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  • Removing elements from heap

    - by user193138
    I made a heap. I am curious if there's something subtley wrong with my remove function: int Heap::remove() { if (n == 0) exit(1); int temp = arr[0]; arr[0] = arr[--n]; heapDown(0); arr[n] = 0; return temp; } void Heap::heapDown(int i) { int l = left(i); int r = right(i); // comparing parent to left/right child // each has an inner if to handle if the first swap causes a second swap // ie 1 -> 3 -> 5 // 3 5 1 5 1 3 if (l < n && arr[i] < arr[l]) { swap(arr[i], arr[l]); heapDown(l); if (r < n && arr[i] < arr[r]) { swap(arr[i], arr[r]); heapDown(r); } } else if (r < n && arr[i] < arr[r]) { swap(arr[i], arr[r]); heapDown(r); if (l < n && arr[i] < arr[l]) { swap(arr[i], arr[l]); heapDown(l); } } } Here's my output i1i2i3i4i5i6i7 p Active heap: 7 4 6 1 3 2 5 r Removed 7 r Removed 6 p Active heap: 5 3 4 1 2 Here's my teacher's sample output: p Active heap : 7 4 6 1 3 2 5 r Removed 7 r Removed 6 p Active heap : 5 4 2 1 3 s Heapsorted : 1 2 3 4 5 While our outputs are completely different, I do seem to hold maxheap principle of having everything left oriented and for all nodes parent child(in every case I tried). I try to do algs like this from scratch, so maybe I'm just doing something really weird and wrong (I would only consider it "wrong" if it's O(lg n), as removes are intended to be for heaps). Is there anything in particular "wrong" about my remove? Thanks, http://ideone.com/PPh4eQ

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  • Do (statically linked) DLLs use a different heap than the main program?

    - by happy_emi
    I'm new to Windows programming and I've just "lost" two hours hunting a bug which everyone seems aware of: you cannot create an object on the heap in a DLL and destroy it in another DLL (or in the main program). I'm almost sure that on Linux/Unix this is NOT the case (if it is, please say it, but I'm pretty sure I did that thousands of times without problems...). At this point I have a couple of questions: 1) Do statically linked DLLs use a different heap than the main program? 2) Is the statically linked DLL mapped in the same process space of the main program? (I'm quite sure the answer here is a big YES otherwise it wouldn't make sense passing pointers from a function in the main program to a function in a DLL). I'm talking about plain/regular DLL, not COM/ATL services EDIT: By "statically linked" I mean that I don't use LoadLibrary to load the DLL but I link with the stub library

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  • Java Refuses to Start - Could not reserve enough space for object heap

    - by Randyaa
    Background We have a pool of aproximately 20 linux blades. Some are running Suse, some are running Redhat. ALL share NAS space which contains the following 3 folders: /NAS/app/java - a symlink that points to an installation of a Java JDK. Currently version 1.5.0_10 /NAS/app/lib - a symlink that points to a version of our application. /NAS/data - directory where our output is written All our machines have 2 processors (hyperthreaded) with 4gb of physical memory and 4gb of swap space. We limit the number of 'jobs' each machine can process at a given time to 6 (this number likely needs to change, but that does not enter into the current problem so please ignore it for the time being). Some of our jobs set a Max Heap size of 512mb, some others reserve a Max Heap size of 2048mb. Again, we realize we could go over our available memory if 6 jobs started on the same machine with the heap size set to 2048, but to our knowledge this has not yet occurred. The Problem Once and a while a Job will fail immediately with the following message: Error occurred during initialization of VM Could not reserve enough space for object heap Could not create the Java virtual machine. We used to chalk this up to too many jobs running at the same time on the same machine. The problem happened infrequently enough (MAYBE once a month) that we'd just restart it and everything would be fine. The problem has recently gotten much worse. All of our jobs which request a max heap size of 2048m fail immediately almost every time and need to get restarted several times before completing. We've gone out to individual machines and tried executing them manually with the same result. Debugging It turns out that the problem only exists for our SuSE boxes. The reason it has been happening more frequently is becuase we've been adding more machines, and the new ones are SuSE. 'cat /proc/version' on the SuSE boxes give us: Linux version 2.6.5-7.244-bigsmp (geeko@buildhost) (gcc version 3.3.3 (SuSE Linux)) #1 SMP Mon Dec 12 18:32:25 UTC 2005 'cat /proc/version' on the RedHat boxes give us: Linux version 2.4.21-32.0.1.ELsmp ([email protected]) (gcc version 3.2.3 20030502 (Red Hat Linux 3.2.3-52)) #1 SMP Tue May 17 17:52:23 EDT 2005 'uname -a' gives us the following on BOTH types of machines: UTC 2005 i686 i686 i386 GNU/Linux No jobs are running on the machine, and no other processes are utilizing much memory. All of the processes currently running might be using 100mb total. 'top' currently shows the following: Mem: 4146528k total, 3536360k used, 610168k free, 132136k buffers Swap: 4194288k total, 0k used, 4194288k free, 3283908k cached 'vmstat' currently shows the following: procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 0 0 0 610292 132136 3283908 0 0 0 2 26 15 0 0 100 0 If we kick off a job with the following command line (Max Heap of 1850mb) it starts fine: java/bin/java -Xmx1850M -cp helloworld.jar HelloWorld Hello World If we bump up the max heap size to 1875mb it fails: java/bin/java -Xmx1875M -cp helloworld.jar HelloWorld Error occurred during initialization of VM Could not reserve enough space for object heap Could not create the Java virtual machine. It's quite clear that the memory currently being used is for Buffering/Caching and that's why so little is being displayed as 'free'. What isn't clear is why there is a magical 1850mb line where anything higher means Java can't start. Any explanations would be greatly appreciated.

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  • Coldfusion on VPS, how much JVM heap memory?

    - by Steven Filipowicz
    Recently I got a VPS server and I'm running Coldfusion, the website was running fine until it got more and more traffic and I started to encounter 'OutOfMemory' exceptions. I thought simply to rise the memory of the VPS server, but this didn't help. After doing some Google searches I found a setting in de CF Admin settings to set the JVM Heap memory. It was on the standard: Max Heap size 512MB and Min Heap size was empty. After playing around a bit I have now set it to Min 50MB and Max 200MB, good things is that I'm not getting the 'OutOfMemory' exceptions anymore. So far so good! But with about 50 active visitors on the website, the website starts to get slow. The CPU usage is only about 8% (Windows Taskmanager), also the taskmanager show only about 30% of the 3GB RAM in use. So I'm thinking that my values could be tweaked to use more of the RAM. Honestly I don't understand these JVM Memory heap settings, so I have no clue what is a good setting for me. I found a CF script that displays the memory usage, the details are: Heap Memory Usage - Committed 194 MB Heap Memory Usage - Initial 50.0 MB Heap Memory Usage - Max 194 MB Heap Memory Usage - Used 163 MB JVM - Free Memory 31.2 MB JVM - Max Memory 194 MB JVM - Total Memory 194 MB JVM - Used Memory 163 MB Memory Pool - Code Cache - Used 13.0 MB Memory Pool - PS Eden Space - Used 6.75 MB Memory Pool - PS Old Gen - Used 155 MB Memory Pool - PS Perm Gen - Used 64.2 MB Memory Pool - PS Survivor Space - Used 1.07 MB Non-Heap Memory Usage - Committed 77.4 MB Non-Heap Memory Usage - Initial 18.3 MB Non-Heap Memory Usage - Max 240 MB Non-Heap Memory Usage - Used 77.2 MB Free Allocated Memory: 30mb Total Memory Allocated: 194mb Max Memory Available to JVM: 194mb % of Free Allocated Memory: 16% % of Available Memory Allocated: 100% My JVM arguments are: -server -Dsun.io.useCanonCaches=false -XX:MaxPermSize=192m -XX:+UseParallelGC - Dcoldfusion.rootDir={application.home}/../ -Dcoldfusion.libPath={application.home}/../lib Can I give the JVM more memory? If so, what settings should I use? Thanks very much!!

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  • Memory fragmentation @ boost::asio ?

    - by Poni
    I'm pretty much stuck with a question I never got an answer for, a question which addresses an extremely important issue; memory fragmentation at boost::asio. Found nothing at the documentation nor here at SO. The functions at boost::asio, for example async_write() & async_read_some() always allocate something. (in my case it's 144 & 96 bytes respectively, in VC9 Debug build). How do I know about it? I connect a client to the "echo server" example provided with this library. I put a breakpoint at "new.cpp" at the code of "operator new(size_t size)". Then I send "123". Breakpoint is hit! Now using the stack trace I can clearly see that the root to the "new" call is coming from the async_write() & async_read_some() calls I make in the function handlers. So memory fragmentation will come sooner or later, thus I can't use ASIO, and I wish I could! Any idea? Any helpful code example?

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  • to understand the code- how the heap is written in process migration in solaris

    - by akshay
    hi guys i need help understanding what this piece of code actually does as it is a part of my project i am stuck here. the code is from libckpt on solaris. /********************************** * function: write_heap * args: map_fd -- file descriptor for map file * data_fd -- file descriptor for data file * returns: no. of chunks written on success, -1 on failure * side effects: writes all included segments of the heap to ckpt files * misc.: If we are forking and copyonwrite is set, we will write the heap from bottom to top, moving the brk pointer up each time so that we don't get a page copied if the * called from: take_ckpt() ***********************************/ static int write_heap(int map_fd, int data_fd) { Dlist curptr, endptr; int no_chunks=0, pn; long size; caddr_t stop, addr; if(ckptflags.incremental){ /-- incremental checkpointing on? --/ endptr = ckptglobals.inc_list-main-flink; /*-- for each included chunk of the heap --*/ for(curptr = ckptglobals.inc_list->main->blink->blink; curptr != endptr; curptr = curptr->blink){ /*-- write out the last page in the included chunk --*/ stop = curptr->addr; pn = ((long)curptr->stop - (long)sys.DATASTART) / PAGESIZE; if(isdirty(pn)){ addr = (caddr_t)max((long)curptr->addr, (long)((pn * PAGESIZE) + sys.DATASTART)); size = (long)curptr->stop - (long)addr; debug(stderr, "DEBUG: Writing heap from 0x%x to 0x%x, pn = %d\n", addr, addr+size, pn); if(write_chunk(addr, size, map_fd, data_fd) == -1){ return -1; } if((int)addr > (int)(&end) && ckptflags.enhanced_fork){ brk(addr); } no_chunks++; } /*-- write out all the whole pages in the middle of the chunk --*/ for(pn--; pn * PAGESIZE + sys.DATASTART >= stop; pn--){ if(isdirty(pn)){ addr = (caddr_t)((pn * PAGESIZE) + sys.DATASTART); debug(stderr, "DEBUG: Writing heap from 0x%x to 0x%x, pn = %d\n", addr, addr+PAGESIZE, pn); if(write_chunk(addr, PAGESIZE, map_fd, data_fd) == -1){ return -1; } if((int)addr > (int)(&end) && ckptflags.enhanced_fork){ brk(addr); } no_chunks++; } } /*-- write out the first page in the included chunk --*/ addr = curptr->addr; size = ((pn+1) * PAGESIZE + sys.DATASTART) - addr; if(size > 0 && (isdirty(pn))){ debug(stderr, "DEBUG: Writing heap from 0x%x to 0x%x\n", addr, addr+size); if(write_chunk(addr, size, map_fd, data_fd) == -1){ return -1; } if((int)addr > (int)(&end) && ckptflags.enhanced_fork){ brk(addr); } no_chunks++; } } } else{ /-- incremental checkpointing off! --/ endptr = ckptglobals.inc_list-main-blink; /*-- for each included chunk of the heap --*/ for(curptr = ckptglobals.inc_list->main->flink->flink; curptr != endptr; curptr = curptr->flink){ debug(stderr, "DEBUG: saving memory from 0x%x to 0x%x\n", curptr->addr, curptr->addr+curptr->size); if(write_chunk(curptr->addr, curptr->size, map_fd, data_fd) == -1){ return -1; } if((int)addr > (int)(&end) && ckptflags.enhanced_fork){ brk(addr); } no_chunks++; } } return no_chunks; }

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  • Is it possible to run Weblogic with 8gb heap size in a 64bit java/linux environment

    - by Per Arneng
    Setup: 64bit Linux 64bit SUN Jvm 1.6.0_20 Weblogic 10.3 Is it possible to run Weblogic 10.3 in this setup with a maximum heap size of 8gb? We have recived answers from oracle support that states that it might not be possible to address more than 4gb with this setup. Please submit any official links that support any statements that it is possible to run this setup with more than 4gb of heap size. We can not find any documentation of any limits of heap size when running with this setup. Thanx

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  • Retrieve Heap memory size and its usage statistics etc...?

    - by AKN
    Lets say I open some application or process. Did some work with that. Now I closed it. Need to know whether this application caused any memory leak. i.e used up some heap memory and not cleared it properly. Can I get this statistics some how? I'm using Visual Studio (for development) under Windows OS. Even I would be interested in knowing this information for any 3rd party application.

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  • Size of Objects in Java Heap w/ Regards to Methods

    - by Eric
    I know about primitives and objects living on the heap, but how does the number of methods effect heap size of the object? For example: public class A { int x; public getX() { return x; } } public class B { int x; public getX() { return x; } public getXString() { return String.valueOf(x); } public doMoreInterestingStuff() { return x * 42; } //etc } When instantiated, both objects live on the heap, both have memory allocated to their primitive x, but is B allocated more heap space due to having more method signatures? Or are those ONLY on the classLoader? In this example its trivial, but when there are 100,000+ of these objects in memory at any given time I imagine it could add up.

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  • Go - Using a container/heap to implement a priority queue

    - by Seth Hoenig
    In the big picture, I'm trying to implement Dijkstra's algorithm using a priority queue. According to members of golang-nuts, the idiomatic way to do this in Go is to use the heap interface with a custom underlying data structure. So I have created Node.go and PQueue.go like so: //Node.go package pqueue type Node struct { row int col int myVal int sumVal int } func (n *Node) Init(r, c, mv, sv int) { n.row = r n.col = c n.myVal = mv n.sumVal = sv } func (n *Node) Equals(o *Node) bool { return n.row == o.row && n.col == o.col } And PQueue.go: // PQueue.go package pqueue import "container/vector" import "container/heap" type PQueue struct { data vector.Vector size int } func (pq *PQueue) Init() { heap.Init(pq) } func (pq *PQueue) IsEmpty() bool { return pq.size == 0 } func (pq *PQueue) Push(i interface{}) { heap.Push(pq, i) pq.size++ } func (pq *PQueue) Pop() interface{} { pq.size-- return heap.Pop(pq) } func (pq *PQueue) Len() int { return pq.size } func (pq *PQueue) Less(i, j int) bool { I := pq.data.At(i).(Node) J := pq.data.At(j).(Node) return (I.sumVal + I.myVal) < (J.sumVal + J.myVal) } func (pq *PQueue) Swap(i, j int) { temp := pq.data.At(i).(Node) pq.data.Set(i, pq.data.At(j).(Node)) pq.data.Set(j, temp) } And main.go: (the action is in SolveMatrix) // Euler 81 package main import "fmt" import "io/ioutil" import "strings" import "strconv" import "./pqueue" const MATSIZE = 5 const MATNAME = "matrix_small.txt" func main() { var matrix [MATSIZE][MATSIZE]int contents, err := ioutil.ReadFile(MATNAME) if err != nil { panic("FILE IO ERROR!") } inFileStr := string(contents) byrows := strings.Split(inFileStr, "\n", -1) for row := 0; row < MATSIZE; row++ { byrows[row] = (byrows[row])[0 : len(byrows[row])-1] bycols := strings.Split(byrows[row], ",", -1) for col := 0; col < MATSIZE; col++ { matrix[row][col], _ = strconv.Atoi(bycols[col]) } } PrintMatrix(matrix) sum, len := SolveMatrix(matrix) fmt.Printf("len: %d, sum: %d\n", len, sum) } func PrintMatrix(mat [MATSIZE][MATSIZE]int) { for r := 0; r < MATSIZE; r++ { for c := 0; c < MATSIZE; c++ { fmt.Printf("%d ", mat[r][c]) } fmt.Print("\n") } } func SolveMatrix(mat [MATSIZE][MATSIZE]int) (int, int) { var PQ pqueue.PQueue var firstNode pqueue.Node var endNode pqueue.Node msm1 := MATSIZE - 1 firstNode.Init(0, 0, mat[0][0], 0) endNode.Init(msm1, msm1, mat[msm1][msm1], 0) if PQ.IsEmpty() { // make compiler stfu about unused variable fmt.Print("empty") } PQ.Push(firstNode) // problem return 0, 0 } The problem is, upon compiling i get the error message: [~/Code/Euler/81] $ make 6g -o pqueue.6 Node.go PQueue.go 6g main.go main.go:58: implicit assignment of unexported field 'row' of pqueue.Node in function argument make: *** [all] Error 1 And commenting out the line PQ.Push(firstNode) does satisfy the compiler. But I don't understand why I'm getting the error message in the first place. Push doesn't modify the argument in any way.

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  • Heap Dump Root Classes

    - by Adnan Memon
    We have production system going into infinite loop of full gc and memory drops form 8 gigs to like 1 MB in just 2 minutes. After taking heap dump it tells me there an is an array of java.lang.Object ([Ljava.lang.Object) with millions of java.lang.String objects having same String taking 99% of heap. But it doesn't tell me which class is referencing to this array so that I can fix it in the code. I took the heap dump using jmap tool on JDK 6 and used JProfiler, NetBeans, SAP Memory Analyzer and IBM Memory Analyzer but none of those tell me what is causing this huge array of objects?? ... like what class is referencing to it or contains it. Do I have to take a different dump with different config in order to get that info? ... Or anything else that can help me find out the culprit class causing this ... it will help a lot.

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  • Heap data structure

    - by turmoil
    Trying to think of a lower bound to the position of say, the nth largest key in a max-heap. Assuming the heap's laid out in array. The upper bound's min(2^n-2, array size -1) i think, but is it always lower bounded by 0?

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  • Heap Consistency Checking on Embedded System

    - by l.thee.a
    I get a crash like this: #0 0x2c58def0 in raise () from /lib/libpthread.so.0 #1 0x2d9b8958 in abort () from /lib/libc.so.0 #2 0x2d9b7e34 in __malloc_consolidate () from /lib/libc.so.0 #3 0x2d9b6dc8 in malloc () from /lib/libc.so.0 I guess it is a heap corruption issue. uclibc does not have mcheck/mprobe. Valgrind does not seem to MIPS support and my app (which is multi-threaded) depends on hw specific drivers. Any suggestions to check the consistency of the heap and to detect corruption?

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  • Understanding max JVM heap size

    - by Marcus
    I've read the max heap size on 32bit Windows is ~1.5GB which is due to the fact that the JVM requires contiguous memory. Can someone explain the concept of "contiguous memory" and why you only have max 1.5GB on Windows? Secondly, what then is the max heap size on 64 bit Windows and why is this different than what's available on 32 bit?

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  • Android : Google étend le champs d'application de l'API "Fragments" pour lutter contre la fragmentation de l'OS

    Android : Google étend le champs d'application de l'API Fragments aux versions 1.6 de son OS Pour lutter contre la fragmentation de sa plate-forme mobile Dans la lutte contre la fragmentation d'Android, Google vient d'étendre aux anciennes versions de l'OS, l'API « Fragments » conçue à l'origine pour Android 3.0 (alias Honeycomb). Initialement, Fragments a été conçue pour faciliter la tâche de rendre les anciennes applications compatibles avec les périphériques à écrans plus larges, notamment les tablettes que ciblent ess...

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  • stack and heap issue for iPhone memory management

    - by Forrest
    From this post I got know that the Objective-C runtime does not allow objects to be instantiated on the stack, but only on the heap; this means that you don’t have “automatic objects”, nor things like auto_ptr objects to help you manage memory; Someone give one example in post Objective C: Memory Allocation on stack vs. heap NSString* str = @"hello"; but this NSString is also not allocated in stack. Feel odd that this str is static. (Who can explain this ? ) Question here is that why there is no heap ? even mixing c++ together with Object C ? /////////////////////////////// Clear my question /////////////////////////////// I am confused , so questions are not clear. Let me put in this way. 1) All Object C objects should be alloc in stack ? ( I think yes ) 2)In C++, there are stack for memory, so for iOS app, also have stack ? ( I think yes ) 3) for iOS app, if only use Object C, so what is the usage of stack ? what kind of objects should use stack then ?

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  • Heap Algorithmic Issue

    - by OberynMarDELL
    I am having this algorithmic problem that I want to discuss about. Its not about find a solution but about optimization in terms of runtime. So here it is: Suppose we have a race court of Length L and a total of N cars that participate on the race. The race rules are simple. Once a car overtakes an other car the second car is eliminated from the race. The race ends when no more overtakes are possible to happen. The tricky part is that the k'th car has a starting point x[k] and a velocity v[k]. The points are given in an ascending order, but the velocities may differ. What I've done so far: Given that a car can get overtaken only by its previous, I calculated the time that it takes for each car to reach its next one t = (x[i] - x[i+1])/(v[i] - v[i+1]) and I insert these times onto a min heap in O(n log n). So in theory I have to pop the first element in O(logn), find its previous, pop it as well , update its time and insert it in the heap once more, much like a priority queue. My main problem is how I can access specific points of a heap in O(log n) or faster in order to keep the complexity in O(n log n) levels. This program should be written on Haskell so I would like to keep things simple as far as possible EDIT: I Forgot to write the actual point of the race. The goal is to find the order in which cars exit the game

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  • TCP/UDP and ethernet MTU Fragmentation

    - by Fantastic Fourier
    I've read various sites and tutorials online but I am still confused. If the message is bigger than IP MTU, then send() returns the byte sent. What happens to the rest of the message? Am I to call send() again and attempt to send rest of the message? Or is that something IP layer should take care of automatically?

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  • Getting Out Of Memory: Java heap space, but while viewing heap space it max uses 50 MB

    - by ikky
    Hi! I'm using ASANT to run a xml file which points to a NARS.jar file. (i do not have the project file of the NARS.jar) I'm getting "java.lang.OutOfMemoryError: Java heap space. I used VisualVM to look at the heap while running the NARS.jar, and it says that it max uses 50 MB of the heapspace. I've set the initial and max size of heapspace to 512 MB. Does anyone have an ide of what could be wrong? I got 1 GB physical Memory and created a 5 GB pagefile (for test purpose). Thanks in advance.

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  • Java Heap Overflow, Forcing Garbage Collection

    - by Nicholas
    I've create a trie tree with an array of children. When deleting a word, I set the children null, which I would assume deletes the node(delete is a relative term). I know that null doesn't delete the child, just sets it to null, which when using a large amount of words it causes to overflow the heap. Running a top on linux, I can see my memory usage spike to 1gb pretty quickly, but if I force garbage collection after the delete (Runtime.gc()) the memory usage goes to 50mb and never above that. From what I'm told, java by default runs garbage collection before a heap overflow happens, but I can't see to make that happen.

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  • Class members allocation on heap/stack? C++

    - by simplebutperfect
    If a class is declared as follows: class MyClass { char * MyMember; MyClass() { MyMember = new char[250]; } ~MyClass() { delete[] MyMember; } }; And it could be done like this: class MyClass { char MyMember[250]; }; How does a class gets allocated on heap, like if i do MyClass * Mine = new MyClass(); Does the allocated memory also allocates the 250 bytes in the second example along with the class instantiation? And will the member be valid for the whole lifetime of MyClass object? As for the first example, is it practical to allocate class members on heap?

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