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  • TechEd 2014 Day 3

    - by John Paul Cook
    There is some confusion about durability of data stored in SQL Server in-memory tables, so some review of the concepts is appropriate. The in-memory option is enabled at the database level. Enabling it at the database level only gives you the option to specify the in-memory feature on a table by table basis. No existing tables or new tables will by default become in-memory tables when you enable the feature at the database level. If you choose to make a table an in-memory table, by default it is...(read more)

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  • Any good stories or blog posts of a startup's server/stack evolving as they got bigger? [closed]

    - by user72245
    I know lots of startups often go for practical, simple, efficient. So maybe tossing a Ruby program on a basic Apache server. Get some users up and running, etc. Then Ruby starts to not be fast enough, so they throw more servers at the problem? And load balancing or something? And then when stuff gets REALLY crazy, language changes, etc? I'm looking for someone who has cleanly and simply told their own company's story like this. Are there any good ones?

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  • How long does it take in practice to warm up large in-memory databases?

    - by Sim
    Companies such as Peak Hosting are offering 64 core machines with 512Gb RAM for $2K/month. This is a very interesting choice for in-memory databases such as Memcached/Redis as well as databases whose performance degrades rapidly when the data & indexes don't fit in RAM, such as MongoDB. My main concern with monster machines such as these is the time it takes to warm up an in-memory database. In my experience, theoretical metrics, e.g., that SATA can load 100Mb/sec, fall short of what happens in practice. Even at that rate, 100Mb/sec means that loading up 512Gb RAM machine from SATA disks can take over 1 1/2 hours (!). I am looking for real-world reports of warm-up times for machines with very large memory. Please, share details of the software on the machine, data size, storage configuration, e.g., SATA or SSD, network, hosting/cloud provider, if relevant, etc.

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  • Why does using 2 memory sticks cause my computer to crash?

    - by hi
    My computer randomly crashes when playing games, but if I remove one memory stick (it does not matter which one I remove), it does not crash anymore. Memory tests do not find errors, I just put in a new power supply (650W), I only have 1 graphics card, so why is this happening? BTW, they are the same memory, same vendor same specs, everything I bought it together (2x2GB) My motherboard is a Asus P5Q Pro, so it supports both dual channel and more than 4gb. Switching slots does nothing, as long as I don't use more than 1 I'm fine.

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  • Why use binary files to stack up different versions on DMSs?

    - by edgarator
    I've used both Liferay and Alfresco trying to use them as the Document Management System for an intranet. I noticed the following: They use the file system and the database to store files They use a GUID to name the file on the filesystem and that GUID is used as an Id in the database. The GUID-named file is a binary file The GUID-named binary file stores all versions for a given file The path for the file in the DMS doesn't match the one in the file system The URL makes reference to the GUID when a certain file is requested What I want to know is why is this, and what would be the best way of doing it. Like how to would you create the binary file (zip?), and what parts would you keep in the binary file and what parts would you store in the database (meta-data, path?). I'm assuming some of the benefits of doing it like this. As having the same URL for a file, regardless of its current document path. And having only one file even if the file has changed names over time.

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  • Why OS X use swap when there is lots of "inactive memory"?

    - by Balchev
    I am using OS X from few months (Lion and now Mountain Lion). I have 8 GB on my mini and almost daily now it get close to that. On Windows 7 machine with 8 GB I never had that kind of problem. Anyway, I read over the net, that the inactive memory is app cache of the programs that are recently closed and can be used for faster reopening.And this inactive memory can be released to a new app if needed. It is not released. Instead OS X starts swapping. So my question is why OS X use swap when there is lots of "inactive memory"? Here a screen that shows what I mean: I really hope there is a away to make OS X to use those 2.69 GB before start swapping.I really do.

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  • C Programming: malloc() inside another function

    - by vikramtheone
    Hi Guys, I need help with malloc() inside another function. I'm passing a pointer and size to the function from my main() and I would like to allocate memory for that pointer dynamically using malloc() from inside that called function, but what I see is that.... the memory which is getting allocated is for the pointer declared withing my called function and not for the pointer which is inside the main(). How should I pass a pointer to a function and allocate memory for the passed pointer from inside the called function? Can anyone throw light on this? Help!!! Vikram I have written the following code and I get the output as shown below SOURCE: main() { unsigned char *input_image; unsigned int bmp_image_size = 262144; if(alloc_pixels(input_image, bmp_image_size)==NULL) printf("\nPoint2: Memory allocated: %d bytes",_msize(input_image)); else printf("\nPoint3: Memory not allocated"); } signed char alloc_pixels(unsigned char *ptr, unsigned int size) { signed char status = NO_ERROR; ptr = NULL; ptr = (unsigned char*)malloc(size); if(ptr== NULL) { status = ERROR; free(ptr); printf("\nERROR: Memory allocation did not complete successfully!"); } printf("\nPoint1: Memory allocated: %d bytes",_msize(ptr)); return status; } PROGRAM OUTPUT: Point1: Memory allocated ptr: 262144 bytes Point2: Memory allocated input_image: 0 bytes

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  • How do I optimize TCP stack for HTTP server?

    - by jcisio
    I have a HTTP server that serves only two kinds of page: about 10 KB and about 16 KB (both compressed, other files are from CDN). As the latency is quite high (ping takes more than 300 ms), I want to optimize the TCP stack so that client receives the whole page ASAP. Thus, I have a double question: Which parameter do I have to change (which value of TCP window)? How to change in (a Debian box, and FYI, there is a Varnish before the HTTP server).

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  • How to get stack dump from crashing ASP.NET process?

    - by Dylan
    An unhandled exception ('System.Net.Sockets.SocketException') occurred in w3wp.exe [9740]. Just-In-Time debugging this exception failed with the following error: Debugger could not be started because no user is logged on. We're getting the above error in the Application log. Is there a way to capture a .NET stack trace that doesn't require user interactivity?

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  • 32bit to 64bit inline assembly porting

    - by Simone Margaritelli
    I have a piece of C++ code (compiled with g++ under a GNU/Linux environment) that load a function pointer (how it does that doesn't matter), pushes some arguments onto the stack with some inline assembly and then calls that function, the code is like : unsigned long stack[] = { 1, 23, 33, 43 }; /* save all the registers and the stack pointer */ unsigned long esp; asm __volatile__ ( "pusha" ); asm __volatile__ ( "mov %%esp, %0" :"=m" (esp)); for( i = 0; i < sizeof(stack); i++ ){ unsigned long val = stack[i]; asm __volatile__ ( "push %0" :: "m"(val) ); } unsigned long ret = function_pointer(); /* restore registers and stack pointer */ asm __volatile__ ( "mov %0, %%esp" :: "m" (esp) ); asm __volatile__ ( "popa" ); I'd like to add some sort of #ifdef _LP64 // 64bit inline assembly #else // 32bit version as above example #endif But i don't know inline assembly for 64bit machines, anyone could help me? Thanks

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  • Python: re-initialize a function's default value for subsequent calls to the function.

    - by Peter Stewart
    I have a function that calls itself to increment and decrement a stack. I need to call it a number of times, and I'd like it to work the same way in subsequent calls but, as expected, it doesn't re-use the default value. I've read that this is a newbie trap and I've seen suggested solutions, but I haven't been able to make any solution work. It would be nice to be able to "fun.reset" def a(x, stack = [None]): print x,' ', stack if x > 5: temp = stack.pop() if x <=5: stack.append(1) if stack == []: return a(x + 1) print a(0) print a(2) #second call print a(3) #third call I expected this to work, but it doesn't. print a(0, [None]) print a(2, [None]) #second call print a(3, [None]) #third call Can I reset the function to it's initial state? Any help would be appreciated.

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  • jQuery action being called when selector isn't met?

    - by dougoftheabaci
    I've been working on a prototype for a client's web site and I've run into a rather significant snag. You can view the prototype here. As you can see, the way it works is you can scroll a set of slides horizontally and, by clicking one, open a stack containing yet more slides. If you then click again on an image in that stack it opens up a lightbox. Clicking on another stack or the close button will close that stack (and open another, as case may be). That all works great. However you get some weird behavior if you do the following: Click to open any stack. Click to open an image's light box (this works best if you click on the image that's level with the main list). Close the light box and the stack either by clicking the close button or clicking on another stack. Click back to the first stack. Instead of reopening the stack, you get the lightbox. This confuses me as the light box should only ever be called if there is a class on the containing UL and that class is removed when the lightbox is closed. I've checked and double-checked this, it's definitely missing. Here are the respective functions: $("ul.hide a.lightbox").live("click",function(){ $("ul.show").removeClass("show").addClass("hide"); $(this).parent().parent().removeClass("hide").addClass("show"); $("ul.hide").animate({opacity: 0.2}); $("ul.show").animate({opacity: 1}); $("#next").animate({opacity: 0.2}); $("#prev").animate({opacity: 0.2}); return false; }); $("ul.show a.lightbox").live("click",function(){ $(this).fancybox().trigger("click"); return false; }); As you can see, in order for the lightbox to be called the containing UL has to have the class of show. However, if you check it with Firebug it won't. For those who are curious, the added .trigger("click"); is because the lightbox will require a double-click to launch otherwise. Any idea how I can fix this?

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  • How solve consumer/producer task using semaphores

    - by user1074896
    I have SimpleProducerConsumer class that illustrate consumer/producer problem (I am not sure that it's correct). public class SimpleProducerConsumer { private Stack<Object> stack = new Stack<Object>(); private static final int STACK_MAX_SIZE = 10; public static void main(String[] args) { SimpleProducerConsumer pc = new SimpleProducerConsumer(); new Thread(pc.new Producer(), "p1").start(); new Thread(pc.new Producer(), "p2").start(); new Thread(pc.new Consumer(), "c1").start(); new Thread(pc.new Consumer(), "c2").start(); new Thread(pc.new Consumer(), "c3").start(); } public synchronized void push(Object d) { while (stack.size() >= STACK_MAX_SIZE) try { wait(); } catch (InterruptedException e) { e.printStackTrace(); } try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } stack.push(new Object()); System.out.println("push " + Thread.currentThread().getName() + " " + stack.size()); notify(); } public synchronized Object pop() { while (stack.size() == 0) try { wait(); } catch (InterruptedException e) { e.printStackTrace(); } try { Thread.sleep(50); } catch (InterruptedException e) { e.printStackTrace(); } stack.pop(); System.out.println("pop " + Thread.currentThread().getName() + " " + stack.size()); notify(); return null; } class Consumer implements Runnable { @Override public void run() { while (true) { pop(); } } } class Producer implements Runnable { @Override public void run() { while (true) { push(new Object()); } } } } I found simple realization of semaphore(here:http://docs.oracle.com/javase/tutorial/essential/concurrency/guardmeth.html I know that there is concurrency package) How I need to change code to exchange java objects monitors to my custom semaphore. (To illustrate C/P problem using semaphores) Semaphore: class Semaphore { private int counter; public Semaphore() { this(0); } public Semaphore(int i) { if (i < 0) throw new IllegalArgumentException(i + " < 0"); counter = i; } public synchronized void release() { if (counter == 0) { notify(); } counter++; } public synchronized void acquire() throws InterruptedException { while (counter == 0) { wait(); } counter--; } }

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  • SQL SERVER – PAGEIOLATCH_DT, PAGEIOLATCH_EX, PAGEIOLATCH_KP, PAGEIOLATCH_SH, PAGEIOLATCH_UP – Wait Type – Day 9 of 28

    - by pinaldave
    It is very easy to say that you replace your hardware as that is not up to the mark. In reality, it is very difficult to implement. It is really hard to convince an infrastructure team to change any hardware because they are not performing at their best. I had a nightmare related to this issue in a deal with an infrastructure team as I suggested that they replace their faulty hardware. This is because they were initially not accepting the fact that it is the fault of their hardware. But it is really easy to say “Trust me, I am correct”, while it is equally important that you put some logical reasoning along with this statement. PAGEIOLATCH_XX is such a kind of those wait stats that we would directly like to blame on the underlying subsystem. Of course, most of the time, it is correct – the underlying subsystem is usually the problem. From Book On-Line: PAGEIOLATCH_DT Occurs when a task is waiting on a latch for a buffer that is in an I/O request. The latch request is in Destroy mode. Long waits may indicate problems with the disk subsystem. PAGEIOLATCH_EX Occurs when a task is waiting on a latch for a buffer that is in an I/O request. The latch request is in Exclusive mode. Long waits may indicate problems with the disk subsystem. PAGEIOLATCH_KP Occurs when a task is waiting on a latch for a buffer that is in an I/O request. The latch request is in Keep mode. Long waits may indicate problems with the disk subsystem. PAGEIOLATCH_SH Occurs when a task is waiting on a latch for a buffer that is in an I/O request. The latch request is in Shared mode. Long waits may indicate problems with the disk subsystem. PAGEIOLATCH_UP Occurs when a task is waiting on a latch for a buffer that is in an I/O request. The latch request is in Update mode. Long waits may indicate problems with the disk subsystem. PAGEIOLATCH_XX Explanation: Simply put, this particular wait type occurs when any of the tasks is waiting for data from the disk to move to the buffer cache. ReducingPAGEIOLATCH_XX wait: Just like any other wait type, this is again a very challenging and interesting subject to resolve. Here are a few things you can experiment on: Improve your IO subsystem speed (read the first paragraph of this article, if you have not read it, I repeat that it is easy to say a step like this than to actually implement or do it). This type of wait stats can also happen due to memory pressure or any other memory issues. Putting aside the issue of a faulty IO subsystem, this wait type warrants proper analysis of the memory counters. If due to any reasons, the memory is not optimal and unable to receive the IO data. This situation can create this kind of wait type. Proper placing of files is very important. We should check file system for the proper placement of files – LDF and MDF on separate drive, TempDB on separate drive, hot spot tables on separate filegroup (and on separate disk), etc. Check the File Statistics and see if there is higher IO Read and IO Write Stall SQL SERVER – Get File Statistics Using fn_virtualfilestats. It is very possible that there are no proper indexes on the system and there are lots of table scans and heap scans. Creating proper index can reduce the IO bandwidth considerably. If SQL Server can use appropriate cover index instead of clustered index, it can significantly reduce lots of CPU, Memory and IO (considering cover index has much lesser columns than cluster table and all other it depends conditions). You can refer to the two articles’ links below previously written by me that talk about how to optimize indexes. Create Missing Indexes Drop Unused Indexes Updating statistics can help the Query Optimizer to render optimal plan, which can only be either directly or indirectly. I have seen that updating statistics with full scan (again, if your database is huge and you cannot do this – never mind!) can provide optimal information to SQL Server optimizer leading to efficient plan. Checking Memory Related Perfmon Counters SQLServer: Memory Manager\Memory Grants Pending (Consistent higher value than 0-2) SQLServer: Memory Manager\Memory Grants Outstanding (Consistent higher value, Benchmark) SQLServer: Buffer Manager\Buffer Hit Cache Ratio (Higher is better, greater than 90% for usually smooth running system) SQLServer: Buffer Manager\Page Life Expectancy (Consistent lower value than 300 seconds) Memory: Available Mbytes (Information only) Memory: Page Faults/sec (Benchmark only) Memory: Pages/sec (Benchmark only) Checking Disk Related Perfmon Counters Average Disk sec/Read (Consistent higher value than 4-8 millisecond is not good) Average Disk sec/Write (Consistent higher value than 4-8 millisecond is not good) Average Disk Read/Write Queue Length (Consistent higher value than benchmark is not good) Note: The information presented here is from my experience and there is no way that I claim it to be accurate. I suggest reading Book OnLine for further clarification. All of the discussions of Wait Stats in this blog is generic and varies from system to system. It is recommended that you test this on a development server before implementing it to a production server. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • Is recursion really bad?

    - by dotneteer
    After my previous post about the stack space, it appears that there is perception from the feedback that recursion is bad and we should avoid deep recursion. After writing a compiler, I know that the modern computer and compiler are complex enough and one cannot automatically assume that a hand crafted code would out-perform the compiler optimization. The only way is to do some prototype to find out. So why recursive code may not perform as well? Compilers place frames on a stack. In additional to arguments and local variables, compiles also need to place frame and program pointers on the frame, resulting in overheads. So why hand-crafted code may not performance as well? The stack used by a compiler is a simpler data structure and can grow and shrink cleanly. To replace recursion with out own stack, our stack is allocated in the heap that is far more complicated to manage. There could be overhead as well if the compiler needs to mark objects for garbage collection. Compiler also needs to worry about the memory fragmentation. Then there is additional complexity: CPUs have registers and multiple levels of cache. Register access is a few times faster than in-CPU cache access and is a few 10s times than on-board memory access. So it is up to the OS and compiler to maximize the use of register and in-CPU cache. For my particular problem, I did an experiment to rewrite my c# version of recursive code with a loop and stack approach. So here are the outcomes of the two approaches:   Recursive call Loop and Stack Lines of code for the algorithm 17 46 Speed Baseline 3% faster Readability Clean Far more complex So at the end, I was able to achieve 3% better performance with other drawbacks. My message is never assuming your sophisticated approach would automatically work out better than a simpler approach with a modern computer and compiler. Gage carefully before committing to a more complex approach.

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  • Best Practices - Dynamic Reconfiguration

    - by jsavit
    This post is one of a series of "best practices" notes for Oracle VM Server for SPARC (formerly named Logical Domains) Overview of dynamic Reconfiguration Oracle VM Server for SPARC supports Dynamic Reconfiguration (DR), making it possible to add or remove resources to or from a domain (virtual machine) while it is running. This is extremely useful because resources can be shifted to or from virtual machines in response to load conditions without having to reboot or interrupt running applications. For example, if an application requires more CPU capacity, you can add CPUs to improve performance, and remove them when they are no longer needed. You can use even use Dynamic Resource Management (DRM) policies that automatically add and remove CPUs to domains based on load. How it works (in broad general terms) Dynamic Reconfiguration is done in coordination with Solaris, which recognises a hypervisor request to change its virtual machine configuration and responds appropriately. In essence, Solaris receives a message saying "you now have 16 more CPUs numbered 16 to 31" or "8GB more RAM starting at address X" or "here's a new network or disk device - have fun with it". These actions take very little time. Solaris then can start using the new resource. In the case of added CPUs, that means dispatching processes and potentially binding interrupts to the new CPUs. For memory, Solaris adds the new memory pages to its "free" list and starts using them. Comparable actions occur with network and disk devices: they are recognised by Solaris and then used. Removing is the reverse process: after receiving the DR message to free specific CPUs, Solaris unbinds interrupts assigned to the CPUs and stops dispatching process threads. That takes very little time. primary # ldm list NAME STATE FLAGS CONS VCPU MEMORY UTIL UPTIME primary active -n-cv- SP 16 4G 1.0% 6d 22h 29m ldom1 active -n---- 5000 16 8G 0.9% 6h 59m primary # ldm set-core 5 ldom1 primary # ldm list NAME STATE FLAGS CONS VCPU MEMORY UTIL UPTIME primary active -n-cv- SP 16 4G 0.2% 6d 22h 29m ldom1 active -n---- 5000 40 8G 0.1% 6h 59m primary # ldm set-core 2 ldom1 primary # ldm list NAME STATE FLAGS CONS VCPU MEMORY UTIL UPTIME primary active -n-cv- SP 16 4G 1.0% 6d 22h 29m ldom1 active -n---- 5000 16 8G 0.9% 6h 59m Memory pages are vacated by copying their contents to other memory locations and wiping them clean. Solaris may have to swap memory contents to disk if the remaining RAM isn't enough to hold all the contents. For this reason, deallocating memory can take longer on a loaded system. Even on a lightly loaded system it took several 7 or 8 seconds to switch the domain below between 8GB and 24GB of RAM. primary # ldm set-mem 24g ldom1 primary # ldm list NAME STATE FLAGS CONS VCPU MEMORY UTIL UPTIME primary active -n-cv- SP 16 4G 0.1% 6d 22h 36m ldom1 active -n---- 5000 16 24G 0.2% 7h 6m primary # ldm set-mem 8g ldom1 primary # ldm list NAME STATE FLAGS CONS VCPU MEMORY UTIL UPTIME primary active -n-cv- SP 16 4G 0.7% 6d 22h 37m ldom1 active -n---- 5000 16 8G 0.3% 7h 7m What if the device is in use? (this is the anecdote that inspired this blog post) If CPU or memory is being removed, releasing it pretty straightforward, using the method described above. The resources are released, and Solaris continues with less capacity. It's not as simple with a network or I/O device: you don't want to yank a device out from underneath an application that might be using it. In the following example, I've added a virtual network device to ldom1 and want to take it away, even though it's been plumbed. primary # ldm rm-vnet vnet19 ldom1 Guest LDom returned the following reason for failing the operation: Resource Information ---------------------------------------------------------- ----------------------- /devices/virtual-devices@100/channel-devices@200/network@1 Network interface net1 VIO operation failed because device is being used in LDom ldom1 Failed to remove VNET instance That's what I call a helpful error message - telling me exactly what was wrong. In this case the problem is easily solved. I know this NIC is seen in the guest as net1 so: ldom1 # ifconfig net1 down unplumb Now I can dispose of it, and even the virtual switch I had created for it: primary # ldm rm-vnet vnet19 ldom1 primary # ldm rm-vsw primary-vsw9 If I had to take away the device disruptively, I could have used ldm rm-vnet -f but that could disrupt whoever was using it. It's better if that can be avoided. Summary Oracle VM Server for SPARC provides dynamic reconfiguration, which lets you modify a guest domain's CPU, memory and I/O configuration on the fly without reboot. You can add and remove resources as needed, and even automate this for CPUs by setting up resource policies. Taking things away can be more complicated than giving, especially for devices like disks and networks that may contain application and system state or be involved in a transaction. LDoms and Solaris cooperative work together to coordinate resource allocation and de-allocation in a safe and effective way. For best practices, use dynamic reconfiguration to make the best use of your system's resources.

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  • How to solve "java.io.IOException: error=12, Cannot allocate memory" calling Runtime#exec()?

    - by Andrea Francia
    On my system I can't run a simple Java application that start a process. I don't know how to solve. Could you give me some hints how to solve? The program is: [root@newton sisma-acquirer]# cat prova.java import java.io.IOException; public class prova { public static void main(String[] args) throws IOException { Runtime.getRuntime().exec("ls"); } } The result is: [root@newton sisma-acquirer]# javac prova.java && java -cp . prova Exception in thread "main" java.io.IOException: Cannot run program "ls": java.io.IOException: error=12, Cannot allocate memory at java.lang.ProcessBuilder.start(ProcessBuilder.java:474) at java.lang.Runtime.exec(Runtime.java:610) at java.lang.Runtime.exec(Runtime.java:448) at java.lang.Runtime.exec(Runtime.java:345) at prova.main(prova.java:6) Caused by: java.io.IOException: java.io.IOException: error=12, Cannot allocate memory at java.lang.UNIXProcess.<init>(UNIXProcess.java:164) at java.lang.ProcessImpl.start(ProcessImpl.java:81) at java.lang.ProcessBuilder.start(ProcessBuilder.java:467) ... 4 more Configuration of the system: [root@newton sisma-acquirer]# java -version java version "1.6.0_0" OpenJDK Runtime Environment (IcedTea6 1.5) (fedora-18.b16.fc10-i386) OpenJDK Client VM (build 14.0-b15, mixed mode) [root@newton sisma-acquirer]# cat /etc/fedora-release Fedora release 10 (Cambridge) EDIT: Solution This solves my problem, I don't know exactly why: echo 0 /proc/sys/vm/overcommit_memory Up-votes for who is able to explain :) Additional informations, top output: top - 13:35:38 up 40 min, 2 users, load average: 0.43, 0.19, 0.12 Tasks: 129 total, 1 running, 128 sleeping, 0 stopped, 0 zombie Cpu(s): 1.5%us, 0.5%sy, 0.0%ni, 94.8%id, 3.2%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 1033456k total, 587672k used, 445784k free, 51672k buffers Swap: 2031608k total, 0k used, 2031608k free, 188108k cached Additional informations, free output: [root@newton sisma-acquirer]# free total used free shared buffers cached Mem: 1033456 588548 444908 0 51704 188292 -/+ buffers/cache: 348552 684904 Swap: 2031608 0 2031608

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  • Why my UTableView with style UITableViewStyleGrouped is consuming memory?

    - by prathumca
    Hello everyone, Currently in my app, I'm using an UITableView with style UITableViewStyleGrouped as shown below. CGRect imgFrame = CGRectMake(0, 0, 320, 650); UITableView *myTable = [[UITableView alloc] initWithFrame:imgFrame style:UITableViewStyleGrouped]; myTable.dataSource = self; myTable.delegate = self; //make the current object the event handler for view [self.view addSubview:myTable]; [myTable release]; And the data has stored in an array "dataArray". dataArray has collection of arrays, where each array represent a section. Currently I have only one section with 100 records. When I installed my app onto my IPhone, I observed that this UITableView is consuming 20 MB of IPhone memory. If I changed the table view style to "UITableViewStylePlain", then it is consuming only 4MB of memory. I'm trying to figure it out, where is the exact problem, but not. What was wrong with "UITableViewStyleGrouped"? Regards, prathumca.

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  • what webserver / mod / technique should I use to serve everything from memory?

    - by reinier
    I've lots of lookuptables from which I'll generate my webresponse. I think IIS with Asp.net enables me to keep static lookuptables in memory which I can use to serve up my responses very fast. Are there however also non .net solutions which can do the same? I've looked at fastcgi, but I think this starts X processes, of which anyone can handle Y requests. But the processes are by definition shielded from eachother. I could configure fastcgi to use just 1 process, but does this have scalability implications? anything using PHP or any other interpreted language won't fly because it is also cgi or fastcgi bound right? I understand memcache could be an option, though this would require another (local) socket connection which I'd rather avoid since everything in memory would be much faster. The solution can work under WIndows or Unix... it doesn't matter too much. The only thing which matters is that there will be a lot of requests (100/sec now and growing to 500/sec in a year), and I want to reduce the amount of webservers needed to process it. The current solution is done using PHP and memcache (and the occasional hit to the SQL server backend). Although it is fast (for php anyway), Apache has real problems when the 50/sec is passed. I've put a bounty on this question since I've not seen enough responses to make a wise choice. At the moment I'm considering either Asp.net or fastcgi with C(++).

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  • _dl_runtime_resolve -- When do the shared objects get loaded in to memory?

    - by windfinder
    We have a message processing system with high performance demands. Recently we have noticed that the first message takes many times longer then subsequent messages. A bunch of transformation and message augmentation happens as this goes through our system, much of it done by way of external lib. I just profiled this issue (using callgrind), comparing a "run" of just one message with a "run" of many messages (providing a baseline of comparison). The main difference I see is the function "do_lookup_x" taking up a huge amount of time. Looking at the various calls to this function, they all seem to be called by the common function: _dl_runtime_resolve. Not sure what this function does, but to me this looks like the first time the various shared libraries are being used, and are then being loaded in to memory by the ld. Is this a correct assumption? That the binary will not load the shared libraries in to memory until they are being prepped for use, therefore we will see a massive slowdown on the first message, but on none of the subsequent? How do we go about avoiding this? Note: We operate on the microsecond scale.

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  • Is there a way to programmatically tell if particular block of memory was not freed by FastMM?

    - by Wodzu
    I am trying to detect if a block of memory was not freed. Of course, the manager tells me that by dialog box or log file, but what if I would like to store results in a database? For example I would like to have in a database table a names of routines which allocated given blocks. After reading a documentation of FastMM I know that since version 4.98 we have a possibility to be notified by manager about memory allocations, frees and reallocations as they occur. For example OnDebugFreeMemFinish event is passing to us a PFullDebugBlockHeader which contains useful informations. There is one thing that PFullDebugBlockHeader is missing - the information if the given block was freed by the application. Unless OnDebugFreeMemFinish is called only for not freed blocks? This is which I do not know and would like to find out. The problem is that even hooking into OnDebugFreeMemFinish event I was unable to find out if the block was freed or not. Here is an example: program MemLeakTest; {$APPTYPE CONSOLE} uses FastMM4, ExceptionLog, SysUtils; procedure MemFreeEvent(APHeaderFreedBlock: PFullDebugBlockHeader; AResult: Integer); begin //This is executed at the end, but how should I know that this block should be freed //by application? Unless this is executed ONLY for not freed blocks. end; procedure Leak; var MyObject: TObject; begin MyObject := TObject.Create; end; begin OnDebugFreeMemFinish := MemFreeEvent; Leak; end. What I am missing is the callback like: procedure OnMemoryLeak(APointer: PFullDebugBlockHeader); After browsing the source of FastMM I saw that there is a procedure: procedure LogMemoryLeakOrAllocatedBlock(APointer: PFullDebugBlockHeader; IsALeak: Boolean); which could be overriden, but maybe there is an easier way?

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  • Question about memory allocation when initializing char arrays in C/C++.

    - by Carlos Nunez
    Before anything, I apologize if this question has been asked before. I am programming a simple packet sniffer for a class project. For a little while, I ran into the issue where the source and destination of a packet appeared to be the same. For example, the source and destination of an Ethernet frame would be the same MAC address all of the time. I custom-made ether_ntoa(char *) because Windows does not seem to have ethernet.h like Linux does. Code snippet is below: char *ether_ntoa(u_char etheraddr[ETHER_ADDR_LEN]) { int i, j; char eout[32]; for(i = 0, j = 0; i < 5; i++) { eout[j++] = etheraddr[i] >> 4; eout[j++] = etheraddr[i] & 0xF; eout[j++] = ':'; } eout[j++] = etheraddr[i] >> 4; eout[j++] = etheraddr[i] & 0xF; eout[j++] = '\0'; for(i = 0; i < 17; i++) { if(eout[i] < 10) eout[i] += 0x30; else if(eout[i] < 16) eout[i] += 0x57; } return(eout); } I solved the problem by using malloc() to have the compiler assign memory (i.e. instead of char eout[32], I used char * eout; eout = (char *) malloc (32);). However, I thought that the compiler assigned different memory locations when one sized a char-array at compile time. Is this incorrect? Thanks! Carlos Nunez

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  • How to store an interger value of 4 bytes in a memory of chunk which is malloced as type char

    - by Adi
    Dear all, Hello Guys!! This is my first post in the forum . I am really looking forward to having good fun in this site. My question is : int mem_size = 10; char *start_ptr; if((start_ptr= malloc(mem_size*1024*1024*sizeof(char)))==NULL) {return -1;} I have allocated a chunk of memory of type char and size is say 10 MB (i.e mem_size = 10 ); Now I want to store the size information in the header of the memory chunk, To make myself more clear Lets Say : start_ptr = 0xaf868004 (This is the value I got from my execution, it changes every time) Now I want to put the size information in the start of this pointer.. i.e *start_ptr = mem_size*1024*1024; But I am not able to put this information in the start_ptr. I think the reason is because my ptr is of type char which only takes one byte but I am trying to store int which takes 4 bytes, is the problem . I am not sure how to fix this problem.. I would greatly appreciate your suggestions. Cheers!! Aditya

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  • How much is too much memory allocation in NDK?

    - by Maximus
    The NDK download page notes that, "Typical good candidates for the NDK are self-contained, CPU-intensive operations that don't allocate much memory, such as signal processing, physics simulation, and so on." I came from a C background and was excited to try to use the NDK to operate most of my OpenGL ES functions and any native functions related to physics, animation of vertices, etc... I'm finding that I'm relying quite a bit on Native code and wondering if I may be making some mistakes. I've had no trouble with testing at this point, but I'm curious if I may run into problems in the future. For example, I have game struct defined (somewhat like is seen in the San-Angeles example). I'm loading vertex information for objects dynamically (just what is needed for an active game area) so there's quite a bit of memory allocation happening for vertices, normals, texture coordinates, indices and texture graphic data... just to name the essentials. I'm quite careful about freeing what is allocated between game areas. Would I be safer setting some caps on array sizes or should I charge bravely forward as I'm going now?

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