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  • Is it ok to perform DB operation on UI thread?

    - by user648462
    I am using a database to persist the state of a search form. I am using the onPause method to persist the data and the onResume method to restore it. My opinion is that restoring and persisting state should be a blocking operation so I plan to perform the database operations on the UI thread. I know this is generally discouraged but the operations should be quick and I think if they were done asynchronously they could lead to inconsistent UI behaviour. Any advice

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  • how to know when a work in a thread is complete?

    - by seinkraft
    I need to create multiple threads when a button is clicked and i've done that with this: Dim myThread As New Threading.Thread(AddressOf getFile) myThread.IsBackground = True myThread.Start() but i need to update a picture box with the downloaded file, buy if i set an event in the function getFile and raise it to notify that the files was downloaded and then update the picturebox.

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  • How long does it take each thread timeslice in Windows XP ?

    - by IHawk
    I am trying to find out how long does it take each thread timeslice (quantum) in Windows but the only information that I found out is about the clock ticks being from 15 to 20ms or 20-30ms. How can I find this information ? I think it may vary from OS to OS, but I am not certain. I appreciate any suggestion on this subject. Thank you.

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  • how to implement a message pump in Non-UI thread in .net?

    - by Benny
    how to implement a message pump in non-ui thread? what i want is that the message can be an object or a command, say an Action/Func, etc. do i have to use separate queue for different type of message? say one queue for object, one queue for Action/Function? Given that the type of messages vary, how to implement it?

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  • Multithreading 2D gravity calculations

    - by Postman
    I'm building a space exploration game and I've currently started working on gravity ( In C# with XNA). The gravity still needs tweaking, but before I can do that, I need to address some performance issues with my physics calculations. This is using 100 objects, normally rendering 1000 of them with no physics calculations gets well over 300 FPS (which is my FPS cap), but any more than 10 or so objects brings the game (and the single thread it runs on) to its knees when doing physics calculations. I checked my thread usage and the first thread was killing itself from all the work, so I figured I just needed to do the physics calculation on another thread. However when I try to run the Gravity.cs class's Update method on another thread, even if Gravity's Update method has nothing in it, the game is still down to 2 FPS. Gravity.cs public void Update() { foreach (KeyValuePair<string, Entity> e in entityEngine.Entities) { Vector2 Force = new Vector2(); foreach (KeyValuePair<string, Entity> e2 in entityEngine.Entities) { if (e2.Key != e.Key) { float distance = Vector2.Distance(entityEngine.Entities[e.Key].Position, entityEngine.Entities[e2.Key].Position); if (distance > (entityEngine.Entities[e.Key].Texture.Width / 2 + entityEngine.Entities[e2.Key].Texture.Width / 2)) { double angle = Math.Atan2(entityEngine.Entities[e2.Key].Position.Y - entityEngine.Entities[e.Key].Position.Y, entityEngine.Entities[e2.Key].Position.X - entityEngine.Entities[e.Key].Position.X); float mult = 0.1f * (entityEngine.Entities[e.Key].Mass * entityEngine.Entities[e2.Key].Mass) / distance * distance; Vector2 VecForce = new Vector2((float)Math.Cos(angle), (float)Math.Sin(angle)); VecForce.Normalize(); Force = Vector2.Add(Force, VecForce * mult); } } } entityEngine.Entities[e.Key].Position += Force; } } Yeah, I know. It's a nested foreach loop, but I don't know how else to do the gravity calculation, and this seems to work, it's just so intensive that it needs its own thread. (Even if someone knows a super efficient way to do these calculations, I'd still like to know how I COULD do it on multiple threads instead) EntityEngine.cs (manages an instance of Gravity.cs) public class EntityEngine { public Dictionary<string, Entity> Entities = new Dictionary<string, Entity>(); public Gravity gravity; private Thread T; public EntityEngine() { gravity = new Gravity(this); } public void Update() { foreach (KeyValuePair<string, Entity> e in Entities) { Entities[e.Key].Update(); } T = new Thread(new ThreadStart(gravity.Update)); T.IsBackground = true; T.Start(); } } EntityEngine is created in Game1.cs, and its Update() method is called within Game1.cs. I need my physics calculation in Gravity.cs to run every time the game updates, in a separate thread so that the calculation doesn't slow the game down to horribly low (0-2) FPS. How would I go about making this threading work? (any suggestions for an improved Planetary Gravity system are welcome if anyone has them) I'm also not looking for a lesson in why I shouldn't use threading or the dangers of using it incorrectly, I'm looking for a straight answer on how to do it. I've already spent an hour googling this very question with little results that I understood or were helpful. I don't mean to come off rude, but it always seems hard as a programming noob to get a straight meaningful answer, I usually rather get an answer so complex I'd easily be able to solve my issue if I understood it, or someone saying why I shouldn't do what I want to do and offering no alternatives (that are helpful). Thank you for the help!

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  • High Resolution Timeouts

    - by user12607257
    The default resolution of application timers and timeouts is now 1 msec in Solaris 11.1, down from 10 msec in previous releases. This improves out-of-the-box performance of polling and event based applications, such as ticker applications, and even the Oracle rdbms log writer. More on that in a moment. As a simple example, the poll() system call takes a timeout argument in units of msec: System Calls poll(2) NAME poll - input/output multiplexing SYNOPSIS int poll(struct pollfd fds[], nfds_t nfds, int timeout); In Solaris 11, a call to poll(NULL,0,1) returns in 10 msec, because even though a 1 msec interval is requested, the implementation rounds to the system clock resolution of 10 msec. In Solaris 11.1, this call returns in 1 msec. In specification lawyer terms, the resolution of CLOCK_REALTIME, introduced by POSIX.1b real time extensions, is now 1 msec. The function clock_getres(CLOCK_REALTIME,&res) returns 1 msec, and any library calls whose man page explicitly mention CLOCK_REALTIME, such as nanosleep(), are subject to the new resolution. Additionally, many legacy functions that pre-date POSIX.1b and do not explicitly mention a clock domain, such as poll(), are subject to the new resolution. Here is a fairly comprehensive list: nanosleep pthread_mutex_timedlock pthread_mutex_reltimedlock_np pthread_rwlock_timedrdlock pthread_rwlock_reltimedrdlock_np pthread_rwlock_timedwrlock pthread_rwlock_reltimedwrlock_np mq_timedreceive mq_reltimedreceive_np mq_timedsend mq_reltimedsend_np sem_timedwait sem_reltimedwait_np poll select pselect _lwp_cond_timedwait _lwp_cond_reltimedwait semtimedop sigtimedwait aiowait aio_waitn aio_suspend port_get port_getn cond_timedwait cond_reltimedwait setitimer (ITIMER_REAL) misc rpc calls, misc ldap calls This change in resolution was made feasible because we made the implementation of timeouts more efficient a few years back when we re-architected the callout subsystem of Solaris. Previously, timeouts were tested and expired by the kernel's clock thread which ran 100 times per second, yielding a resolution of 10 msec. This did not scale, as timeouts could be posted by every CPU, but were expired by only a single thread. The resolution could be changed by setting hires_tick=1 in /etc/system, but this caused the clock thread to run at 1000 Hz, which made the potential scalability problem worse. Given enough CPUs posting enough timeouts, the clock thread could be a performance bottleneck. We fixed that by re-implementing the timeout as a per-CPU timer interrupt (using the cyclic subsystem, for those familiar with Solaris internals). This decoupled the clock thread frequency from timeout resolution, and allowed us to improve default timeout resolution without adding CPU overhead in the clock thread. Here are some exceptions for which the default resolution is still 10 msec. The thread scheduler's time quantum is 10 msec by default, because preemption is driven by the clock thread (plus helper threads for scalability). See for example dispadmin, priocntl, fx_dptbl, rt_dptbl, and ts_dptbl. This may be changed using hires_tick. The resolution of the clock_t data type, primarily used in DDI functions, is 10 msec. It may be changed using hires_tick. These functions are only used by developers writing kernel modules. A few functions that pre-date POSIX CLOCK_REALTIME mention _SC_CLK_TCK, CLK_TCK, "system clock", or no clock domain. These functions are still driven by the clock thread, and their resolution is 10 msec. They include alarm, pcsample, times, clock, and setitimer for ITIMER_VIRTUAL and ITIMER_PROF. Their resolution may be changed using hires_tick. Now back to the database. How does this help the Oracle log writer? Foreground processes post a redo record to the log writer, which releases them after the redo has committed. When a large number of foregrounds are waiting, the release step can slow down the log writer, so under heavy load, the foregrounds switch to a mode where they poll for completion. This scales better because every foreground can poll independently, but at the cost of waiting the minimum polling interval. That was 10 msec, but is now 1 msec in Solaris 11.1, so the foregrounds process transactions faster under load. Pretty cool.

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  • "Unable to initialize module" fileinfo php-pecl-Fileinfo.x86_64

    - by Myers Network
    I have a brand new server server that I am trying to get setup up. This is a 64 bit machine that I can not install "fileinfo" or "memcache". I have uninstalled these and reinstalled them using yum and pecl with no luck. Yum install fine "no error" but then get error when running php. pecl from what I can tell is only installing 32bit. Does not put anything in the lib64 directory. Here is my output from php -v: PHP Warning: PHP Startup: fileinfo: Unable to initialize module Module compiled with module API=20050922, debug=0, thread-safety=0 PHP compiled with module API=20060613, debug=0, thread-safety=0 These options need to match in Unknown on line 0 PHP Warning: PHP Startup: memcache: Unable to initialize module Module compiled with module API=20050922, debug=0, thread-safety=0 PHP compiled with module API=20060613, debug=0, thread-safety=0 These options need to match in Unknown on line 0 PHP 5.2.14 (cli) (built: Aug 12 2010 16:03:48) Copyright (c) 1997-2010 The PHP Group Zend Engine v2.2.0, Copyright (c) 1998-2010 Zend Technologies Here is some other system info incase you need it uname: Linux server.actham.us 2.6.18-194.26.1.el5 #1 SMP Tue Nov 9 12:54:20 EST 2010 x86_64 x86_64 x86_64 GNU/Linux php -m: PHP Warning: PHP Startup: fileinfo: Unable to initialize module Module compiled with module API=20050922, debug=0, thread-safety=0 PHP compiled with module API=20060613, debug=0, thread-safety=0 These options need to match in Unknown on line 0 PHP Warning: PHP Startup: memcache: Unable to initialize module Module compiled with module API=20050922, debug=0, thread-safety=0 PHP compiled with module API=20060613, debug=0, thread-safety=0 These options need to match in Unknown on line 0 [PHP Modules] bz2 calendar ctype curl date dbase dom exif filter ftp gd gettext gmp hash iconv imap json ldap libxml mbstring mcrypt mysql mysqli openssl pcntl pcre PDO pdo_mysql pdo_sqlite readline Reflection session shmop SimpleXML sockets SPL standard tokenizer wddx xml xmlreader xmlrpc xmlwriter xsl zip zlib [Zend Modules] Any help would be greatly appreciated, thanks....

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  • "Unable to initialize module" fileinfo php-pecl-Fileinfo.x86_64

    - by Myers Network
    I have a brand new server server that I am trying to get setup up. This is a 64 bit machine that I can not install "fileinfo" or "memcache". I have uninstalled these and reinstalled them using yum and pecl with no luck. Yum install fine "no error" but then get error when running php. pecl from what I can tell is only installing 32bit. Does not put anything in the lib64 directory. Here is my output from php -v: PHP Warning: PHP Startup: fileinfo: Unable to initialize module Module compiled with module API=20050922, debug=0, thread-safety=0 PHP compiled with module API=20060613, debug=0, thread-safety=0 These options need to match in Unknown on line 0 PHP Warning: PHP Startup: memcache: Unable to initialize module Module compiled with module API=20050922, debug=0, thread-safety=0 PHP compiled with module API=20060613, debug=0, thread-safety=0 These options need to match in Unknown on line 0 PHP 5.2.14 (cli) (built: Aug 12 2010 16:03:48) Copyright (c) 1997-2010 The PHP Group Zend Engine v2.2.0, Copyright (c) 1998-2010 Zend Technologies Here is some other system info incase you need it uname: Linux server.actham.us 2.6.18-194.26.1.el5 #1 SMP Tue Nov 9 12:54:20 EST 2010 x86_64 x86_64 x86_64 GNU/Linux php -m: PHP Warning: PHP Startup: fileinfo: Unable to initialize module Module compiled with module API=20050922, debug=0, thread-safety=0 PHP compiled with module API=20060613, debug=0, thread-safety=0 These options need to match in Unknown on line 0 PHP Warning: PHP Startup: memcache: Unable to initialize module Module compiled with module API=20050922, debug=0, thread-safety=0 PHP compiled with module API=20060613, debug=0, thread-safety=0 These options need to match in Unknown on line 0 [PHP Modules] bz2 calendar ctype curl date dbase dom exif filter ftp gd gettext gmp hash iconv imap json ldap libxml mbstring mcrypt mysql mysqli openssl pcntl pcre PDO pdo_mysql pdo_sqlite readline Reflection session shmop SimpleXML sockets SPL standard tokenizer wddx xml xmlreader xmlrpc xmlwriter xsl zip zlib [Zend Modules] Any help would be greatly appreciated, thanks....

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  • Context migration in CUDA.NET

    - by Vyacheslav
    I'm currently using CUDA.NET library by GASS. I need to initialize cuda arrays (actually cublas vectors, but it doesn't matters) in one CPU thread and use them in other CPU thread. But CUDA context which holding all initialized arrays and loaded functions, can be attached to only one CPU thread. There is mechanism called context migration API to detach context from one thread and attach it to another. But i don't how to properly use it in CUDA.NET. I tried something like this: class Program { private static float[] vector1, vector2; private static CUDA cuda; private static CUBLAS cublas; private static CUdeviceptr ptr; static void Main(string[] args) { cuda = new CUDA(false); cublas = new CUBLAS(cuda); cuda.Init(); cuda.CreateContext(0); AllocateVectors(); cuda.DetachContext(); CUcontext context = cuda.PopCurrentContext(); GetVectorFromDeviceAsync(context); } private static void AllocateVectors() { vector1 = new float[]{1f, 2f, 3f, 4f, 5f}; ptr = cublas.Allocate(vector1.Length, sizeof (float)); cublas.SetVector(vector1, ptr); vector2 = new float[5]; } private static void GetVectorFromDevice(object objContext) { CUcontext localContext = (CUcontext) objContext; cuda.PushCurrentContext(localContext); cuda.AttachContext(localContext); //change vector somehow vector1[0] = -1; //copy changed vector to device cublas.SetVector(vector1, ptr); cublas.GetVector(ptr, vector2); CUDADriver.cuCtxPopCurrent(ref localContext); } private static void GetVectorFromDeviceAsync(CUcontext cUcontext) { Thread thread = new Thread(GetVectorFromDevice); thread.IsBackground = false; thread.Start(cUcontext); } } But execution fails on attempt to copy changed vector to device because context is not attached? Any ideas how i can get it work?

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  • getting SIGSEGV in std::_List_const_iterator<Exiv2::Exifdatum>::operator++ whilst using jni

    - by HJED
    Hi I'm using jni to access the exiv2 API in my Java project and I'm getting a SIGSEGV error in std::_List_const_iterator::operator++. I'm uncertain how to fix this error. I've tried using high -Xmx values as well as running on both jdk1.6.0 (server and cacao JVMs) and 1.7.0 (server JVM). gdb traceback: #0 0x00007fffa36f2363 in std::_List_const_iterator<Exiv2::Exifdatum>::operator++ (this=0x7ffff7fd3500) at /usr/include/c++/4.4/bits/stl_list.h:223 #1 0x00007fffa36f2310 in std::__distance<std::_List_const_iterator<Exiv2::Exifdatum> > (__first=..., __last=...) at /usr/include/c++/4.4/bits/stl_iterator_base_funcs.h:79 #2 0x00007fffa36f224d in std::distance<std::_List_const_iterator<Exiv2::Exifdatum> > (__first=..., __last=...) at /usr/include/c++/4.4/bits/stl_iterator_base_funcs.h:114 #3 0x00007fffa36f1f27 in std::list<Exiv2::Exifdatum, std::allocator<Exiv2::Exifdatum> >::size (this=0x7fffa4030910) at /usr/include/c++/4.4/bits/stl_list.h:805 #4 0x00007fffa36f1d50 in Exiv2::ExifData::count (this=0x7fffa4030910) at /usr/local/include/exiv2/exif.hpp:518 #5 0x00007fffa36f1d30 in Exiv2::ExifData::empty (this=0x7fffa4030910) at /usr/local/include/exiv2/exif.hpp:516 #6 0x00007fffa36f1763 in getVars (path=0x7fffa401d2f0 "/home/hjed/PC100001.JPG", env=0x6131c8, obj=0x7ffff7fd37a8) at src/main.cpp:146 #7 0x00007fffa36f19d8 in Java_photo_exiv2_Exiv2MetaDataStore_impl_1loadFromExiv (env=0x6131c8, obj=0x7ffff7fd37a8, path=0x7ffff7fd37a0, obj2=0x7ffff7fd3798) at src/main.cpp:160 #8 0x00007ffff21d9cc8 in ?? () #9 0x00000000fffffffe in ?? () #10 0x00007ffff7fd3740 in ?? () #11 0x0000000000613000 in ?? () #12 0x00007ffff7fd3738 in ?? () #13 0x00007fffaa1076e0 in ?? () #14 0x00007ffff7fd37a8 in ?? () #15 0x00007fffaa108d10 in ?? () #16 0x0000000000000000 in ?? () Java error: # A fatal error has been detected by the Java Runtime Environment: # # SIGSEGV (0xb) at pc=0x00007fac11223363, pid=11905, tid=140378349111040 # # JRE version: 6.0_20-b20 # Java VM: OpenJDK 64-Bit Server VM (19.0-b09 mixed mode linux-amd64 ) # Derivative: IcedTea6 1.9.2 # Distribution: Ubuntu 10.10, package 6b20-1.9.2-0ubuntu2 # Problematic frame: # C [libExiff2-binding.so+0x4363] _ZNSt20_List_const_iteratorIN5Exiv29ExifdatumEEppEv+0xf # # If you would like to submit a bug report, please include # instructions how to reproduce the bug and visit: # https://bugs.launchpad.net/ubuntu/+source/openjdk-6/ # The crash happened outside the Java Virtual Machine in native code. # See problematic frame for where to report the bug. # --------------- T H R E A D --------------- Current thread (0x0000000000dbf000): JavaThread "main" [_thread_in_native, id=11909, stack(0x00007fac61920000,0x00007fac61a21000)] siginfo:si_signo=SIGSEGV: si_errno=0, si_code=128 (), si_addr=0x0000000000000000 Registers: ... Register to memory mapping: RAX=0x6c8948f0245c8948 0x6c8948f0245c8948 is pointing to unknown location RBX=0x00007fac0c042c00 0x00007fac0c042c00 is pointing to unknown location RCX=0x0000000000000000 0x0000000000000000 is pointing to unknown location RDX=0x6c8948f0245c8948 0x6c8948f0245c8948 is pointing to unknown location RSP=0x00007fac61a1f4e0 0x00007fac61a1f4e0 is pointing into the stack for thread: 0x0000000000dbf000 "main" prio=10 tid=0x0000000000dbf000 nid=0x2e85 runnable [0x00007fac61a1f000] java.lang.Thread.State: RUNNABLE RBP=0x00007fac61a1f4e0 0x00007fac61a1f4e0 is pointing into the stack for thread: 0x0000000000dbf000 "main" prio=10 tid=0x0000000000dbf000 nid=0x2e85 runnable [0x00007fac61a1f000] java.lang.Thread.State: RUNNABLE RSI=0x00007fac61a1f4f0 0x00007fac61a1f4f0 is pointing into the stack for thread: 0x0000000000dbf000 "main" prio=10 tid=0x0000000000dbf000 nid=0x2e85 runnable [0x00007fac61a1f000] java.lang.Thread.State: RUNNABLE RDI=0x00007fac61a1f500 0x00007fac61a1f500 is pointing into the stack for thread: 0x0000000000dbf000 "main" prio=10 tid=0x0000000000dbf000 nid=0x2e85 runnable [0x00007fac61a1f000] java.lang.Thread.State: RUNNABLE R8 =0x00007fac0c054630 0x00007fac0c054630 is pointing to unknown location R9 =0x00007fac61a1f358 0x00007fac61a1f358 is pointing into the stack for thread: 0x0000000000dbf000 "main" prio=10 tid=0x0000000000dbf000 nid=0x2e85 runnable [0x00007fac61a1f000] java.lang.Thread.State: RUNNABLE R10=0x00007fac61a1f270 0x00007fac61a1f270 is pointing into the stack for thread: 0x0000000000dbf000 "main" prio=10 tid=0x0000000000dbf000 nid=0x2e85 runnable [0x00007fac61a1f000] java.lang.Thread.State: RUNNABLE R11=0x00007fac11223354 0x00007fac11223354: _ZNSt20_List_const_iteratorIN5Exiv29ExifdatumEEppEv+0 in /home/hjed/libExiff2-binding.so at 0x00007fac1121f000 R12=0x0000000000dbf000 "main" prio=10 tid=0x0000000000dbf000 nid=0x2e85 runnable [0x00007fac61a1f000] java.lang.Thread.State: RUNNABLE R13=0x00007fac13ad1be8 {method} - klass: {other class} R14=0x00007fac61a1f7a8 0x00007fac61a1f7a8 is pointing into the stack for thread: 0x0000000000dbf000 "main" prio=10 tid=0x0000000000dbf000 nid=0x2e85 runnable [0x00007fac61a1f000] java.lang.Thread.State: RUNNABLE R15=0x0000000000dbf000 "main" prio=10 tid=0x0000000000dbf000 nid=0x2e85 runnable [0x00007fac61a1f000] java.lang.Thread.State: RUNNABLE Top of Stack: (sp=0x00007fac61a1f4e0) ... Instructions: (pc=0x00007fac11223363) ... Stack: [0x00007fac61920000,0x00007fac61a21000], sp=0x00007fac61a1f4e0, free space=1021k Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code) C [libExiff2-binding.so+0x4363] _ZNSt20_List_const_iteratorIN5Exiv29ExifdatumEEppEv+0xf C [libExiff2-binding.so+0x4310] _ZSt10__distanceISt20_List_const_iteratorIN5Exiv29ExifdatumEEENSt15iterator_traitsIT_E15difference_typeES5_S5_St18input_iterator_tag+0x26 C [libExiff2-binding.so+0x424d] _ZSt8distanceISt20_List_const_iteratorIN5Exiv29ExifdatumEEENSt15iterator_traitsIT_E15difference_typeES5_S5_+0x36 C [libExiff2-binding.so+0x3f27] _ZNKSt4listIN5Exiv29ExifdatumESaIS1_EE4sizeEv+0x33 C [libExiff2-binding.so+0x3d50] _ZNK5Exiv28ExifData5countEv+0x18 C [libExiff2-binding.so+0x3d30] _ZNK5Exiv28ExifData5emptyEv+0x18 C [libExiff2-binding.so+0x3763] _Z7getVarsPKcP7JNIEnv_P8_jobject+0x3e3 C [libExiff2-binding.so+0x39d8] Java_photo_exiv2_Exiv2MetaDataStore_impl_1loadFromExiv+0x4b j photo.exiv2.Exiv2MetaDataStore.impl_loadFromExiv(Ljava/lang/String;Lphoto/exiv2/Exiv2MetaDataStore;)V+0 j photo.exiv2.Exiv2MetaDataStore.loadFromExiv2()V+9 j photo.exiv2.Exiv2MetaDataStore.loadData()V+1 j photo.exiv2.Exiv2MetaDataStore.<init>(Lphoto/ImageFile;)V+10 j photo.ImageFile.<init>(Ljava/lang/String;)V+11 j test.Main.main([Ljava/lang/String;)V+67 v ~StubRoutines::call_stub V [libjvm.so+0x428698] V [libjvm.so+0x4275c8] V [libjvm.so+0x432943] V [libjvm.so+0x447f91] C [java+0x3495] JavaMain+0xd75 Java frames: (J=compiled Java code, j=interpreted, Vv=VM code) j photo.exiv2.Exiv2MetaDataStore.impl_loadFromExiv(Ljava/lang/String;Lphoto/exiv2/Exiv2MetaDataStore;)V+0 j photo.exiv2.Exiv2MetaDataStore.loadFromExiv2()V+9 j photo.exiv2.Exiv2MetaDataStore.loadData()V+1 j photo.exiv2.Exiv2MetaDataStore.<init>(Lphoto/ImageFile;)V+10 j photo.ImageFile.<init>(Ljava/lang/String;)V+11 j test.Main.main([Ljava/lang/String;)V+67 v ~StubRoutines::call_stub --------------- P R O C E S S --------------- Java Threads: ( => current thread ) 0x00007fac0c028000 JavaThread "Low Memory Detector" daemon [_thread_blocked, id=11924, stack(0x00007fac11532000,0x00007fac11633000)] 0x00007fac0c025800 JavaThread "CompilerThread1" daemon [_thread_blocked, id=11923, stack(0x00007fac11633000,0x00007fac11734000)] 0x00007fac0c022000 JavaThread "CompilerThread0" daemon [_thread_blocked, id=11922, stack(0x00007fac11734000,0x00007fac11835000)] 0x00007fac0c01f800 JavaThread "Signal Dispatcher" daemon [_thread_blocked, id=11921, stack(0x00007fac11835000,0x00007fac11936000)] 0x00007fac0c001000 JavaThread "Finalizer" daemon [_thread_blocked, id=11920, stack(0x00007fac11e2d000,0x00007fac11f2e000)] 0x0000000000e36000 JavaThread "Reference Handler" daemon [_thread_blocked, id=11919, stack(0x00007fac11f2e000,0x00007fac1202f000)] =>0x0000000000dbf000 JavaThread "main" [_thread_in_native, id=11909, stack(0x00007fac61920000,0x00007fac61a21000)] Other Threads: 0x0000000000e2f800 VMThread [stack: 0x00007fac1202f000,0x00007fac12130000] [id=11918] 0x00007fac0c02b000 WatcherThread [stack: 0x00007fac11431000,0x00007fac11532000] [id=11925] ... Heap PSYoungGen total 18432K, used 632K [0x00007fac47210000, 0x00007fac486a0000, 0x00007fac5bc10000) eden space 15808K, 4% used [0x00007fac47210000,0x00007fac472ae188,0x00007fac48180000) from space 2624K, 0% used [0x00007fac48410000,0x00007fac48410000,0x00007fac486a0000) to space 2624K, 0% used [0x00007fac48180000,0x00007fac48180000,0x00007fac48410000) PSOldGen total 42240K, used 0K [0x00007fac1de10000, 0x00007fac20750000, 0x00007fac47210000) object space 42240K, 0% used [0x00007fac1de10000,0x00007fac1de10000,0x00007fac20750000) PSPermGen total 21248K, used 2831K [0x00007fac13810000, 0x00007fac14cd0000, 0x00007fac1de10000) object space 21248K, 13% used [0x00007fac13810000,0x00007fac13ad3d80,0x00007fac14cd0000) Dynamic libraries: ... VM Arguments: jvm_args: -Dfile.encoding=UTF-8 java_command: test.Main Launcher Type: SUN_STANDARD Environment Variables: PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games USERNAME=hjed LD_LIBRARY_PATH=/usr/lib/jvm/java-6-openjdk/jre/lib/amd64/server:/usr/lib/jvm/java-6-openjdk/jre/lib/amd64:/usr/lib/jvm/java-6-openjdk/jre/../lib/amd64 SHELL=/bin/bash DISPLAY=:0.0 Signal Handlers: ... --------------- S Y S T E M --------------- OS:Ubuntu 10.10 (maverick) uname:Linux 2.6.35-24-generic #42-Ubuntu SMP Thu Dec 2 02:41:37 UTC 2010 x86_64 libc:glibc 2.12.1 NPTL 2.12.1 rlimit: STACK 8192k, CORE 0k, NPROC infinity, NOFILE 1024, AS infinity load average:0.27 0.31 0.30 /proc/meminfo: MemTotal: 4048200 kB MemFree: 106552 kB Buffers: 838212 kB Cached: 1172496 kB SwapCached: 0 kB Active: 1801316 kB Inactive: 1774880 kB Active(anon): 1224708 kB Inactive(anon): 355012 kB Active(file): 576608 kB Inactive(file): 1419868 kB Unevictable: 64 kB Mlocked: 64 kB SwapTotal: 7065596 kB SwapFree: 7065596 kB Dirty: 20 kB Writeback: 0 kB AnonPages: 1565608 kB Mapped: 213424 kB Shmem: 14216 kB Slab: 164812 kB SReclaimable: 102576 kB SUnreclaim: 62236 kB KernelStack: 4784 kB PageTables: 44908 kB NFS_Unstable: 0 kB Bounce: 0 kB WritebackTmp: 0 kB CommitLimit: 9089696 kB Committed_AS: 3676872 kB VmallocTotal: 34359738367 kB VmallocUsed: 332952 kB VmallocChunk: 34359397884 kB HardwareCorrupted: 0 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 2048 kB DirectMap4k: 48704 kB DirectMap2M: 4136960 kB CPU:total 8 (4 cores per cpu, 2 threads per core) family 6 model 26 stepping 5, cmov, cx8, fxsr, mmx, sse, sse2, sse3, ssse3, sse4.1, sse4.2, popcnt, ht Memory: 4k page, physical 4048200k(106552k free), swap 7065596k(7065596k free) vm_info: OpenJDK 64-Bit Server VM (19.0-b09) for linux-amd64 JRE (1.6.0_20-b20), built on Dec 10 2010 19:45:55 by "buildd" with gcc 4.4.5 main.cpp: jobject toJava(std::auto_ptr<Exiv2::Value> v, const char * type, JNIEnv * env) { jclass stringClass; jmethodID cid; jobject result; stringClass = env->FindClass("photo/exiv2/Value"); cid = env->GetMethodID(stringClass, "<init>", "(Ljava/lang/String;Ljava/lang/Object;)V"); jvalue val; if ((strcmp(type, "String") == 0) || (strcmp(type, "String") == 0)) { val.l = env->NewStringUTF(v->toString().c_str()); } else if (strcmp(type, "Short") == 0) { val.s = v->toLong(0); } else if (strcmp(type, "Long") == 0) { val.j = v->toLong(0); } result = env->NewObject(stringClass, cid, env->NewStringUTF(v->toString().c_str()), val); return result; } void inLoop(std::auto_ptr<MetadataContainer> md, JNIEnv * env, jmethodID mid, jobject obj) { jvalue values[2]; const char* key = md->key().c_str(); values[0].l = env->NewStringUTF(key); /** md->value().toString().c_str(); const char* value = md->typeName(); values[1].l = env->NewStringUTF(value); TODO: do type conversions */ //std::cout << md->typeName() << std::endl; /** const char* type = md->value().toString().c_str(); values[1].l = env->NewStringUTF(type);*/ values[1].l = toJava(md->getValue(), md->typeName(), env); env->CallVoidMethodA(obj, mid, values); } void getVars(const char* path, JNIEnv * env, jobject obj) { //Load image Exiv2::Image::AutoPtr image = Exiv2::ImageFactory::open(path); assert(image.get() != 0); image->readMetadata(); //load method jclass cls = env->GetObjectClass(obj); jmethodID mid = env->GetMethodID(cls, "exiv2_reciveElement", "(Ljava/lang/String;Lphoto/exiv2/Value;)V"); //Load IPTC data /**loadIPTC(image, path, env, obj, mid); loadEXIF(image, path, env, obj, mid);*/ Exiv2::IptcData &iptcData = image->iptcData(); if (mid != NULL) { //is there any IPTC data AND check that method exists if (iptcData.empty()) { std::string error(path); error += ": failed loading IPTC data, there may not be any data"; } else { Exiv2::IptcData::iterator end = iptcData.end(); for (Exiv2::IptcData::iterator md = iptcData.begin(); md != end; ++md) { std::auto_ptr<MetadataContainer> meta(new MetadataContainer(md)); inLoop(meta, env, mid, obj); } } Exiv2::ExifData &exifData = image->exifData(); //is there any Exif data AND check that method exists if (exifData.empty()) { //error occurs here (main.cpp:146) std::string error(path); error += ": failed loading Exif data, there may not be any data"; } else { Exiv2::ExifData::iterator end = exifData.end(); for (Exiv2::ExifData::iterator md = exifData.begin(); md != end; ++md) { std::auto_ptr<MetadataContainer> meta(new MetadataContainer(md)); inLoop(meta, env, mid, obj); } } } else { std::string error(path); error += ": failed to load method"; } } JNIEXPORT void JNICALL Java_photo_exiv2_Exiv2MetaDataStore_impl_1loadFromExiv(JNIEnv * env, jobject obj, jstring path, jobject obj2) { const char* path2 = env->GetStringUTFChars(path, NULL); getVars(path2, env, obj); env->ReleaseStringUTFChars(path, path2); } Thanks for any help, HJED EDIT This is the output when runing the jvm with the -cacao option: run: null:/usr/local/lib Error: Directory Olympus2 with 1536 entries considered invalid; not read. LOG: [0x00007ff005376700] We received a SIGSEGV and tried to handle it, but we were LOG: [0x00007ff005376700] unable to find a Java method at: LOG: [0x00007ff005376700] LOG: [0x00007ff005376700] PC=0x00007feffe4ee67d LOG: [0x00007ff005376700] LOG: [0x00007ff005376700] Dumping the current stacktrace: at photo.exiv2.Exiv2MetaDataStore.impl_loadFromExiv(Ljava/lang/String;Lphoto/exiv2/Exiv2MetaDataStore;)V(Native Method) at photo.exiv2.Exiv2MetaDataStore.loadFromExiv2()V(Exiv2MetaDataStore.java:38) at photo.exiv2.Exiv2MetaDataStore.loadData()V(Exiv2MetaDataStore.java:29) at photo.exiv2.MetaDataStore.<init>(Lphoto/ImageFile;)V(MetaDataStore.java:33) at photo.exiv2.Exiv2MetaDataStore.<init>(Lphoto/ImageFile;)V(Exiv2MetaDataStore.java:20) at photo.ImageFile.<init>(Ljava/lang/String;)V(ImageFile.java:22) at test.Main.main([Ljava/lang/String;)V(Main.java:28) LOG: [0x00007ff005376700] vm_abort: WARNING, port me to C++ and use os::abort() instead. LOG: [0x00007ff005376700] Exiting... LOG: [0x00007ff005376700] Backtrace (15 stack frames): LOG: [0x00007ff005376700] /usr/lib/jvm/java-6-openjdk/jre/lib/amd64/cacao/libjvm.so(+0x4ff54) [0x7ff004306f54] LOG: [0x00007ff005376700] /usr/lib/jvm/java-6-openjdk/jre/lib/amd64/cacao/libjvm.so(+0x5ac01) [0x7ff004311c01] LOG: [0x00007ff005376700] /usr/lib/jvm/java-6-openjdk/jre/lib/amd64/cacao/libjvm.so(+0x66e9a) [0x7ff00431de9a] LOG: [0x00007ff005376700] /usr/lib/jvm/java-6-openjdk/jre/lib/amd64/cacao/libjvm.so(+0x76408) [0x7ff00432d408] LOG: [0x00007ff005376700] /usr/lib/jvm/java-6-openjdk/jre/lib/amd64/cacao/libjvm.so(+0x79a4c) [0x7ff004330a4c] LOG: [0x00007ff005376700] /lib/libpthread.so.0(+0xfb40) [0x7ff004d53b40] LOG: [0x00007ff005376700] /home/hjed/libExiff2-binding.so(_ZNSt20_List_const_iteratorIN5Exiv29ExifdatumEEppEv+0xf) [0x7feffe4ee67d] LOG: [0x00007ff005376700] /home/hjed/libExiff2-binding.so(_ZSt10__distanceISt20_List_const_iteratorIN5Exiv29ExifdatumEEENSt15iterator_traitsIT_E15difference_typeES5_S5_St18input_iterator_tag+0x26) [0x7feffe4ee62a] LOG: [0x00007ff005376700] /home/hjed/libExiff2-binding.so(_ZSt8distanceISt20_List_const_iteratorIN5Exiv29ExifdatumEEENSt15iterator_traitsIT_E15difference_typeES5_S5_+0x36) [0x7feffe4ee567] LOG: [0x00007ff005376700] /home/hjed/libExiff2-binding.so(_ZNKSt4listIN5Exiv29ExifdatumESaIS1_EE4sizeEv+0x33) [0x7feffe4ee22b] LOG: [0x00007ff005376700] /home/hjed/libExiff2-binding.so(_ZNK5Exiv28ExifData5countEv+0x18) [0x7feffe4ee054] LOG: [0x00007ff005376700] /home/hjed/libExiff2-binding.so(_ZNK5Exiv28ExifData5emptyEv+0x18) [0x7feffe4ee034] LOG: [0x00007ff005376700] /home/hjed/libExiff2-binding.so(_Z7getVarsPKcP7JNIEnv_P8_jobject+0x3d7) [0x7feffe4ed947] LOG: [0x00007ff005376700] /home/hjed/libExiff2-binding.so(Java_photo_exiv2_Exiv2MetaDataStore_impl_1loadFromExiv+0x4b) [0x7feffe4edcdc] LOG: [0x00007ff005376700] [0x7feffe701ccd] Java Result: 134 BUILD SUCCESSFUL (total time: 0 seconds)

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  • Qt Socket blocking functions required to run in QThread where created. Any way past this?

    - by Alexander Kondratskiy
    The title is very cryptic, so here goes! I am writing a client that behaves in a very synchronous manner. Due to the design of the protocol and the server, everything has to happen sequentially (send request, wait for reply, service reply etc.), so I am using blocking sockets. Here is where Qt comes in. In my application I have a GUI thread, a command processing thread and a scripting engine thread. I create the QTcpSocket in the command processing thread, as part of my Client class. The Client class has various methods that boil down to writing to the socket, reading back a specific number of bytes, and returning a result. The problem comes when I try to directly call Client methods from the scripting engine thread. The Qt sockets randomly time out and when using a debug build of Qt, I get these warnings: QSocketNotifier: socket notifiers cannot be enabled from another thread QSocketNotifier: socket notifiers cannot be disabled from another thread Anytime I call these methods from the command processing thread (where Client was created), I do not get these problems. To simply phrase the situation: Calling blocking functions of QAbstractSocket, like waitForReadyRead(), from a thread other than the one where the socket was created (dynamically allocated), causes random behaviour and debug asserts/warnings. Anyone else experienced this? Ways around it? Thanks in advance.

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  • Handling user interface in a multi-threaded application (or being forced to have a UI-only main thre

    - by Patrick
    In my application, I have a 'logging' window, which shows all the logging, warnings, errors of the application. Last year my application was still single-threaded so this worked [quite] good. Now I am introducing multithreading. I quickly noticed that it's not a good idea to update the logging window from different threads. Reading some articles on keeping the UI in the main thread, I made a communication buffer, in which the other threads are adding their logging messages, and from which the main thread takes the messages and shows them in the logging window (this is done in the message loop). Now, in a part of my application, the memory usage increases dramatically, because the separate threads are generating lots of logging messages, and the main thread cannot empty the communication buffer quickly enough. After the while the memory decreases again (if the other threads have finished their work and the main thread gradually empties the communication buffer). I solved this problem by having a maximum size on the communication buffer, but then I run into a problem in the following situation: the main thread has to perform a complex action the main thread takes some parts of the action and let's separate threads execute this while the seperate threads are executing their logic, the main thread processes the results from the other threads and continues with its work if the other threads are finished Problem is that in this situation, if the other threads perform logging, there is no UI-message loop, and so the communication buffer is filled, but not emptied. I see two solutions in solving this problem: require the main thread to do regular polling of the communication buffer only performing user interface logic in the main thread (no other logic) I think the second solution seems the best, but this may not that easy to introduce in a big application (in my case it performs mathematical simulations). Are there any other solutions or tips? Or is one of the two proposed the best, easiest, most-pragmatic solution? Thanks, Patrick

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  • first major web app

    - by vbNewbie
    I have created a web app version of my previous crawler app and the initial form has controls to allow the client to make selections and start a search 'job'. These searches 'jobs' will be run my different threads created individually and added to a list to keep track of. Now the idea is to have another web form that will display this list of 'jobs' and their current status and will allow the jobs to be cancelled or removed only from the server side. This second form contains a grid to display these jobs. Now I have no idea if I should create the threads in the initial form code or send all user input to my main class which runs the search and if so how do I pass the the thread list to the second form to have it displayed on the grid. Any ideas really appreciated. Dim count As Integer = 0 Dim numThread As Integer = 0 Dim jobStartTime As Date Dim thread = New Thread(AddressOf ResetFormControlValues) 'StartBlogDiscovery) jobStartTime = Date.Now thread.Name = "Job" & jobStartTime 'clientName Session("Job") = "Job" & jobStartTime 'clientName thread.start() thread.sleep(50000) If numThread >= 10 Then For Each thread In threadlist thread.Join() Next Else numThread = numThread + 1 SyncLock threadlist threadlist.Enqueue(thread) End SyncLock End If this is the code that is called when the user clicks the search button on the inital form. this is what I just thought might work on the second web form if i used the session method. Try If Not Page.IsPostBack Then If Not Session("Job") = Nothing Then Grid1.DataSource = Session("Job") Grid1.DataBind() End If End If Finally

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  • How do I pause main() until all other threads have died?

    - by thechiman
    In my program, I am creating several threads in the main() method. The last line in the main method is a call to System.out.println(), which I don't want to call until all the threads have died. I have tried calling Thread.join() on each thread however that blocks each thread so that they execute sequentially instead of in parallel. Is there a way to block the main() thread until all other threads have finished executing? Here is the relevant part of my code: public static void main(String[] args) { //some other initialization code //Make array of Thread objects Thread[] racecars = new Thread[numberOfRaceCars]; //Fill array with RaceCar objects for(int i=0; i<numberOfRaceCars; i++) { racecars[i] = new RaceCar(laps, args[i]); } //Call start() on each Thread for(int i=0; i<numberOfRaceCars; i++) { racecars[i].start(); try { racecars[i].join(); //This is where I tried to using join() //It just blocks all other threads until the current //thread finishes. } catch(InterruptedException e) { e.printStackTrace(); } } //This is the line I want to execute after all other Threads have finished System.out.println("It's Over!"); } Thanks for the help guys! Eric

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  • CLR via C# 3rd Edition is out

    - by Abhijeet Patel
    Time for some book news update. CLR via C#, 3rd Edition seems to have been out for a little while now. The book was released in early Feb this year, and needless to say my copy is on it’s way. I can barely wait to dig in and chew on the goodies that one of the best technical authors and software professionals I respect has in store. The 2nd edition of the book was an absolute treat and this edition promises to be no less. Here is a brief description of what’s new and updated from the 2nd edition. Part I – CLR Basics Chapter 1-The CLR’s Execution Model Added about discussion about C#’s /optimize and /debug switches and how they relate to each other. Chapter 2-Building, Packaging, Deploying, and Administering Applications and Types Improved discussion about Win32 manifest information and version resource information. Chapter 3-Shared Assemblies and Strongly Named Assemblies Added discussion of TypeForwardedToAttribute and TypeForwardedFromAttribute. Part II – Designing Types Chapter 4-Type Fundamentals No new topics. Chapter 5-Primitive, Reference, and Value Types Enhanced discussion of checked and unchecked code and added discussion of new BigInteger type. Also added discussion of C# 4.0’s dynamic primitive type. Chapter 6-Type and Member Basics No new topics. Chapter 7-Constants and Fields No new topics. Chapter 8-Methods Added discussion of extension methods and partial methods. Chapter 9-Parameters Added discussion of optional/named parameters and implicitly-typed local variables. Chapter 10-Properties Added discussion of automatically-implemented properties, properties and the Visual Studio debugger, object and collection initializers, anonymous types, the System.Tuple type and the ExpandoObject type. Chapter 11-Events Added discussion of events and thread-safety as well as showing a cool extension method to simplify the raising of an event. Chapter 12-Generics Added discussion of delegate and interface generic type argument variance. Chapter 13-Interfaces No new topics. Part III – Essential Types Chapter 14-Chars, Strings, and Working with Text No new topics. Chapter 15-Enums Added coverage of new Enum and Type methods to access enumerated type instances. Chapter 16-Arrays Added new section on initializing array elements. Chapter 17-Delegates Added discussion of using generic delegates to avoid defining new delegate types. Also added discussion of lambda expressions. Chapter 18-Attributes No new topics. Chapter 19-Nullable Value Types Added discussion on performance. Part IV – CLR Facilities Chapter 20-Exception Handling and State Management This chapter has been completely rewritten. It is now about exception handling and state management. It includes discussions of code contracts and constrained execution regions (CERs). It also includes a new section on trade-offs between writing productive code and reliable code. Chapter 21-Automatic Memory Management Added discussion of C#’s fixed state and how it works to pin objects in the heap. Rewrote the code for weak delegates so you can use them with any class that exposes an event (the class doesn’t have to support weak delegates itself). Added discussion on the new ConditionalWeakTable class, GC Collection modes, Full GC notifications, garbage collection modes and latency modes. I also include a new sample showing how your application can receive notifications whenever Generation 0 or 2 collections occur. Chapter 22-CLR Hosting and AppDomains Added discussion of side-by-side support allowing multiple CLRs to be loaded in a single process. Added section on the performance of using MarshalByRefObject-derived types. Substantially rewrote the section on cross-AppDomain communication. Added section on AppDomain Monitoring and first chance exception notifications. Updated the section on the AppDomainManager class. Chapter 23-Assembly Loading and Reflection Added section on how to deploy a single file with dependent assemblies embedded inside it. Added section comparing reflection invoke vs bind/invoke vs bind/create delegate/invoke vs C#’s dynamic type. Chapter 24-Runtime Serialization This is a whole new chapter that was not in the 2nd Edition. Part V – Threading Chapter 25-Threading Basics Whole new chapter motivating why Windows supports threads, thread overhead, CPU trends, NUMA Architectures, the relationship between CLR threads and Windows threads, the Thread class, reasons to use threads, thread scheduling and priorities, foreground thread vs background threads. Chapter 26-Performing Compute-Bound Asynchronous Operations Whole new chapter explaining the CLR’s thread pool. This chapter covers all the new .NET 4.0 constructs including cooperative cancelation, Tasks, the aralle class, parallel language integrated query, timers, how the thread pool manages its threads, cache lines and false sharing. Chapter 27-Performing I/O-Bound Asynchronous Operations Whole new chapter explaining how Windows performs synchronous and asynchronous I/O operations. Then, I go into the CLR’s Asynchronous Programming Model, my AsyncEnumerator class, the APM and exceptions, Applications and their threading models, implementing a service asynchronously, the APM and Compute-bound operations, APM considerations, I/O request priorities, converting the APM to a Task, the event-based Asynchronous Pattern, programming model soup. Chapter 28-Primitive Thread Synchronization Constructs Whole new chapter discusses class libraries and thread safety, primitive user-mode, kernel-mode constructs, and data alignment. Chapter 29-Hybrid Thread Synchronization Constructs Whole new chapter discussion various hybrid constructs such as ManualResetEventSlim, SemaphoreSlim, CountdownEvent, Barrier, ReaderWriterLock(Slim), OneManyResourceLock, Monitor, 3 ways to solve the double-check locking technique, .NET 4.0’s Lazy and LazyInitializer classes, the condition variable pattern, .NET 4.0’s concurrent collection classes, the ReaderWriterGate and SyncGate classes.

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  • Parallelism implies concurrency but not the other way round right?

    - by Cedric Martin
    I often read that parallelism and concurrency are different things. Very often the answerers/commenters go as far as writing that they're two entirely different things. Yet in my view they're related but I'd like some clarification on that. For example if I'm on a multi-core CPU and manage to divide the computation into x smaller computation (say using fork/join) each running in its own thread, I'll have a program that is both doing parallel computation (because supposedly at any point in time several threads are going to run on several cores) and being concurrent right? While if I'm simply using, say, Java and dealing with UI events and repaints on the Event Dispatch Thread plus running the only thread I created myself, I'll have a program that is concurrent (EDT + GC thread + my main thread etc.) but not parallel. I'd like to know if I'm getting this right and if parallelism (on a "single but multi-cores" system) always implies concurrency or not? Also, are multi-threaded programs running on multi-cores CPU but where the different threads are doing totally different computation considered to be using "parallelism"?

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  • Is true multithreading really necessary?

    - by Jonathan Graef
    So yeah, I'm creating a programming language. And the language allows multiple threads. But, all threads are synchronized with a global interpreter lock, which means only one thread is allowed to execute at a time. The only way to get the threads to switch off is to explicitly tell the current thread to wait, which allows another thread to execute. Parallel processing is of course possible by spawning multiple processes, but the variables and objects in one process cannot be accessed from another. However the language does have a fairly efficient IPC interface for communicating between processes. My question is: Would there ever be a reason to have multiple, unsynchronized threads within a single process (thus circumventing the GIL)? Why not just put thread.wait() statements in key positions in the program logic (presuming thread.wait() isn't a CPU hog, of course)? I understand that certain other languages that use a GIL have processor scheduling issues (cough Python), but they have all been resolved.

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  • What if we run out of stack space in C# or Python?

    - by dotneteer
    Supposing we are running a recursive algorithm on a very large data set that requires, say, 1 million recursive calls. Normally, one would solve such a large problem by converting recursion to a loop and a stack, but what if we do not want to or cannot rewrite the algorithm? Python has the sys.setrecursionlimit(int) method to set the number of recursions. However, this is only part of the story; the program can still run our of stack space. C# does not have a equivalent method. Fortunately, both C# and Python have option to set the stack space when creating a thread. In C#, there is an overloaded constructor for the Thread class that accepts a parameter for the stack size: Thread t = new Thread(work, stackSize); In Python, we can set the stack size by calling: threading.stack_size(67108864) We can then run our work under a new thread with increased stack size.

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  • Multithreading synchronization interview question: Find n words given m threads

    - by rplusg
    I came across this question: You are given a paragraph , which contain n number of words, you are given m threads. What you need to do is , each thread should print one word and give the control to next thread, this way each thread will keep on printing one word , in case last thread come, it should invoke the first thread. Printing will repeat until all the words are printed in paragraph. Finally all threads should exit gracefully. What kind of synchronization will use? I strongly feel we cannot take any advantage of threads here but interviewer is trying to understand my synchronization skills? No need of code, just put some thoughts. I will implement by myself.

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