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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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  • Hot to make COM ActiveX object work in IE 64 bit?

    - by Kurtevich
    Hi! I have a COM object embeded in ASP.NET page using <object classid="clsid:XXX...">. It works in IE 32 bit, but does not work in IE 64 bit - can't access its functions. There are no error messages, no event logs where I can get some information. The dll is in C#, includes COM visible class, compiled for Any CPU (though I also tried x86), and registered during client installation by executing regasm. This creates registry keys, well everything works fine except for IE 64. I searched internet about the issue or at least some guidlines and didn't find anything. I received an answer on another forum, something about _MERGE_PROXYSTUB (I guess it's preprocessor definition?) and ProxyStubClsid32 registry key, but not very detailed. Well, I searched again, didn't find much, and experimented: rebuilt with _MERGE_PROXYSTUB defined, created ProxyStubClsid32 keys everywhere, but with no result. What can be at least possible solutions or points to look at? Maybe there is a way at least to get the logs about why IE 64 can't access it?

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  • What's the largest (most complex) PHP algorithm ever implemented in a single monolithic PHP script?

    - by Alex R
    I'm working on a tool which converts PHP code to Scala. As one of the finishing touches, I'm in need of a really good (er, somewhat biased) benchmark. By dumb luck my first benchmark attempt was with some code which uses bcmath extensively, which unfortunately is 1000x slower in Java, making the Scala code 22x slower overall than the original PHP. So I'm looking for some meaningful PHP benchmark with the following characteristics: The source needs to be in a single file. I need it to be simple to setup - no databases, hard-to-find input files, etc. Simple text input and output preferred. It should not use features that are slow in Java (BigInteger, trigonometric functions, etc). It should not use exoteric or dynamic PHP functions (e.g. no "eval" or "variable vars"). It should not over-rely on built-in libraries, e.g. MD5, crypt, etc. It should not be I/O bound. A CPU-bound memory-hungry algorithm is preferred. Basically, intensive OO operations, integer and string manipulation, recursion, etc would be great. Thanks

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  • Calculate shortest path through a grocery store

    - by Bart
    Hi, I'm trying to find a way to find the shortest path through a grocery store, visiting a list of locations (shopping list). The path should start at a specified startposition and can end at multiple endpositions (there are multiple checkout counters). Also, I have some predefined constraints on the path, such as "item x on the shopping list needs to be the last, second last, or third last item on the path". There is a function that will return true or false for a given path. Finally, this needs to be calculated with limited cpu power (on a smartphone) and within a second or so. If this isn't possible, then an approximation to the optimal path is also ok. Is this possible? So far I think I need to start by calculating the distance between every item on the list using something like A* or Dijkstra's. After that, should I treat it like the travelling salesman problem? Because in my problem there is a specified startnode, specified endnodes, and some constraints, which are not in the travelling salesman problem. Any help would be appreciated :)

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  • Socket Read In Multi-Threaded Application Returns Zero Bytes or EINTR (104)

    - by user309670
    Hi. Am a c-coder for a while now - neither a newbie nor an expert. Now, I have a certain daemoned application in C on a PPC Linux. I use PHP's socket_connect as a client to connect to this service locally. The server uses epoll for multiplexing connections via a Unix socket. A user submitted string is parsed for certain characters/words using strstr() and if found, spawns 4 joinable threads to different websites simultaneously. I use socket, connect, write and read, to interact with the said webservers via TCP on their port 80 in each thread. All connections and writes seems successful. Reads to the webserver sockets fail however, with either (A) all 3 threads seem to hang, and only one thread returns -1 and errno is set to 104. The responding thread takes like 10 minutes - an eternity long:-(. *I read somewhere that the 104 (is EINTR?), which in the network context suggests that ...'the connection was reset by peer'; or (B) 0 bytes from 3 threads, and only 1 of the 4 threads actually returns some data. Isn't the socket read/write thread-safe? I use thread-safe (and reentrant) libc functions such as strtok_r, gethostbyname_r, etc. *I doubt that the said webhosts are actually resetting the connection, because when I run a single-threaded standalone (everything else equal) all things works perfectly right, but of course in series not parallel. There's a second problem too (oops), I can't write back to the client who connect to my epoll-ed Unix socket. My daemon application will hang and hog CPU 100% for ever. Yet nothing is written to the clients end. Am sure the client (a very typical PHP socket application) hasn't closed the connection whenever this is happening - no error(s) detected either. Any ideas? I cannot figure-out whatever is wrong even with Valgrind, GDB or much logging. Kindly help where you can.

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  • Locating memory leak in Apache httpd process, PHP/Doctrine-based application

    - by Sam
    I have a PHP application using these components: Apache 2.2.3-31 on Centos 5.4 PHP 5.2.10 Xdebug 2.0.5 with Remote Debugging enabled APC 3.0.19 Doctrine ORM for PHP 1.2.1 using Query Caching and Results Caching via APC MySQL 5.0.77 using Query Caching I've noticed that when I start up Apache, I eventually end up 10 child processes. As time goes on, each process will grow in memory until each one approaches 10% of available memory, which begins to slow the server to a crawl since together they grow to take up 100% of memory. Here is a snapshot of my top output: PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 1471 apache 16 0 626m 201m 18m S 0.0 10.2 1:11.02 httpd 1470 apache 16 0 622m 198m 18m S 0.0 10.1 1:14.49 httpd 1469 apache 16 0 619m 197m 18m S 0.0 10.0 1:11.98 httpd 1462 apache 18 0 622m 197m 18m S 0.0 10.0 1:11.27 httpd 1460 apache 15 0 622m 195m 18m S 0.0 10.0 1:12.73 httpd 1459 apache 16 0 618m 191m 18m S 0.0 9.7 1:13.00 httpd 1461 apache 18 0 616m 190m 18m S 0.0 9.7 1:14.09 httpd 1468 apache 18 0 613m 190m 18m S 0.0 9.7 1:12.67 httpd 7919 apache 18 0 116m 75m 15m S 0.0 3.8 0:19.86 httpd 9486 apache 16 0 97.7m 56m 14m S 0.0 2.9 0:13.51 httpd I have no long-running scripts (they all terminate eventually, the longest being maybe 2 minutes long), and I am working under the assumption that once each script terminates, the memory it uses gets deallocated. (Maybe someone can correct me on that). My hunch is that it could be APC, since it stores data between requests, but at the same time, it seems weird that it would store data inside the httpd process. How can I track down which part of my app is causing the memory leak? What tools can I use to see how the memory usage is growing inside the httpd process and what is contributing to it?

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  • Is there a PHP benchmark that meets these specific criteria? [closed]

    - by Alex R
    I'm working on a tool which converts PHP code to Scala. As one of the finishing touches, I'm in need of a really good (er, somewhat biased) benchmark. By dumb luck my first benchmark attempt was with some code which uses bcmath extensively, which unfortunately is 1000x slower in Java, making the Scala code 22x slower overall than the original PHP. So I'm looking for some meaningful PHP benchmark with the following characteristics: The PHP source needs to be in a single file. It should solve a real-world problem. No silly looping over empty methods etc. I need it to be simple to setup - no databases, hard-to-find input files, etc. Simple text input and output preferred. It should not use features that are slow in Java (BigInteger, trigonometric functions, etc). It should not use exoteric or dynamic PHP functions (e.g. no "eval" or "variable vars"). It should not over-rely on built-in libraries, e.g. MD5, crypt, etc. It should not be I/O bound. A CPU-bound memory-hungry algorithm is preferred. Basically, intensive OO operations, integer and string manipulation, recursion, etc would be great. Thanks

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  • How to terminate all [grand]child processes using C# on WXP (and newer MSWindows)

    - by NVRAM
    Question: How can I determine all processes in the child's Process Tree to kill them? I have an application, written in C# that will: Get a set of data from the server, Spawn a 3rd party utility to process the data, then Return the results to the server. This is working fine. But since a run consumes a lot of CPU and may take as long as an hour, I want to add the ability to have my app terminate its child processes. Some issues that make the simple solutions I've found elsewhere are: My app's child process "A" (InstallAnywhere EXE I think) spawns the real processing app "B" (a java.exe), which in turns spawns more children "C1".."Cn" (most of which are also written in Java). There will likely be multiple copies of my application (and hence, multiple sets of its children) running on the same machine. The child process is not in my control so there might be some "D" processes in the future. My application must run on 32-bit and 64-bit versions of MSWindows. On the plus side there is no issue of data loss, a "clean" shutdown doesn't matter as long as the processes end fairly quickly.

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  • Why is my Python OpenGL render2DTexture function so slow?

    - by Barakat
    SOLVED: The problem was actually using time.time() every CPU cycle to see whether the next frame should be drawn or not. The time it takes to execute time.time() was having an impact on the FPS. I made this function for drawing 2D textures as images in a 2D view in my OpenGL application. After doing some testing I found that it takes up 1-2 fps per texture. I know I am probably doing something wrong in this code. Any ideas? I am limiting the FPS to 60. Edit: When I disable the texture rendering it adds about 15% fps back. When I disabled text rendering it adds about 15% fps back. When i disable both barely any fps is consumed anymore. IE: 20 out of 60 fps with both on. 30 out of 60 when one is disabled. 58 out of 60 when both are disabled. When rendering the text on a button ( the control I'm using to test this ), it only "prepares" the text when the button label is set. Updated code, still running at the same speed but still works the same: def render2DTexture( self, texture, rect, texrect ): glEnable( GL_TEXTURE_2D ) glBindTexture( GL_TEXTURE_2D, texture ) glBegin( GL_QUADS ) glTexCoord2f( texrect.left, texrect.bottom ) glVertex2i( rect.left, self.windowSize[1] - rect.top ) glTexCoord2f( texrect.right, texrect.bottom ) glVertex2i( rect.left + rect.right, self.windowSize[1] - rect.top ) glTexCoord2f( texrect.right, texrect.top ) glVertex2i( rect.left + rect.right, self.windowSize[1] - ( rect.top + rect.bottom ) ) glTexCoord2f( texrect.left, texrect.top ) glVertex2i( rect.left, self.windowSize[1] - ( rect.top + rect.bottom ) ) glEnd() glDisable( GL_TEXTURE_2D ) def prepareText( self, text, fontFace, color ): self.loadFont( fontFace ) bmp = self.fonts[ fontFace ].render( text, 1, color ) return ( pygame.image.tostring( bmp, 'RGBA', 1 ), bmp.get_width(), bmp.get_height() ) def renderText( self, pText, position ): glRasterPos2i( position[0], self.windowSize[1] - ( position[1] + pText[2] ) ) glDrawPixels( pText[1], pText[2], GL_RGBA, GL_UNSIGNED_BYTE, pText[0] )

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  • Python MD5 Hash Faster Calculation

    - by balgan
    Hi everyone. I will try my best to explain my problem and my line of thought on how I think I can solve it. I use this code for root, dirs, files in os.walk(downloaddir): for infile in files: f = open(os.path.join(root,infile),'rb') filehash = hashlib.md5() while True: data = f.read(10240) if len(data) == 0: break filehash.update(data) print "FILENAME: " , infile print "FILE HASH: " , filehash.hexdigest() and using start = time.time() elapsed = time.time() - start I measure how long it takes to calculate an hash. Pointing my code to a file with 653megs this is the result: root@Mars:/home/tiago# python algorithm-timer.py FILENAME: freebsd.iso FILE HASH: ace0afedfa7c6e0ad12c77b6652b02ab 12.624 root@Mars:/home/tiago# python algorithm-timer.py FILENAME: freebsd.iso FILE HASH: ace0afedfa7c6e0ad12c77b6652b02ab 12.373 root@Mars:/home/tiago# python algorithm-timer.py FILENAME: freebsd.iso FILE HASH: ace0afedfa7c6e0ad12c77b6652b02ab 12.540 Ok now 12 seconds +- on a 653mb file, my problem is I intend to use this code on a program that will run through multiple files, some of them might be 4/5/6Gb and it will take wayy longer to calculate. What am wondering is if there is a faster way for me to calculate the hash of the file? Maybe by doing some multithreading? I used a another script to check the use of the CPU second by second and I see that my code is only using 1 out of my 2 CPUs and only at 25% max, any way I can change this? Thank you all in advance for the given help.

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  • Encoding h.264 with libavcodec/x264

    - by Leviathan
    I am attempting to encode video using libavcodec/libavformat. I'm trying to change the standard output-example.c from ffmpeg source. The AVI file is created on the disk, but the only sound is encoded. I tried adding a lot of options for x264 from here. All the other codecs works fine, mpeg2, mpeg4, mjpeg, xvid. In addition to specifying the parameters x264, I also set the codec to AVOutputFormat structure. That's all I've done. AVOutputFormat *pOutFormat; // in header file av_register_all(); AVCodec *codec = avcodec_find_encoder_by_name("libx264"); pOutFormat = guess_format("avi", NULL, NULL); pOutFormat->video_codec = codec->id; The debug output of my application: Output #0, mp4, to 'D:\1.avi': Stream #0.0: Video: libx264, yuv420p, 320x240, q=10-51, 500 kb/s, 90k tbn, 25 tbc Stream #0.1: Audio: aac, 44100 Hz, 1 channels, s16, 128 kb/s [libx264 @ 0x694010]using cpu capabilities: MMX2 SSE2Fast SSSE3 FastShuffle SSE4.2 [libx264 @ 0x694010]bitrate tolerance too small, using .01 [libx264 @ 0x694010]profile Main, level 2.0 [libx264 @ 0x694010]frame I:150 Avg QP:14.76 size: 2534 [libx264 @ 0x694010]mb I I16..4: 75.9% 0.0% 24.1% [libx264 @ 0x694010]final ratefactor: 17.57 [libx264 @ 0x694010]coded y,uvDC,uvAC intra: 42.7% 92.4% 47.4% [libx264 @ 0x694010]i16 v,h,dc,p: 11% 14% 2% 73% [libx264 @ 0x694010]i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 21% 18% 29% 5% 8% 10% 3% 3% 2% [libx264 @ 0x694010]kb/s:506.79

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  • ASP.NET MVC intermittent slow response

    - by arehman
    Problem In our production environment, system occasionally delays the page response of an ASP.NET MVC application up to 30 seconds or so, even though same page renders in 2-3 seconds most of the times. This happens randomly with any arbitrary page, and GET or POST type requests. For example, log files indicates, system took 15 seconds to complete a request for jquery script file or for other small css file it took 10 secs. Similar Problems: Random Slow Downs Production Environment: Windows Server 2008 - Standard (32-bit) - App Pool running in integrated mode. ASP.NET MVC 1.0 We have tried followings/observations: Moved the application to a stand alone web server, but, it didn't help. We didn't ever notice same issue on the server for any 'ASP.NET' application. App Pool settings are fine. No abrupt recycles/shutdowns. No cpu spikes or memory problems. No delays due to SQL queries or so. It seems as something causing delay along HTTP Pipeline or worker processor seeing the request late. Looking for other suggestions. -- Thanks

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  • Debugging an unresponsive iPhone UI

    - by buggles
    I have an application that needs to update its display every minute or so. To achieve this I was using performSelector:withObject:afterDelay, calling the selector that most of the time just changes some text in a label based on a very simple (and quick) calculation. [self performSelector:@selector(updateDisplay) withObject:nil afterDelay:60]; Occasionally during an update, I have to go off and get some data from the web, and so I do that in another thread using detachNewThreadSelector. That all worked and the "performSelector after Delay" call completes in a tiny fraction of a second, and only runs once a minute. Despite this, and despite running fine on the simulator, the single button in the app is largely unresponsive, not responding to multiple stabs. So, I had assumed peformSelector:afterDelay would not block, but I'm now wondering if it is blocking in some way? I even tried NOT doing the web-look-up incase this was somehow still impacting the responsiveness. No joy. [NSThread detachNewThreadSelector:@selector(updateFromURL) toTarget:self withObject:nil]; I then pushed it through shark to see if I could see anything obvious. From here I can see the web-lookup is the only thing taking any time, but it is only being done every couple of minutes, and then clearly not running on the main thread. The app itself is consuming a tiny fraction of 1% of the CPU (0.0000034%) over 20 minutes, so it just must be a blocking issue. So, am I missing something about performSelector:afterDelay? What other common newbie mistakes might I be making. If it helps, although I've been developing applications for over 20 years, the previous 10 have been largely Java. Perhaps I have a Java assumption loaded :-) Essentially I have assumed the main thread is like the EDT (only do UI stuff on it, but keep everything else off it).

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  • How can I open VLC via browser with PHP (Mac OS X)

    - by Damiqib
    I'm trying to open VLC via browser and make it instantly play the given video file on Mac OS X. This runs on my local server and is only meant to run locally - therefore I already run apache (MAMP) with my username and with group "staff" (defined in httpd.conf). YES - I do know that VLC has http interface - however that is not what I need, so do not suggest that... My current system works without any problems when I run it via Terminal: php /var/www/Movies/index.php - This leads to VLC opening and video starts playing fullscreen like intented. Problems start when I run the same PHP-page with browser. Then the VLC-process starts, but there's no GUI for it, video file won't start playing and the VLC-process takes nearly 100% of CPU. Both; terminal and browser started VLC-processes run with the same user (mine) Both have "Parent process" bash VLC-process begun with Terminal has empty "Process group" (only process id-number) and browser started has "httpd" + (id-number) VLC-process started via browser makes 1000-times more "Mach System Calls" than it's Terminal-started counterpart. Could anyone give me any pointers on how to get this thing working? index.php # $j is a file path to the videofile and is defined before exec('/var/www/Movies/vlc.sh "' . $j . '" > /dev/null 2>&1 & echo $!;'); # If I do this in the given PHP-page it tells me that apache is running # with my username and with the group "staff" like it should be... exec('whoamI'); vlc.sh #!/bin/bash # Activate VLC in 5 seconds to make it the front-most window (sleep 5; open -a VLC) & # Open video file /Applications/VLC.app/Contents/MacOS/VLC --quiet --fullscreen "$1"

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  • Why is it assumed that send may return with less than requested data transmitted on a blocking socke

    - by Ernelli
    The standard method to send data on a stream socket has always been to call send with a chunk of data to write, check the return value to see if all data was sent and then keep calling send again until the whole message has been accepted. For example this is a simple example of a common scheme: int send_all(int sock, unsigned char *buffer, int len) { int nsent; while(len 0) { nsent = send(sock, buffer, len, 0); if(nsent == -1) // error return -1; buffer += nsent; len -= nsent; } return 0; // ok, all data sent } Even the BSD manpage mentions that ...If no messages space is available at the socket to hold the message to be transmitted, then send() normally blocks... Which indicates that we should assume that send may return without sending all data. Now I find this rather broken but even W. Richard Stevens assumes this in his standard reference book about network programming, not in the beginning chapters, but the more advanced examples uses his own writen (write all data) function instead of calling write. Now I consider this still to be more or less broken, since if send is not able to transmit all data or accept the data in the underlying buffer and the socket is blocking, then send should block and return when the whole send request has been accepted. I mean, in the code example above, what will happen if send returns with less data sent is that it will be called right again with a new request. What has changed since last call? At max a few hundred CPU cycles have passed so the buffer is still full. If send now accepts the data why could'nt it accept it before? Otherwise we will end upp with an inefficient loop where we are trying to send data on a socket that cannot accept data and keep trying, or else? So it seems like the workaround, if needed, results in heavily inefficient code and in those circumstances blocking sockets should be avoided at all an non blocking sockets together with select should be used instead.

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  • C#: Why am I still getting an RCW error when exiting my application?

    - by shifuimam
    To be specific, the error is: An attempt has been made to free an RCW that is in use. The RCW is in use on the active thread or another thread. Attempting to free an in-use RCW can cause corruption or data loss. The application in question is a small applet that displays the current clock speed of the CPU as a system tray icon. I'm using a System.Timers.Timer object to refresh the systray icon at an interval of 2.5 seconds. There's a single context menu item to exit the application, which uses the following function to unload everything: public void ExitApp(object sender, EventArgs e) { //stop and disable the timer theInterval.Stop(); theInterval.Enabled = false; //unload the system tray icon TheIcon.Visible = false; //exit the application Application.Exit(); } If I take out everything but Application.Exit(); I get an RCW error and the systray icon doesn't go away until I mouse over it. Everything was working perfectly until I changed the window style of the hidden form used to initialize the systray icon and the timer. If it helps any, I'm using C# 2010 Express.

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  • Performance of java on different hardware?

    - by tangens
    In another SO question I asked why my java programs run faster on AMD than on Intel machines. But it seems that I'm the only one who has observed this. Now I would like to invite you to share the numbers of your local java performance with the SO community. I observed a big performance difference when watching the startup of JBoss on different hardware, so I set this program as the base for this comparison. For participation please download JBoss 5.1.0.GA and run: jboss-5.1.0.GA/bin/run.sh (or run.bat) This starts a standard configuration of JBoss without any extra applications. Then look for the last line of the start procedure which looks like this: [ServerImpl] JBoss (Microcontainer) [5.1.0.GA (build: SVNTag=JBoss_5_1_0_GA date=200905221634)] Started in 25s:264ms Please repeat this procedure until the printed time is somewhat stable and post this line together with some comments on your hardware (I used cpu-z to get the infos) and operating system like this: java version: 1.6.0_13 OS: Windows XP Board: ASUS M4A78T-E Processor: AMD Phenom II X3 720, 2.8 GHz RAM: 2*2 GB DDR3 (labeled 1333 MHz) GPU: NVIDIA GeForce 9400 GT disc: Seagate 1.5 TB (ST31500341AS) Use your votes to bring the fastest configuration to the top. I'm very curious about the results. EDIT: Up to now only a few members have shared their results. I'd really be interested in the results obtained with some other architectures. If someone works with a MAC (desktop) or runs an Intel i7 with less than 3 GHz, please once start JBoss and share your results. It will only take a few minutes.

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  • More than 100 connection to sql server 2008 in "sleeping" status - Solved

    - by Allende
    I have a big trouble here, well at my server. I have an ASP .net web (framework 4.x) running on muy server, all the transactions/select/update/insert are made with ADO.NET. Well my problem is that after being using for a while (a couple of updates/selects/inserts) sometimes I got more than 100 connections on "sleeping" status when check for the connections on sql server with this query: SELECT spid, a.status, hostname, program_name, cmd, cpu, physical_io, blocked, b.name, loginame FROM master.dbo.sysprocesses a INNER JOIN master.dbo.sysdatabases b ON a.dbid = b.dbid where program_name like '%TMS%' ORDER BY spid I've been checking my code and closing every time I make a connection, I'm gonna test the new class, but I'm afraid the problem doesn't be fixed. It suppose that the connection pooling, keep the connections to re-use them, but until I see don't re-use them always. Any idea besides check for close all the connections open after use them? SOLVED(now I have just one and beautiful connection on "sleeping" status): Besides the anwser of David Stratton, I would like to share this link that help explain really well how the connection pool it works: http://dinesql.blogspot.com/2010/07/sql-server-sleeping-status-and.html Just to be short, you need to close every connection (sql connection objects) in order that the connection pool can re-use the connection and use the same connectinos string, to ensure this is highly recommended use one of the webConfig. Be careful with dataReaders you sould close its connection to (that was what make got out of my mind for while).

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  • Eclipse does not start on Windows 7

    - by van
    Suddenly Eclipse today has decides to stop working. The last thing I did was close all perspectives and close Eclipse. When loading eclipse from the command prompt, using: "eclipse.exe -clean" the splash screen loads for a split second then exits. When I run the command: eclipsec -consoleLog -debug it results in the following output: Start VM: -Dosgi.requiredJavaVersion=1.6 -Dhelp.lucene.tokenizer=standard -Xms4096m -Xmx4096m -XX:MaxPermSize=512m -Djava.class.path=d:\devtools\eclipse\\plugins/org.eclipse.equinox.launcher_1.3. 0.v20130327-1440.jar -os win32 -ws win32 -arch x86_64 -showsplash d:\devtools\eclipse\\plugins\org.eclipse.platform_4.3.0.v20130605-20 00\splash.bmp -launcher d:\devtools\eclipse\eclipsec.exe -name Eclipsec --launcher.library d:\devtools\eclipse\\plugins/org.eclipse.equinox.launcher.win 32.win32.x86_64_1.1.200.v20130521-0416\eclipse_1503.dll -startup d:\devtools\eclipse\\plugins/org.eclipse.equinox.launcher_1.3.0.v201303 27-1440.jar --launcher.appendVmargs -product org.eclipse.epp.package.standard.product -consoleLog -debug -vm C:/Program Files/Java/jdk1.6.0_37/bin\..\jre\bin\server\jvm.dll -vmargs -Dosgi.requiredJavaVersion=1.6 -Dhelp.lucene.tokenizer=standard -Xms4096m -Xmx4096m -XX:MaxPermSize=512m -Djava.class.path=d:\devtools\eclipse\\plugins/org.eclipse.equinox.launcher_1.3. 0.v20130327-1440.jar Error occurred during initialization of VM Incompatible minimum and maximum heap sizes specified Checking Task Manager shows no Java process running and both the CPU and memory usage are very low. I have tried: Re-installing Eclipse Re-starting my machine But running eclipsec -consoleLog -debug from the command prompt still results in the issue: Error occurred during initialization of VM Incompatible minimum and maximum heap sizes specified

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  • GCC - How to realign stack?

    - by psihodelia
    I try to build an application which uses pthreads and __m128 SSE type. According to GCC manual, default stack alignment is 16 bytes. In order to use __m128, the requirement is the 16-byte alignment. My target CPU supports SSE. I use a GCC compiler which doesn't support runtime stack realignment (e.g. -mstackrealign). I cannot use any other GCC compiler version. My test application looks like: #include <xmmintrin.h> #include <pthread.h> void *f(void *x){ __m128 y; ... } int main(void){ pthread_t p; pthread_create(&p, NULL, f, NULL); } The application generates an exception and exits. After a simple debugging (printf "%p", &y), I found that the variable y is not 16-byte aligned. My question is: how can I realign the stack properly (16-byte) without using any GCC flags and attributes (they don't help)? Should I use GCC inline Assembler within this thread function f()?

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  • Slow MySQL Query not using filesort

    - by Canadaka
    I have a query on my homepage that is getting slower and slower as my database table grows larger. tablename = tweets_cache rows = 572,327 this is the query I'm currently using that is slow, over 5 seconds. SELECT * FROM tweets_cache t WHERE t.province='' AND t.mp='0' ORDER BY t.published DESC LIMIT 50; If I take out either the WHERE or the ORDER BY, then the query is super fast 0.016 seconds. I have the following indexes on the tweets_cache table. PRIMARY published mp category province author So i'm not sure why its not using the indexes since mp, provice and published all have indexes? Doing a profile of the query shows that its not using an index to sort the query and is using filesort which is really slow. possible_keys = mp,province Extra = Using where; Using filesort I tried adding a new multie-colum index with "profiles & mp". The explain shows that this new index listed under "possible_keys" and "key", but the query time is unchanged, still over 5 seconds. Here is a screenshot of the profiler info on the query. http://i355.photobucket.com/albums/r469/canadaka_bucket/slow_query_profile.png Something weird, I made a dump of my database to test on my local desktop so i don't screw up the live site. The same query on my local runs super fast, milliseconds. So I copied all the same mysql startup variables from the server to my local to make sure there wasn't some setting that might be causing this. But even after that the local query runs super fast, but the one on the live server is over 5 seconds. My database server is only using around 800MB of the 4GB it has available. here are the related my.ini settings i'm using default-storage-engine = MYISAM max_connections = 800 skip-locking key_buffer = 512M max_allowed_packet = 1M table_cache = 512 sort_buffer_size = 4M read_buffer_size = 4M read_rnd_buffer_size = 16M myisam_sort_buffer_size = 64M thread_cache_size = 8 query_cache_size = 128M # Try number of CPU's*2 for thread_concurrency thread_concurrency = 8 # Disable Federated by default skip-federated key_buffer = 512M sort_buffer_size = 256M read_buffer = 2M write_buffer = 2M key_buffer = 512M sort_buffer_size = 256M read_buffer = 2M write_buffer = 2M

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  • Shared classes are build under VS2008 only but not under MSBuild.

    - by Vasiliy Borovyak
    We share our classes between silverlight 3.0 client and server as is it described here. Everything works fine under Visual Studio 2008 only. Using msbuild with following command line parameters: C:\Windows\Microsoft.NET\Framework\v3.5\msbuild.exe FoobarApplication.sln /t:Rebuild /p:Configuration=Release /p:Platform="Any CPU" we get following error: Class1.cs(28,54): error CS0234: The type or namespace name 'WcfService' does not exist in the namespace 'Company.FoobarApplication' (are you missing an assembly reference?) Service References\geoServiceReference1\Reference.cs(24,81): error CS0234: The type or namespace name 'WcfService' does not exist in the namespace 'Company.FoobarApplication' (are you missing an assembly reference?) Done Building Project "C:\work\bov-tmp\FoobarApplication\SilverlightClassLibrary3\SilverlightClassLibrary3.csproj" (Rebuild target(s)) -- FAILED. Done Building Project "C:\work\bov-tmp\FoobarApplication\FoobarApplication.sln" (Rebuild target(s)) -- FAILED. I found exactly the same question here. There are 4 workarounds there, I tried first 3 of them and those did not worked out. The 4-th workaround is not the acceptable solution. Any thoughts how to build the solution?

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  • Threads, Sockets, and Designing Low-Latency, High Concurrency Servers

    - by lazyconfabulator
    I've been thinking a lot lately about low-latency, high concurrency servers. Specifically, http servers. http servers (fast ones, anyway) can serve thousands of users simultaneously, with very little latency. So how do they do it? As near as I can tell, they all use events. Cherokee and Lighttpd use libevent. Nginx uses it's own event library performing much the same function of libevent, that is, picking a platform optimal strategy for polling events (like kqueue on *bsd, epoll on linux, /dev/poll on Solaris, etc). They all also seem to employ a strategy of multiprocess or multithread once the connection is made - using worker threads to handle the more cpu intensive tasks while another thread continues to listen and handle connections (via events). This is the extent of my understanding and ability to grok the thousand line sources of these applications. What I really want are finer details about how this all works. In examples of using events I've seen (and written) the events are handling both input and output. To this end, do the workers employ some sort of input/output queue to the event handling thread? Or are these worker threads handling their own input and output? I imagine a fixed amount of worker threads are spawned, and connections are lined up and served on demand, but how does the event thread feed these connections to the workers? I've read about FIFO queues and circular buffers, but I've yet to see any implementations to work from. Are there any? Do any use compare-and-swap instructions to avoid locking or is locking less detrimental to event polling than I think? Or have I misread the design entirely? Ultimately, I'd like to take enough away to improve some of my own event-driven network services. Bonus points to anyone providing solid implementation details (especially for stuff like low-latency queues) in C, as that's the language my network services are written in.

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  • Memory Bandwidth Performance for Modern Machines

    - by porgarmingduod
    I'm designing a real-time system that occasionally has to duplicate a large amount of memory. The memory consists of non-tiny regions, so I expect the copying performance will be fairly close to the maximum bandwidth the relevant components (CPU, RAM, MB) can do. This led me to wonder what kind of raw memory bandwidth modern commodity machine can muster? My aging Core2Duo gives me 1.5 GB/s if I use 1 thread to memcpy() (and understandably less if I memcpy() with both cores simultaneously.) While 1.5 GB is a fair amount of data, the real-time application I'm working on will have have something like 1/50th of a second, which means 30 MB. Basically, almost nothing. And perhaps worst of all, as I add multiple cores, I can process a lot more data without any increased performance for the needed duplication step. But a low-end Core2Due isn't exactly hot stuff these days. Are there any sites with information, such as actual benchmarks, on raw memory bandwidth on current and near-future hardware? Furthermore, for duplicating large amounts of data in memory, are there any shortcuts, or is memcpy() as good as it will get? Given a bunch of cores with nothing to do but duplicate as much memory as possible in a short amount of time, what's the best I can do?

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  • What is faster- Java or C# (Or good old C)?

    - by Rexsung
    I'm currently deciding on a platform to build a scientific computational product on, and am deciding on either C#, Java, or plain C with Intels compiler on Core2 Quad CPU's. It's mostly integer arithmetic. My benchmarks so far show Java and C are about on par with each other, and dotNET/C# trails by about 5%- however a number of my coworkers are claiming that dotNET with the right optimizations will beat both of these given enough time for the JIT to do its work. I always assume that the JIT would have done it's job within a few minutes of the app starting (Probably a few seconds in my case, as it's mostly tight loops), so I'm not sure whether to believe them Can anyone shed any light on the situation? Would dotNET beat Java? (Or am I best just sticking with C at this point?). The code is highly multithreaded and data sets are several terabytes in size. Haskell/erlang etc are not options in this case as there is a significant quantity of existing legacy C code that will be ported to the new system, and porting C to Java/C# is a lot simpler than to Haskell or Erlang. (Unless of course these provide a significant speedup). Edit: We are considering moving to C# or Java because they may, in theory, be faster. Every percent we can shave off our processing time saves us tens of thousands of dollars per year. At this point we are just trying to evaluate whether C, Java, or c# would be faster.

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