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  • How can I tell if I am overusing multi-threading?

    - by exhuma
    NOTE: This is a complete re-write of the question. The text before was way too lengthy and did not get to the point! If you're interested in the original question, you can look it up in the edit history. I currently feel like I am over-using multi-threading. I have 3 types of data, A, B and C. Each A can be converted to multiple Bs and each B can be converted to multiple Cs. I am only interested in treating Cs. I could write this fairly easily with a couple of conversion functions. But I caught myself implementing it with threads, three queues (queue_a, queue_b and queue_c). There are two threads doing the different conversions, and one worker: ConverterA reads from queue_a and writes to queue_b ConverterB reads from queue_b and writes to queue_c Worker handles each element from queue_c The conversions are fairly mundane, and I don't know if this model is too convoluted. But it seems extremely robust to me. Each "converter" can start working even before data has arrived on the queues, and at any time in the code I can just "submit" new As or Bs and it will trigger the conversion pipeline which in turn will trigger a job by the worker thread. Even the resulting code looks simpler. But I still am unsure if I am abusing threads for something simple.

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  • World Record Batch Rate on Oracle JD Edwards Consolidated Workload with SPARC T4-2

    - by Brian
    Oracle produced a World Record batch throughput for single system results on Oracle's JD Edwards EnterpriseOne Day-in-the-Life benchmark using Oracle's SPARC T4-2 server running Oracle Solaris Containers and consolidating JD Edwards EnterpriseOne, Oracle WebLogic servers and the Oracle Database 11g Release 2. The workload includes both online and batch workload. The SPARC T4-2 server delivered a result of 8,000 online users while concurrently executing a mix of JD Edwards EnterpriseOne Long and Short batch processes at 95.5 UBEs/min (Universal Batch Engines per minute). In order to obtain this record benchmark result, the JD Edwards EnterpriseOne, Oracle WebLogic and Oracle Database 11g Release 2 servers were executed each in separate Oracle Solaris Containers which enabled optimal system resources distribution and performance together with scalable and manageable virtualization. One SPARC T4-2 server running Oracle Solaris Containers and consolidating JD Edwards EnterpriseOne, Oracle WebLogic servers and the Oracle Database 11g Release 2 utilized only 55% of the available CPU power. The Oracle DB server in a Shared Server configuration allows for optimized CPU resource utilization and significant memory savings on the SPARC T4-2 server without sacrificing performance. This configuration with SPARC T4-2 server has achieved 33% more Users/core, 47% more UBEs/min and 78% more Users/rack unit than the IBM Power 770 server. The SPARC T4-2 server with 2 processors ran the JD Edwards "Day-in-the-Life" benchmark and supported 8,000 concurrent online users while concurrently executing mixed batch workloads at 95.5 UBEs per minute. The IBM Power 770 server with twice as many processors supported only 12,000 concurrent online users while concurrently executing mixed batch workloads at only 65 UBEs per minute. This benchmark demonstrates more than 2x cost savings by consolidating the complete solution in a single SPARC T4-2 server compared to earlier published results of 10,000 users and 67 UBEs per minute on two SPARC T4-2 and SPARC T4-1. The Oracle DB server used mirrored (RAID 1) volumes for the database providing high availability for the data without impacting performance. Performance Landscape JD Edwards EnterpriseOne Day in the Life (DIL) Benchmark Consolidated Online with Batch Workload System Rack Units BatchRate(UBEs/m) Online Users Users /Units Users /Core Version SPARC T4-2 (2 x SPARC T4, 2.85 GHz) 3 95.5 8,000 2,667 500 9.0.2 IBM Power 770 (4 x POWER7, 3.3 GHz, 32 cores) 8 65 12,000 1,500 375 9.0.2 Batch Rate (UBEs/m) — Batch transaction rate in UBEs per minute Configuration Summary Hardware Configuration: 1 x SPARC T4-2 server with 2 x SPARC T4 processors, 2.85 GHz 256 GB memory 4 x 300 GB 10K RPM SAS internal disk 2 x 300 GB internal SSD 2 x Sun Storage F5100 Flash Arrays Software Configuration: Oracle Solaris 10 Oracle Solaris Containers JD Edwards EnterpriseOne 9.0.2 JD Edwards EnterpriseOne Tools (8.98.4.2) Oracle WebLogic Server 11g (10.3.4) Oracle HTTP Server 11g Oracle Database 11g Release 2 (11.2.0.1) Benchmark Description JD Edwards EnterpriseOne is an integrated applications suite of Enterprise Resource Planning (ERP) software. Oracle offers 70 JD Edwards EnterpriseOne application modules to support a diverse set of business operations. Oracle's Day in the Life (DIL) kit is a suite of scripts that exercises most common transactions of JD Edwards EnterpriseOne applications, including business processes such as payroll, sales order, purchase order, work order, and manufacturing processes, such as ship confirmation. These are labeled by industry acronyms such as SCM, CRM, HCM, SRM and FMS. The kit's scripts execute transactions typical of a mid-sized manufacturing company. The workload consists of online transactions and the UBE – Universal Business Engine workload of 61 short and 4 long UBEs. LoadRunner runs the DIL workload, collects the user’s transactions response times and reports the key metric of Combined Weighted Average Transaction Response time. The UBE processes workload runs from the JD Enterprise Application server. Oracle's UBE processes come as three flavors: Short UBEs < 1 minute engage in Business Report and Summary Analysis, Mid UBEs > 1 minute create a large report of Account, Balance, and Full Address, Long UBEs > 2 minutes simulate Payroll, Sales Order, night only jobs. The UBE workload generates large numbers of PDF files reports and log files. The UBE Queues are categorized as the QBATCHD, a single threaded queue for large and medium UBEs, and the QPROCESS queue for short UBEs run concurrently. Oracle's UBE process performance metric is Number of Maximum Concurrent UBE processes at transaction rate, UBEs/minute. Key Points and Best Practices Two JD Edwards EnterpriseOne Application Servers, two Oracle WebLogic Servers 11g Release 1 coupled with two Oracle Web Tier HTTP server instances and one Oracle Database 11g Release 2 database on a single SPARC T4-2 server were hosted in separate Oracle Solaris Containers bound to four processor sets to demonstrate consolidation of multiple applications, web servers and the database with best resource utilizations. Interrupt fencing was configured on all Oracle Solaris Containers to channel the interrupts to processors other than the processor sets used for the JD Edwards Application server, Oracle WebLogic servers and the database server. A Oracle WebLogic vertical cluster was configured on each WebServer Container with twelve managed instances each to load balance users' requests and to provide the infrastructure that enables scaling to high number of users with ease of deployment and high availability. The database log writer was run in the real time RT class and bound to a processor set. The database redo logs were configured on the raw disk partitions. The Oracle Solaris Container running the Enterprise Application server completed 61 Short UBEs, 4 Long UBEs concurrently as the mixed size batch workload. The mixed size UBEs ran concurrently from the Enterprise Application server with the 8,000 online users driven by the LoadRunner. See Also SPARC T4-2 Server oracle.com OTN JD Edwards EnterpriseOne oracle.com OTN Oracle Solaris oracle.com OTN Oracle Database 11g Release 2 Enterprise Edition oracle.com OTN Oracle Fusion Middleware oracle.com OTN Disclosure Statement Copyright 2012, Oracle and/or its affiliates. All rights reserved. Oracle and Java are registered trademarks of Oracle and/or its affiliates. Other names may be trademarks of their respective owners. Results as of 09/30/2012.

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  • Operating systems theory -- using minimum number of semaphores

    - by stackuser
    This situation is prone to deadlock of processes in an operating system and I'd like to solve it with the minimum of semaphores. Basically there are three cooperating processes that all read data from the same input device. Each process, when it gets the input device, must read two consecutive data. I want to use mutual exclusion to do this. Semaphores should be used to synchronize: P1: P2: P3: input(a1,a2) input (b1,b2) input(c1,c2) Y=a1+c1 W=b2+c2 Z=a2+b1 Print (X) X=Z-Y+W The declaration and initialization that I think would work here are: semaphore s=1 sa1 = 0, sa2 = 0, sb1 = 0, sb2 = 0, sc1 = 0, sc2 = 0 I'm sure that any kernel programmers that happen on this can knock this out in a minute or 2. Diagram of cooperating Processes and one input device: It seems like P1 and P2 would start something like: wait(s) input (a1/b1, a2/b2) signal(s)

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  • Selling Visual Studio ALM

    - by Tarun Arora
    Introduction As a consultant I have been selling Application Lifecycle Management services using Visual Studio and Team Foundation Server. I’ve been contacted various times by friends working in organization telling me that ALM processes in their company were benchmarked when dinosaurs walked the earth. Most of these individuals already know the great features Microsoft ALM tools offer and are keen to start a conversation with the CIO but don’t exactly know where to start. It is very important how you engage in your first conversation, if you start the conversation with ‘There is this great tooling from Microsoft which offers amazing features to boost developer productivity, … ‘ from experience I can tell you the reply from your CIO would be ‘I already know! Our existing landscape has a combination of bleeding edge open source and cutting edge licensed tools which already cover these features quite well, more over Microsoft products have a high licensing cost associated to them.’ You will always find it harder to sell by feature, the trick is to highlight the gap in the existing processes & tools and then highlight the impact of these gaps to the overall development processes, by now you would have captured enough attention to show off how the ALM tooling offered by Microsoft not only fills those gaps but offers great value adds to take their development practices to the next level. Rangers ALM Assessment Guide Image 1 – Welcome! First look at the Rangers ALM assessment guide Most organization already have some processes in place to cover aspects of ALM. How do you go about proving that there isn’t enough cover in place? This is where Visual Studio ALM Rangers ALM Assessment guide can help. The ALM assessment guide is really a tool that helps you gather information about Development practices and processes within a customer's environment. Several questionnaires are used to identify the current state of individual development lifecycle areas and decide on a desired state for those processes. It also presents guidance and roll-up summaries to help with recommendations moving forward. The ALM Rangers assessment guide can be downloaded from here. Image 2 – ALM Assessment guide divided into different functions of SDLC The assessment guide is divided into different functions of Software Development Lifecycle (listed below), this gives you the ability to access how mature the company is in different areas of SDLC. Architecture & Design Requirement Engineering & UX Development Software Configuration Management Governance Deployment & Operations Testing & Quality Assurance Project Planning & Management Each section has a set of questions, fill in the assessment by selecting “Never/Sometimes/Always” from the Answer column in the question sheets.  Each answer has weightage to the overall score. Each question has a link next to it, clicking the link takes you to the Reference sheet which gives you more details about the question along with a reason for “why you need to ask this question?”, “other ways to phrase the question” and “what to expect as an answer from the customer”. The trick is to engage the customer in a discussion. You need to probe a lot, listen to the customer and have a discussion with several team members, preferably without management to ensure that you receive candid feedback. This reminds me of a funny incident when during an ALM review a customer told me that they have a sophisticated semi-automated application deployment process, further discussions revealed that deployment actually involved 72 manual configuration steps per production node. Such observations can be recorded in the Issue Brainstorming worksheet for further consideration later. It is also worth mentioning the different levels of ALM maturity to the customer. By default the desired state of ALM maturity is set to Standard, it is possible to set a desired state by area, you should strive for Advanced or Dynamic, it always helps by explaining the classification and advantages. Image 3 – ALM levels by description The ALM assessment guide helps you arrive at a quantitative measure of the company’s ALM maturity. The resultant graph plotted on a spider’s web shows you the company’s current state of ALM maturity and the desired state of ALM maturity. Further since the results are classified by area you can immediately spot the areas where the customer needs immediate help. Image 4 – The spiders web! The red cross icons are areas shouting out for immediate attention, the yellow exclamation icons are areas that need improvement. These icons are calculated on the difference between the Current State of ALM maturity VS the Desired state of ALM maturity. Image 5 – Results by area Conclusion To conclude the Rangers ALM assessment guide gives you the ability to, Measure the customer’s current ALM maturity level Understand the ALM maturity level the customer desires to achieve Capture a healthy list of issues the customer wants to brainstorm further Now What’s next…? Download and get started with the Rangers ALM Assessment Guide. If you have successfully captured the above listed three pieces of information you are in a great state to make recommendations on the identified areas highlighting the benefits that Visual Studio ALM tools would offer. In the next post I will be covering how to take the ALM assessment results as the base to actually convert your recommendation into a sell.  Remember to subscribe to http://feeds.feedburner.com/TarunArora. I would love to hear your feedback! If you have any recommendations on things that I should consider or any questions or feedback, feel free to leave a comment. *** A special thanks goes out to fellow ranges Willy, Ethem and Philip for reviewing the blog post and providing valuable feedback. ***

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  • WPF Using commands to slow to update UI controls

    - by toni
    Hi, I bind a command to a button through command property and doing a command binding in the page it is placed. In execute method I create an instance of a class that contains the background worker and I start it (this is a long task). The background worker (bw) class contains a variable isRunning that it is set to true before DoWork method is executed and to false when RunWorkerCompleted is executed. So from the code behind of the page where button is placed, in CanExecute method I set e.canExecute to true if bw is no running (isRunning = false), and e.canExecute to false if isRunning = true. WHen I press the button, it launch bw process for a long time and the button gets disabled. Ok this is correct, but when background worker (bw) finishes, the button doesn't returns to enabled until I press it again. When it is disabled and I press (when bw is finished) it gets enabled. Why the button is not returning automatically to enabled at the end of the bw? my code snippet: <Page x:Class="GParts.Pages.MyPage" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:Microsoft_Windows_Themes="clr-namespace:Microsoft.Windows.Themes; assembly=PresentationFramework.Aero" xmlns:local="clr-namespace:GParts" Loaded="Page_Loaded" Unloaded="Page_Unloaded" Height="Auto"> <Page.CommandBindings> <CommandBinding Command="{x:Static local:Pages.MyPage.rcmd}" Executed="CommandBinding_Executed" CanExecute="CommandBinding_CanExecute"/> </Page.CommandBindings> <...> <Button Command="{x:Static local:Pages.MyPage.rcmd}" /> <...> </Page> The code behind of the page: namespace GParts.Pages { public partial class MyPage : Page { public static RoutedCommand rcmd = new RoutedCommand(); private cBgWorker bw; <...> // ExecutedRoutedEventHandler for the custom button remove all command. private void CommandBinding_Executed(object sender, ExecutedRoutedEventArgs e) { // get an isntance of the background worker class bw = new cBgWorker(); // start the long task bw.StartTask(); } // CanExecuteRoutedEventHandler for the custom button remove all command. private void CommandBinding_CanExecute(object sender, CanExecuteRoutedEventArgs e) { // bw is the instance of background worker class if (bw == null) { e.CanExecute = true; } else { e.CanExecute = !bw.isRunning;// isRunning indicates if bw is //executing now } } <...> } // end class } // end namespace

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  • OS Analytics with Oracle Enterprise Manager (by Eran Steiner)

    - by Zeynep Koch
    Oracle Enterprise Manager Ops Center provides a feature called "OS Analytics". This feature allows you to get a better understanding of how the Operating System is being utilized. You can research the historical usage as well as real time data. This post will show how you can benefit from OS Analytics and how it works behind the scenes. The recording of our call to discuss this blog is available here: https://oracleconferencing.webex.com/oracleconferencing/ldr.php?AT=pb&SP=MC&rID=71517797&rKey=4ec9d4a3508564b3Download the presentation here See also: Blog about Alert Monitoring and Problem Notification Blog about Using Operational Profiles to Install Packages and other content Here is quick summary of what you can do with OS Analytics in Ops Center: View historical charts and real time value of CPU, memory, network and disk utilization Find the top CPU and Memory processes in real time or at a certain historical day Determine proper monitoring thresholds based on historical data Drill down into a process details Where to start To start with OS Analytics, choose the OS asset in the tree and click the Analytics tab. You can see the CPU utilization, Memory utilization and Network utilization, along with the current real time top 5 processes in each category (click the image to see a larger version):  In the above screen, you can click each of the top 5 processes to see a more detailed view of that process. Here is an example of one of the processes: One of the cool things is that you can see the process tree for this process along with some port binding and open file descriptors. Next, click the "Processes" tab to see real time information of all the processes on the machine: An interesting column is the "Target" column. If you configured Ops Center to work with Enterprise Manager Cloud Control, then the two products will talk to each other and Ops Center will display the correlated target from Cloud Control in this table. If you are only using Ops Center - this column will remain empty. The "Threshold" tab is particularly helpful - you can view historical trends of different monitored values and based on the graph - determine what the monitoring values should be: You can ask Ops Center to suggest monitoring levels based on the historical values or you can set your own. The different colors in the graph represent the current set levels: Red for critical, Yellow for warning and Blue for Information, allowing you to quickly see how they're positioned against real data. It's important to note that when looking at longer periods, Ops Center smooths out the data and uses averages. So when looking at values such as CPU Usage, try shorter time frames which are more detailed, such as one hour or one day. Applying new monitoring values When first applying new values to monitored attributes - a popup will come up asking if it's OK to get you out of the current Monitoring Policy. This is OK if you want to either have custom monitoring for a specific machine, or if you want to use this current machine as a "Gold image" and extract a Monitoring Policy from it. You can later apply the new Monitoring Policy to other machines and also set it as a default Monitoring Profile. Once you're done with applying the different monitoring values, you can review and change them in the "Monitoring" tab. You can also click the "Extract a Monitoring Policy" in the actions pane on the right to save all the new values to a new Monitoring Policy, which can then be found under "Plan Management" -> "Monitoring Policies". Visiting the past Under the "History" tab you can "go back in time". This is very helpful when you know that a machine was busy a few hours ago (perhaps in the middle of the night?), but you were not around to take a look at it in real time. Here's a view into yesterday's data on one of the machines: You can see an interesting CPU spike happening at around 3:30 am along with some memory use. In the bottom table you can see the top 5 CPU and Memory consumers at the requested time. Very quickly you can see that this spike is related to the Solaris 11 IPS repository synchronization process using the "pkgrecv" command. The "time machine" doesn't stop here - you can also view historical data to determine which of the zones was the busiest at a given time: Under the hood The data collected is stored on each of the agents under /var/opt/sun/xvm/analytics/historical/ An "os.zip" file exists for the main OS. Inside you will find many small text files, named after the Epoch time stamp in which they were taken If you have any zones, there will be a file called "guests.zip" containing the same small files for all the zones, as well as a folder with the name of the zone along with "os.zip" in it If this is the Enterprise Controller or the Proxy Controller, you will have folders called "proxy" and "sat" in which you will find the "os.zip" for that controller The actual script collecting the data can be viewed for debugging purposes as well: On Linux, the location is: /opt/sun/xvmoc/private/os_analytics/collect If you would like to redirect all the standard error into a file for debugging, touch the following file and the output will go into it: # touch /tmp/.collect.stderr   The temporary data is collected under /var/opt/sun/xvm/analytics/.collectdb until it is zipped. If you would like to review the properties for the Analytics, you can view those per each agent in /opt/sun/n1gc/lib/XVM.properties. Find the section "Analytics configurable properties for OS and VSC" to view the Analytics specific values. I hope you find this helpful! Please post questions in the comments below. Eran Steiner

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  • Operating systems -- using minimum number of semaphores

    - by stackuser
    The three cooperating processes all read data from the same input device. Each process, when it gets the input device, must read two consecutive data. I want to use mutual exclusion to do this. The declaration and initialization that I think would work here are: semaphore s=1 sa1 = 0, sa2 = 0, sb1 = 0, sb2 = 0, sc1 = 0, sc2 = 0 I'd like to use semaphores to synchronize the following processes: P1: P2: P3: input(a1,a2) input (b1,b2) input(c1,c2) Y=a1+c1 W=b2+c2 Z=a2+b1 Print (X) X=Z-Y+W I'm wondering how to use the minimum number of semaphores to solve this. Diagram of cooperating Processes and one input device: It seems like P1 and P2 would start something like: wait(s) input (a1/b1, a2/b2) signal(s)

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  • AWR Performance Report and Read by Other Session Waits

    - by user702295
    For the questions regarding "read by other session" and its relation to "db file sequential/scattered read", the logic is like this: When a "db file sequential/scattered read" is done, the blocks are either already in the cache or on the disk.  Since any operation on blocks is done in the cache and since and the issue is "read by other session" I will relate to the case the blocks are on the disk. Process A is reading the needed block from the disk to the cache.  During that time, if process B (and C and others) need the same block, it will wait on "read by other session".  A and B can be threads of the same process running in parallel or unrelated processes.  For example two processes doing full table scan on mdp_matrix etc. Solutions for that can be lowering the number of processes competing on the same blocks, increasing PCTFREE.  If it is a full table scan, maybe an index is missing that can result in less blocks being read from the cache and so on.

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  • linked list elements gone?

    - by Hristo
    I create a linked list dynamically and initialize the first node in main(), and I add to the list every time I spawn a worker process. Before the worker process exits, I print the list. Also, I print the list inside my sigchld signal handler. in main(): head = NULL; tail = NULL; // linked list to keep track of worker process dll_node_t *node; node = (dll_node_t *) malloc(sizeof(dll_node_t)); // initialize list, allocate memory append_node(node); node->pid = mainPID; // the first node is the MAIN process node->type = MAIN; in a fork()'d process: // add to list dll_node_t *node; node = (dll_node_t *) malloc(sizeof(dll_node_t)); append_node(node); node->pid = mmapFileWorkerStats->childPID; node->workerFileName = mmapFileWorkerStats->workerFileName; node->type = WORK; functions: void append_node(dll_node_t *nodeToAppend) { /* * append param node to end of list */ // if the list is empty if (head == NULL) { // create the first/head node head = nodeToAppend; nodeToAppend->prev = NULL; } else { tail->next = nodeToAppend; nodeToAppend->prev = tail; } // fix the tail to point to the new node tail = nodeToAppend; nodeToAppend->next = NULL; } finally... the signal handler: void chld_signalHandler() { dll_node_t *temp1 = head; while (temp1 != NULL) { printf("2. node's pid: %d\n", temp1->pid); temp1 = temp1->next; } int termChildPID = waitpid(-1, NULL, WNOHANG); dll_node_t *temp = head; while (temp != NULL) { if (temp->pid == termChildPID) { printf("found process: %d\n", temp->pid); } temp = temp->next; } return; } Is it true that upon the worker process exiting, the SIGCHLD signal handler is triggered? If so, that would mean that after I print the tree before exiting, the next thing I do is in the signal handler which is print the tree... which would mean i would print the tree twice? But the tree isn't the same. The node I add in the worker process doesn't exist when I print in the signal handler or at the very end of main(). Any idea why? Thanks, Hristo

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  • Dynamically loading modules in Python (+ threading question)

    - by morpheous
    I am writing a Python package which reads the list of modules (along with ancillary data) from a configuration file. I then want to iterate through each of the dynamically loaded modules and invoke a do_work() function in it which will spawn a new thread, so that the code runs in a separate thread. At the moment, I am importing the list of all known modules at the beginning of my main script - this is a nasty hack I feel, and is not very flexible, as well as being a maintenance pain. This is the function that spawns the threads. I will like to modify it to dynamically load the module when it is encountered. The key in the dictionary is the name of the module containing the code: def do_work(work_info): for (worker, dataset) in work_info.items(): #import the module defined by variable worker here... t = threading.Thread(target=worker.do_work, args=[dataset]) # I'll NOT dameonize since spawned children need to clean up on shutdown # Since the threads will be holding resources #t.daemon = True t.start() Question 1 When I call the function in my script (as written above), I get the following error: AttributeError: 'str' object has no attribute 'do_work' Which makes sense, since the dictionary key is a string (name of the module to be imported). When I add the statement: import worker before spawning the thread, I get the error: ImportError: No module named worker This is strange, since the variable name rather than the value it holds are being used - when I print the variable, I get the value (as I expect) whats going on? Question 2 As I mentioned in the comments section, I realize that the do_work() function written in the spawned children needs to cleanup after itself. My understanding is to write a clean_up function that is called when do_work() has completed successfully, or an unhandled exception is caught - is there anything more I need to do to ensure resources don't leak or leave the OS in an unstable state? Question 3 If I comment out the t.daemon flag statement, will the code stil run ASYNCHRONOUSLY?. The work carried out by the spawned children are pretty intensive, and I don't want to have to be waiting for one child to finish before spawning another child. BTW, I am aware that threading in Python is in reality, a kind of time sharing/slicing - thats ok Lastly is there a better (more Pythonic) way of doing what I'm trying to do?

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  • Should we design programs to randomly kill themselves?

    - by jimbojw
    In a nutshell, should we design death into our programs, processes, and threads at a low level, for the good of the overall system? Failures happen. Processes die. We plan for disaster and occasionally recover from it. But we rarely design and implement unpredictable program death. We hope that our services' uptimes are as long as we care to keep them running. A macro-example of this concept is Netflix's Chaos Monkey, which randomly terminates AWS instances in some scenarios. They claim that this has helped them discover problems and build more redundant systems. What I'm talking about is lower level. The idea is for traditionally long-running processes to randomly exit. This should force redundancy into the design and ultimately produce more resilient systems. Does this concept already have a name? Is it already being used in the industry?

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  • C#&ndash;Using a delegate to raise an event from one class to another

    - by Bill Osuch
    Even though this may be a relatively common task for many people, I’ve had to show it to enough new developers that I figured I’d immortalize it… MSDN says “Events enable a class or object to notify other classes or objects when something of interest occurs. The class that sends (or raises) the event is called the publisher and the classes that receive (or handle) the event are called subscribers.” Any time you add a button to a Windows Form or Web app, you can subscribe to the OnClick event, and you can also create your own event handlers to pass events between classes. Here I’ll show you how to raise an event from a separate class to a console application (or Windows Form). First, create a console app project (you could create a Windows Form, but this is easier for this demo). Add a class file called MyEvent.cs (it doesn’t really need to be a separate file, this is just for clarity) with the following code: public delegate void MyHandler1(object sender, MyEvent e); public class MyEvent : EventArgs {     public string message; } Your event can have whatever public properties you like; here we’re just got a single string. Next, add a class file called WorkerDLL.cs; this will simulate the class that would be doing all the work in the project. Add the following code: class WorkerDLL {     public event MyHandler1 Event1;     public WorkerDLL()     {     }     public void DoWork()     {         FireEvent("From Worker: Step 1");         FireEvent("From Worker: Step 5");         FireEvent("From Worker: Step 10");     }     private void FireEvent(string message)     {         MyEvent e1 = new MyEvent();         e1.message = message;         if (Event1 != null)         {             Event1(this, e1);         }         e1 = null;     } } Notice that the FireEvent method creates an instance of the MyEvent class and passes it to the Event1 handler (which we’ll create in just a second). Finally, add the following code to Program.cs: static void Main(string[] args) {     Program p = new Program(args); } public Program(string[] args) {     Console.WriteLine("From Console: Creating DLL");     WorkerDLL wd = new WorkerDLL();     Console.WriteLine("From Console: Wiring up event handler");     WireEventHandlers(wd);     Console.WriteLine("From Console: Doing the work");     wd.DoWork();     Console.WriteLine("From Console: Done - press any key to finish.");     Console.ReadLine(); } private void WireEventHandlers(WorkerDLL wd) {     MyHandler1 handler = new MyHandler1(OnHandler1);     wd.Event1 += handler; } public void OnHandler1(object sender, MyEvent e) {     Console.WriteLine(e.message); } The OnHandler1 method is called any time the event handler “hears” an event matching the specified signature – you could have it log to a file, write to a database, etc. Run the app in debug mode and you should see output like this: You can distinctly see which lines were written by the console application itself (Program.cs) and which were written by the worker class (WorkerDLL.cs). Technorati Tags: Csharp

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  • Cloudformation with Ubuntu throwing errors

    - by Sammaye
    I have been doing some reading and have come to the understanding that if you wish to use a launchConfig with Ubuntu you will need to install the cfn-init file yourself which I have done: "Properties" : { "KeyName" : { "Ref" : "KeyName" }, "SpotPrice" : "0.05", "ImageId" : { "Fn::FindInMap" : [ "AWSRegionArch2AMI", { "Ref" : "AWS::Region" }, { "Fn::FindInMap" : [ "AWSInstanceType2Arch", { "Ref" : "InstanceType" }, "Arch" ] } ] }, "SecurityGroups" : [ { "Ref" : "InstanceSecurityGroup" } ], "InstanceType" : { "Ref" : "InstanceType" }, "UserData" : { "Fn::Base64" : { "Fn::Join" : ["", [ "#!/bin/bash\n", "apt-get -y install python-setuptools\n", "easy_install https://s3.amazonaws.com/cloudformation-examples/aws-cfn-bootstrap-1.0-6.tar.gz\n", "cfn-init ", " --stack ", { "Ref" : "AWS::StackName" }, " --resource LaunchConfig ", " --configset ALL", " --access-key ", { "Ref" : "WorkerKeys" }, " --secret-key ", {"Fn::GetAtt": ["WorkerKeys", "SecretAccessKey"]}, " --region ", { "Ref" : "AWS::Region" }, " || error_exit 'Failed to run cfn-init'\n" ]]}} But I have a problem with this setup that I cannot seem to get a decent answer to. I keep getting this error in the logs: Jun 15 12:02:34 ip-0 [CLOUDINIT] __init__.py[DEBUG]: config-scripts-per-once already ran once Jun 15 12:02:34 ip-0 [CLOUDINIT] __init__.py[DEBUG]: handling scripts-per-boot with freq=None and args=[] Jun 15 12:02:34 ip-0 [CLOUDINIT] __init__.py[DEBUG]: handling scripts-per-instance with freq=None and args=[] Jun 15 12:02:34 ip-0 [CLOUDINIT] __init__.py[DEBUG]: handling scripts-user with freq=None and args=[] Jun 15 12:02:34 ip-0 [CLOUDINIT] cc_scripts_user.py[WARNING]: failed to run-parts in /var/lib/cloud/instance/scripts Jun 15 12:02:34 ip-0 [CLOUDINIT] __init__.py[WARNING]: Traceback (most recent call last):#012 File "/usr/lib/python2.7/dist-packages/cloudinit/CloudConfig/__init__.py", line 117, in run_cc_modules#012 cc.handle(name, run_args, freq=freq)#012 File "/usr/lib/python2.7/dist-packages/cloudinit/CloudConfig/__init__.py", line 78, in handle#012 [name, self.cfg, self.cloud, cloudinit.log, args])#012 File "/usr/lib/python2.7/dist-packages/cloudinit/__init__.py", line 326, in sem_and_run#012 func(*args)#012 File "/usr/lib/python2.7/dist-packages/cloudinit/CloudConfig/cc_scripts_user.py", line 31, in handle#012 util.runparts(runparts_path)#012 File "/usr/lib/python2.7/dist-packages/cloudinit/util.py", line 223, in runparts#012 raise RuntimeError('runparts: %i failures' % failed)#012RuntimeError: runparts: 1 failures Jun 15 12:02:34 ip-0 [CLOUDINIT] __init__.py[ERROR]: config handling of scripts-user, None, [] failed Jun 15 12:02:34 ip-0 [CLOUDINIT] __init__.py[DEBUG]: handling keys-to-console with freq=None and args=[] Jun 15 12:02:34 ip-0 [CLOUDINIT] __init__.py[DEBUG]: handling phone-home with freq=None and args=[] Jun 15 12:02:34 ip-0 [CLOUDINIT] __init__.py[DEBUG]: handling final-message with freq=None and args=[] Jun 15 12:02:34 ip-0 [CLOUDINIT] cloud-init-cfg[ERROR]: errors running cloud_config [final]: ['scripts-user'] I have absolutely no idea what scripts-user means and Google is not helping much here either. I can, when I ssh into the server, see that it runs the userdata script since I can access cfn-init as a command whereas I cannot in the original AMI the instance is made from. However I have a launchConfig: "Comment" : "Install a simple PHP application", "AWS::CloudFormation::Init" : { "configSets" : { "ALL" : ["WorkerRole"] }, "WorkerRole" : { "files" : { "/etc/cron.d/worker.cron" : { "content" : "*/1 * * * * ubuntu /home/ubuntu/worker_cron.php &> /home/ubuntu/worker.log\n", "mode" : "000644", "owner" : "root", "group" : "root" }, "/home/ubuntu/worker_cron.php" : { "content" : { "Fn::Join" : ["", [ "#!/usr/bin/env php", "<?php", "define('ROOT', dirname(__FILE__));", "const AWS_KEY = \"", { "Ref" : "WorkerKeys" }, "\";", "const AWS_SECRET = \"", { "Fn::GetAtt": ["WorkerKeys", "SecretAccessKey"]}, "\";", "const QUEUE = \"", { "Ref" : "InputQueue" }, "\";", "exec('git clone x '.ROOT.'/worker');", "if(!file_exists(ROOT.'/worker/worker_despatcher.php')){", "echo 'git not downloaded right';", "exit();", "}", "echo 'git downloaded';", "include_once ROOT.'/worker/worker_despatcher.php';" ]]}, "mode" : "000755", "owner" : "ubuntu", "group" : "ubuntu" } } } } Which does not seem to run at all. I have checked for the files existance in my home directory and it's not there. I have checked for the cronjob entry and it's not there either. I cannot, after reading through the documentation, seem to see what's potentially wrong with my code. Any thoughts on why this is not working? Am I missing something blatant?

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  • Apache mod_jk Setting for Tomcat - workers.properties

    - by sissonb
    I am trying to direct files with .jsp extensions to tomcat. Otherwise I want apache to serve the file directly (no tomcat). Currently I have a test.jsp which is supposed to create an HTML page with the current date in the body. Instead when I go to that .jsp I see the JK Status Manager. The mod_jk.logs only show, init_jk::mod_jk.c (3365): mod_jk/1.2.35 initialized. I have tomcat and apache setup on my server. Apache runs on 80 and tomcat runs on 8080. localhost:8080 show the tomcat welcome page. I downloaded tomcat-connectors-1.2.35-windows-i386-httpd-2.2.x and copied the mod_jk.so to C:\apache\modules. Then I added LoadModule jk_module modules/mod_jk.so to my httpd.conf. I restart apache and the module loads just fine. Next I downloaded the mod_jk source to get the workers.properties file. I copy workers.properties to C:\apache\confg. Then I added this user, workers.tomcat_home="C:/Program Files/Apache Software Foundation/Tomcat 7.0" workers.java_home="C:/Program Files/Java/jdk1.7.0_03" worker.list=ajp13 worker.ajp13.port=8080 worker.ajp13.host=localhost worker.ajp13.type=ajp13 worker.ajp13.socket_timeout=10 When I try to use the ajp13 user in my httpd.conf I get the following error in my mod_jk.log, [Wed Mar 28 13:08:51 2012] [2196:4100] [info] ajp_connection_tcp_get_message::jk_ajp_common.c (1258): (ajp13) can't receive the response header message from tomcat, network problems or tomcat (127.0.0.1:8080) is down (errno=60) [Wed Mar 28 13:08:51 2012] [2196:4100] [error] ajp_get_reply::jk_ajp_common.c (2117): (ajp13) Tomcat is down or refused connection. No response has been sent to the client (yet) [Wed Mar 28 13:08:51 2012] [2196:4100] [info] ajp_service::jk_ajp_common.c (2614): (ajp13) sending request to tomcat failed (recoverable), (attempt=1) Next I update my httpd.conf with, JkWorkersFile C:/apache/conf/workers.properties JkLogFile C:/apache/logs/mod_jk.log JkLogLevel info JkLogStampFormat "[%a %b %d %H:%M:%S %Y] " Also I added JkMount /*.jsp jk-status to my virtual host like this, <VirtualHost 192.168.5.250:80> JkMount /*.jsp jk-status #JkMount /*.jsp ajp13 ServerName bgsisson.com ServerAlias www.bgsisson.com DocumentRoot C:/www/resume </VirtualHost> I think i need to include a uriworkermap.properties file, but this is where I am getting stuck. I have put up a test .jsp at bgsisson.com/test.jsp It shows the JK Status Manager when I use JkMount /*.jsp jk-status and 502 Bad Gateway when I use JkMount /*.jsp ajp13 test.jsp <%-- use the 'taglib' directive to make the JSTL 1.0 core tags available; use the uri "http://java.sun.com/jsp/jstl/core" for JSTL 1.1 --%> <%@ taglib uri="http://java.sun.com/jstl/core" prefix="c" %> <%-- use the 'jsp:useBean' standard action to create the Date object; the object is set as an attribute in page scope --%> <jsp:useBean id="date" class="java.util.Date" /> <html> <head><title>First JSP</title></head> <body> <h2>Here is today's date</h2> <c:out value="${date}" /> </body> </html>

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  • "Unable to associated Elastic IP with cluster" in Eclipse Plugin Tutorial

    - by Jeffrey Chee
    Hi all, I am currently trying to evaluate AWS for my company and was trying to follow the tutorials on the web. http://developer.amazonwebservices.com/connect/entry.jspa?externalID=2241 However I get the below error during startup of the server instance: Unable to associated Elastic IP with cluster: Unable to detect that the Elastic IP was orrectly associated. java.lang.Exception: Unable to detect that the Elastic IP was correctly associated at com.amazonaws.ec2.cluster.Cluster.associateElasticIp(Cluster.java:802) at com.amazonaws.ec2.cluster.Cluster.start(Cluster.java:311) at com.amazonaws.eclipse.wtp.ElasticClusterBehavior.launch(ElasticClusterBehavior.java:611) at com.amazonaws.eclipse.wtp.Ec2LaunchConfigurationDelegate.launch(Ec2LaunchConfigurationDelegate.java:47) at org.eclipse.debug.internal.core.LaunchConfiguration.launch(LaunchConfiguration.java:853) at org.eclipse.debug.internal.core.LaunchConfiguration.launch(LaunchConfiguration.java:703) at org.eclipse.debug.internal.core.LaunchConfiguration.launch(LaunchConfiguration.java:696) at org.eclipse.wst.server.core.internal.Server.startImpl2(Server.java:3051) at org.eclipse.wst.server.core.internal.Server.startImpl(Server.java:3001) at org.eclipse.wst.server.core.internal.Server$StartJob.run(Server.java:300) at org.eclipse.core.internal.jobs.Worker.run(Worker.java:55) Then after a while, another error occur: Unable to publish server configuration files: Unable to copy remote file after trying 4 timeslocal file: 'XXXXXXXX/XXX.zip' Results from first attempt: Unexpected exception: java.net.ConnectException: Connection timed out: connect root cause: java.net.ConnectException: Connection timed out: connect at com.amazonaws.eclipse.ec2.RemoteCommandUtils.copyRemoteFile(RemoteCommandUtils.java:128) at com.amazonaws.eclipse.wtp.tomcat.Ec2TomcatServer.publishServerConfiguration(Ec2TomcatServer.java:172) at com.amazonaws.ec2.cluster.Cluster.publishServerConfiguration(Cluster.java:369) at com.amazonaws.eclipse.wtp.ElasticClusterBehavior.publishServer(ElasticClusterBehavior.java:538) at org.eclipse.wst.server.core.model.ServerBehaviourDelegate.publish(ServerBehaviourDelegate.java:866) at org.eclipse.wst.server.core.model.ServerBehaviourDelegate.publish(ServerBehaviourDelegate.java:708) at org.eclipse.wst.server.core.internal.Server.publishImpl(Server.java:2731) at org.eclipse.wst.server.core.internal.Server$PublishJob.run(Server.java:278) at org.eclipse.core.internal.jobs.Worker.run(Worker.java:55) Can anyone point me to what I'm doing wrong? I followed the tutorials and the video tutorials on youtube exactly. Best Regards ~Jeffrey

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  • Liferay 5.1.1 solr plugin ClassCastException

    - by Mustafa Zidan
    solr-pulgin throw the following exception [SolrIndexSearcherImpl:79] Error while sending request to Solr java.lang.ClassCastException: com.liferay.portal.kernel.util.HttpUtil cannot be cast to com.liferay.portal.kernel.util.HttpUtil at com.liferay.portal.kernel.util.HttpUtil._getUtil(HttpUtil.java:317) at com.liferay.portal.kernel.util.HttpUtil.getHttp(HttpUtil.java:96) at com.liferay.portal.kernel.util.HttpUtil.addParameter(HttpUtil.java:68) at com.liferay.portal.search.solr.SolrIndexSearcherImpl.search(SolrIndexSearcherImpl.java:71) at com.liferay.portal.search.solr.SolrSearchEngineUtil.search(SolrSearchEngineUtil.java:78) at com.liferay.portal.search.solr.messaging.SolrReaderMessageListener.doCommandSearch(SolrReaderMessageListener.java:92) at com.liferay.portal.search.solr.messaging.SolrReaderMessageListener.doReceive(SolrReaderMessageListener.java:75) at com.liferay.portal.search.solr.messaging.SolrReaderMessageListener.receive(SolrReaderMessageListener.java:46) at com.liferay.portal.kernel.messaging.InvokerMessageListener.receive(InvokerMessageListener.java:69) at com.liferay.portal.kernel.messaging.ParallelDestination$1.run(ParallelDestination.java:59) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) at java.lang.Thread.run(Thread.java:619) 16:08:16,174 ERROR [SolrReaderMessageListener:49] Unable to process message com.liferay.portal.kernel.messaging.Message@2c591d98 com.liferay.portal.kernel.search.SearchException: java.lang.ClassCastException: com.liferay.portal.kernel.util.HttpUtil cannot be cast to com.liferay.portal.kernel.util.HttpUtil at com.liferay.portal.search.solr.SolrIndexSearcherImpl.search(SolrIndexSearcherImpl.java:81) at com.liferay.portal.search.solr.SolrSearchEngineUtil.search(SolrSearchEngineUtil.java:78) at com.liferay.portal.search.solr.messaging.SolrReaderMessageListener.doCommandSearch(SolrReaderMessageListener.java:92) at com.liferay.portal.search.solr.messaging.SolrReaderMessageListener.doReceive(SolrReaderMessageListener.java:75) at com.liferay.portal.search.solr.messaging.SolrReaderMessageListener.receive(SolrReaderMessageListener.java:46) at com.liferay.portal.kernel.messaging.InvokerMessageListener.receive(InvokerMessageListener.java:69) at com.liferay.portal.kernel.messaging.ParallelDestination$1.run(ParallelDestination.java:59) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) can anyone help me on this

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  • Nonblocking Tcp server

    - by hoodoos
    It's not a question really, i'm just looking for some guidelines :) I'm currently writing some abstract tcp server which should use as low number of threads as it can. Currently it works this way. I have a thread doing listening and some worker threads. Listener thread is just sits and wait for clients to connect I expect to have a single listener thread per server instance. Worker threads are doing all read/write/processing job on clients socket. So my problem is in building efficient worker process. And I came to some problem I can't really solve yet. Worker code is something like that(code is really simple just to show a place where i have my problem): List<Socket> readSockets = new List<Socket>(); List<Socket> writeSockets = new List<Socket>(); List<Socket> errorSockets = new List<Socket>(); while( true ){ Socket.Select( readSockets, writeSockets, errorSockets, 10 ); foreach( readSocket in readSockets ){ // do reading here } foreach( writeSocket in writeSockets ){ // do writing here } // POINT2 and here's the problem i will describe below } it works all smothly accept for 100% CPU utilization because of while loop being cycling all over again, if I have my clients doing send-receive-disconnect routine it's not that painful, but if I try to keep alive doing send-receive-send-receive all over again it really eats up all CPU. So my first idea was to put a sleep there, I check if all sockets have their data send and then putting Thread.Sleep in POINT2 just for 10ms, but this 10ms later on produces a huge delay of that 10ms when I want to receive next command from client socket.. For example if I don't try to "keep alive" commands are being executed within 10-15ms and with keep alive it becomes worse by atleast 10ms :( Maybe it's just a poor architecture? What can be done so my processor won't get 100% utilization and my server to react on something appear in client socket as soon as possible? Maybe somebody can point a good example of nonblocking server and architecture it should maintain?

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  • Seeking help with a MT design pattern

    - by SamG
    I have a queue of 1000 work items and a n-proc machine (assume n = 4).The main thread spawns n (=4) worker threads at a time ( 25 outer iterations) and waits for all threads to complete before processing the next n (=4) items until the entire queue is processed for(i= 0 to queue.Length / numprocs) for(j= 0 to numprocs) { CreateThread(WorkerThread,WorkItem) } WaitForMultipleObjects(threadHandle[]) The work done by each (worker) thread is not homogeneous.Therefore in 1 batch (of n) if thread 1 spends 1000 s doing work and rest of the 3 threads only 1 s , above design is inefficient,becaue after 1 sec other 3 processors are idling. Besides there is no pooling - 1000 distinct threads are being created How do I use the NT thread pool (I am not familiar enough- hence the long winded question) and QueueUserWorkitem to achieve the above. The following constraints should hold The main thread requires that all worker items are processed before it can proceed.So I would think that a waitall like construct above is required I want to create as many threads as processors (ie not 1000 threads at a time) Also I dont want to create 1000 distinct events, pass to the worker thread, and wait on all events using the QueueUserWorkitem API or otherwise Exisitng code is in C++.Prefer C++ because I dont know c# I suspect that the above is a very common pattern and was looking for input from you folks.

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  • LINQ Datacontext Disposal Issues

    - by Refracted Paladin
    I am getting a Cannot access object: DataContext after it's been disposed in the below DAL method. I thought that I would be okay calling dispose there. result is an IEnumurable and I thought it was IQueryable that caused these kinds of problems. What am I doing wrong? How SHOULD I be disposing of my DataContext. Is there something better to be returning then a DataTable? This is a Desktop app that points at SQL 2005. Example method that causes this error -- public static DataTable GetEnrolledMembers(Guid workerID) { var DB = CmoDataContext.Create(); var AllEnrollees = from enrollment in DB.tblCMOEnrollments where enrollment.CMOSocialWorkerID == workerID || enrollment.CMONurseID == workerID join supportWorker in DB.tblSupportWorkers on enrollment.EconomicSupportWorkerID equals supportWorker.SupportWorkerID into workerGroup from worker in workerGroup.DefaultIfEmpty() select new { enrollment.ClientID, enrollment.CMONurseID, enrollment.CMOSocialWorkerID, enrollment.EnrollmentDate, enrollment.DisenrollmentDate, ESFirstName = worker.FirstName, ESLastName = worker.LastName, ESPhone = worker.Phone }; var result = from enrollee in AllEnrollees.AsEnumerable() where (enrollee.DisenrollmentDate == null || enrollee.DisenrollmentDate > DateTime.Now) //let memberName = BLLConnect.MemberName(enrollee.ClientID) let lastName = BLLConnect.MemberLastName(enrollee.ClientID) let firstName = BLLConnect.MemberFirstName(enrollee.ClientID) orderby enrollee.DisenrollmentDate ascending, lastName ascending select new { enrollee.ClientID, //MemberName = memberName, LastName = lastName, FirstName = firstName, NurseName = BLLAspnetdb.NurseName(enrollee.CMONurseID), SocialWorkerName = BLLAspnetdb.SocialWorkerName(enrollee.CMOSocialWorkerID), enrollee.EnrollmentDate, enrollee.DisenrollmentDate, ESWorkerName = enrollee.ESFirstName + " " + enrollee.ESLastName, enrollee.ESPhone }; DB.Dispose(); return result.CopyLinqToDataTable(); } partial class where I create the DataContext -- partial class CmoDataContext { public static bool IsDisconnectedUser { get { return Settings.Default.IsDisconnectedUser; } } public static CmoDataContext Create() { var cs = IsDisconnectedUser ? Settings.Default.CMOConnectionString : Settings.Default.Central_CMOConnectionString; return new CmoDataContext(cs); }

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  • Running another process without GUI freezing

    - by Adam
    I'm having trouble getting my GUI to appear and not freeze while running (and waiting for) an outside process. In this case, drivers.exe is a very simply program where the user simply clicks "OK". So whenever I click OK, it exits. I am trying to simply make my status strip count numbers up (really fast) as drivers.exe is executing. But in practice, my GUI never appears at all until drivers.exe exits. private void run_drivers() { Console.WriteLine("Start Driver"); int driver_timeout_in_minutes = 20; System.Diagnostics.Process driverproc = System.Diagnostics.Process.Start(Application.StartupPath + "\\" + "drivers.exe"); driverproc.WaitForExit(driver_timeout_in_minutes * 1000 * 60); //uses milliseconds, we must convert } private void Form1_Load(object sender, EventArgs e) { ThreadStart worker = new ThreadStart(run_drivers); Console.WriteLine("Main - Creating worker thread"); toolStripStatusLabel1.Text = "hi"; Thread t = new Thread(worker); t.IsBackground = true; t.Start(); Console.WriteLine("Main - Have requested the start of worker thread"); int i = 0; while (t.IsAlive) { i++; toolStripStatusLabel1.Text = i.ToString(); } Console.WriteLine("Dead"); }

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  • Does this use of Monitor.Wait/Pulse have a race condition?

    - by jw
    I have a simple producer/consumer scenario, where there is only ever a single item being produced/consumed. Also, the producer waits for the worker thread to finish before continuing. I realize that kind of obviates the whole point of multithreading, but please just assume it really needs to be this way (: This code doesn't compile, but I hope you get the idea: // m_data is initially null // This could be called by any number of producer threads simultaneously void SetData(object foo) { lock(x) // Line A { assert(m_data == null); m_data = foo; Monitor.Pulse(x) // Line B while(m_data != null) Monitor.Wait(x) // Line C } } // This is only ever called by a single worker thread void UseData() { lock(x) // Line D { while(m_data == null) Monitor.Wait(x) // Line E // here, do something with m_data m_data = null; Monitor.Pulse(x) // Line F } } Here is the situation that I am not sure about: Suppose many threads call SetData() with different inputs. Only one of them will get inside the lock, and the rest will be blocked on Line A. Suppose the one that got inside the lock sets m_data and makes its way to Line C. Question: Could the Wait() on Line C allow another thread at Line A to obtain the lock and overwrite m_data before the worker thread even gets to it? Supposing that doesn't happen, and the worker thread processes the original m_data, and eventually makes its way to Line F, what happens when that Pulse() goes off? Will only the thread waiting on Line C be able to get the lock? Or will it be competing with all the other threads waiting on Line A as well? Essentially, I want to know if Pulse()/Wait() communicate with each other specially "under the hood" or if they are on the same level with lock(). The solution to these problems, if they exist, is obvious of course - just surround SetData() with another lock - say, lock(y). I'm just curious if it's even an issue to begin with.

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  • Reading Data from DDFS ValueError: No JSON object could be decoded

    - by secumind
    I'm running dozens of map reduce jobs for a number of different purposes using disco. My data has grown enormous and I thought I would try using DDFS for a change rather than standard txt files. I've followed the DISCO map/reduce example Counting Words as a map/reduce job, without to much difficulty and with the help of others, Reading JSON specific data into DISCO I've gotten past one of my latest problems. I'm trying to read data in/out of ddfs to better chunk and distribute it but am having a bit of trouble. Here's an example file: file.txt {"favorited": false, "in_reply_to_user_id": null, "contributors": null, "truncated": false, "text": "I'll call him back tomorrow I guess", "created_at": "Mon Feb 13 05:34:27 +0000 2012", "retweeted": false, "in_reply_to_status_id_str": null, "coordinates": null, "in_reply_to_user_id_str": null, "entities": {"user_mentions": [], "hashtags": [], "urls": []}, "in_reply_to_status_id": null, "id_str": "168931016843603968", "place": null, "user": {"follow_request_sent": null, "profile_use_background_image": true, "profile_background_image_url_https": "https://si0.twimg.com/profile_background_images/305726905/FASHION-3.png", "verified": false, "profile_image_url_https": "https://si0.twimg.com/profile_images/1818996723/image_normal.jpg", "profile_sidebar_fill_color": "292727", "is_translator": false, "id": 113532729, "profile_text_color": "000000", "followers_count": 78, "protected": false, "location": "With My Niggas In Paris!", "default_profile_image": false, "listed_count": 0, "utc_offset": -21600, "statuses_count": 6733, "description": "Made in CHINA., Educated && Making My Own $$. Fear GOD && Put Him 1st. #TeamFollowBack #TeamiPhone\n", "friends_count": 74, "profile_link_color": "b03f3f", "profile_image_url": "http://a2.twimg.com/profile_images/1818996723/image_normal.jpg", "notifications": null, "show_all_inline_media": false, "geo_enabled": true, "profile_background_color": "1f9199", "id_str": "113532729", "profile_background_image_url": "http://a3.twimg.com/profile_background_images/305726905/FASHION-3.png", "name": "Bee'Jay", "lang": "en", "profile_background_tile": true, "favourites_count": 19, "screen_name": "OohMyBEEsNice", "url": "http://www.bitchimpaid.org", "created_at": "Fri Feb 12 03:32:54 +0000 2010", "contributors_enabled": false, "time_zone": "Central Time (US & Canada)", "profile_sidebar_border_color": "000000", "default_profile": false, "following": null}, "in_reply_to_screen_name": null, "retweet_count": 0, "geo": null, "id": 168931016843603968, "source": "<a href=\"http://twitter.com/#!/download/iphone\" rel=\"nofollow\">Twitter for iPhone</a>"} {"favorited": false, "in_reply_to_user_id": 50940453, "contributors": null, "truncated": false, "text": "@LegaMrvica @MimozaBand makasi om artis :D kadoo kadoo", "created_at": "Mon Feb 13 05:34:27 +0000 2012", "retweeted": false, "in_reply_to_status_id_str": "168653037894770688", "coordinates": null, "in_reply_to_user_id_str": "50940453", "entities": {"user_mentions": [{"indices": [0, 11], "screen_name": "LegaMrvica", "id": 50940453, "name": "Lega_thePianis", "id_str": "50940453"}, {"indices": [12, 23], "screen_name": "MimozaBand", "id": 375128905, "name": "Mimoza", "id_str": "375128905"}], "hashtags": [], "urls": []}, "in_reply_to_status_id": 168653037894770688, "id_str": "168931016868761600", "place": null, "user": {"follow_request_sent": null, "profile_use_background_image": true, "profile_background_image_url_https": "https://si0.twimg.com/profile_background_images/347686061/Galungan_dan_Kuningan.jpg", "verified": false, "profile_image_url_https": "https://si0.twimg.com/profile_images/1803845596/Picture_20124_normal.jpg", "profile_sidebar_fill_color": "DDFFCC", "is_translator": false, "id": 48293450, "profile_text_color": "333333", "followers_count": 182, "protected": false, "location": "\u00dcT: -6.906799,107.622383", "default_profile_image": false, "listed_count": 0, "utc_offset": -28800, "statuses_count": 3052, "description": "Fashion design maranatha '11 // traditional dancer (bali) at sanggar tampak siring & Natya Nataraja", "friends_count": 206, "profile_link_color": "0084B4", "profile_image_url": "http://a3.twimg.com/profile_images/1803845596/Picture_20124_normal.jpg", "notifications": null, "show_all_inline_media": false, "geo_enabled": true, "profile_background_color": "9AE4E8", "id_str": "48293450", "profile_background_image_url": "http://a0.twimg.com/profile_background_images/347686061/Galungan_dan_Kuningan.jpg", "name": "nana afiff", "lang": "en", "profile_background_tile": true, "favourites_count": 2, "screen_name": "hasnfebria", "url": null, "created_at": "Thu Jun 18 08:50:29 +0000 2009", "contributors_enabled": false, "time_zone": "Pacific Time (US & Canada)", "profile_sidebar_border_color": "BDDCAD", "default_profile": false, "following": null}, "in_reply_to_screen_name": "LegaMrvica", "retweet_count": 0, "geo": null, "id": 168931016868761600, "source": "<a href=\"http://blackberry.com/twitter\" rel=\"nofollow\">Twitter for BlackBerry\u00ae</a>"} {"favorited": false, "in_reply_to_user_id": 27260086, "contributors": null, "truncated": false, "text": "@justinbieber u were born to be somebody, and u're super important in beliebers' life. thanks for all biebs. I love u. follow me? 84", "created_at": "Mon Feb 13 05:34:27 +0000 2012", "retweeted": false, "in_reply_to_status_id_str": null, "coordinates": null, "in_reply_to_user_id_str": "27260086", "entities": {"user_mentions": [{"indices": [0, 13], "screen_name": "justinbieber", "id": 27260086, "name": "Justin Bieber", "id_str": "27260086"}], "hashtags": [], "urls": []}, "in_reply_to_status_id": null, "id_str": "168931016856178688", "place": null, "user": {"follow_request_sent": null, "profile_use_background_image": true, "profile_background_image_url_https": "https://si0.twimg.com/profile_background_images/416005864/Captura.JPG", "verified": false, "profile_image_url_https": "https://si0.twimg.com/profile_images/1808883280/Captura6_normal.JPG", "profile_sidebar_fill_color": "f5e7f3", "is_translator": false, "id": 406750700, "profile_text_color": "333333", "followers_count": 1122, "protected": false, "location": "Adentro de una supra.", "default_profile_image": false, "listed_count": 0, "utc_offset": -14400, "statuses_count": 20966, "description": "Mi \u00eddolo es @justinbieber , si te gusta \u00a1genial!, si no, solo respetalo. El cambi\u00f3 mi vida completamente y mi sue\u00f1o es conocerlo #TrueBelieber . ", "friends_count": 1015, "profile_link_color": "9404b8", "profile_image_url": "http://a1.twimg.com/profile_images/1808883280/Captura6_normal.JPG", "notifications": null, "show_all_inline_media": false, "geo_enabled": false, "profile_background_color": "f9fcfa", "id_str": "406750700", "profile_background_image_url": "http://a3.twimg.com/profile_background_images/416005864/Captura.JPG", "name": "neversaynever,right?", "lang": "es", "profile_background_tile": false, "favourites_count": 22, "screen_name": "True_Belieebers", "url": "http://www.wehavebieber-fever.tumblr.com", "created_at": "Mon Nov 07 04:17:40 +0000 2011", "contributors_enabled": false, "time_zone": "Santiago", "profile_sidebar_border_color": "C0DEED", "default_profile": false, "following": null}, "in_reply_to_screen_name": "justinbieber", "retweet_count": 0, "geo": null, "id": 168931016856178688, "source": "<a href=\"http://yfrog.com\" rel=\"nofollow\">Yfrog</a>"} I load it into DDFS with: # ddfs chunk data:test1 ./file.txt created: disco://localhost/ddfs/vol0/blob/44/file_txt-0$549-db27b-125e1 I test that the file is indeed loaded into ddfs with: # ddfs xcat data:test1 {"favorited": false, "in_reply_to_user_id": null, "contributors": null, "truncated": false, "text": "I'll call him back tomorrow I guess", "created_at": "Mon Feb 13 05:34:27 +0000 2012", "retweeted": false, "in_reply_to_status_id_str": null, "coordinates": null, "in_reply_to_user_id_str": null, "entities": {"user_mentions": [], "hashtags": [], "urls": []}, "in_reply_to_status_id": null, "id_str": "168931016843603968", "place": null, "user": {"follow_request_sent": null, "profile_use_background_image": true, "profile_background_image_url_https": "https://si0.twimg.com/profile_background_images/305726905/FASHION-3.png", "verified": false, "profile_image_url_https": "https://si0.twimg.com/profile_images/1818996723/image_normal.jpg", "profile_sidebar_fill_color": "292727", "is_translator": false, "id": 113532729, "profile_text_color": "000000", "followers_count": 78, "protected": false, "location": "With My Niggas In Paris!", "default_profile_image": false, "listed_count": 0, "utc_offset": -21600, "statuses_count": 6733, "description": "Made in CHINA., Educated && Making My Own $$. Fear GOD && Put Him 1st. #TeamFollowBack #TeamiPhone\n", "friends_count": 74, "profile_link_color": "b03f3f", "profile_image_url": "http://a2.twimg.com/profile_images/1818996723/image_normal.jpg", "notifications": null, "show_all_inline_media": false, "geo_enabled": true, "profile_background_color": "1f9199", "id_str": "113532729", "profile_background_image_url": "http://a3.twimg.com/profile_background_images/305726905/FASHION-3.png", "name": "Bee'Jay", "lang": "en", "profile_background_tile": true, "favourites_count": 19, "screen_name": "OohMyBEEsNice", "url": "http://www.bitchimpaid.org", "created_at": "Fri Feb 12 03:32:54 +0000 2010", "contributors_enabled": false, "time_zone": "Central Time (US & Canada)", "profile_sidebar_border_color": "000000", "default_profile": false, "following": null}, "in_reply_to_screen_name": null, "retweet_count": 0, "geo": null, "id": 168931016843603968, "source": "<a href=\"http://twitter.com/#!/download/iphone\" rel=\"nofollow\">Twitter for iPhone</a>"} {"favorited": false, "in_reply_to_user_id": 50940453, "contributors": null, "truncated": false, "text": "@LegaMrvica @MimozaBand makasi om artis :D kadoo kadoo", "created_at": "Mon Feb 13 05:34:27 +0000 2012", "retweeted": false, "in_reply_to_status_id_str": "168653037894770688", "coordinates": null, "in_reply_to_user_id_str": "50940453", "entities": {"user_mentions": [{"indices": [0, 11], "screen_name": "LegaMrvica", "id": 50940453, "name": "Lega_thePianis", "id_str": "50940453"}, {"indices": [12, 23], "screen_name": "MimozaBand", "id": 375128905, "name": "Mimoza", "id_str": "375128905"}], "hashtags": [], "urls": []}, "in_reply_to_status_id": 168653037894770688, "id_str": "168931016868761600", "place": null, "user": {"follow_request_sent": null, "profile_use_background_image": true, "profile_background_image_url_https": "https://si0.twimg.com/profile_background_images/347686061/Galungan_dan_Kuningan.jpg", "verified": false, "profile_image_url_https": "https://si0.twimg.com/profile_images/1803845596/Picture_20124_normal.jpg", "profile_sidebar_fill_color": "DDFFCC", "is_translator": false, "id": 48293450, "profile_text_color": "333333", "followers_count": 182, "protected": false, "location": "\u00dcT: -6.906799,107.622383", "default_profile_image": false, "listed_count": 0, "utc_offset": -28800, "statuses_count": 3052, "description": "Fashion design maranatha '11 // traditional dancer (bali) at sanggar tampak siring & Natya Nataraja", "friends_count": 206, "profile_link_color": "0084B4", "profile_image_url": "http://a3.twimg.com/profile_images/1803845596/Picture_20124_normal.jpg", "notifications": null, "show_all_inline_media": false, "geo_enabled": true, "profile_background_color": "9AE4E8", "id_str": "48293450", "profile_background_image_url": "http://a0.twimg.com/profile_background_images/347686061/Galungan_dan_Kuningan.jpg", "name": "nana afiff", "lang": "en", "profile_background_tile": true, "favourites_count": 2, "screen_name": "hasnfebria", "url": null, "created_at": "Thu Jun 18 08:50:29 +0000 2009", "contributors_enabled": false, "time_zone": "Pacific Time (US & Canada)", "profile_sidebar_border_color": "BDDCAD", "default_profile": false, "following": null}, "in_reply_to_screen_name": "LegaMrvica", "retweet_count": 0, "geo": null, "id": 168931016868761600, "source": "<a href=\"http://blackberry.com/twitter\" rel=\"nofollow\">Twitter for BlackBerry\u00ae</a>"} {"favorited": false, "in_reply_to_user_id": 27260086, "contributors": null, "truncated": false, "text": "@justinbieber u were born to be somebody, and u're super important in beliebers' life. thanks for all biebs. I love u. follow me? 84", "created_at": "Mon Feb 13 05:34:27 +0000 2012", "retweeted": false, "in_reply_to_status_id_str": null, "coordinates": null, "in_reply_to_user_id_str": "27260086", "entities": {"user_mentions": [{"indices": [0, 13], "screen_name": "justinbieber", "id": 27260086, "name": "Justin Bieber", "id_str": "27260086"}], "hashtags": [], "urls": []}, "in_reply_to_status_id": null, "id_str": "168931016856178688", "place": null, "user": {"follow_request_sent": null, "profile_use_background_image": true, "profile_background_image_url_https": "https://si0.twimg.com/profile_background_images/416005864/Captura.JPG", "verified": false, "profile_image_url_https": "https://si0.twimg.com/profile_images/1808883280/Captura6_normal.JPG", "profile_sidebar_fill_color": "f5e7f3", "is_translator": false, "id": 406750700, "profile_text_color": "333333", "followers_count": 1122, "protected": false, "location": "Adentro de una supra.", "default_profile_image": false, "listed_count": 0, "utc_offset": -14400, "statuses_count": 20966, "description": "Mi \u00eddolo es @justinbieber , si te gusta \u00a1genial!, si no, solo respetalo. El cambi\u00f3 mi vida completamente y mi sue\u00f1o es conocerlo #TrueBelieber . ", "friends_count": 1015, "profile_link_color": "9404b8", "profile_image_url": "http://a1.twimg.com/profile_images/1808883280/Captura6_normal.JPG", "notifications": null, "show_all_inline_media": false, "geo_enabled": false, "profile_background_color": "f9fcfa", "id_str": "406750700", "profile_background_image_url": "http://a3.twimg.com/profile_background_images/416005864/Captura.JPG", "name": "neversaynever,right?", "lang": "es", "profile_background_tile": false, "favourites_count": 22, "screen_name": "True_Belieebers", "url": "http://www.wehavebieber-fever.tumblr.com", "created_at": "Mon Nov 07 04:17:40 +0000 2011", "contributors_enabled": false, "time_zone": "Santiago", "profile_sidebar_border_color": "C0DEED", "default_profile": false, "following": null}, "in_reply_to_screen_name": "justinbieber", "retweet_count": 0, "geo": null, "id": 168931016856178688, "source": "<a href=\"http://yfrog.com\" rel=\"nofollow\">Yfrog</a> At this point everything is great, I load up the script that resulted from a previous Stack Post: from disco.core import Job, result_iterator import gzip def map(line, params): import unicodedata import json r = json.loads(line).get('text') s = unicodedata.normalize('NFD', r).encode('ascii', 'ignore') for word in s.split(): yield word, 1 def reduce(iter, params): from disco.util import kvgroup for word, counts in kvgroup(sorted(iter)): yield word, sum(counts) if __name__ == '__main__': job = Job().run(input=["tag://data:test1"], map=map, reduce=reduce) for word, count in result_iterator(job.wait(show=True)): print word, count NOTE: That this script runs file if the input=["file.txt"], however when I run it with "tag://data:test1" I get the following error: # DISCO_EVENTS=1 python count_normal_words.py Job@549:db30e:25bd8: Status: [map] 0 waiting, 1 running, 0 done, 0 failed 2012/11/25 21:43:26 master New job initialized! 2012/11/25 21:43:26 master Starting job 2012/11/25 21:43:26 master Starting map phase 2012/11/25 21:43:26 master map:0 assigned to solice 2012/11/25 21:43:26 master ERROR: Job failed: Worker at 'solice' died: Traceback (most recent call last): File "/home/DISCO/data/solice/01/Job@549:db30e:25bd8/usr/local/lib/python2.7/site-packages/disco/worker/__init__.py", line 329, in main job.worker.start(task, job, **jobargs) File "/home/DISCO/data/solice/01/Job@549:db30e:25bd8/usr/local/lib/python2.7/site-packages/disco/worker/__init__.py", line 290, in start self.run(task, job, **jobargs) File "/home/DISCO/data/solice/01/Job@549:db30e:25bd8/usr/local/lib/python2.7/site-packages/disco/worker/classic/worker.py", line 286, in run getattr(self, task.mode)(task, params) File "/home/DISCO/data/solice/01/Job@549:db30e:25bd8/usr/local/lib/python2.7/site-packages/disco/worker/classic/worker.py", line 299, in map for key, val in self['map'](entry, params): File "count_normal_words.py", line 12, in map File "/usr/lib64/python2.7/json/__init__.py", line 326, in loads return _default_decoder.decode(s) File "/usr/lib64/python2.7/json/decoder.py", line 366, in decode obj, end = self.raw_decode(s, idx=_w(s, 0).end()) File "/usr/lib64/python2.7/json/decoder.py", line 384, in raw_decode raise ValueError("No JSON object could be decoded") ValueError: No JSON object could be decoded 2012/11/25 21:43:26 master WARN: Job killed Status: [map] 1 waiting, 0 running, 0 done, 1 failed Traceback (most recent call last): File "count_normal_words.py", line 28, in <module> for word, count in result_iterator(job.wait(show=True)): File "/usr/local/lib/python2.7/site-packages/disco/core.py", line 348, in wait timeout, poll_interval * 1000) File "/usr/local/lib/python2.7/site-packages/disco/core.py", line 309, in check_results raise JobError(Job(name=jobname, master=self), "Status %s" % status) disco.error.JobError: Job Job@549:db30e:25bd8 failed: Status dead The Error states: ValueError: No JSON object could be decoded. Again, this works fine using the text file as input but now DDFS. Any ideas, I'm open to suggestions?

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  • strategy for choosing proper object and proper method

    - by zerkms
    in the code below at first if statements block (there will be more than just "worker" condition, joined with else if) i select proper filter_object. After this in the same conditional block i select what filter should be applied by filter object. This code is silly. public class Filter { public static List<data.Issue> fetch(string type, string filter) { Filter_Base filter_object = new Filter_Base(filter); if (type == "worker") { filter_object = new Filter_Worker(filter); } else if (type == "dispatcher") { filter_object = new Filter_Dispatcher(filter); } List<data.Issue> result = new List<data.Issue>(); if (filter == "new") { result = filter_object.new_issues(); } else if (filter == "ended") { result = filter_object.ended_issues(); } return result; } } public class Filter_Base { protected string _filter; public Filter_Base(string filter) { _filter = filter; } public virtual List<data.Issue> new_issues() { return new List<data.Issue>(); } public virtual List<data.Issue> ended_issues() { return new List<data.Issue>(); } } public class Filter_Worker : Filter_Base { public Filter_Worker(string filter) : base(filter) { } public override List<data.Issue> new_issues() { return (from i in data.db.GetInstance().Issues where (new int[] { 4, 5 }).Contains(i.RequestStatusId) select i).Take(10).ToList(); } } public class Filter_Dispatcher : Filter_Base { public Filter_Dispatcher(string filter) : base(filter) { } } it will be used in some kind of: Filter.fetch("worker", "new"); this code means, that for user that belongs to role "worker" only "new" issues will be fetched (this is some kind of small and simple CRM). Or another: Filter.fetch("dispatcher", "ended"); // here we get finished issues for dispatcher role Any proposals on how to improve it?

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  • BackgroundWorker might be causing my application to hang

    - by alexD
    I have a Form that uses a BackgroundWorker to execute a series of tests. I use the ProgressChanged event to send messages to the main thread, which then does all of the updates on the UI. I've combed through my code to make sure I'm not doing anything to the UI in the background worker. There are no while loops in my code and the BackgroundWorker has a finite execution time (measured in seconds or minutes). However, for some reason when I lock my computer, often times the application will be hung when I log back in. The thing is, the BackgroundWorker isn't even running when this happens. The reason I believe it is related to the BackgroundWorker though is because the form only hangs when the BackgroundWorker has been executed since the application was loaded (it only runs when given a certain user input). I pass this thread a List of TreeNodes from a TreeView in my UI through the RunWorkerAsync method, but I only read those nodes in the worker thread..any modifications I make to them is done in the UI thread through the progressChanged event. I do use Thread.Sleep in my worker thread to execute tests at timed intervals (which involves sending messages over a TCP socket, which was not created in the worker thread). I am completely perplexed as to why my application might be hanging. I'm sure I'm doing something 'illegal' somewhere, I just don't know what.

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  • Why is my GUI unresponsive while a SwingWorker thread runs?

    - by Starchy
    Hello, I have a SwingWorker thread with an IOBound task which is totally locking up the interface while it runs. Swapping out the normal workload for a counter loop has the same result. The SwingWorker looks basically like this: public class BackupWorker extends SwingWorker<String, String> { private static String uname = null; private static String pass = null; private static String filename = null; static String status = null; BackupWorker (String uname, String pass, String filename) { this.uname = uname; this.pass = pass; this.filename = filename; } @Override protected String doInBackground() throws Exception { BackupObject bak = newBackupObject(uname,pass,filename); return "Done!"; } } The code that kicks it off lives in a class that extends JFrame: public void actionPerformed(ActionEvent event) { String cmd = event.getActionCommand(); if (BACKUP.equals(cmd)) { SwingUtilities.invokeLater(new Runnable() { public void run() { final StatusFrame statusFrame = new StatusFrame(); statusFrame.setVisible(true); SwingUtilities.invokeLater(new Runnable() { public void run () { statusFrame.beginBackup(uname,pass,filename); } }); } }); } } Here's the interesting part of StatusFrame: public void beginBackup(final String uname, final String pass, final String filename) { worker = new BackupWorker(uname, pass, filename); worker.execute(); try { System.out.println(worker.get()); } catch (InterruptedException e) { e.printStackTrace(); } catch (ExecutionException e) { e.printStackTrace(); } } } So far as I can see, everything "long-running" is handled by the worker, and everything that touches the GUI on the EDT. Have I tangled things up somewhere, or am I expecting too much of SwingWorker?

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