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• Java map / nio / NFS issue causing a VM fault: "a fault occurred in a recent unsafe memory access op

  - by Matthew Bloch

  I have written a parser class for a particular binary format (nfdump if anyone is interested) which uses java.nio's MappedByteBuffer to read through files of a few GB each. The binary format is just a series of headers and mostly fixed-size binary records, which are fed out to the called by calling nextRecord(), which pushes on the state machine, returning null when it's done. It performs well. It works on a development machine. On my production host, it can run for a few minutes or hours, but always seems to throw "java.lang.InternalError: a fault occurred in a recent unsafe memory access operation in compiled Java code", fingering one of the Map.getInt, getShort methods, i.e. a read operation in the map. The uncontroversial (?) code that sets up the map is this: /** Set up the map from the given filename and position */ protected void open() throws IOException { // Set up buffer, is this all the flexibility we'll need? channel = new FileInputStream(file).getChannel(); MappedByteBuffer map1 = channel.map(FileChannel.MapMode.READ_ONLY, 0, channel.size()); map1.load(); // we want the whole thing, plus seems to reduce frequency of crashes? map = map1; // assumes the host writing the files is little-endian (x86), ought to be configurable map.order(java.nio.ByteOrder.LITTLE_ENDIAN); map.position(position); } and then I use the various map.get* methods to read shorts, ints, longs and other sequences of bytes, before hitting the end of the file and closing the map. I've never seen the exception thrown on my development host. But the significant point of difference between my production host and development is that on the former, I am reading sequences of these files over NFS (probably 6-8TB eventually, still growing). On my dev machine, I have a smaller selection of these files locally (60GB), but when it blows up on the production host it's usually well before it gets to 60GB of data. Both machines are running java 1.6.0_20-b02, though the production host is running Debian/lenny, the dev host is Ubuntu/karmic. I'm not convinced that will make any difference. Both machines have 16GB RAM, and are running with the same java heap settings. I take the view that if there is a bug in my code, there is enough of a bug in the JVM not to throw me a proper exception! But I think it is just a particular JVM implementation bug due to interactions between NFS and mmap, possibly a recurrence of 6244515 which is officially fixed. I already tried adding in a "load" call to force the MappedByteBuffer to load its contents into RAM - this seemed to delay the error in the one test run I've done, but not prevent it. Or it could be coincidence that was the longest it had gone before crashing! If you've read this far and have done this kind of thing with java.nio before, what would your instinct be? Right now mine is to rewrite it without nio :)

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• How do I speed up and cache mmap file access over NFS on Linux?

  - by Zan Lynx

  The server and client are both 64-bit Ubuntu 10.04 LTS. The application in question is a custom app that uses mmap() for fast random file access. Its ideal state is when the entire file is cached in RAM. The network connections are really fast 10Gb Ethernet. It is a virtual server blade setup. It isn't the network connections slowing things down because everything performs superbly when using a virtual disk (iSCSI to the SAN). But when we run the application on a NFS home directory mount, performance goes to the dogs. It appears that the Linux kernel isn't caching anything. So it is reading every single disk block needed by mmap() accesses over and over and over again. The NFS mount is done through autofs, which has only default settings. /proc/mounts shows the NFS mount is done with the following options: rw,relatime,vers=3,rsize=131072,wsize=131072,namlen=255,hard,proto=tcp,timeo=600,retrans=2,sec=sys,mountaddr=192.168.11.52,mountvers=3,mountproto=tcp,addr=192.168.11.52 How can I make Ubuntu 10.04 cache the file instead of reloading it all the time?

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• using BOOST_FOREACH with std::map

  - by kmote

  I'd like to iterate over a std::map using BOOST_FOREACH and edit the values. I can't quite get it. typedef std::pair<int, int> IdSizePair_t; std::map<int,int> mmap; mmap[1] = 1; mmap[2] = 2; mmap[3] = 3; BOOST_FOREACH( IdSizePair_t i, mmap ) i.second++; // mmap should contain {2,3,4} here Of course this doesn't change anything because I'm not iterating by reference. So I substitute this line instead (as per the example in the Boost docs): BOOST_FOREACH( IdSizePair_t &i, mmap ) and I get the compiler error: error C2440: 'initializing' : cannot convert from 'std::pair<_Ty1,_Ty2>' to 'IdSizePair_t &' with [ _Ty1=const int, _Ty2=int ] Any suggestions?

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• Find Adjacent Nodes A Star Path-Finding C++

  - by Infinity James

  Is there a better way to handle my FindAdjacent() function for my A Star algorithm? It's awfully messy, and it doesn't set the parent node correctly. When it tries to find the path, it loops infinitely because the parent of the node has a pent of the node and the parents are always each other. Any help would be amazing. This is my function: void AStarImpl::FindAdjacent(Node* pNode) { for (int i = -1; i <= 1; i++) { for (int j = -1; j <= 1; j++) { if (pNode->mX != Map::GetInstance()->mMap[pNode->mX + i][pNode->mY + j].mX || pNode->mY != Map::GetInstance()->mMap[pNode->mX + i][pNode->mY + j].mY) { if (pNode->mX + i <= 14 && pNode->mY + j <= 14) { if (pNode->mX + i >= 0 && pNode->mY + j >= 0) { if (Map::GetInstance()->mMap[pNode->mX + i][pNode->mY + j].mTypeID != NODE_TYPE_SOLID) { if (find(mOpenList.begin(), mOpenList.end(), &Map::GetInstance()->mMap[pNode->mX + i][pNode->mY + j]) == mOpenList.end()) { Map::GetInstance()->mMap[pNode->mX+i][pNode->mY+j].mParent = &Map::GetInstance()->mMap[pNode->mX][pNode->mY]; mOpenList.push_back(&Map::GetInstance()->mMap[pNode->mX+i][pNode->mY+j]); } } } } } } } mClosedList.push_back(&Map::GetInstance()->mMap[pNode->mX][pNode->mY]); } If you'd like any more code, just ask and I can post it.

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• Physics System ignores collision in some rare cases

  - by Gajoo

  I've been developing a simple physics engine for my game. since the game physics is very simple I've decided to increase accuracy a little bit. Instead of formal integration methods like fourier or RK4, I'm directly computing the results after delta time "dt". based on the very first laws of physics : dx = 0.5 * a * dt^2 + v0 * dt dv = a * dt where a is acceleration and v0 is object's previous velocity. Also to handle collisions I've used a method which is somehow different from those I've seen so far. I'm detecting all the collision in the given time frame, stepping the world forward to the nearest collision, resolving it and again check for possible collisions. As I said the world consist of very simple objects, so I'm not loosing any performance due to multiple collision checking. First I'm checking if the ball collides with any walls around it (which is working perfectly) and then I'm checking if it collides with the edges of the walls (yellow points in the picture). the algorithm seems to work without any problem except some rare cases, in which the collision with points are ignored. I've tested everything and all the variables seem to be what they should but after leaving the system work for a minute or two the system the ball passes through one of those points. Here is collision portion of my code, hopefully one of you guys can give me a hint where to look for a potential bug! void PhysicalWorld::checkForPointCollision(Vec2 acceleration, PhysicsComponent& ball, Vec2& collisionNormal, float& collisionTime, Vec2 target) { // this function checks if there will be any collision between a circle and a point // ball contains informations about the circle (it's current velocity, position and radius) // collisionNormal is an output variable // collisionTime is also an output varialbe // target is the point I want to check for collisions Vec2 V = ball.mVelocity; Vec2 A = acceleration; Vec2 P = ball.mPosition - target; float wallWidth = mMap->getWallWidth() / (mMap->getWallWidth() + mMap->getHallWidth()) / 2; float r = ball.mRadius / (mMap->getWallWidth() + mMap->getHallWidth()); // r is ball radius scaled to match actual rendered object. if (A.any()) // todo : I need to first correctly solve the collisions in case there is no acceleration return; if (V.any()) // if object is not moving there will be no collisions! { float D = P.x * V.y - P.y * V.x; float Delta = r*r*V.length2() - D*D; if(Delta < eps) return; Delta = sqrt(Delta); float sgnvy = V.y > 0 ? 1: (V.y < 0?-1:0); Vec2 c1(( D*V.y+sgnvy*V.x*Delta) / V.length2(), (-D*V.x+fabs(V.y)*Delta) / V.length2()); Vec2 c2(( D*V.y-sgnvy*V.x*Delta) / V.length2(), (-D*V.x-fabs(V.y)*Delta) / V.length2()); float t1 = (c1.x - P.x) / V.x; float t2 = (c2.x - P.x) / V.x; if(t1 > eps && t1 <= collisionTime) { collisionTime = t1; collisionNormal = c1; } if(t2 > eps && t2 <= collisionTime) { collisionTime = t2; collisionNormal = c2; } } } // this function should step the world forward by dt. it doesn't check for collision of any two balls (components) // it just checks if there is a collision between the current component and 4 points forming a rectangle around it. void PhysicalWorld::step(float dt) { for (unsigned i=0;i<mObjects.size();i++) { PhysicsComponent &current = *mObjects[i]; Vec2 acceleration = current.mForces * current.mInvMass; float rt=dt; // stores how much more the world should advance while(rt > eps) { float collisionTime = rt; Vec2 collisionNormal = Vec2(0,0); float halfWallWidth = mMap->getWallWidth() / (mMap->getWallWidth() + mMap->getHallWidth()) / 2; // we check if there is any collision with any of those 4 points around the ball // if there is a collision both collisionNormal and collisionTime variables will change // after these functions collisionTime will be exactly the value of nearest collision (if any) // and if there was, collisionNormal will report in which direction the ball should return. checkForPointCollision(acceleration,current,collisionNormal,collisionTime,Vec2(floor(current.mPosition.x) + halfWallWidth,floor(current.mPosition.y) + halfWallWidth)); checkForPointCollision(acceleration,current,collisionNormal,collisionTime,Vec2(floor(current.mPosition.x) + halfWallWidth, ceil(current.mPosition.y) - halfWallWidth)); checkForPointCollision(acceleration,current,collisionNormal,collisionTime,Vec2( ceil(current.mPosition.x) - halfWallWidth,floor(current.mPosition.y) + halfWallWidth)); checkForPointCollision(acceleration,current,collisionNormal,collisionTime,Vec2( ceil(current.mPosition.x) - halfWallWidth, ceil(current.mPosition.y) - halfWallWidth)); // either if there is a collision or if there is not we step the forward since we are sure there will be no collision before collisionTime current.mPosition += collisionTime * (collisionTime * acceleration * 0.5 + current.mVelocity); current.mVelocity += collisionTime * acceleration; // if the ball collided with anything collisionNormal should be at least none zero in one of it's axis if (collisionNormal.any()) { collisionNormal *= Dot(collisionNormal, current.mVelocity) / collisionNormal.length2(); current.mVelocity -= 2 * collisionNormal; // simply reverse velocity along collision normal direction } rt -= collisionTime; } // reset all forces for current object so it'll be ready for later game event current.mForces.zero(); } }

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• Apache strace to hunt down a memory leak

  - by Zipp

  We have a server with a memory issue: the server keeps allocating itself memory and doesn't release it. We're running Apache. I set MaxReqsPerClient to a really low value just so the threads don't hold a lot of memory, but has anyone seen calls like this? Am I wrong in thinking that it's probably Drupal pulling too much data back from the cache in DB? read(52, "h_index\";a:2:{s:6:\"weight\";i:1;s"..., 6171) = 1368 read(52, "\";a:2:{s:6:\"author\";a:3:{s:5:\"la"..., 4803) = 1368 read(52, ":\"description\";s:19:\"Term name t"..., 3435) = 1368 read(52, "abel\";s:4:\"Name\";s:11:\"descripti"..., 2067) = 1368 read(52, "ions\";a:2:{s:4:\"form\";a:3:{s:4:\""..., 16384) = 708 brk(0x2ab554396000) = 0x2ab5542f5000 mmap(NULL, 1048576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x2ab55f653000 brk(0x2ab554356000) = 0x2ab5542f5000 mmap(NULL, 1048576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x2ab55f753000 brk(0x2ab554356000) = 0x2ab5542f5000 mmap(NULL, 1048576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x2ab55f853000 brk(0x2ab554356000) = 0x2ab5542f5000 mmap(NULL, 1048576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x2ab55f953000 brk(0x2ab554356000) = 0x2ab5542f5000 mmap(NULL, 1048576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x2ab55fa53000 brk(0x2ab554356000) = 0x2ab5542f5000 mmap(NULL, 1048576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x2ab55fb53000 brk(0x2ab554356000) = 0x2ab5542f5000 mmap(NULL, 1048576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x2ab55fc53000 poll([{fd=52, events=POLLIN|POLLPRI}], 1, 0) = 0 (Timeout) write(52, "d\0\0\0\3SELECT cid, data, created, "..., 104) = 104 read(52, "\1\0\0\1\5E\0\0\2\3def\23drupal_database_nam"..., 16384) = 1368 read(52, ";s:11:\"granularity\";a:5:{s:4:\"ye"..., 34783) = 1368 read(52, ":4:\"date\";}s:9:\"datestamp\";a:9:{"..., 33415) = 1368 read(52, "\";i:0;s:15:\"display_default\";i:0"..., 32047) = 1368 read(52, "e as an integer value.\";s:8:\"set"..., 30679) = 1368 read(52, "label' pairs, i.e. 'Fraction': 0"..., 29311) = 1368 top (the procs just keep growing in memory..): 12845 apache 15 0 581m 246m 37m S 0.0 4.1 0:17.39 httpd 12846 apache 15 0 571m 235m 37m S 0.0 4.0 0:12.13 httpd 12833 apache 15 0 420m 117m 37m S 0.0 2.0 0:06.04 httpd 12851 apache 15 0 412m 113m 37m S 0.0 1.9 0:05.32 httpd 13871 apache 15 0 409m 109m 37m S 0.0 1.8 0:04.90 httpd 12844 apache 15 0 407m 108m 37m S 0.0 1.8 0:04.50 httpd 13870 apache 15 0 407m 108m 37m S 0.3 1.8 0:03.50 httpd 14903 apache 15 0 402m 103m 37m S 0.3 1.7 0:01.29 httpd 14850 apache 15 0 397m 100m 37m S 0.0 1.7 0:02.08 httpd 14907 apache 15 0 390m 93m 36m S 0.0 1.6 0:01.32 httpd 13872 apache 15 0 386m 91m 37m S 0.0 1.5 0:03.13 httpd 12843 apache 15 0 373m 81m 37m S 0.0 1.4 0:02.51 httpd 14901 apache 15 0 370m 75m 33m S 0.0 1.3 0:00.78 httpd 14904 apache 15 0 335m 29m 15m S 0.0 0.5 0:00.26 httpd

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• start apache2 in chroot environment

  - by xero

  This is my first time I am trying to install Apache2 HTTP server in a chroot environment. That's why i decided to follow this procedure : http://www.symantec.com/connect/articles/securing-apache-2-step-step my web server start with successful : root@ubuntu:/usr/local/apache2/bin/apachectl start [Tue Oct 29 01:49:15.879868 2013] [core:warn] [pid 10835] AH00117: Ignoring deprecated use of DefaultType in line 60 of /usr/local/apache2/conf/httpd.conf. AH00548: NameVirtualHost has no effect and will be removed in the next release /usr/local/apache2/conf/httpd.conf:81 AH00558: httpd: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1. Set the 'ServerName' directive globally to suppress this message root@ubuntu:/chroot/httpd/etc# netstat -antu Active Internet connections (servers and established) Proto Recv-Q Send-Q Local Address Foreign Address State tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN But at the end of part "Chrooting the server" i have always the same problem. When i try to start apache2 in chroot i have always this error : root@ubuntu:/chroot/httpd/etc# chroot /chroot/httpd /usr/local/apache2/bin/apachectl chroot: failed to run command `/usr/local/apache2/bin/apachectl': No such file or directory however my apachectl file exist : root@ubuntu:/chroot/httpd/etc# ls -l /chroot/httpd/usr/local/apache2/bin/apachectl -rwxr-xr-x 1 root root 3437 Oct 29 02:28 /chroot/httpd/usr/local/apache2/bin/apachectl when I use strace to debug, there are errors with coreutils.mo and libc.mo : root@ubuntu:/chroot/httpd/etc# chroot /chroot/httpd /usr/local/apache2/bin/httpd group hosts nsswitch.conf passwd passwords resolv.conf root@ubuntu:/chroot/httpd/etc# strace chroot /chroot/httpd /usr/local/apache2/bin/apachectl execve("/usr/sbin/chroot", ["chroot", "/chroot/httpd", "/usr/local/apache2/bin/apachectl"], [/* 18 vars */]) = 0 brk(0) = 0x1e46000 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory) mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fe89563b000 access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory) open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3 fstat(3, {st_mode=S_IFREG|0644, st_size=18263, ...}) = 0 mmap(NULL, 18263, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7fe895636000 close(3) = 0 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory) open("/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3 read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\200\30\2\0\0\0\0\0"..., 832) = 832 fstat(3, {st_mode=S_IFREG|0755, st_size=1815224, ...}) = 0 mmap(NULL, 3929304, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7fe89505b000 mprotect(0x7fe895210000, 2097152, PROT_NONE) = 0 mmap(0x7fe895410000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1b5000) = 0x7fe895410000 mmap(0x7fe895416000, 17624, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7fe895416000 close(3) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fe895635000 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fe895634000 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fe895633000 arch_prctl(ARCH_SET_FS, 0x7fe895634700) = 0 mprotect(0x7fe895410000, 16384, PROT_READ) = 0 mprotect(0x606000, 4096, PROT_READ) = 0 mprotect(0x7fe89563d000, 4096, PROT_READ) = 0 munmap(0x7fe895636000, 18263) = 0 brk(0) = 0x1e46000 brk(0x1e67000) = 0x1e67000 open("/usr/lib/locale/locale-archive", O_RDONLY|O_CLOEXEC) = 3 fstat(3, {st_mode=S_IFREG|0644, st_size=2919792, ...}) = 0 mmap(NULL, 2919792, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7fe894d92000 close(3) = 0 chroot("/chroot/httpd") = 0 chdir("/") = 0 execve("/usr/local/apache2/bin/apachectl", ["/usr/local/apache2/bin/apachectl"], [/* 18 vars */]) = -1 ENOENT (No such file or directory) open("/usr/share/locale/locale.alias", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory) open("/usr/share/locale/en_US.UTF-8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory) open("/usr/share/locale/en_US.utf8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory) open("/usr/share/locale/en_US/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory) open("/usr/share/locale/en.UTF-8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory) open("/usr/share/locale/en.utf8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory) open("/usr/share/locale/en/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory) open("/usr/share/locale-langpack/en_US.UTF-8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory) open("/usr/share/locale-langpack/en_US.utf8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory) open("/usr/share/locale-langpack/en_US/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory) open("/usr/share/locale-langpack/en.UTF-8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory) open("/usr/share/locale-langpack/en.utf8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory) open("/usr/share/locale-langpack/en/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory) write(2, "chroot: ", 8chroot: ) = 8 write(2, "failed to run command `/usr/loca"..., 56failed to run command `/usr/local/apache2/bin/apachectl') = 56 open("/usr/share/locale/en_US.UTF-8/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory) open("/usr/share/locale/en_US.utf8/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory) open("/usr/share/locale/en_US/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory) open("/usr/share/locale/en.UTF-8/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory) open("/usr/share/locale/en.utf8/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory) open("/usr/share/locale/en/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory) open("/usr/share/locale-langpack/en_US.UTF-8/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory) open("/usr/share/locale-langpack/en_US.utf8/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory) open("/usr/share/locale-langpack/en_US/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory) open("/usr/share/locale-langpack/en.UTF-8/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory) open("/usr/share/locale-langpack/en.utf8/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory) open("/usr/share/locale-langpack/en/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory) write(2, ": No such file or directory", 27: No such file or directory) = 27 write(2, "\n", 1 ) = 1 close(1) = 0 close(2) = 0 exit_group(127) = ? using the tutorial I did not find and copie libraries following on my server. I suppose there is no link with coreutils.mo and libc.mo : /usr/libexec/ld-elf.so.1 /var/run/ld-elf.so.hints I don't understand what files i forgot to copy in my chroot environment to be able to start my apache2. Any ideas ?

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• A cross between std::multimap and std::vector?

  - by Milan Babuškov

  I'm looking for a STL container that works like std::multimap, but has constant access time to random n-th element. I need this because I have such structure in memory that is std::multimap for many reasons, but items stored in it have to be presented to the user in a listbox. Since amount of data is huge, I'm using list box with virtual items (i.e. list control polls for value at line X). As a workaround I'm currently using additional std::vector to store "indexes" into std::map, and I fill it like this: std::vector<MMap::data_type&> vec; for (MMap::iterator it = mmap.begin(); it != mmap.end(); ++it) vec.push_back((*it).second); But this is not very elegant solution. Is there some such containter?

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• What's the equivalence of os.fork() on Windows with Python?

  - by prosseek

  This code works well in Mac/Linux, but not in Windows. import mmap import os map = mmap.mmap(-1, 13) map.write("Hello world!") pid = os.fork() if pid == 0: # In a child process print 'child' map.seek(0) print map.readline() map.close() else: print 'parent' What's the equivalent function of os.fork() on Windows?

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• Process: Unable to start service com.google.android.gms.checkin.CheckinService with Intent

  - by AndyRoid

  I'm trying to build a Google map application but keep receiving this in my LogCat. I have all the permissions and meta-data set in my manifest, but am still dumbfounded by this error. Have looked everywhere on SO for this specific error but found nothing relating to com.google.android.gms.checkin A little bit about my structural hierarchy. MainActivity extends ActionBarActivity with three tabs underneath actionbar. Each tab has it's own fragment. On the gMapFragment I create a GPSTrack object from my GPSTrack class which extends Service and implements LocationListener. The problem is that when I start the application I get this message: I have all my libraries imported properly and I even added the google-play-services.jar into my libs folder. I also installed Google Play Services APKs through CMD onto my emulator. Furthermore the LocationManager lm = = (LocationManager) mContext.getSystemService(LOCATION_SERVICE); in my GPSTrack class always returns null. Why is this and how can I fix these issues? Would appreciate an explanation along with solution too, I want to understand what's going on here. ============== Code: gMapFragment.java public class gMapFragment extends SupportMapFragment { private final String TAG = "gMapFragment"; private GoogleMap mMap; protected SupportMapFragment mapFrag; private Context mContext = getActivity(); private static View view; @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { if (view != null) { ViewGroup parent = (ViewGroup) view.getParent(); if (parent != null) { parent.removeView(view); } } try { super.onCreateView(inflater, container, savedInstanceState); view = inflater.inflate(R.layout.fragment_map, container, false); setupGoogleMap(); } catch (Exception e) { /* * Map already there , just return as view */ } return view; } private void setupGoogleMap() { mapFrag = (SupportMapFragment) getFragmentManager().findFragmentById( R.id.mapView); if (mapFrag == null) { FragmentManager fragManager = getFragmentManager(); FragmentTransaction fragTransaction = fragManager .beginTransaction(); mapFrag = SupportMapFragment.newInstance(); fragTransaction.replace(R.id.mapView, mapFrag).commit(); } if (mapFrag != null) { mMap = mapFrag.getMap(); if (mMap != null) { setupMap(); mMap.setOnMapClickListener(new OnMapClickListener() { @Override public void onMapClick(LatLng point) { // TODO your click stuff on map } }); } } } @Override public void onAttach(Activity activity) { super.onAttach(activity); Log.d("Attach", "on attach"); } @Override public void onDetach() { super.onDetach(); } @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); } @Override public void onResume() { super.onResume(); } @Override public void onPause() { super.onPause(); } @Override public void onDestroy() { super.onDestroy(); } private void setupMap() { GPSTrack gps = new GPSTrack(mContext); // Enable MyLocation layer of google map mMap.setMyLocationEnabled(true); Log.d(TAG, "MyLocation enabled"); // Set Map type mMap.setMapType(GoogleMap.MAP_TYPE_NORMAL); // Grab current location **ERROR HERE/Returns Null** Location location = gps.getLocation(); Log.d(TAG, "Grabbing location..."); if (location != null) { Log.d(TAG, "location != null"); // Grab Latitude and Longitude double latitude = location.getLatitude(); double longitude = location.getLongitude(); Log.d(TAG, "Getting lat, long.."); // Initialize LatLng object LatLng latLng = new LatLng(latitude, longitude); Log.d(TAG, "LatLng initialized"); // Show current location on google map mMap.moveCamera(CameraUpdateFactory.newLatLng(latLng)); // Zoom in on google map mMap.animateCamera(CameraUpdateFactory.zoomTo(20)); mMap.addMarker(new MarkerOptions().position( new LatLng(latitude, longitude)).title("You are here.")); } else { gps.showSettingsAlert(); } } } GPSTrack.java public class GPSTrack extends Service implements LocationListener{ private final Context mContext; private boolean isGPSEnabled = false; //See if network is connected to internet private boolean isNetworkEnabled = false; //See if you can grab the location private boolean canGetLocation = false; protected Location location = null; protected double latitude; protected double longitude; private static final long MINIMUM_DISTANCE_CHANGE_FOR_UPDATES = 10; //10 Meters private static final long MINIMUM_TIME_CHANGE_FOR_UPDATES = 1000 * 60 * 1; //1 minute protected LocationManager locationManager; public GPSTrack(Context context) { this.mContext = context; getLocation(); } public Location getLocation() { try { //Setup locationManager for controlling location services **ERROR HERE/Return Null** locationManager = (LocationManager) mContext.getSystemService(LOCATION_SERVICE); //See if GPS is enabled isGPSEnabled = locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER); //See if Network is connected to the internet or carrier service isNetworkEnabled = locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER); if (!isGPSEnabled && !isNetworkEnabled) { Toast.makeText(getApplicationContext(), "No Network Provider Available", Toast.LENGTH_SHORT).show(); } else { this.canGetLocation = true; if (isNetworkEnabled) { locationManager.requestLocationUpdates( LocationManager.NETWORK_PROVIDER, MINIMUM_TIME_CHANGE_FOR_UPDATES, MINIMUM_DISTANCE_CHANGE_FOR_UPDATES, this); Log.d("GPS", "GPS Enabled"); if (locationManager != null) { location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER); if (location != null) { latitude = location.getLatitude(); longitude = location.getLongitude(); } } } } } catch (Exception e) { e.printStackTrace(); } return location; } public void stopUsingGPS() { if (locationManager != null) { locationManager.removeUpdates(GPSTrack.this); } } public double getLatitude() { if (location != null) { latitude = location.getLatitude(); } return latitude; } public double getLongitude() { if (location != null) { longitude = location.getLongitude(); } return longitude; } public boolean canGetLocation() { return this.canGetLocation; } public void showSettingsAlert() { AlertDialog.Builder alertDialog = new AlertDialog.Builder(mContext); //AlertDialog title alertDialog.setTitle("GPS Settings"); //AlertDialog message alertDialog.setMessage("GPS is not enabled. Do you want to go to Settings?"); alertDialog.setPositiveButton("Settings", new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialog, int which) { // TODO Auto-generated method stub Intent i = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS); mContext.startActivity(i); } }); alertDialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialog, int which) { // TODO Auto-generated method stub dialog.cancel(); } }); alertDialog.show(); } @Override public void onLocationChanged(Location location) { // TODO Auto-generated method stub } @Override public void onStatusChanged(String provider, int status, Bundle extras) { // TODO Auto-generated method stub } @Override public void onProviderEnabled(String provider) { // TODO Auto-generated method stub } @Override public void onProviderDisabled(String provider) { // TODO Auto-generated method stub } @Override public IBinder onBind(Intent intent) { // TODO Auto-generated method stub return null; } } logcat 06-08 22:35:03.441: E/AndroidRuntime(1370): FATAL EXCEPTION: main 06-08 22:35:03.441: E/AndroidRuntime(1370): Process: com.google.android.gms, PID: 1370 06-08 22:35:03.441: E/AndroidRuntime(1370): java.lang.RuntimeException: Unable to start service com.google.android.gms.checkin.CheckinService@b1094e48 with Intent { cmp=com.google.android.gms/.checkin.CheckinService }: java.lang.SecurityException: attempting to read gservices without permission: Neither user 10053 nor current process has com.google.android.providers.gsf.permission.READ_GSERVICES. 06-08 22:35:03.441: E/AndroidRuntime(1370): at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:2719) 06-08 22:35:03.441: E/AndroidRuntime(1370): at android.app.ActivityThread.access$2100(ActivityThread.java:135) 06-08 22:35:03.441: E/AndroidRuntime(1370): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1293) 06-08 22:35:03.441: E/AndroidRuntime(1370): at android.os.Handler.dispatchMessage(Handler.java:102) 06-08 22:35:03.441: E/AndroidRuntime(1370): at android.os.Looper.loop(Looper.java:136) 06-08 22:35:03.441: E/AndroidRuntime(1370): at android.app.ActivityThread.main(ActivityThread.java:5017) 06-08 22:35:03.441: E/AndroidRuntime(1370): at java.lang.reflect.Method.invokeNative(Native Method) 06-08 22:35:03.441: E/AndroidRuntime(1370): at java.lang.reflect.Method.invoke(Method.java:515) 06-08 22:35:03.441: E/AndroidRuntime(1370): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779) 06-08 22:35:03.441: E/AndroidRuntime(1370): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595) 06-08 22:35:03.441: E/AndroidRuntime(1370): at dalvik.system.NativeStart.main(Native Method) 06-08 22:35:03.441: E/AndroidRuntime(1370): Caused by: java.lang.SecurityException: attempting to read gservices without permission: Neither user 10053 nor current process has com.google.android.providers.gsf.permission.READ_GSERVICES. 06-08 22:35:03.441: E/AndroidRuntime(1370): at android.app.ContextImpl.enforce(ContextImpl.java:1685) 06-08 22:35:03.441: E/AndroidRuntime(1370): at android.app.ContextImpl.enforceCallingOrSelfPermission(ContextImpl.java:1714) 06-08 22:35:03.441: E/AndroidRuntime(1370): at android.content.ContextWrapper.enforceCallingOrSelfPermission(ContextWrapper.java:572) 06-08 22:35:03.441: E/AndroidRuntime(1370): at imq.c(SourceFile:107) 06-08 22:35:03.441: E/AndroidRuntime(1370): at imq.a(SourceFile:121) 06-08 22:35:03.441: E/AndroidRuntime(1370): at imq.a(SourceFile:227) 06-08 22:35:03.441: E/AndroidRuntime(1370): at bwq.c(SourceFile:166) 06-08 22:35:03.441: E/AndroidRuntime(1370): at com.google.android.gms.checkin.CheckinService.a(SourceFile:237) 06-08 22:35:03.441: E/AndroidRuntime(1370): at com.google.android.gms.checkin.CheckinService.onStartCommand(SourceFile:211) 06-08 22:35:03.441: E/AndroidRuntime(1370): at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:2702) AndroidManifest <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.app" android:versionCode="1" android:versionName="1.0" > <uses-sdk android:minSdkVersion="14" android:targetSdkVersion="19" /> <uses-permission android:name="com.curio.permission.MAPS_RECEIVE" /> <uses-permission android:name="android.permission.CAMERA" /> <uses-permission android:name="android.permission.INTERNET" /> <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" /> <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" /> <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" /> <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" /> <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> <uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES" /> <uses-permission android:name="android.permission.ACCESS_MOCK_LOCATION" /> <uses-feature android:name="android.hardware.camera" android:required="true" /> <uses-feature android:glEsVersion="0x00020000" android:required="true" /> <application android:allowBackup="true" android:icon="@drawable/ic_launcher" android:label="@string/app_name" android:theme="@style/AppTheme" > <activity android:name="com.app.MainActivity" android:label="@string/app_name" > <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> <meta-data android:name="com.google.android.gms.version" android:value="@integer/google_play_services_version" /> <meta-data android:name="com.google.android.maps.v2.API_KEY" android:value="AI........................" /> </application>

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• Wikipedia A* pathfinding algorithm takes a lot of time

  - by Vee

  I've successfully implemented A* pathfinding in C# but it is very slow, and I don't understand why. I even tried not sorting the openNodes list but it's still the same. The map is 80x80, and there are 10-11 nodes. I took the pseudocode from here Wikipedia And this is my implementation: public static List<PGNode> Pathfind(PGMap mMap, PGNode mStart, PGNode mEnd) { mMap.ClearNodes(); mMap.GetTile(mStart.X, mStart.Y).Value = 0; mMap.GetTile(mEnd.X, mEnd.Y).Value = 0; List<PGNode> openNodes = new List<PGNode>(); List<PGNode> closedNodes = new List<PGNode>(); List<PGNode> solutionNodes = new List<PGNode>(); mStart.G = 0; mStart.H = GetManhattanHeuristic(mStart, mEnd); solutionNodes.Add(mStart); solutionNodes.Add(mEnd); openNodes.Add(mStart); // 1) Add the starting square (or node) to the open list. while (openNodes.Count > 0) // 2) Repeat the following: { openNodes.Sort((p1, p2) => p1.F.CompareTo(p2.F)); PGNode current = openNodes[0]; // a) We refer to this as the current square.) if (current == mEnd) { while (current != null) { solutionNodes.Add(current); current = current.Parent; } return solutionNodes; } openNodes.Remove(current); closedNodes.Add(current); // b) Switch it to the closed list. List<PGNode> neighborNodes = current.GetNeighborNodes(); double cost = 0; bool isCostBetter = false; for (int i = 0; i < neighborNodes.Count; i++) { PGNode neighbor = neighborNodes[i]; cost = current.G + 10; isCostBetter = false; if (neighbor.Passable == false || closedNodes.Contains(neighbor)) continue; // If it is not walkable or if it is on the closed list, ignore it. if (openNodes.Contains(neighbor) == false) { openNodes.Add(neighbor); // If it isn’t on the open list, add it to the open list. isCostBetter = true; } else if (cost < neighbor.G) { isCostBetter = true; } if (isCostBetter) { neighbor.Parent = current; // Make the current square the parent of this square. neighbor.G = cost; neighbor.H = GetManhattanHeuristic(current, neighbor); } } } return null; } Here's the heuristic I'm using: private static double GetManhattanHeuristic(PGNode mStart, PGNode mEnd) { return Math.Abs(mStart.X - mEnd.X) + Math.Abs(mStart.Y - mEnd.Y); } What am I doing wrong? It's an entire day I keep looking at the same code.

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• APC PHP cache size does not exceed 32MB, even though settings allow for more

  - by hardy101

  I am setting up APC (v 3.1.9) on a high-traffic WordPress installation on CentOS 6.0 64 bit. I have figured out many of the quirks with APC, but something is still not quite right. No matter what settings I change, APC never actually caches more than 32MB. I'm trying to bump it up to 256 MB. 32MB is a default amount for apc.shm_size, so I am wondering if it's stuck there somehow. I have run the following echo '2147483648' > /proc/sys/kernel/shmmax to increase my system's shared memory to 2G (half of my 4G box). Then ran ipcs -lm which returns ------ Shared Memory Limits -------- max number of segments = 4096 max seg size (kbytes) = 2097152 max total shared memory (kbytes) = 8388608 min seg size (bytes) = 1 Also made a change in /etc/sysctl.conf then ran sysctl -p to make the settings stick on the server. Rebooted, too, for good measure. In my APC settings, I have mmap enabled (which happens by default in recent versions of APC). php.ini looks like: apc.stat=0 apc.shm_size="256M" apc.max_file_size="10M" apc.mmap_file_mask="/tmp/apc.XXXXXX" apc.ttl="7200" I am aware that mmap mode will ignore references to apc.shm_segments, so I have left it out with default 1. phpinfo() indicates the following about APC: Version 3.1.9 APC Debugging Disabled MMAP Support Enabled MMAP File Mask /tmp/apc.bPS7rB Locking type pthread mutex Locks Serialization Support php Revision $Revision: 308812 $ Build Date Oct 11 2011 22:55:02 Directive Local Value apc.cache_by_default On apc.canonicalize O apc.coredump_unmap Off apc.enable_cli Off apc.enabled On On apc.file_md5 Off apc.file_update_protection 2 apc.filters no value apc.gc_ttl 3600 apc.include_once_override Off apc.lazy_classes Off apc.lazy_functions Off apc.max_file_size 10M apc.mmap_file_mask /tmp/apc.bPS7rB apc.num_files_hint 1000 apc.preload_path no value apc.report_autofilter Off apc.rfc1867 Off apc.rfc1867_freq 0 apc.rfc1867_name APC_UPLOAD_PROGRESS apc.rfc1867_prefix upload_ apc.rfc1867_ttl 3600 apc.serializer default apc.shm_segments 1 apc.shm_size 256M apc.slam_defense On apc.stat Off apc.stat_ctime Off apc.ttl 7200 apc.use_request_time On apc.user_entries_hint 4096 apc.user_ttl 0 apc.write_lock On apc.php reveals the following graph, no matter how long the server runs (cache size fluctuates and hovers at just under 32MB. See image http://i.stack.imgur.com/2bwMa.png You can see that the cache is trying to allocate 256MB, but the brown piece of the pie keeps getting recycled at 32MB. This is confirmed as refreshing the apc.php page shows cached file counts that move up and down (implying that the cache is not holding onto all of its files). Does anyone have an idea of how to get APC to use more than 32 MB for its cache size?? **Note that the identical behavior occurs for eaccelerator, xcache, and APC. I read here: http://www.litespeedtech.com/support/forum/archive/index.php/t-5072.html that suEXEC could cause this problem.

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• Condition Variable in Shared Memory - is this code POSIX-conformant?

  - by GrahamS

  We've been trying to use a mutex and condition variable to synchronise access to named shared memory on a LynuxWorks LynxOS-SE system (POSIX-conformant). One shared memory block is called "/sync" and contains the mutex and condition variable, the other is "/data" and contains the actual data we are syncing access to. We're seeing failures from pthread_cond_signal() if both processes don't perform the mmap() calls in exactly the same order, or if one process mmaps in some other piece of shared memory before it mmaps the sync memory. This example code is about as short as I can make it: #include <sys/types.h> #include <sys/stat.h> #include <sys/mman.h> #include <sys/file.h> #include <stdlib.h> #include <pthread.h> #include <errno.h> #include <iostream> #include <string> using namespace std; static const string shm_name_sync("/sync"); static const string shm_name_data("/data"); struct shared_memory_sync { pthread_mutex_t mutex; pthread_cond_t condition; }; struct shared_memory_data { int a; int b; }; //Create 2 shared memory objects // - sync contains 2 shared synchronisation objects (mutex and condition) // - data not important void create() { // Create and map 'sync' shared memory int fd_sync = shm_open(shm_name_sync.c_str(), O_CREAT|O_RDWR, S_IRUSR|S_IWUSR); ftruncate(fd_sync, sizeof(shared_memory_sync)); void* addr_sync = mmap(0, sizeof(shared_memory_sync), PROT_READ|PROT_WRITE, MAP_SHARED, fd_sync, 0); shared_memory_sync* p_sync = static_cast<shared_memory_sync*> (addr_sync); // init the cond and mutex pthread_condattr_t cond_attr; pthread_condattr_init(&cond_attr); pthread_condattr_setpshared(&cond_attr, PTHREAD_PROCESS_SHARED); pthread_cond_init(&(p_sync->condition), &cond_attr); pthread_condattr_destroy(&cond_attr); pthread_mutexattr_t m_attr; pthread_mutexattr_init(&m_attr); pthread_mutexattr_setpshared(&m_attr, PTHREAD_PROCESS_SHARED); pthread_mutex_init(&(p_sync->mutex), &m_attr); pthread_mutexattr_destroy(&m_attr); // Create the 'data' shared memory int fd_data = shm_open(shm_name_data.c_str(), O_CREAT|O_RDWR, S_IRUSR|S_IWUSR); ftruncate(fd_data, sizeof(shared_memory_data)); void* addr_data = mmap(0, sizeof(shared_memory_data), PROT_READ|PROT_WRITE, MAP_SHARED, fd_data, 0); shared_memory_data* p_data = static_cast<shared_memory_data*> (addr_data); // Run the second process while it sleeps here. sleep(10); int res = pthread_cond_signal(&(p_sync->condition)); assert(res==0); // <--- !!!THIS ASSERT WILL FAIL ON LYNXOS!!! munmap(addr_sync, sizeof(shared_memory_sync)); shm_unlink(shm_name_sync.c_str()); munmap(addr_data, sizeof(shared_memory_data)); shm_unlink(shm_name_data.c_str()); } //Open the same 2 shared memory objects but in reverse order // - data // - sync void open() { sleep(2); int fd_data = shm_open(shm_name_data.c_str(), O_RDWR, S_IRUSR|S_IWUSR); void* addr_data = mmap(0, sizeof(shared_memory_data), PROT_READ|PROT_WRITE, MAP_SHARED, fd_data, 0); shared_memory_data* p_data = static_cast<shared_memory_data*> (addr_data); int fd_sync = shm_open(shm_name_sync.c_str(), O_RDWR, S_IRUSR|S_IWUSR); void* addr_sync = mmap(0, sizeof(shared_memory_sync), PROT_READ|PROT_WRITE, MAP_SHARED, fd_sync, 0); shared_memory_sync* p_sync = static_cast<shared_memory_sync*> (addr_sync); // Wait on the condvar pthread_mutex_lock(&(p_sync->mutex)); pthread_cond_wait(&(p_sync->condition), &(p_sync->mutex)); pthread_mutex_unlock(&(p_sync->mutex)); munmap(addr_sync, sizeof(shared_memory_sync)); munmap(addr_data, sizeof(shared_memory_data)); } int main(int argc, char** argv) { if(argc>1) { open(); } else { create(); } return (0); } Run this program with no args, then another copy with args, and the first one will fail at the assert checking the pthread_cond_signal(). But change the open() function to mmap() the "/sync" memory first and it will all work fine. This seems like a major bug in LynxOS but LynuxWorks claim that using mutex and condition variable in this way is not covered by the POSIX standard, so they are not interested. Can anyone determine if this code does violate POSIX? Or does anyone have any convincing documentation that it is POSIX compliant?

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• change file descriptor for socket in python

  - by Dani

  Hello everybody I'm trying to manually create the file descriptor associated with a socket in python and then loaded directly into memory with mmap. Create a file into memory with mmap is simple, but I can not find a way to associate the file with a socket. Anyone know how? thank you very much.

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• Tracing Silex from PHP to the OS with DTrace

  - by cj

  In this blog post I show the full stack tracing of Brendan Gregg's php_syscolors.d script in the DTrace Toolkit. The Toolkit contains a dozen very useful PHP DTrace scripts and many more scripts for other languages and the OS. For this example, I'll trace the PHP micro framework Silex, which was the topic of the second of two talks by Dustin Whittle at a recent SF PHP Meetup. His slides are at Silex: From Micro to Full Stack. Installing DTrace and PHP The php_syscolors.d script uses some static PHP probes and some kernel probes. For Oracle Linux I discussed installing DTrace and PHP in DTrace PHP Using Oracle Linux 'playground' Pre-Built Packages. On other platforms with DTrace support, follow your standard procedures to enable DTrace and load the correct providers. The sdt and systrace providers are required in addition to fasttrap. On Oracle Linux, I loaded the DTrace modules like: # modprobe fasttrap # modprobe sdt # modprobe systrace # chmod 666 /dev/dtrace/helper Installing the DTrace Toolkit I download DTraceToolkit-0.99.tar.gz and extracted it: $ tar -zxf DTraceToolkit-0.99.tar.gz The PHP scripts are in the Php directory and examples in the Examples directory. Installing Silex I downloaded the "fat" Silex .tgz file from the download page and extracted it: $ tar -zxf silex_fat.tgz I changed the demonstration silex/web/index.php so I could use the PHP development web server: <?php // web/index.php $filename = __DIR__.preg_replace('#(\?.*)$#', '', $_SERVER['REQUEST_URI']); if (php_sapi_name() === 'cli-server' && is_file($filename)) { return false; } require_once __DIR__.'/../vendor/autoload.php'; $app = new Silex\Application(); //$app['debug'] = true; $app->get('/hello', function() { return 'Hello!'; }); $app->run(); ?> Running DTrace The php_syscolors.d script uses the -Z option to dtrace, so it can be started before PHP, i.e. when there are zero of the requested probes available to be traced. I ran DTrace like: # cd DTraceToolkit-0.99/Php # ./php_syscolors.d Next, I started the PHP developer web server in a second terminal: $ cd silex $ php -S localhost:8080 -t web web/index.php At this point, the web server is idle, waiting for requests. DTrace is idle, waiting for the probes in php_syscolors.d to be fired, at which time the action associated with each probe will run. I then loaded the demonstration page in a browser: http://localhost:8080/hello When the request was fulfilled and the simple output of "Hello" was displayed, I ^C'd php and dtrace in their terminals to stop them. DTrace output over a thousand lines long had been generated. Here is one snippet from when run() was invoked: C PID/TID DELTA(us) FILE:LINE TYPE -- NAME ... 1 4765/4765 21 Application.php:487 func -> run 1 4765/4765 29 ClassLoader.php:182 func -> loadClass 1 4765/4765 17 ClassLoader.php:198 func -> findFile 1 4765/4765 31 ":- syscall -> access 1 4765/4765 26 ":- syscall <- access 1 4765/4765 16 ClassLoader.php:198 func <- findFile 1 4765/4765 25 ":- syscall -> newlstat 1 4765/4765 15 ":- syscall <- newlstat 1 4765/4765 13 ":- syscall -> newlstat 1 4765/4765 13 ":- syscall <- newlstat 1 4765/4765 22 ":- syscall -> newlstat 1 4765/4765 14 ":- syscall <- newlstat 1 4765/4765 15 ":- syscall -> newlstat 1 4765/4765 60 ":- syscall <- newlstat 1 4765/4765 13 ":- syscall -> newlstat 1 4765/4765 13 ":- syscall <- newlstat 1 4765/4765 20 ":- syscall -> open 1 4765/4765 16 ":- syscall <- open 1 4765/4765 26 ":- syscall -> newfstat 1 4765/4765 12 ":- syscall <- newfstat 1 4765/4765 17 ":- syscall -> newfstat 1 4765/4765 12 ":- syscall <- newfstat 1 4765/4765 12 ":- syscall -> newfstat 1 4765/4765 12 ":- syscall <- newfstat 1 4765/4765 20 ":- syscall -> mmap 1 4765/4765 14 ":- syscall <- mmap 1 4765/4765 3201 ":- syscall -> mmap 1 4765/4765 27 ":- syscall <- mmap 1 4765/4765 1233 ":- syscall -> munmap 1 4765/4765 53 ":- syscall <- munmap 1 4765/4765 15 ":- syscall -> close 1 4765/4765 13 ":- syscall <- close 1 4765/4765 34 Request.php:32 func -> main 1 4765/4765 22 Request.php:32 func <- main 1 4765/4765 31 ClassLoader.php:182 func <- loadClass 1 4765/4765 33 Request.php:249 func -> createFromGlobals 1 4765/4765 29 Request.php:198 func -> __construct 1 4765/4765 24 Request.php:218 func -> initialize 1 4765/4765 26 ClassLoader.php:182 func -> loadClass 1 4765/4765 89 ClassLoader.php:198 func -> findFile 1 4765/4765 43 ":- syscall -> access ... The output shows PHP functions being called and returning (and where they are located) and which system calls the PHP functions in turn invoked. The time each line took from the previous one is displayed in the third column. The first column is the CPU number. In this example, the process was always on CPU 1 so the output is naturally ordered without requiring post-processing, or the D script requiring to be modified to display a time stamp. On a terminal, the output of php_syscolors.d is color-coded according to whether each function is a PHP or system one, hence the file name. Summary With one tool, I was able to trace the interaction of a user application with the operating system. I was able to do this to an application running "live" in a web context. The DTrace Toolkit provides a very handy repository of DTrace information. Even though the PHP scripts were created in the time frame of the original PHP DTrace PECL extension, which only had PHP function entry and return probes, the scripts provide core examples for custom investigation and resolution scripts. You can easily adapt the ideas and and create scripts using the other PHP static probes, which are listed in the PHP Manual. Because DTrace is "always on", you can take advantage of it to resolve development questions or fix production situations.

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• How to control virtual memory management in linux?

  - by chmike

  I'm writing a program that uses an mmap file to hold a huge buffer organized as an array of 64 MB blocks. The blocks are used to aggregate data received from different hosts through the network. As a consequence the total data size written in each block is not known in advance. Most of the time it is only 2MB but in some cases it can be up to 20MB or more. The data doesn't stay long in the buffer. 90% is deleted after less than a second and the rest is transmitted to another host. I would like to know if there is a way to tell the virtual memory manager that ram pages are not dirty anymore when data is deleted. Should I use mmap and munmap when a block is used and released to control the virtual memory ? What would be the overhead of doing this ? Also, some colleagues expressed concerns about the performance impact of allocating such a big mmap space. I expect it to behave like a swap file so that only dirty pages are to be considered.

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• APC (PHP Cache) Uptime 0 minutes, not caching

  - by Jussi

  My goal is to implement APC for opcode cache for a drupal 6 production site. I have so far tested APC with several php files with and without including other php files with include_once. Also tried to tweak the apc.ini values for shm_size, apc.include_once_override and apc.stat. Restarted apache every time. Resulting in apc.php not showing any changes in any values. (except of course the changed apc.ini values are shown as they should) Every time i refresh the apc.php test page, the start time resets as the current time showing uptime 0 minutes. apc.php -testpage shows: General Cache InformationAPC Version 3.1.9 PHP Version 5.2.10 APC Host xxxx.xx.xx Server Software Apache/2.2.3 (CentOS) Shared Memory 1 Segment(s) with 128.0 MBytes (mmap memory, pthread mutex Locks locking) Start Time 2011/07/26 11:53:56 Uptime 0 minutes File Upload Support 1 Cached Files 0 ( 0.0 Bytes) Hits 1 Misses 1 Request Rate (hits, misses) 2.00 cache requests/second Hit Rate 1.00 cache requests/second Miss Rate 1.00 cache requests/second Insert Rate 0.00 cache requests/second Cache full count 0 Cached Variables 0 ( 0.0 Bytes) Hits 0 Misses 0 Request Rate (hits, misses) 0.00 cache requests/second Hit Rate 0.00 cache requests/second Miss Rate 0.00 cache requests/second Insert Rate 0.00 cache requests/second Cache full count 0 apc.cache_by_default 1 apc.canonicalize 1 apc.coredump_unmap 0 apc.enable_cli 0 apc.enabled 1 apc.file_md5 0 apc.file_update_protection 2 apc.filters apc.gc_ttl 3600 apc.include_once_override 0 apc.lazy_classes 0 apc.lazy_functions 0 apc.max_file_size 16 apc.mmap_file_mask /tmp/apcphp5.095eRm apc.num_files_hint 1024 apc.preload_path apc.report_autofilter 0 apc.rfc1867 0 apc.rfc1867_freq 0 apc.rfc1867_name APC_UPLOAD_PROGRESS apc.rfc1867_prefix upload_ apc.rfc1867_ttl 3600 apc.serializer default apc.shm_segments 1 apc.shm_size 128M apc.slam_defense 0 apc.stat 0 apc.stat_ctime 0 apc.ttl 7200 apc.use_request_time 1 apc.user_entries_hint 4096 apc.user_ttl 7200 apc.write_lock 1 Host Status Diagrams: Free: 128.0 MBytes (100.0%) Hits: 1 (50.0%) Used: 20.3 KBytes (0.0%) Misses: 1 (50.0%) Detailed Memory Usage and Fragmentation: Fragmentation: 0% phpinfo shows: Server API CGI/FastCGI APC: Version 3.1.9 APC Debugging Enabled MMAP Support Enabled MMAP File Mask /tmp/apcphp5.JkKDk7 Locking type pthread mutex Locks Serialization Support php Revision $Revision: 308812 $ Build Date Jul 21 2011 14:31:12 I followed these steps to find if suexec settings would prevent caching: http://www.litespeedtech.com/support/forum/showthread.php?t=4189 [root@host /]# ps -ef|grep lsphp root 20402 17833 0 11:21 pts/0 00:00:00 grep lsphp [root@host /]# ps -waux root 17833 0.0 0.1 5004 1484 pts/0 S 10:39 0:00 bash ..indicates that there is no lsphp running on the host also I read the following article and comments, concluding that in my case the problem is not the suexec as the user apache is the httpd process owner http://www.brandonturner.net/blog/2009/07/fastcgi_with_php_opcode_cache/ also suexec command is not recognized when logged and launced as root @ host also i'm almost confident that there is no cPanel running on the host to check if a setting there would reset the running cache process at some interval This leaves me with few clues where to head next. I tried to set (with chown and chgrp) apache as the owner of the apc.php file and some test php files resulting in 500 server error. Is there a way to check if the file permissions prevent the apc stay running? I'm tremendously grateful for any suggestions or help.

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• Can NFS be forced to refresh stale files/directories when not using noac on the mount?

  - by johnnycrash

  We mount without using noac. I have a file that I append to once every 20 minutes. Then it will be read with mmap about 5,000 times a minute. We only mmap a couple blocks for each read. Needless to say, noac just kills the access performance, so we don't use it. I add data to the end of the file using a mount with noac and read from a mount without noac. The mounts that are reading are not seeing the new data. I want to know if there is a function I can call from c to refresh the attributes of a path and all its files. EDIT: I should add we cannot mount and unmount since there are 16 servers running on each system and they are constantly accessing the files. Well...maybe we could mount and unmount if each server used their own mount. I'd like to avoid that if possible. thanks!

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• MySQL hangs if connection comes from outside the LAN

  - by Subito

  I have a MySQL Server operating just fine if I access him from his local LAN (192.168.100.0/24). If I try to access hin from another LAN (192.168.113.0/24 in this case) it hangs for a really long time before delivering the result. SHOW PROCESSLIST; shows this process in Sleep, State empty. If I strace -p this process I get the following Output (23512 is the PID of the corresponding mysqld process): Process 23512 attached - interrupt to quit restart_syscall(<... resuming interrupted call ...>) = 1 fcntl(10, F_GETFL) = 0x2 (flags O_RDWR) fcntl(10, F_SETFL, O_RDWR|O_NONBLOCK) = 0 accept(10, {sa_family=AF_INET, sin_port=htons(51696), sin_addr=inet_addr("192.168.113.4")}, [16]) = 33 fcntl(10, F_SETFL, O_RDWR) = 0 rt_sigaction(SIGCHLD, {SIG_DFL, [CHLD], SA_RESTORER|SA_RESTART, 0x7f9ce7ca34f0}, {SIG_DFL, [CHLD], SA_RESTORER|SA_RESTART, 0x7f9ce7ca34f0}, ) = 0 getpeername(33, {sa_family=AF_INET, sin_port=htons(51696), sin_addr=inet_addr("192.168.113.4")}, [16]) = 0 getsockname(33, {sa_family=AF_INET, sin_port=htons(3306), sin_addr=inet_addr("192.168.100.190")}, [16]) = 0 open("/etc/hosts.allow", O_RDONLY) = 64 fstat(64, {st_mode=S_IFREG|0644, st_size=580, ...}) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f9ce9839000 read(64, "# /etc/hosts.allow: list of host"..., 4096) = 580 read(64, "", 4096) = 0 close(64) = 0 munmap(0x7f9ce9839000, 4096) = 0 open("/etc/hosts.deny", O_RDONLY) = 64 fstat(64, {st_mode=S_IFREG|0644, st_size=880, ...}) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f9ce9839000 read(64, "# /etc/hosts.deny: list of hosts"..., 4096) = 880 read(64, "", 4096) = 0 close(64) = 0 munmap(0x7f9ce9839000, 4096) = 0 getsockname(33, {sa_family=AF_INET, sin_port=htons(3306), sin_addr=inet_addr("192.168.100.190")}, [16]) = 0 fcntl(33, F_SETFL, O_RDONLY) = 0 fcntl(33, F_GETFL) = 0x2 (flags O_RDWR) setsockopt(33, SOL_SOCKET, SO_RCVTIMEO, "\36\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0", 16) = 0 setsockopt(33, SOL_SOCKET, SO_SNDTIMEO, "<\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0", 16) = 0 fcntl(33, F_SETFL, O_RDWR|O_NONBLOCK) = 0 setsockopt(33, SOL_IP, IP_TOS, [8], 4) = 0 setsockopt(33, SOL_TCP, TCP_NODELAY, [1], 4) = 0 futex(0x7f9cea5c9564, FUTEX_WAKE_OP_PRIVATE, 1, 1, 0x7f9cea5c9560, {FUTEX_OP_SET, 0, FUTEX_OP_CMP_GT, 1}) = 1 futex(0x7f9cea5c6fe0, FUTEX_WAKE_PRIVATE, 1) = 1 poll([{fd=10, events=POLLIN}, {fd=12, events=POLLIN}], 2, -1) = 1 ([{fd=10, revents=POLLIN}]) fcntl(10, F_GETFL) = 0x2 (flags O_RDWR) fcntl(10, F_SETFL, O_RDWR|O_NONBLOCK) = 0 accept(10, {sa_family=AF_INET, sin_port=htons(51697), sin_addr=inet_addr("192.168.113.4")}, [16]) = 31 fcntl(10, F_SETFL, O_RDWR) = 0 rt_sigaction(SIGCHLD, {SIG_DFL, [CHLD], SA_RESTORER|SA_RESTART, 0x7f9ce7ca34f0}, {SIG_DFL, [CHLD], SA_RESTORER|SA_RESTART, 0x7f9ce7ca34f0}, ) = 0 getpeername(31, {sa_family=AF_INET, sin_port=htons(51697), sin_addr=inet_addr("192.168.113.4")}, [16]) = 0 getsockname(31, {sa_family=AF_INET, sin_port=htons(3306), sin_addr=inet_addr("192.168.100.190")}, [16]) = 0 open("/etc/hosts.allow", O_RDONLY) = 33 fstat(33, {st_mode=S_IFREG|0644, st_size=580, ...}) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f9ce9839000 read(33, "# /etc/hosts.allow: list of host"..., 4096) = 580 read(33, "", 4096) = 0 close(33) = 0 munmap(0x7f9ce9839000, 4096) = 0 open("/etc/hosts.deny", O_RDONLY) = 33 fstat(33, {st_mode=S_IFREG|0644, st_size=880, ...}) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f9ce9839000 read(33, "# /etc/hosts.deny: list of hosts"..., 4096) = 880 read(33, "", 4096) = 0 close(33) = 0 munmap(0x7f9ce9839000, 4096) = 0 getsockname(31, {sa_family=AF_INET, sin_port=htons(3306), sin_addr=inet_addr("192.168.100.190")}, [16]) = 0 fcntl(31, F_SETFL, O_RDONLY) = 0 fcntl(31, F_GETFL) = 0x2 (flags O_RDWR) setsockopt(31, SOL_SOCKET, SO_RCVTIMEO, "\36\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0", 16) = 0 setsockopt(31, SOL_SOCKET, SO_SNDTIMEO, "<\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0", 16) = 0 fcntl(31, F_SETFL, O_RDWR|O_NONBLOCK) = 0 setsockopt(31, SOL_IP, IP_TOS, [8], 4) = 0 setsockopt(31, SOL_TCP, TCP_NODELAY, [1], 4) = 0 futex(0x7f9cea5c9564, FUTEX_WAKE_OP_PRIVATE, 1, 1, 0x7f9cea5c9560, {FUTEX_OP_SET, 0, FUTEX_OP_CMP_GT, 1}) = 1 futex(0x7f9cea5c6fe0, FUTEX_WAKE_PRIVATE, 1) = 1 poll([{fd=10, events=POLLIN}, {fd=12, events=POLLIN}], 2, -1^C <unfinished ...> Process 23512 detached This output repeats itself until the answer gets send. It could take up to 15 Minutes until the request gets served. In the local LAN its a matter of Milliseconds. Why is this and how can I debug this further? [Edit] tcpdump shows a ton of this: 14:49:44.103107 IP cassandra-test.mysql > 192.168.X.6.64626: Flags [S.], seq 1434117703, ack 1793610733, win 14600, options [mss 1460,nop,nop,sackOK,nop,wscale 7], length 0 14:49:44.135187 IP 192.168.X.6.64625 > cassandra-test.mysql: Flags [P.], seq 106:145, ack 182, win 4345, length 39 14:49:44.135293 IP cassandra-test.mysql > 192.168.X.6.64625: Flags [P.], seq 182:293, ack 145, win 115, length 111 14:49:44.167025 IP 192.168.X.6.64624 > cassandra-test.mysql: Flags [.], ack 444, win 4280, length 0 14:49:44.168933 IP 192.168.X.6.64626 > cassandra-test.mysql: Flags [.], ack 1, win 4390, length 0 14:49:44.169088 IP cassandra-test.mysql > 192.168.X.6.64626: Flags [P.], seq 1:89, ack 1, win 115, length 88 14:49:44.169672 IP 192.168.X.6.64625 > cassandra-test.mysql: Flags [P.], seq 145:171, ack 293, win 4317, length 26 14:49:44.169726 IP cassandra-test.mysql > 192.168.X.6.64625: Flags [P.], seq 293:419, ack 171, win 115, length 126 14:49:44.275111 IP 192.168.X.6.64626 > cassandra-test.mysql: Flags [P.], seq 1:74, ack 89, win 4368, length 73 14:49:44.275131 IP cassandra-test.mysql > 192.168.X.6.64626: Flags [.], ack 74, win 115, length 0 14:49:44.275149 IP 192.168.X.6.64625 > cassandra-test.mysql: Flags [P.], seq 171:180, ack 419, win 4286, length 9 14:49:44.275189 IP cassandra-test.mysql > 192.168.X.6.64626: Flags [P.], seq 89:100, ack 74, win 115, length 11 14:49:44.275264 IP 192.168.X.6.64625 > cassandra-test.mysql: Flags [P.], seq 180:185, ack 419, win 4286, length 5 14:49:44.275281 IP cassandra-test.mysql > 192.168.X.6.64625: Flags [.], ack 185, win 115, length 0 14:49:44.275295 IP cassandra-test.mysql > 192.168.X.6.64625: Flags [F.], seq 419, ack 185, win 115, length 0 14:49:44.275650 IP 192.168.X.6.64625 > cassandra-test.mysql: Flags [F.], seq 185, ack 419, win 4286, length 0 14:49:44.275660 IP cassandra-test.mysql > 192.168.X.6.64625: Flags [.], ack 186, win 115, length 0 14:49:44.275910 IP 192.168.X.6.64627 > cassandra-test.mysql: Flags [S], seq 2336421549, win 8192, options [mss 1351,nop,wscale 2,nop,nop,sackOK], length 0 14:49:44.275921 IP cassandra-test.mysql > 192.168.X.6.64627: Flags [S.], seq 3289359778, ack 2336421550, win 14600, options [mss 1460,nop,nop,sackOK,nop,wscale 7], length 0

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• google maps, cellid to location

  - by Dels

  According to this sample: http://www.codeproject.com/KB/mobile/DeepCast.aspx It's possible to request a gps coordinate (longitude & latitude) including range when sending cellid information (MCC, MNC, towerid, etc) Can someone tell me the actual parameter to request/post to this address? http://www.google.com/glm/mmap It could be something like this http://www.google.com/glm/mmap?mcc=xxx&mnc=xxx&towerid=xxx And i would like to know what response we would get. I have observe OpenCellid website and they provide some nice API to begin with, but i want to know about that in google map too (since they have more completed database). OpenCellID API

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• Logging Mechanism using memory mapping technique

  - by Tushar

  Just create a mapping of the file of the required size (CreateFileMapping or mmap), write the lines in the buffer and start over when the maximum number is reached. -- Your answer for write-a-circular-file-in-c. I am also writing the LogWriter module. In this caase i am mapping the whole file to the memory using mmap(). I am maintaining the Read and Write pointers.I want to write the log to the file in append mode. Then when logger service is started first time it writes it appends the logs. But when system gets shutdown next time when i run the service it doesn't append the data at the end. I want to maintain the write and read offsets even if system shut down.How to achieve this ..? How to find the how much data is written to the log file. ??

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• In a GUI based Application in Linux It is working properly in some systems,But segmentation fault (Because of SIGSEGV signal) is coming in others.Why? [closed]

  - by Sreejith

  The application consists of Driver code,a Source Object file(.so) ,and a Application code to interact with a hardware Card.. The problem comes in a mmap().It reads address from a card. But it is not getting the correct address in some systems.The Error is because of It is receiving a SIGSEGV signal and segmentation fault followed to that.But in some system which having the same version of kernel is not at all facing the problem and working properly. So please any one suggest the Reason and Remedy for this Problem.

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• APC + FPM memory fragmentation without a reason

  - by palmic

  My setup @ debian 6-testing is: nginx 1.1.8 + php 5.3.8 + php-fpm + APC 3.1.9 Because i use automatic deployment with apc_clear_cache() after deploy, my target is to set up APC to cache all my project (up to 612 php files smaller than 1MB) without files changes checking. My confs: FPM: pm.max_children = 25 pm.start_servers = 4 pm.min_spare_servers = 2 pm.max_spare_servers = 10 pm.max_requests = 500 APC: pc.enabled="1" apc.shm_segments = 1 apc.shm_size="64M" apc.num_files_hint = 640 apc.user_entries_hint = 0 apc.ttl="7200" apc.user_ttl="7200" apc.gc_ttl="600" apc.cache_by_default="1" apc.filters = "apc\.php$,apc_clear.php$" apc.canonicalize="0" apc.slam_defense="1" apc.localcache="1" apc.localcache.size="512M" apc.mmap_file_mask="/tmp/apc-php5.XXXXXX" apc.enable_cli="0" apc.max_file_size = 2M apc.write_lock="1" apc.localcache = 1 apc.localcache.size = 512 apc.report_autofilter="0" apc.include_once_override="0" apc.coredump_unmap="0" apc.stat="0" apc.stat_ctime="0" The problem is i have my APC memory fragmented into 5 pieces at 14,5MB loaded into memory which capacity is 64M. My system memory is 640MB, used about 270MB at most. The http responses lasts about 300ms - 5s. When i switch on apc.stat="1", the responses are about 50ms - 80ms which is quite good, but i cannot understand why is apc.stat="0" so much whorse. The APC diagnostic tool shows "1 Segment(s) with 64.0 MBytes (mmap memory, pthread mutex Locks locking)" in general cache information window so i hope i am right that it's mmap setup which allows tweaking APC shm onto upper values than shows system limit in /proc/sys/kernel/shmmax (my shows 33MB).

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• php crashes with no core file and this message : apc_mmap failed

  - by greg0ire

  Description of the problem Regularly, cron php processes crash on our production server, which result in mails with the following body : PHP Fatal error: PHP Startup: apc_mmap: mmap failed: in Unknown on line 0 Segmentation fault (core dumped) I think the Segmentation fault (core dumped) should result in core files being handled by apport and then written in /var/crashes, but the files I can see there are there since yesterday, although the last crash occured today : -rw-r----- 1 root whoopsie 1138528 mai 22 04:09 _usr_bin_php5.0.crash -rw-r----- 1 frontoffice whoopsie 1166373 mai 20 18:00 _usr_bin_php5.1005.crash -rw-r----- 1 frontoffice whoopsie 81622658 mai 22 00:05 _usr_sbin_php5-fpm.1005.crash I tried to download the last one anyway, and ran gdb /usr/sbin/php5-fpm /tmp/_usr_sbin_php5-fpm.1005.crash, only to be told that the file is not a core file (its format was not recognized). Here is the server's apc configuration : cat /etc/php5/cli/conf.d/20-apc.ini extension=apc.so apc.shm_size=512M apc.ttl=3600 apc.user_ttl=3600 apc.enable_cli=1 I'm mostly worried about the apc.shm_size… isn't it too high or too low ? I understand it has to do with the size of memory segments. Question(s) What could be the problem ? How can I troubleshoot it (how can I get a valid core file ?) ? System information free total used free shared buffers cached Mem: 5081296 4354684 726612 0 374744 959968 -/+ buffers/cache: 3019972 2061324 Swap: 522236 516888 5348 cat /etc/lsb-release DISTRIB_ID=Ubuntu DISTRIB_RELEASE=12.04 DISTRIB_CODENAME=precise DISTRIB_DESCRIPTION="Ubuntu 12.04.2 LTS" php -v PHP 5.4.17-1~precise+1 (cli) (built: Jul 17 2013 18:14:06) Copyright (c) 1997-2013 The PHP Group Zend Engine v2.4.0, Copyright (c) 1998-2013 Zend Technologies php -i excerpt : Configuration apc APC Support => enabled Version => 3.1.13 APC Debugging => Disabled MMAP Support => Enabled MMAP File Mask => Locking type => pthread mutex Locks Serialization Support => php Revision => $Revision: 327136 $ Build Date => Nov 20 2012 18:41:36 Directive => Local Value => Master Value apc.cache_by_default => On => On apc.canonicalize => On => On apc.coredump_unmap => Off => Off apc.enable_cli => On => On apc.enabled => On => On apc.file_md5 => Off => Off apc.file_update_protection => 2 => 2 apc.filters => no value => no value apc.gc_ttl => 3600 => 3600 apc.include_once_override => Off => Off apc.lazy_classes => Off => Off apc.lazy_functions => Off => Off apc.max_file_size => 1M => 1M apc.mmap_file_mask => no value => no value apc.num_files_hint => 1000 => 1000 apc.preload_path => no value => no value apc.report_autofilter => Off => Off apc.rfc1867 => Off => Off apc.rfc1867_freq => 0 => 0 apc.rfc1867_name => APC_UPLOAD_PROGRESS => APC_UPLOAD_PROGRESS apc.rfc1867_prefix => upload_ => upload_ apc.rfc1867_ttl => 3600 => 3600 apc.serializer => default => default apc.shm_segments => 1 => 1 apc.shm_size => 512M => 512M apc.shm_strings_buffer => 4M => 4M apc.slam_defense => On => On apc.stat => On => On apc.stat_ctime => Off => Off apc.ttl => 3600 => 3600 apc.use_request_time => On => On apc.user_entries_hint => 4096 => 4096 apc.user_ttl => 3600 => 3600 apc.write_lock => On => On php -m [PHP Modules] apc bcmath bz2 calendar Core ctype curl date dba dom ereg exif fileinfo filter ftp gd gettext hash iconv imagick intl json ldap libxml mbstring memcache memcached mhash mysql mysqli openssl pcntl pcre PDO pdo_mysql pdo_pgsql pdo_sqlite pgsql Phar posix Reflection session shmop SimpleXML soap sockets SPL sqlite3 standard sysvmsg sysvsem sysvshm tidy tokenizer wddx xml xmlreader xmlwriter zip zlib [Zend Modules] ulimit -a core file size (blocks, -c) 0 data seg size (kbytes, -d) unlimited scheduling priority (-e) 0 file size (blocks, -f) unlimited pending signals (-i) 39531 max locked memory (kbytes, -l) 64 max memory size (kbytes, -m) unlimited open files (-n) 1024 pipe size (512 bytes, -p) 8 POSIX message queues (bytes, -q) 819200 real-time priority (-r) 0 stack size (kbytes, -s) 8192 cpu time (seconds, -t) unlimited max user processes (-u) 39531 virtual memory (kbytes, -v) unlimited file locks (-x) unlimited

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• Problem saving file on Motorola Droid, Android 2.1?

  - by Rob Kent

  Two of my users have reported a problem with my Android application, OftSeen Gestures. Both of them are using a Motorola Droid. The app saves a text file which is just a list of gesture names and phone numbers, both strings. It saves the file to the private data area. I don't know that it is this code that is failing but they report the assigned numbers disappearing after the phone comes out of screen sleep. Since the file is reread in OnCreate each time, I'm assuming the file doesn't exist on return. As soon as I can get my hands on a Droid I will debug it but in the meantime can you see a reason why this save operation would fail on Droid (no other users have reported this)? OutputStreamWriter out = new OutputStreamWriter(AppGlobal.getContext().openFileOutput(MAPPINGS_FILE_NAME, 0)); for (String key : mMap.keySet()) { String number = mMap.get(key).number; out.write(String.format("%s,%s\n", key, number == null ? "" : number)); } out.close(); AppGlobal.getContext returns the application context and the MAPPINGS_FILE_NAME resolves to "gesture_mappings.txt". Like I say, I don't know that this is the problem. It could be something else to do with state management inside the app. If anyone has a Droid, maybe they could download the app from Market and test it for me? Note this is a genuine request for help - not an attempt to increase my downloads.

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