end up with is: SOURCE  TARGET SchemaA.Table1 -> SchemaA.Table1 SchemaB.Table1 -> (no object exists) When this comparison is synchronized, we will see that SchemaB.Table1 does not exist, so we will try the following sequence of actions: Create SchemaB.Table1 Rebuild SchemaA.Table1, with foreign key to SchemaB.Table1 Oops. Because the dependencies are only followed within a single database, we’ve tried to create an object that already exists. To fix this we can include any objects found as dependencies in the source or target databases in the object population of both databases. SchemaB.Table1 will then be included in the target database population, and we won’t try and create objects that already exist. All good? Well, consider the following schema (again, only explicitly populating SchemaA, and synchronizing SchemaA.Table1): SOURCE   TARGET CREATE TABLE SchemaA.Table1 ( Col1 NUMBER REFERENCES SchemaB.Table1(col1));   CREATE TABLE SchemaA.Table1 ( Col1 VARCHAR2(100)); CREATE TABLE SchemaB.Table1 ( Col1 NUMBER PRIMARY KEY);   CREATE TABLE SchemaB.Table1 ( Col1 VARCHAR2(100) PRIMARY KEY); CREATE TABLE SchemaC.Table1 ( Col1 NUMBER);   CREATE TABLE SchemaC.Table1 ( Col1 VARCHAR2(100) REFERENCES SchemaB.Table1); Although we’re now including SchemaB.Table1 on both sides of the comparison, there’s a third table (SchemaC.Table1) that we don’t know about that will cause the rebuild of SchemaB.Table1 to fail if we try and synchronize SchemaA.Table1. That’s because we’re only running the dependency query on the schemas we’re explicitly populating; to solve this issue, we would have to run the dependency query again, but this time starting the graph traversal from the objects found in the other database. Furthermore, this dependency chain could be arbitrarily extended.This leads us to the following algorithm for finding all the dependencies of a comparison: Find initial dependencies of schemas the user has selected to compare on the source and target Include these objects in both the source and target object populations Run the dependency query on the source, starting with the objects found as dependents on the target, and vice versa Repeat 2 & 3 until no more objects are found For the schema above, this will result in the following sequence of actions: Find initial dependenciesSchemaA.Table1 -> SchemaB.Table1 found on sourceNo objects found on target Include objects in both source and targetSchemaB.Table1 included in source and target Run dependency query, starting with found objectsNo objects to start with on sourceSchemaB.Table1 -> SchemaC.Table1 found on target Include objects in both source and targetSchemaC.Table1 included in source and target Run dependency query on found objectsNo objects found in sourceNo objects to start with in target Stop This will ensure that we include all the necessary objects to make any synchronization work. However, there is still the issue of query performance; the CONNECT BY on the entire database dependency graph is still too slow. After much sitting down and drawing complicated diagrams, we decided to move the graph traversal algorithm from the server onto the client (which turned out to run much faster on the client than on the server); and to ensure we don’t read the entire dependency graph onto the client we also pull the graph across in bits – we start off with dependency edges involving schemas selected for explicit population, and whenever the graph traversal comes across a dependency reference to a schema we don’t yet know about a thunk is hit that pulls in the dependency information for that schema from the database. We continue passing more dependent objects back and forth between the source and target until no more dependency references are found. This gives us the list of all the extra objects to populate in the source and target, and object population can then proceed. 4. Object blacklists and fast dependencies When we tested this solution, we were puzzled in that in some of our databases most of the system schemas (WMSYS, ORDSYS, EXFSYS, XDB, etc) were being pulled in, and this was increasing the database registration and comparison time quite significantly. After debugging, we discovered that the culprits were database tables that used one of the Oracle PL/SQL types (eg the SDO_GEOMETRY spatial type). These were creating a dependency chain from the database tables we were populating to the system schemas, and hence pulling in most of the system objects in that schema. To solve this we introduced blacklists of objects we wouldn’t follow any dependency chain through. As well as the Oracle-supplied PL/SQL types (MDSYS.SDO_GEOMETRY, ORDSYS.SI_COLOR, among others) we also decided to blacklist the entire PUBLIC and SYS schemas, as any references to those would likely lead to a blow up in the dependency graph that would massively increase the database registration time, and could result in the client running out of memory. Even with these improvements, each dependency query was taking upwards of a minute. We discovered from Oracle execution plans that there were some columns, with dependency information we required, that were querying system tables with no indexes on them! To cut a long story short, running the following query: SELECT * FROM all_tab_cols WHERE data_type_owner = ‘XDB’; results in a full table scan of the SYS.COL$ system table! This single clause was responsible for over half the execution time of the dependency query. Hence, the ‘Ignore slow dependencies’ option was born – not querying this and a couple of similar clauses to drastically speed up the dependency query execution time, at the expense of producing incorrect sync scripts in rare edge cases. Needless to say, along with the sync script action ordering, the dependency code in the database registration is one of the most complicated and most rewritten parts of the Schema Compare for Oracle engine. The beta of Schema Compare for Oracle is out now; if you find a bug in it, please do tell us so we can get it fixed!

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• Dependency Analyser

  - by tsutha

  I have been watching 3 videos put together by SSIS team on Dependency Analyser. I am happy Microsoft have made an effort to do something about it. I have been asking for this feature since SQL 2005 TAP. Still a long way to go before they catch up with competetion. It looks like it currently supports SSIS and SQL dependencies. Release note states its still in development and support only limited sets of tasks. You still would not know the impact of dropping a column on cubes, reports etc. I hope that changes by the time RTM comes out. I am struggling to understand why it is impossible to do it across the solution. Ideally if you have a BI solution which holds DB, SSIS, SSAS, SSRS & PPS projects I would like to right click and execute a dependency analyser, stating what impact would have if I drop / rename a specific column. Has anyone else looked at it and what are your thoughts? ThanksSutha  

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• What are the most commonly used and basic Apache htaccess redirects?

  - by bybe

  This question is here so we can offer users who are looking for information on how to make one or more common or basic redirects in Apache using the htaccess file. All future questions pertaining to finding information that is that is covered by the question should be closed as a duplication of this question. As per this Meta question. Whats the point in this question? The idea while not perfect is catch the most commonly asked questions regarding redirects using the htaccess on the Apache platform either on some type of lamp or a live server. The type of answers should be generally those that you could imagine are used by 100,000’s of sites world-wide and are constantly asked here at Pro Webmasters repeatedly over and over in various forms. A few examples of the type of answers we are looking for: How can I redirect non-www to www? How can I redirect a sub domain to the main domain? How can I redirect a sub folder from domain to a root or a subdomain? How can I redirect an old URL to a new URL? A few examples of the types of answers that we are not looking for: Answers that do not involve a redirect. Any answers relating to NGinx, IIS or any other non-Apache platform. Answers that involve custom and complex string or query removals. Resources for Advanced to Complex Mod_Rewrite Rules: Everything you ever wanted to know about mod rewrite rules but were afraid to ask Please note: that this question is still in construction and may need some refining either by myself or a real moderator of Pro Webmasters, if you have any concerns or questions please use the meta page I made a few days back here.

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• Good practice or service for monitoring unhandled application errors for a small organization

  - by palto

  I'm working with multiple software with varying ways of monitoring for errors. When I make software, I usually send email with the stack trace to admins(usually me). Some customer software is monitored by a team who check that a particular batch run was successfull. Other software might not have any monitoring at all(someone will call when things go wrong horribly). Sending emails is good, except when things start going wrong, my mail gets filled fast. Also I don't want to solve the same problem in code for every software. Is there some relatively cheap and low maintenance software or practice to handle this. I want it to be cheap/low maintenance because usually I work alone or in teams of 5 or smaller. For example it would be great if errors would be aggregated so I don't get 10 000 emails when something unexpected happens... For clarification: By unhandled errors I mean Exceptions that were unhandled by application code that were propagated to Tomcat or Jboss. I don't need help with how to catch those errors. I need help with what to do with them. Is there any cloud application that I could send my errors to? Or some simple server to install? Or some library that can handle errors using configuration files. I use Java if that is any help.

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• Is there a command-line utility app which can find a specific block of lines in a text file, and replace it?

  - by fred.bear

  UPDATE (see end of question) The text "search and replace" utility programs I've seen, seem to only search on a line-by-line basis... Is there a command-line tool which can locate one block of lines (in a text file), and replace it with another block of lines.? For example: Does the test file file contain this exact group of lines: 'Twas brillig, and the slithy toves Did gyre and gimble in the wabe: All mimsy were the borogoves, And the mome raths outgrabe. 'Beware the Jabberwock, my son! The jaws that bite, the claws that catch! Beware the Jubjub bird, and shun The frumious Bandersnatch!' I want this, so that I can replace multiple lines of text in a file and know I'm not overwriting the wrong lines. I would never replace "The Jabberwocky" (Lewis Carroll), but it makes a novel example :) UPDATE: ..(sub-update) My following comment about reasons when not use sed are only in the context of; don't push any tool too far beyond its design intent (I use sed quite often, and consider it to be invaluable.) I just now found an interesting web page about sed and when not to use it. So, because of all the sed answers, I"ll post the link.. it is part of the sed FAQ on sourceforge Also, I'm pretty sure there is some way diff can do the job of locating the block of text (once it's located, the replacement is quite straight foward; using head and tail) ... 'diff' dumps all the necessary data, but I haven't yet worked out how to filter it , ... (I'm still working on it)

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• Using R to Analyze G1GC Log Files

  - by user12620111

  Using R to Analyze G1GC Log Files body, td { font-family: sans-serif; background-color: white; font-size: 12px; margin: 8px; } tt, code, pre { font-family: 'DejaVu Sans Mono', 'Droid Sans Mono', 'Lucida Console', Consolas, Monaco, monospace; } h1 { font-size:2.2em; } h2 { font-size:1.8em; } h3 { font-size:1.4em; } h4 { font-size:1.0em; } h5 { font-size:0.9em; } h6 { font-size:0.8em; } a:visited { color: rgb(50%, 0%, 50%); } pre { margin-top: 0; max-width: 95%; border: 1px solid #ccc; white-space: pre-wrap; } pre code { display: block; padding: 0.5em; } code.r, code.cpp { background-color: #F8F8F8; } table, td, th { border: none; } blockquote { color:#666666; margin:0; padding-left: 1em; border-left: 0.5em #EEE solid; } hr { height: 0px; border-bottom: none; border-top-width: thin; border-top-style: dotted; border-top-color: #999999; } @media print { * { background: transparent !important; color: black !important; filter:none !important; -ms-filter: none !important; } body { 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  Using R to Analyze G1GC Log Files   Using R to Analyze G1GC Log Files Introduction Working in Oracle Platform Integration gives an engineer opportunities to work on a wide array of technologies. My team’s goal is to make Oracle applications run best on the Solaris/SPARC platform. When looking for bottlenecks in a modern applications, one needs to be aware of not only how the CPUs and operating system are executing, but also network, storage, and in some cases, the Java Virtual Machine. I was recently presented with about 1.5 GB of Java Garbage First Garbage Collector log file data. If you’re not familiar with the subject, you might want to review Garbage First Garbage Collector Tuning by Monica Beckwith. The customer had been running Java HotSpot 1.6.0_31 to host a web application server. I was told that the Solaris/SPARC server was running a Java process launched using a commmand line that included the following flags: -d64 -Xms9g -Xmx9g -XX:+UseG1GC -XX:MaxGCPauseMillis=200 -XX:InitiatingHeapOccupancyPercent=80 -XX:PermSize=256m -XX:MaxPermSize=256m -XX:+PrintGC -XX:+PrintGCTimeStamps -XX:+PrintHeapAtGC -XX:+PrintGCDateStamps -XX:+PrintFlagsFinal -XX:+DisableExplicitGC -XX:+UnlockExperimentalVMOptions -XX:ParallelGCThreads=8 Several sources on the internet indicate that if I were to print out the 1.5 GB of log files, it would require enough paper to fill the bed of a pick up truck. Of course, it would be fruitless to try to scan the log files by hand. Tools will be required to summarize the contents of the log files. Others have encountered large Java garbage collection log files. There are existing tools to analyze the log files: IBM’s GC toolkit The chewiebug GCViewer gchisto HPjmeter Instead of using one of the other tools listed, I decide to parse the log files with standard Unix tools, and analyze the data with R. Data Cleansing The log files arrived in two different formats. I guess that the difference is that one set of log files was generated using a more verbose option, maybe -XX:+PrintHeapAtGC, and the other set of log files was generated without that option. Format 1 In some of the log files, the log files with the less verbose format, a single trace, i.e. the report of a singe garbage collection event, looks like this: {Heap before GC invocations=12280 (full 61): garbage-first heap total 9437184K, used 7499918K [0xfffffffd00000000, 0xffffffff40000000, 0xffffffff40000000) region size 4096K, 1 young (4096K), 0 survivors (0K) compacting perm gen total 262144K, used 144077K [0xffffffff40000000, 0xffffffff50000000, 0xffffffff50000000) the space 262144K, 54% used [0xffffffff40000000, 0xffffffff48cb3758, 0xffffffff48cb3800, 0xffffffff50000000) No shared spaces configured. 2014-05-14T07:24:00.988-0700: 60586.353: [GC pause (young) 7324M->7320M(9216M), 0.1567265 secs] Heap after GC invocations=12281 (full 61): garbage-first heap total 9437184K, used 7496533K [0xfffffffd00000000, 0xffffffff40000000, 0xffffffff40000000) region size 4096K, 0 young (0K), 0 survivors (0K) compacting perm gen total 262144K, used 144077K [0xffffffff40000000, 0xffffffff50000000, 0xffffffff50000000) the space 262144K, 54% used [0xffffffff40000000, 0xffffffff48cb3758, 0xffffffff48cb3800, 0xffffffff50000000) No shared spaces configured. } A simple grep can be used to extract a summary: $ grep "\[ GC pause (young" g1gc.log 2014-05-13T13:24:35.091-0700: 3.109: [GC pause (young) 20M->5029K(9216M), 0.0146328 secs] 2014-05-13T13:24:35.440-0700: 3.459: [GC pause (young) 9125K->6077K(9216M), 0.0086723 secs] 2014-05-13T13:24:37.581-0700: 5.599: [GC pause (young) 25M->8470K(9216M), 0.0203820 secs] 2014-05-13T13:24:42.686-0700: 10.704: [GC pause (young) 44M->15M(9216M), 0.0288848 secs] 2014-05-13T13:24:48.941-0700: 16.958: [GC pause (young) 51M->20M(9216M), 0.0491244 secs] 2014-05-13T13:24:56.049-0700: 24.066: [GC pause (young) 92M->26M(9216M), 0.0525368 secs] 2014-05-13T13:25:34.368-0700: 62.383: [GC pause (young) 602M->68M(9216M), 0.1721173 secs] But that format wasn't easily read into R, so I needed to be a bit more tricky. I used the following Unix command to create a summary file that was easy for R to read. $ echo "SecondsSinceLaunch BeforeSize AfterSize TotalSize RealTime" $ grep "\[GC pause (young" g1gc.log | grep -v mark | sed -e 's/[A-SU-z\(\),]/ /g' -e 's/->/ /' -e 's/: / /g' | more SecondsSinceLaunch BeforeSize AfterSize TotalSize RealTime 2014-05-13T13:24:35.091-0700 3.109 20 5029 9216 0.0146328 2014-05-13T13:24:35.440-0700 3.459 9125 6077 9216 0.0086723 2014-05-13T13:24:37.581-0700 5.599 25 8470 9216 0.0203820 2014-05-13T13:24:42.686-0700 10.704 44 15 9216 0.0288848 2014-05-13T13:24:48.941-0700 16.958 51 20 9216 0.0491244 2014-05-13T13:24:56.049-0700 24.066 92 26 9216 0.0525368 2014-05-13T13:25:34.368-0700 62.383 602 68 9216 0.1721173 Format 2 In some of the log files, the log files with the more verbose format, a single trace, i.e. the report of a singe garbage collection event, was more complicated than Format 1. Here is a text file with an example of a single G1GC trace in the second format. As you can see, it is quite complicated. It is nice that there is so much information available, but the level of detail can be overwhelming. I wrote this awk script (download) to summarize each trace on a single line. #!/usr/bin/env awk -f BEGIN { printf("SecondsSinceLaunch IncrementalCount FullCount UserTime SysTime RealTime BeforeSize AfterSize TotalSize\n") } ###################### # Save count data from lines that are at the start of each G1GC trace. # Each trace starts out like this: # {Heap before GC invocations=14 (full 0): # garbage-first heap total 9437184K, used 325496K [0xfffffffd00000000, 0xffffffff40000000, 0xffffffff40000000) ###################### /{Heap.*full/{ gsub ( "\\)" , "" ); nf=split($0,a,"="); split(a[2],b," "); getline; if ( match($0, "first") ) { G1GC=1; IncrementalCount=b[1]; FullCount=substr( b[3], 1, length(b[3])-1 ); } else { G1GC=0; } } ###################### # Pull out time stamps that are in lines with this format: # 2014-05-12T14:02:06.025-0700: 94.312: [GC pause (young), 0.08870154 secs] ###################### /GC pause/ { DateTime=$1; SecondsSinceLaunch=substr($2, 1, length($2)-1); } ###################### # Heap sizes are in lines that look like this: # [ 4842M->4838M(9216M)] ###################### /\[ .*]$/ { gsub ( "\\[" , "" ); gsub ( "\ \]" , "" ); gsub ( "->" , " " ); gsub ( "\\( " , " " ); gsub ( "\ \)" , " " ); split($0,a," "); if ( split(a[1],b,"M") > 1 ) {BeforeSize=b[1]*1024;} if ( split(a[1],b,"K") > 1 ) {BeforeSize=b[1];} if ( split(a[2],b,"M") > 1 ) {AfterSize=b[1]*1024;} if ( split(a[2],b,"K") > 1 ) {AfterSize=b[1];} if ( split(a[3],b,"M") > 1 ) {TotalSize=b[1]*1024;} if ( split(a[3],b,"K") > 1 ) {TotalSize=b[1];} } ###################### # Emit an output line when you find input that looks like this: # [Times: user=1.41 sys=0.08, real=0.24 secs] ###################### /\[Times/ { if (G1GC==1) { gsub ( "," , "" ); split($2,a,"="); UserTime=a[2]; split($3,a,"="); SysTime=a[2]; split($4,a,"="); RealTime=a[2]; print DateTime,SecondsSinceLaunch,IncrementalCount,FullCount,UserTime,SysTime,RealTime,BeforeSize,AfterSize,TotalSize; G1GC=0; } } The resulting summary is about 25X smaller that the original file, but still difficult for a human to digest. SecondsSinceLaunch IncrementalCount FullCount UserTime SysTime RealTime BeforeSize AfterSize TotalSize ... 2014-05-12T18:36:34.669-0700: 3985.744 561 0 0.57 0.06 0.16 1724416 1720320 9437184 2014-05-12T18:36:34.839-0700: 3985.914 562 0 0.51 0.06 0.19 1724416 1720320 9437184 2014-05-12T18:36:35.069-0700: 3986.144 563 0 0.60 0.04 0.27 1724416 1721344 9437184 2014-05-12T18:36:35.354-0700: 3986.429 564 0 0.33 0.04 0.09 1725440 1722368 9437184 2014-05-12T18:36:35.545-0700: 3986.620 565 0 0.58 0.04 0.17 1726464 1722368 9437184 2014-05-12T18:36:35.726-0700: 3986.801 566 0 0.43 0.05 0.12 1726464 1722368 9437184 2014-05-12T18:36:35.856-0700: 3986.930 567 0 0.30 0.04 0.07 1726464 1723392 9437184 2014-05-12T18:36:35.947-0700: 3987.023 568 0 0.61 0.04 0.26 1727488 1723392 9437184 2014-05-12T18:36:36.228-0700: 3987.302 569 0 0.46 0.04 0.16 1731584 1724416 9437184 Reading the Data into R Once the GC log data had been cleansed, either by processing the first format with the shell script, or by processing the second format with the awk script, it was easy to read the data into R. g1gc.df = read.csv("summary.txt", row.names = NULL, stringsAsFactors=FALSE,sep="") str(g1gc.df) ## 'data.frame': 8307 obs. of 10 variables: ## $ row.names : chr "2014-05-12T14:00:32.868-0700:" "2014-05-12T14:00:33.179-0700:" "2014-05-12T14:00:33.677-0700:" "2014-05-12T14:00:35.538-0700:" ... ## $ SecondsSinceLaunch: num 1.16 1.47 1.97 3.83 6.1 ... ## $ IncrementalCount : int 0 1 2 3 4 5 6 7 8 9 ... ## $ FullCount : int 0 0 0 0 0 0 0 0 0 0 ... ## $ UserTime : num 0.11 0.05 0.04 0.21 0.08 0.26 0.31 0.33 0.34 0.56 ... ## $ SysTime : num 0.04 0.01 0.01 0.05 0.01 0.06 0.07 0.06 0.07 0.09 ... ## $ RealTime : num 0.02 0.02 0.01 0.04 0.02 0.04 0.05 0.04 0.04 0.06 ... ## $ BeforeSize : int 8192 5496 5768 22528 24576 43008 34816 53248 55296 93184 ... ## $ AfterSize : int 1400 1672 2557 4907 7072 14336 16384 18432 19456 21504 ... ## $ TotalSize : int 9437184 9437184 9437184 9437184 9437184 9437184 9437184 9437184 9437184 9437184 ... head(g1gc.df) ## row.names SecondsSinceLaunch IncrementalCount ## 1 2014-05-12T14:00:32.868-0700: 1.161 0 ## 2 2014-05-12T14:00:33.179-0700: 1.472 1 ## 3 2014-05-12T14:00:33.677-0700: 1.969 2 ## 4 2014-05-12T14:00:35.538-0700: 3.830 3 ## 5 2014-05-12T14:00:37.811-0700: 6.103 4 ## 6 2014-05-12T14:00:41.428-0700: 9.720 5 ## FullCount UserTime SysTime RealTime BeforeSize AfterSize TotalSize ## 1 0 0.11 0.04 0.02 8192 1400 9437184 ## 2 0 0.05 0.01 0.02 5496 1672 9437184 ## 3 0 0.04 0.01 0.01 5768 2557 9437184 ## 4 0 0.21 0.05 0.04 22528 4907 9437184 ## 5 0 0.08 0.01 0.02 24576 7072 9437184 ## 6 0 0.26 0.06 0.04 43008 14336 9437184 Basic Statistics Once the data has been read into R, simple statistics are very easy to generate. All of the numbers from high school statistics are available via simple commands. For example, generate a summary of every column: summary(g1gc.df) ## row.names SecondsSinceLaunch IncrementalCount FullCount ## Length:8307 Min. : 1 Min. : 0 Min. : 0.0 ## Class :character 1st Qu.: 9977 1st Qu.:2048 1st Qu.: 0.0 ## Mode :character Median :12855 Median :4136 Median : 12.0 ## Mean :12527 Mean :4156 Mean : 31.6 ## 3rd Qu.:15758 3rd Qu.:6262 3rd Qu.: 61.0 ## Max. :55484 Max. :8391 Max. :113.0 ## UserTime SysTime RealTime BeforeSize ## Min. :0.040 Min. :0.0000 Min. : 0.0 Min. : 5476 ## 1st Qu.:0.470 1st Qu.:0.0300 1st Qu.: 0.1 1st Qu.:5137920 ## Median :0.620 Median :0.0300 Median : 0.1 Median :6574080 ## Mean :0.751 Mean :0.0355 Mean : 0.3 Mean :5841855 ## 3rd Qu.:0.920 3rd Qu.:0.0400 3rd Qu.: 0.2 3rd Qu.:7084032 ## Max. :3.370 Max. :1.5600 Max. :488.1 Max. :8696832 ## AfterSize TotalSize ## Min. : 1380 Min. :9437184 ## 1st Qu.:5002752 1st Qu.:9437184 ## Median :6559744 Median :9437184 ## Mean :5785454 Mean :9437184 ## 3rd Qu.:7054336 3rd Qu.:9437184 ## Max. :8482816 Max. :9437184 Q: What is the total amount of User CPU time spent in garbage collection? sum(g1gc.df$UserTime) ## [1] 6236 As you can see, less than two hours of CPU time was spent in garbage collection. Is that too much? To find the percentage of time spent in garbage collection, divide the number above by total_elapsed_time*CPU_count. In this case, there are a lot of CPU’s and it turns out the the overall amount of CPU time spent in garbage collection isn’t a problem when viewed in isolation. When calculating rates, i.e. events per unit time, you need to ask yourself if the rate is homogenous across the time period in the log file. Does the log file include spikes of high activity that should be separately analyzed? Averaging in data from nights and weekends with data from business hours may alias problems. If you have a reason to suspect that the garbage collection rates include peaks and valleys that need independent analysis, see the “Time Series” section, below. Q: How much garbage is collected on each pass? The amount of heap space that is recovered per GC pass is surprisingly low: At least one collection didn’t recover any data. (“Min.=0”) 25% of the passes recovered 3MB or less. (“1st Qu.=3072”) Half of the GC passes recovered 4MB or less. (“Median=4096”) The average amount recovered was 56MB. (“Mean=56390”) 75% of the passes recovered 36MB or less. (“3rd Qu.=36860”) At least one pass recovered 2GB. (“Max.=2121000”) g1gc.df$Delta = g1gc.df$BeforeSize - g1gc.df$AfterSize summary(g1gc.df$Delta) ## Min. 1st Qu. Median Mean 3rd Qu. Max. ## 0 3070 4100 56400 36900 2120000 Q: What is the maximum User CPU time for a single collection? The worst garbage collection (“Max.”) is many standard deviations away from the mean. The data appears to be right skewed. summary(g1gc.df$UserTime) ## Min. 1st Qu. Median Mean 3rd Qu. Max. ## 0.040 0.470 0.620 0.751 0.920 3.370 sd(g1gc.df$UserTime) ## [1] 0.3966 Basic Graphics Once the data is in R, it is trivial to plot the data with formats including dot plots, line charts, bar charts (simple, stacked, grouped), pie charts, boxplots, scatter plots histograms, and kernel density plots. Histogram of User CPU Time per Collection I don't think that this graph requires any explanation. hist(g1gc.df$UserTime, main="User CPU Time per Collection", xlab="Seconds", ylab="Frequency") Box plot to identify outliers When the initial data is viewed with a box plot, you can see the one crazy outlier in the real time per GC. Save this data point for future analysis and drop the outlier so that it’s not throwing off our statistics. Now the box plot shows many outliers, which will be examined later, using times series analysis. Notice that the scale of the x-axis changes drastically once the crazy outlier is removed. par(mfrow=c(2,1)) boxplot(g1gc.df$UserTime,g1gc.df$SysTime,g1gc.df$RealTime, main="Box Plot of Time per GC\n(dominated by a crazy outlier)", names=c("usr","sys","elapsed"), xlab="Seconds per GC", ylab="Time (Seconds)", horizontal = TRUE, outcol="red") crazy.outlier.df=g1gc.df[g1gc.df$RealTime > 400,] g1gc.df=g1gc.df[g1gc.df$RealTime < 400,] boxplot(g1gc.df$UserTime,g1gc.df$SysTime,g1gc.df$RealTime, main="Box Plot of Time per GC\n(crazy outlier excluded)", names=c("usr","sys","elapsed"), xlab="Seconds per GC", ylab="Time (Seconds)", horizontal = TRUE, outcol="red") box(which = "outer", lty = "solid") Here is the crazy outlier for future analysis: crazy.outlier.df ## row.names SecondsSinceLaunch IncrementalCount ## 8233 2014-05-12T23:15:43.903-0700: 20741 8316 ## FullCount UserTime SysTime RealTime BeforeSize AfterSize TotalSize ## 8233 112 0.55 0.42 488.1 8381440 8235008 9437184 ## Delta ## 8233 146432 R Time Series Data To analyze the garbage collection as a time series, I’ll use Z’s Ordered Observations (zoo). “zoo is the creator for an S3 class of indexed totally ordered observations which includes irregular time series.” require(zoo) ## Loading required package: zoo ## ## Attaching package: 'zoo' ## ## The following objects are masked from 'package:base': ## ## as.Date, as.Date.numeric head(g1gc.df[,1]) ## [1] "2014-05-12T14:00:32.868-0700:" "2014-05-12T14:00:33.179-0700:" ## [3] "2014-05-12T14:00:33.677-0700:" "2014-05-12T14:00:35.538-0700:" ## [5] "2014-05-12T14:00:37.811-0700:" "2014-05-12T14:00:41.428-0700:" options("digits.secs"=3) times=as.POSIXct( g1gc.df[,1], format="%Y-%m-%dT%H:%M:%OS%z:") g1gc.z = zoo(g1gc.df[,-c(1)], order.by=times) head(g1gc.z) ## SecondsSinceLaunch IncrementalCount FullCount ## 2014-05-12 17:00:32.868 1.161 0 0 ## 2014-05-12 17:00:33.178 1.472 1 0 ## 2014-05-12 17:00:33.677 1.969 2 0 ## 2014-05-12 17:00:35.538 3.830 3 0 ## 2014-05-12 17:00:37.811 6.103 4 0 ## 2014-05-12 17:00:41.427 9.720 5 0 ## UserTime SysTime RealTime BeforeSize AfterSize ## 2014-05-12 17:00:32.868 0.11 0.04 0.02 8192 1400 ## 2014-05-12 17:00:33.178 0.05 0.01 0.02 5496 1672 ## 2014-05-12 17:00:33.677 0.04 0.01 0.01 5768 2557 ## 2014-05-12 17:00:35.538 0.21 0.05 0.04 22528 4907 ## 2014-05-12 17:00:37.811 0.08 0.01 0.02 24576 7072 ## 2014-05-12 17:00:41.427 0.26 0.06 0.04 43008 14336 ## TotalSize Delta ## 2014-05-12 17:00:32.868 9437184 6792 ## 2014-05-12 17:00:33.178 9437184 3824 ## 2014-05-12 17:00:33.677 9437184 3211 ## 2014-05-12 17:00:35.538 9437184 17621 ## 2014-05-12 17:00:37.811 9437184 17504 ## 2014-05-12 17:00:41.427 9437184 28672 Example of Two Benchmark Runs in One Log File The data in the following graph is from a different log file, not the one of primary interest to this article. I’m including this image because it is an example of idle periods followed by busy periods. It would be uninteresting to average the rate of garbage collection over the entire log file period. More interesting would be the rate of garbage collect in the two busy periods. Are they the same or different? Your production data may be similar, for example, bursts when employees return from lunch and idle times on weekend evenings, etc. Once the data is in an R Time Series, you can analyze isolated time windows. Clipping the Time Series data Flashing back to our test case… Viewing the data as a time series is interesting. You can see that the work intensive time period is between 9:00 PM and 3:00 AM. Lets clip the data to the interesting period:     par(mfrow=c(2,1)) plot(g1gc.z$UserTime, type="h", main="User Time per GC\nTime: Complete Log File", xlab="Time of Day", ylab="CPU Seconds per GC", col="#1b9e77") clipped.g1gc.z=window(g1gc.z, start=as.POSIXct("2014-05-12 21:00:00"), end=as.POSIXct("2014-05-13 03:00:00")) plot(clipped.g1gc.z$UserTime, type="h", main="User Time per GC\nTime: Limited to Benchmark Execution", xlab="Time of Day", ylab="CPU Seconds per GC", col="#1b9e77") box(which = "outer", lty = "solid") Cumulative Incremental and Full GC count Here is the cumulative incremental and full GC count. When the line is very steep, it indicates that the GCs are repeating very quickly. Notice that the scale on the Y axis is different for full vs. incremental. plot(clipped.g1gc.z[,c(2:3)], main="Cumulative Incremental and Full GC count", xlab="Time of Day", col="#1b9e77") GC Analysis of Benchmark Execution using Time Series data In the following series of 3 graphs: The “After Size” show the amount of heap space in use after each garbage collection. Many Java objects are still referenced, i.e. alive, during each garbage collection. This may indicate that the application has a memory leak, or may indicate that the application has a very large memory footprint. Typically, an application's memory footprint plateau's in the early stage of execution. One would expect this graph to have a flat top. The steep decline in the heap space may indicate that the application crashed after 2:00. The second graph shows that the outliers in real execution time, discussed above, occur near 2:00. when the Java heap seems to be quite full. The third graph shows that Full GCs are infrequent during the first few hours of execution. The rate of Full GC's, (the slope of the cummulative Full GC line), changes near midnight.   plot(clipped.g1gc.z[,c("AfterSize","RealTime","FullCount")], xlab="Time of Day", col=c("#1b9e77","red","#1b9e77")) GC Analysis of heap recovered Each GC trace includes the amount of heap space in use before and after the individual GC event. During garbage coolection, unreferenced objects are identified, the space holding the unreferenced objects is freed, and thus, the difference in before and after usage indicates how much space has been freed. The following box plot and bar chart both demonstrate the same point - the amount of heap space freed per garbage colloection is surprisingly low. par(mfrow=c(2,1)) boxplot(as.vector(clipped.g1gc.z$Delta), main="Amount of Heap Recovered per GC Pass", xlab="Size in KB", horizontal = TRUE, col="red") hist(as.vector(clipped.g1gc.z$Delta), main="Amount of Heap Recovered per GC Pass", xlab="Size in KB", breaks=100, col="red") box(which = "outer", lty = "solid") This graph is the most interesting. The dark blue area shows how much heap is occupied by referenced Java objects. This represents memory that holds live data. The red fringe at the top shows how much data was recovered after each garbage collection. barplot(clipped.g1gc.z[,c("AfterSize","Delta")], col=c("#7570b3","#e7298a"), xlab="Time of Day", border=NA) legend("topleft", c("Live Objects","Heap Recovered on GC"), fill=c("#7570b3","#e7298a")) box(which = "outer", lty = "solid") When I discuss the data in the log files with the customer, I will ask for an explaination for the large amount of referenced data resident in the Java heap. There are two are posibilities: There is a memory leak and the amount of space required to hold referenced objects will continue to grow, limited only by the maximum heap size. After the maximum heap size is reached, the JVM will throw an “Out of Memory” exception every time that the application tries to allocate a new object. If this is the case, the aplication needs to be debugged to identify why old objects are referenced when they are no longer needed. The application has a legitimate requirement to keep a large amount of data in memory. The customer may want to further increase the maximum heap size. Another possible solution would be to partition the application across multiple cluster nodes, where each node has responsibility for managing a unique subset of the data. Conclusion In conclusion, R is a very powerful tool for the analysis of Java garbage collection log files. The primary difficulty is data cleansing so that information can be read into an R data frame. Once the data has been read into R, a rich set of tools may be used for thorough evaluation.

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• Check parameters annotated with @Nonnull for null?

  - by David Harkness

  We've begun using FindBugs with and annotating our parameters with @Nonnull appropriately, and it works great to point out bugs early in the cycle. So far we have continued checking these arguments for null using Guava's checkNotNull, but I would prefer to check for null only at the edges--places where the value can come in without having been checked for null, e.g., a SOAP request. // service layer accessible from outside public Person createPerson(@CheckForNull String name) { return new Person(Preconditions.checkNotNull(name)); } ... // internal constructor accessed only by the service layer public Person(@Nonnull String name) { this.name = Preconditions.checkNotNull(name); // remove this check? } I understand that @Nonnull does not block null values itself. However, given that FindBugs will point out anywhere a value is transferred from an unmarked field to one marked @Nonnull, can't we depend on it to catch these cases (which it does) without having to check these values for null everywhere they get passed around in the system? Am I naive to want to trust the tool and avoid these verbose checks? Bottom line: While it seems safe to remove the second null check below, is it bad practice? This question is perhaps too similar to Should one check for null if he does not expect null, but I'm asking specifically in relation to the @Nonnull annotation.

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• 25 Favorite JCP Award Memories

  - by heathervc

  As we celebrated the 10th Annual JCP Awards and Party at JavaOne last week, we asked attendees to share their favorite memories.  Add yours to the retrospective list below... The 10th Award party will be the best :-) I won a DSLR camera at the 2011 JCP party and have taken many awesome photos of my family with it ever since!  Thanks JCP! Remembering the password to get in! It was very fascinating talking to all those JUG Members of last years' (2011) party and hearing about their hopes & expectations.  Especially from members of SouJava and LJC. Hanging out with my friends Best food and one of my colleagues won the raffle prize. My friend Brian won a jacket 3 years ago and my friend Craig won a camera last year. 2010 when I took home 2 awards on behalf of JSRs I'm on. When Patrick & Scott sang 'Light My Fire'! Catch up with friends! Being able to attend my first JCP party and and joining JCP community. Of course it's when some people won the award (SouJava and LJC)!   Meeting Crazy Bob! This is my first. Mike  to be JCP Member of the Year in 2011. When SouJava and London Java Community won Member of the Year award! JBoss making CDI Everything! When SouJava won the JCP Member of the Year award. I love feeling like it is the Oscars! First Party! Winning JCP Member of the Year last year. The year I was running for it (JCP Award). 2009 music and hostess. Obscured on legal advice.

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• Install GRUB to Ubuntu Partition

  - by Noel

  So my computer has the following partitions: /dev/sda -- (I know this isn't a real partition, but more so the boot loader) /dev/sda1 -- (Windows 7 Boot Loader) /dev/sda3 -- (Windows 7) /dev/sda4 -- (Data partition, NTFS) that means i have /dev/sda2 as free space. I do not want to change the MBR of the computer. I would like /dev/sda2 to contain GRUB AND Ubuntu. So ideally when I turn my computer on, BIOS would ask if I'd like to boot Windows 7 or Ubuntu(or Grub or partition 2), and I could choose either one. But I would like Grub and Ubuntu to be on the same partition, so they will not interfere in any way with windows or window's boot loader/partition (sda3) How can I do this? Catch: when formatting partitions, Ubuntu does not give me the option to make them virtual partitions, so that makes things harder. I tried: installing Ubuntu to /dev/sda2 (which I formatted as ext4) and then told the Ubuntu installer to install the bootloader to /dev/sda2. But when I select "Ubuntu" from BIOS's boot selection, it loads a black screen and says "invalid arch independent ELF magic grub rescue _" and allows me to input stuff. How can I fix this, or tell my computer where Grub is?

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• Anonymouse VS Logged in users on my site & Google Analytics

  - by Flowpoke

  I'd like to be able to run two different 'tracks' for Google Analytics; One for anonymous users of the site and another for Users whom are logged-in. I say "track" because Im not sure of the term--but I definitely know I want it to all be in the same "Analytics Account", I just want to segregate my logged-in users... In the site template, I can very easily add a conditional to display one or the other (Analytics code snippet)... Which Im hoping this comes down to and although Im not sure, it seems that the last digit in your Analytics ID (e.g. UA-15XXXX0-X) could be incremented to gain such additional 'tracks'....? Any tips? Am I doin it wrong? My current footer snippet: <script type="text/javascript"> var gaJsHost = (("https:" == document.location.protocol) ? "https://ssl." : "http://www."); document.write(unescape("%3Cscript src='" + gaJsHost + "google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E")); </script> <script type="text/javascript"> try { var pageTracker = _gat._getTracker("UA-XXXXXXX-1"); pageTracker._trackPageview(); } catch(err) {} </script>

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• South Florida Stony Brook Alumni &amp; Friends Reception 2011

  - by Sam Abraham

  It’s official, we are kicking off a local South Florida Chapter for Stony Brook alumni and friends in the area to keep in touch.  Our first networking event will be taking place at Champps, Ft Lauderdale on November 17th, 6:00-8:00 PM. Admission is free and open for everyone, whether or not they are Stony Brook Alums. The team at Champps is offering us great specials (Happy hour deals, half-price appetizers,etc.) that we can choose to enjoy while we network and catch up. (Event Announcement: http://alumniandfriends.stonybrook.edu/page.aspx?pid=299&cid=1&ceid=171&cerid=0&cdt=11%2f17%2f2011) I look forward to share and revive my college experience which I believe was the starting line of my ongoing life journey. It would be also great to hear others’ take as they reflect on their experiences throughout their college years. I invite anyone interested in keeping in touch with friends and alums of Stony Brook to join our LinkedIn or Facebook groups.   The Stony Brook Alumni Association – South Florida Chapter LinkedIn Group: http://www.linkedin.com/groups?gid=3665306&trk=myg_ugrp_ovr The Stony Brook Alumni Association – South Florida Chapter Facebook Group: http://www.facebook.com/#!/groups/114760941910314/

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• What can be done to decrease the number of live issues with applications?

  - by User Smith

  First off I have seen this post which is slightly similar to my question. : What can you do to decrease the number of deployment bugs of a live website? Let me layout the situation for you. The team of programmers that I belong to have metrics associated with our code. Over the last several months our errors in our live system have increased by a large amount. We require that our updates to applications be tested by at least one other programmer prior to going live. I personally am completely against this as I think that applications should be tested by end users as end users are much better testers than programmers, I am not against programmers testing, obviously programmers need to test code, but they are most of the times too close to the code. The reason I specify that I think end users should test in our scenario is due to the fact that we don't have business analysts, we just have programmers. I come from a background where BAs took care of all the testing once programmers checked off it was ready to go live. We do have a staging environment in place that is a clone of the live environment that we use to ensure that we don't have issues between development and live environments this does catch some bugs. We don't do end user testing really at all, I should say we don't really have anyone testing our code except programmers, which I think gets us into this mess (Ideally, we would have BAs or QA or professional testers test). We don't have a QA team or anything of that nature. We don't have test cases for our projects that are fully laid out. Ok, I am just a peon programmer at the bottom of the rung, but I am probably more tired of these issues than the managers complaining about them. So, I don't have the ability to tell them you are doing it all wrong.....I have tried gentle pushes in the correct direction. Any advice or suggestions on how to alleviate this issue ?

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• Generic software code style enforcer

  - by FuzziBear

  It seems to me to be a fairly common thing to do, where you have some code that you'd like to automatically run through a code style tool to catch when people break your coding style guide(s). Particularly if you're working on code that has multiple languages (which is becoming more common with web-language-x and javascript), you generally want to apply similar code style guides to both and have them enforced. I've done a bit of research, but I've only been able to find tools to enforce code style guidelines (not necessarily applying the code style, just telling you when you break code style guidelines) for a particular language. It would seem to me a reasonably trivial thing to do by just using current IDE rules for syntax highlighting (so that you don't check style guide rules inside quotes or strings, etc) and a whole lot of regexes to enforce some really generic things. Examples: if ( rather than if( checking lines with only whitespace Are there any tools that do this kind of really generic style checking? I'd prefer it to be easily configurable for different languages (because like it or not, some things would just not work cross language) and to add new "rules" to check new things.

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• Can non-IT people handle a wiki?

  - by Andrew Heath

  (I'm hoping that some of you will have encountered this issue before and can offer some insights...) My company is looking to improve their market research data management. Current data management style: "Hey Jimbo, where's that picture of our WhatZit 2.0? "yeah I remember that email about that company from that guy, gimme a few minutes to search my Outlook" "who has the newest copy of the Important Competitor's product catalogue? Mine is from '09." ... "Colleen does, and she's on maternity leave. You'll have to call her to get her workstation password..." Desired data management style: data organized neatly by topic (legal, economic, industrial, competitor) for each topic, multiple media types stored together (company product images, press releases, contact info) but still neatly sorted by type data editing histories communal access (no data silos) I was thinking about setting up a department wiki for all users to access. It seems to satisfy the four criteria above, but I'm a little concerned about how user-friendly (read: decipherable to non-technical people) it is for the more advanced features like image galleries, article formatting, and the like. Has anyone here setup a wiki for non-IT people and had it not catch on fire//become a ghost town//look like Geocities? Bonus question: can you see any obvious drawbacks to my choice of MediaWiki (or any other wiki) for solving this problem? Thank you.

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• how to use opengl blend mode/functions to brighten/darken a texture.

  - by Jigar

  Tried this code, but the texture didnot get any lighter. try { texture = TextureLoader.getTexture("png", Game.class.getResourceAsStream("/brick.png"), true, GL_NEAREST); } catch (IOException e) { e.printStackTrace(); } GL11.glBindTexture(GL11.GL_TEXTURE_2D, texture.getTextureID()); glEnable(GL_BLEND); glBlendFunc(GL_CONSTANT_ALPHA, GL_CONSTANT_ALPHA); GL14.glBlendColor(1.0f, 1.0f, 1.0f, 0.5f); glColor4f(1, 1, 1, 0.5f); GL11.glBegin(GL11.GL_QUADS); // Start Drawing Quads // Front Face GL11.glNormal3f(0.0f, 0.0f, 1.0f); // Normal Pointing Towards Viewer GL11.glTexCoord2f(0.0f, 0.0f); GL11.glVertex3f(-1.0f, -1.0f, 1.0f); // Point 1 (Front) GL11.glTexCoord2f(1.0f, 0.0f); GL11.glVertex3f(1.0f, -1.0f, 1.0f); // Point 2 (Front) GL11.glTexCoord2f(1.0f, 1.0f); GL11.glVertex3f(1.0f, 1.0f, 1.0f); // Point 3 (Front) GL11.glTexCoord2f(0.0f, 1.0f); GL11.glVertex3f(-1.0f, 1.0f, 1.0f); // Point 4 (Front) glEnd();

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• Dynamically load images inside jar

  - by Rahat Ahmed

  I'm using Slick2d for a game, and while it runs fine in Eclipse, i'm trying to figure out how to make it work when exported to a runnable .jar. I have it set up to where I load every image located in the res/ directory. Here's the code /** * Loads all .png images located in source folders. * @throws SlickException */ public static void init() throws SlickException { loadedImages = new HashMap<>(); try { URI uri = new URI(ResourceLoader.getResource("res").toString()); File[] files = new File(uri).listFiles(new FilenameFilter(){ @Override public boolean accept(File dir, String name) { if(name.endsWith(".png")) return true; return false; } }); System.out.println("Naming filenames now."); for(File f:files) { System.out.println(f.getName()); FileInputStream fis = new FileInputStream(f); Image image = new Image(fis, f.getName(), false); loadedImages.put(f.getName(), image); } } catch (URISyntaxException | FileNotFoundException e) { System.err.println("UNABLE TO LOAD IMAGES FROM RES FOLDER!"); e.printStackTrace(); } font = new AngelCodeFont("res/bitmapfont.fnt",Art.get("bitmapfont.png")); } Now the obvious problem is the line URI uri = new URI(ResourceLoader.getResource("res").toString()); If I pack the res folder into the .jar there will not be a res folder on the filesystem. How can I iterate through all the images in the compiled .jar itself, or what is a better system to automatically load all images?

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• What's the best way to learn/increase problem-solving skills?

  - by tucaz

  Hi all! I'm not sure this is the right place to ask this question, neither if this is the right way to ask this question but I hope you help me if it is not. I work as a programmer since I was 15 (will be 24 next week) so learning programming logic was somehow natural during the course of my career and I think that it helped me to get pretty good problem-solving. One thing none of us (programmers) can deny is that programming logic helps us in a lot of fields outside computer programming. So I'd say it is a very valuable resource that one should learn. My girlfriend is not a programmer and graduated in college on a non related course (Foreign Relations) because she didn't know what to study back then. As the years passed she discovered that she liked Logistics and started to work with it almost two years ago. However, since she does not have a technical background (not even basic Math) she is really having a hard time with it. She is already trying to catch up with Math, but even simple questions/brain-teasers are hard to her. For example, trying to find the missing numbers of this sequence: 0, 1, 1, 2, 3, 5, 8, _, _, 34 and so on. We know that this is Fibonacci but if we didn't we would probably be able to get to the correct answer just by "guessing" (using our acquired problem-solving skills). I'm not sure if problem-solving skills or logic are the correct name for it, but this is what I mean: quick solve problems, brain-teasers, find patterns, have a "sharp" mind. So, the question is: what is the best way for someone to learn this kind of skills without being a programmer (or studying algorithms and such)? If you say it is a book, could you please recommend one? Thanks a lot!

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• C# Simple Twitter Update

  - by mroberts

  For what it's worth a simple twitter update. using System; using System.IO; using System.Net; using System.Text; namespace Server.Actions { public class TwitterUpdate { public string Body { get; set; } public string Login { get; set; } public string Password { get; set; } public override void Execute() { try { //encode user name and password string creds = Convert.ToBase64String(Encoding.ASCII.GetBytes(string.Format("{0}:{1}", this.Login, this.Password))); //encode tweet byte[] tweet = Encoding.ASCII.GetBytes("status=" + this.Body); //setup request HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://twitter.com/statuses/update.xml"); request.Method = "POST"; request.ServicePoint.Expect100Continue = false; request.Headers.Add("Authorization", string.Format("Basic {0}", creds)); request.ContentType = "application/x-www-form-urlencoded"; request.ContentLength = tweet.Length; //write to stream Stream reqStream = request.GetRequestStream(); reqStream.Write(tweet, 0, tweet.Length); reqStream.Close(); //check response HttpWebResponse response = (HttpWebResponse)request.GetResponse(); //... } catch (Exception e) { //... } } } }

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• How do I prevent my platformer's character from clipping on wall tiles?

  - by Jonathan Hobbs

  Currently, I have a platformer with tiles for terrain (graphics borrowed from Cave Story). The game is written from scratch using XNA, so I'm not using an existing engine or physics engine. The tile collisions are described pretty much exactly as described in this answer (with simple SAT for rectangles and circles), and everything works fine. Except when the player runs into a wall whilst falling/jumping. In that case, they'll catch on a tile and begin thinking they've hit a floor or ceiling that isn't actually there. The player is moving right and falling downwards. So after movement, collisions are checked - and first, it turns out the player character is colliding with the tile 3rd from the floor, and pushed upwards. Second, he's found to be colliding with the tile beside him, and pushed sideways - the end result being the player character thinks he's on the ground and isn't falling, and 'catches' on the tile for as long as he's running into it. I could solve this by defining the tiles from top to bottom instead, which makes him fall smoothly, but then the inverse case happens and he'll hit a ceiling that isn't there when jumping upwards against the wall. How should I approach resolving this, so that the player character can just fall along the wall as it should?

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• Consolidating multiple domain names

  - by Mike

  I have a client that has three separately hosted copies of their website, each on a separate domain name. The websites are all essentially the same, bar a few discrepancies caused by badly managed updates in the past. I will soon be launching a completely new website for them, at which point, all three domain names are to resolve to the same web server. One domain name will become the default domain name that they refer to in all their literature, and the other two will simply be used as catch-alls for old links, bookmarks, and so on. I would like to know what people consider the best route to achieve this. My plan so far is: Get the new site up and running on the new webserver. Change the relevant A record of the default domain name to point to the new webserver. a) Keep the existing hosting accounts in operation. Create a list of 301 redirects from old page names on the old site to new page names on the new site. or b) Configure CNAME records for the non-default domain names, each pointing to the new webserver. Create a list of 301 redirects on the new site that redirect from old page names to new page names. If my understanding is correct, 3a will help to maintain whatever search engine rankings the sites already have (I know it's not going to be perfect), while at the same time informing search engines that the old domain names are no longer in use. What's a good approach to take here?

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• Navigation in Win8 Metro Style applications

  - by Dennis Vroegop

  In Windows 8, Touch is, as they say, a first class citizen. Now, to be honest: they also said that in Windows 7. However in Win8 this is actually true. Applications are meant to be used by touch. Yes, you can still use mouse, keyboard and pen and your apps should take that into account but touch is where you should focus on initially. Will all users have touch enabled devices? No, not in the first place. I don’t think touchscreens will be on every device sold next year. But in 5 years? Who knows? Don’t forget: if your app is successful it will be around for a long time and by that time touchscreens will be everywhere. Another reason to embrace touch is that it’s easier to develop a touch-oriented app and then to make sure that keyboard, nouse and pen work as doing it the other way around. Porting a mouse-based application to a touch based application almost never works. The reverse gives you much more chances for success. That being said, there are some things that you need to think about. Most people have more than one finger, while most users only use one mouse at the time. Still, most touch-developers translate their mouse-knowledge to the touch and think they did a good job. Martin Tirion from Microsoft said that since Touch is a new language people face the same challenges they do when learning a new real spoken language. The first thing people try when learning a new language is simply replace the words in their native language to the newly learned words. At first they don’t care about grammar. To a native speaker of that other language this sounds all wrong but they still will be able to understand what the intention was. If you don’t believe me: try Google translate to translate something for you from your language to another and then back and see what happens. The same thing happens with Touch. Most developers translate a mouse-click into a tap-event and think they’re done. Well matey, you’re not done. Not by far. There are things you can do with a mouse that you cannot do with touch. Think hover. A mouse has the ability to ‘slide’ over UI elements. Touch doesn’t (I know: with Pen you can do this but I’m talking about actual fingers here). A touch is either there or it isn’t. And right-click? Forget about it. A click is a click.  Yes, you have more than one finger but the machine doesn’t know which finger you use… The other way around is also true. Like I said: most users only have one mouse but they are likely to have more than one finger. So how do we take that into account? Thinking about this is really worth the time: you might come up with some surprisingly good ideas! Still: don’t forget that not every user has touch-enabled hardware so make sure your app is useable for both groups. Keep this in mind: we’re going to need it later on! Now. Apps should be easy to use. You don’t want your user to read through pages and pages of documentation before they can use the app. Imagine that spotter next to an airfield suddenly seeing a prototype of a Concorde 2 landing on the nearby runway. He probably wants to enter that information in our app NOW and not after he’s taken a 3 day course. Even if he still has to download the app, install it for the first time and then run it he should be on his way immediately. At least, fast enough to note down the details of that unique, rare and possibly exciting sighting he just did. So.. How do we do this? Well, I am not talking about games here. Games are in a league of their own. They fall outside the scope of the apps I am describing. But all the others can roughly be characterized as being one of two flavors: the navigation is either flat or hierarchical. That’s it. And if it’s hierarchical it’s no more than three levels deep. Not more. Your users will get lost otherwise and we don’t want that. Flat is simple. Just imagine we have one screen that is as high as our physical screen is and as wide as you need it to be. Don’t worry if it doesn’t fit on the screen: people can scroll to the right and left. Don’t combine up/down and left/right scrolling: it’s confusing. Next to that, since most users will hold their device in landscape mode it’s very natural to scroll horizontal. So let’s use that when we have a flat model. The same applies to the hierarchical model. Try to have at most three levels. If you need more space, find a way to group the items in such a way that you can fit it in three, very wide lanes. At the highest level we have the so called hub level. This is the entry point of the app and as such it should give the user an immediate feeling of what the app is all about. If your app has categories if items then you might show these categories here. And while you’re at it: also show 2 or 3 of the items itself here to give the user a taste of what lies beneath. If the user selects a category you go to the section part. Here you show several sections (again, go as wide as you need) with again some detail examples. After that: the details layer shows each item. By giving some samples of the underlaying layer you achieve several things: you make the layer attractive by showing several different things, you show some highlights so the user sees actual content and you provide a shortcut to the layers underneath. The image below is borrowed from the http://design.windows.com website which has tons and tons of examples: For our app we’ll use this layout. So what will we show? Well, let’s see what sorts of features our app has to offer. I’ll repeat them here: Note planes Add pictures of that plane Notify friends of new spots Share new spots on social media Write down arrival times Write down departure times Write down the runway they take I am sure you can think of some more items but for now we'll use these. In the hub we’ll show something that represents “Spots”, “Friends”, “Social”. Apparently we have an inner list of spotter-friends that are in the app, while we also have to whole world in social. In the layer below we show something else, depending on what the user choose. When they choose “Spots” we’ll display the last spots, last spots by our friends (so we can actually jump from this category to the one next to it) and so on. When they choose a “spot” (or press the + icon in the App bar, which I’ll talk about next time) they go to the lowest and final level that shows details about that spot, including a picture, date and time and the notes belonging to that entry. You’d be amazed at how easy it is to organize your app this way. If you don’t have enough room in these three layers you probably could easily get away with grouping items. Take a look at our hub: we have three completely different things in one place. If you still can’t fit it all in in a logical and consistent way, chances are you are trying to do too much in this app. Go back to your mission statement, determine if it is specific enough and if your feature list helps that statement or makes it unclear. Go ahead. Give it a go! Next time we’ll talk about the look and feel, the charms and the app-bar….

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