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  • Is it thread safe to read a form controls value (but not change it) without using Invoke/BeginInvoke from another thread

    - by goku_da_master
    I know you can read a gui control from a worker thread without using Invoke/BeginInvoke because my app is doing it now. The cross thread exception error is not being thrown and my System.Timers.Timer thread is able to read gui control values just fine (unlike this guy: can a worker thread read a control in the GUI?) Question 1: Given the cardinal rule of threads, should I be using Invoke/BeginInvoke to read form control values? And does this make it more thread-safe? The background to this question stems from a problem my app is having. It seems to randomly corrupt form controls another thread is referencing. (see question 2) Question 2: I have a second thread that needs to update form control values so I Invoke/BeginInvoke to update those values. Well this same thread needs a reference to those controls so it can update them. It holds a list of these controls (say DataGridViewRow objects). Sometimes (not always), the DataGridViewRow reference gets "corrupt". What I mean by corrupt, is the reference is still valid, but some of the DataGridViewRow properties are null (ex: row.Cells). Is this caused by question 1 or can you give me any tips on why this might be happening? Here's some code (the last line has the problem): public partial class MyForm : Form { void Timer_Elapsed(object sender) { // we're on a new thread (this function gets called every few seconds) UpdateUiHelper updateUiHelper = new UpdateUiHelper(this); foreach (DataGridViewRow row in dataGridView1.Rows) { object[] values = GetValuesFromDb(); updateUiHelper.UpdateRowValues(row, values[0]); } // .. do other work here updateUiHelper.UpdateUi(); } } public class UpdateUiHelper { private readonly Form _form; private Dictionary<DataGridViewRow, object> _rows; private delegate void RowDelegate(DataGridViewRow row); private readonly object _lockObject = new object(); public UpdateUiHelper(Form form) { _form = form; _rows = new Dictionary<DataGridViewRow, object>(); } public void UpdateRowValues(DataGridViewRow row, object value) { if (_rows.ContainsKey(row)) _rows[row] = value; else { lock (_lockObject) { _rows.Add(row, value); } } } public void UpdateUi() { foreach (DataGridViewRow row in _rows.Keys) { SetRowValueThreadSafe(row); } } private void SetRowValueThreadSafe(DataGridViewRow row) { if (_form.InvokeRequired) { _form.Invoke(new RowDelegate(SetRowValueThreadSafe), new object[] { row }); return; } // now we're on the UI thread object newValue = _rows[row]; row.Cells[0].Value = newValue; // randomly errors here with NullReferenceException, but row is never null! }

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  • How to block writing in pipes, until the read has taken place ? (in C)

    - by user492194
    Hi everyone :) I'm currently working on some C program, and I'd like to know if there's any chance to block writing in the writer process (until the read is done) ? i.e. I have 3 pipes between the parent process and the children processes (the parent writes and the children read), I'd like to let the parent to write only to the process that finishes its reading :) I hope it's clear.. Thanks in advance.

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  • How to remove the hint in the terminal?

    - by jiangchengwu
    As a normal user , when I run some command like ps\netstat, the terminal hint me: (Not all processes could be identified, non-owned process info will not be shown, you would have to be root to see it all.) I know could redirect STDERR to /dev/null can remove this hint. But I want to know is there any way to remove it , such as edit some configuration files ? [deploy@storage2 ~]$ ps -V (Not all processes could be identified, non-owned process info will not be shown, you would have to be root to see it all.) procps version 3.2.7 [deploy@storage2 ~]$ ps -V 2>/dev/null procps version 3.2.7 My OS info: [deploy@storage2 ~]$ uname -a Linux storage2 2.6.18-243.el5 #1 SMP Mon Feb 7 18:47:27 EST 2011 x86_64 x86_64 x86_64 GNU/Linux [deploy@storage2 ~]$ lsb_release LSB Version: :core-3.1-amd64:core-3.1-ia32:core-3.1-noarch:graphics-3.1-amd64:graphics-3.1-ia32:graphics-3.1-noarch [deploy@storage2 ~]$ netstat -V (Not all processes could be identified, non-owned process info will not be shown, you would have to be root to see it all.) net-tools 1.60 netstat 1.42 (2001-04-15) Fred Baumgarten, Alan Cox, Bernd Eckenfels, Phil Blundell, Tuan Hoang and others +NEW_ADDRT +RTF_IRTT +RTF_REJECT +FW_MASQUERADE +I18N AF: (inet) +UNIX +INET +INET6 +IPX +AX25 +NETROM +X25 +ATALK +ECONET +ROSE HW: +ETHER +ARC +SLIP +PPP +TUNNEL +TR +AX25 +NETROM +X25 +FR +ROSE +ASH +SIT +FDDI +HIPPI +HDLC/LAPB There are more info from strace: [deploy@storage2 ~]$ strace ps -V execve("/bin/ps", ["ps", "-V"], [/* 27 vars */]) = 0 brk(0) = 0x929a000 access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory) open("/etc/ld.so.cache", O_RDONLY) = 3 fstat64(3, {st_mode=S_IFREG|0644, st_size=99752, ...}) = 0 mmap2(NULL, 99752, PROT_READ, MAP_PRIVATE, 3, 0) = 0xfffffffff7fde000 close(3) = 0 open("/lib/libnsl.so.1", O_RDONLY) = 3 read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0 \241\210\0004\0\0\0"..., 512) = 512 fstat64(3, {st_mode=S_IFREG|0755, st_size=101404, ...}) = 0 mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xfffffffff7fdd000 mmap2(0x887000, 92104, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x887000 mmap2(0x89a000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x12) = 0x89a000 mmap2(0x89c000, 6088, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x89c000 close(3) = 0 open("/lib/libdl.so.2", O_RDONLY) = 3 read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0Pzt\0004\0\0\0"..., 512) = 512 fstat64(3, {st_mode=S_IFREG|0755, st_size=16428, ...}) = 0 mmap2(0x747000, 12408, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x747000 mmap2(0x749000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1) = 0x749000 close(3) = 0 open("/lib/libm.so.6", O_RDONLY) = 3 read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\20\204p\0004\0\0\0"..., 512) = 512 fstat64(3, {st_mode=S_IFREG|0755, st_size=208352, ...}) = 0 mmap2(0x705000, 155760, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x705000 mmap2(0x72a000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x24) = 0x72a000 close(3) = 0 open("/lib/libcrypt.so.1", O_RDONLY) = 3 read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\340\246q\0004\0\0\0"..., 512) = 512 fstat64(3, {st_mode=S_IFREG|0755, st_size=45288, ...}) = 0 mmap2(0x71a000, 201020, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xfffffffff7fab000 mmap2(0xf7fb4000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x8) = 0xfffffffff7fb4000 mmap2(0xf7fb6000, 155964, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0xfffffffff7fb6000 close(3) = 0 open("/lib/libutil.so.1", O_RDONLY) = 3 read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0 \n\0\0004\0\0\0"..., 512) = 512 fstat64(3, {st_mode=S_IFREG|0755, st_size=13420, ...}) = 0 mmap2(NULL, 12428, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xfffffffff7fa7000 mmap2(0xf7fa9000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1) = 0xfffffffff7fa9000 close(3) = 0 open("/lib/libpthread.so.0", O_RDONLY) = 3 read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0@(s\0004\0\0\0"..., 512) = 512 fstat64(3, {st_mode=S_IFREG|0755, st_size=129716, ...}) = 0 mmap2(0x72e000, 90596, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x72e000 mmap2(0x741000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x13) = 0x741000 mmap2(0x743000, 4580, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x743000 close(3) = 0 open("/lib/libc.so.6", O_RDONLY) = 3 read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\340?]\0004\0\0\0"..., 512) = 512 fstat64(3, {st_mode=S_IFREG|0755, st_size=1611564, ...}) = 0 mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xfffffffff7fa6000 mmap2(0x5be000, 1328580, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x5be000 mmap2(0x6fd000, 12288, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x13f) = 0x6fd000 mmap2(0x700000, 9668, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x700000 close(3) = 0 mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xfffffffff7fa5000 set_thread_area(0xffd61bb4) = 0 mprotect(0x6fd000, 8192, PROT_READ) = 0 mprotect(0x741000, 4096, PROT_READ) = 0 mprotect(0xf7fa9000, 4096, PROT_READ) = 0 mprotect(0xf7fb4000, 4096, PROT_READ) = 0 mprotect(0x72a000, 4096, PROT_READ) = 0 mprotect(0x749000, 4096, PROT_READ) = 0 mprotect(0x89a000, 4096, PROT_READ) = 0 mprotect(0x5ba000, 4096, PROT_READ) = 0 munmap(0xf7fde000, 99752) = 0 set_tid_address(0xf7fa5708) = 20214 set_robust_list(0xf7fa5710, 0xc) = 0 futex(0xffd61f74, FUTEX_WAKE_PRIVATE, 1) = 0 rt_sigaction(SIGRTMIN, {0x4007323d0, [], 0}, NULL, 8) = 0 rt_sigaction(SIGRT_1, {0x10000004007322e0, [], 0}, NULL, 8) = 0 rt_sigprocmask(SIG_UNBLOCK, [RTMIN RT_1], NULL, 8) = 0 getrlimit(RLIMIT_STACK, {rlim_cur=-4284481536, rlim_max=67108864*1024}) = 0 uname({sys="Linux", node="storage2", ...}) = 0 readlink("/proc/self/exe", "/bin/ps"..., 260) = 7 brk(0) = 0x929a000 brk(0x92bb000) = 0x92bb000 open("/bin/ps", O_RDONLY|O_LARGEFILE) = 3 _llseek(3, -12, [711660], SEEK_END) = 0 read(3, "\274U!\253\2\0\0\0\224\237\t\0", 12) = 12 mmap2(NULL, 634880, PROT_READ, MAP_SHARED, 3, 0x13) = 0xfffffffff7f0a000 mmap2(NULL, 630784, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xfffffffff7e70000 close(3) = 0 futex(0x74a06c, FUTEX_WAKE_PRIVATE, 2147483647) = 0 geteuid32() = 501 socket(PF_FILE, SOCK_STREAM, 0) = 3 fcntl64(3, F_SETFL, O_RDWR|O_NONBLOCK) = 0 connect(3, {sa_family=AF_FILE, path="/var/run/nscd/socket"...}, 110) = -1 ENOENT (No such file or directory) close(3) = 0 socket(PF_FILE, SOCK_STREAM, 0) = 3 fcntl64(3, F_SETFL, O_RDWR|O_NONBLOCK) = 0 connect(3, {sa_family=AF_FILE, path="/var/run/nscd/socket"...}, 110) = -1 ENOENT (No such file or directory) close(3) = 0 open("/etc/nsswitch.conf", O_RDONLY) = 3 fstat64(3, {st_mode=S_IFREG|0644, st_size=1696, ...}) = 0 mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xfffffffff7ff6000 read(3, "#\n# /etc/nsswitch.conf\n#\n# An ex"..., 4096) = 1696 read(3, "", 4096) = 0 close(3) = 0 munmap(0xf7ff6000, 4096) = 0 open("/etc/ld.so.cache", O_RDONLY) = 3 fstat64(3, {st_mode=S_IFREG|0644, st_size=99752, ...}) = 0 mmap2(NULL, 99752, PROT_READ, MAP_PRIVATE, 3, 0) = 0xfffffffff7fde000 close(3) = 0 open("/lib/libnss_files.so.2", O_RDONLY) = 3 read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\300\30\0\0004\0\0\0"..., 512) = 512 fstat64(3, {st_mode=S_IFREG|0755, st_size=46680, ...}) = 0 mmap2(NULL, 41616, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xfffffffff7e65000 mmap2(0xf7e6e000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x8) = 0xfffffffff7e6e000 close(3) = 0 mprotect(0xf7e6e000, 4096, PROT_READ) = 0 munmap(0xf7fde000, 99752) = 0 open("/etc/passwd", O_RDONLY) = 3 fcntl64(3, F_GETFD) = 0 fcntl64(3, F_SETFD, FD_CLOEXEC) = 0 fstat64(3, {st_mode=S_IFREG|0644, st_size=2166, ...}) = 0 mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xfffffffff7ff6000 read(3, "root:x:0:0:root:/root:/bin/bash\n"..., 4096) = 2166 close(3) = 0 munmap(0xf7ff6000, 4096) = 0 mkdir("/tmp/pdk-deploy/", 0755) = -1 EEXIST (File exists) mkdir("/tmp/pdk-deploy/fcb734befe617ec3ae1edc38da810a5a", 0755) = -1 EEXIST (File exists) open("/tmp/pdk-deploy/fcb734befe617ec3ae1edc38da810a5a/libperl.so", O_RDONLY|O_LARGEFILE) = 3 close(3) = 0 open("/tmp/pdk-deploy/fcb734befe617ec3ae1edc38da810a5a/libperl.so", O_RDONLY) = 3 read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\300!\2\0004\0\0\0"..., 512) = 512 fstat64(3, {st_mode=S_IFREG|0664, st_size=1264090, ...}) = 0 mmap2(NULL, 1140104, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xfffffffff7d4e000 mmap2(0xf7e5a000, 45056, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x10b) = 0xfffffffff7e5a000 close(3) = 0 rt_sigaction(SIGFPE, {0x1000000000000001, [], SA_RESTORER|SA_STACK|SA_RESTART|SA_INTERRUPT|SA_NODEFER|SA_RESETHAND|SA_SIGINFO|0x3d61cb8, (nil)}, {SIG_DFL, ~[HUP INT ILL ABRT BUS SEGV USR2 PIPE ALRM TERM STOP TSTP TTIN TTOU XCPU WINCH IO PWR SYS RTMIN RT_1 RT_2 RT_4 RT_5 RT_8 RT_9 RT_11 RT_12 RT_13 RT_16 RT_17 RT_18 RT_22 RT_24 RT_25 RT_26 RT_27 RT_28 RT_29 RT_30 RT_31], SA_RESTART|SA_RESETHAND|0x22302d0}, 8) = 0 getuid32() = 501 geteuid32() = 501 getgid32() = 502 getegid32() = 502 open("/usr/lib/locale/locale-archive", O_RDONLY|O_LARGEFILE) = 3 fstat64(3, {st_mode=S_IFREG|0644, st_size=56454896, ...}) = 0 mmap2(NULL, 2097152, PROT_READ, MAP_PRIVATE, 3, 0) = 0xfffffffff7b4e000 mmap2(NULL, 241664, PROT_READ, MAP_PRIVATE, 3, 0x13ec) = 0xfffffffff7b13000 mmap2(NULL, 4096, PROT_READ, MAP_PRIVATE, 3, 0x1466) = 0xfffffffff7b12000 close(3) = 0 mmap2(NULL, 135168, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xfffffffff7af1000 time(NULL) = 1348210009 readlink("/proc/self/exe", "/bin/ps"..., 4095) = 7 ioctl(0, SNDCTL_TMR_TIMEBASE or TCGETS, {B38400 opost isig icanon echo ...}) = 0 _llseek(0, 0, 0xffd618d0, SEEK_CUR) = -1 ESPIPE (Illegal seek) ioctl(1, SNDCTL_TMR_TIMEBASE or TCGETS, 0xffd618a8) = -1 EINVAL (Invalid argument) _llseek(1, 0, 0xffd618d0, SEEK_CUR) = -1 ESPIPE (Illegal seek) ioctl(2, SNDCTL_TMR_TIMEBASE or TCGETS, 0xffd618a8) = -1 EINVAL (Invalid argument) _llseek(2, 0, 0xffd618d0, SEEK_CUR) = -1 ESPIPE (Illegal seek) open("/dev/null", O_RDONLY|O_LARGEFILE) = 3 ioctl(3, SNDCTL_TMR_TIMEBASE or TCGETS, 0xffd61978) = -1 ENOTTY (Inappropriate ioctl for device) _llseek(3, 0, [0], SEEK_CUR) = 0 fcntl64(3, F_SETFD, FD_CLOEXEC) = 0 rt_sigaction(SIGCHLD, NULL, {SIG_DFL, [], SA_RESTART|SA_RESETHAND|0x22302d0}, 8) = 0 brk(0x92dc000) = 0x92dc000 getppid() = 20212 stat64("/opt/ActivePerl-5.8/site/lib/sitecustomize.pl", 0xffd61560) = -1 ENOENT (No such file or directory) close(3) = 0 open("/usr/lib/.khostd/.hostconf", O_RDONLY|O_LARGEFILE) = 3 ioctl(3, SNDCTL_TMR_TIMEBASE or TCGETS, 0xffd61828) = -1 ENOTTY (Inappropriate ioctl for device) _llseek(3, 0, [0], SEEK_CUR) = 0 fstat64(3, {st_mode=S_IFREG|0644, st_size=334, ...}) = 0 fcntl64(3, F_SETFD, FD_CLOEXEC) = 0 read(3, "bindport=9001\ntrustip=221.122.57"..., 4096) = 334 read(3, "", 4096) = 0 close(3) = 0 pipe([3, 4]) = 0 pipe([5, 6]) = 0 clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0) = 20215 close(6) = 0 close(4) = 0 read(5, "", 4) = 0 close(5) = 0 ioctl(3, SNDCTL_TMR_TIMEBASE or TCGETS, 0xffd61868) = -1 EINVAL (Invalid argument) _llseek(3, 0, 0xffd61890, SEEK_CUR) = -1 ESPIPE (Illegal seek) fstat64(3, {st_mode=S_IFIFO|0600, st_size=0, ...}) = 0 read(3, (Not all processes could be identified, non-owned process info will not be shown, you would have to be root to see it all.) "tcp 0 0 0.0.0.0:9001"..., 4096) = 109 read(3, "", 4096) = 0 --- SIGCHLD (Child exited) @ 0 (0) --- fstat64(3, {st_mode=S_IFIFO|0600, st_size=0, ...}) = 0 close(3) = 0 rt_sigaction(SIGHUP, {0x1, [], SA_STACK|0x129b3d8}, {SIG_DFL, ~[HUP INT ILL TRAP KILL SEGV ALRM TERM STKFLT CHLD TSTP TTOU RT_1 RT_2 RT_3 RT_6 RT_9 RT_11 RT_14 RT_15 RT_16 RT_17 RT_20 RT_22], SA_RESTART|SA_RESETHAND|0x22302d0}, 8) = 0 rt_sigaction(SIGINT, {0x1, [], SA_STACK|0x129b3d8}, {SIG_DFL, [TRAP BUS FPE USR1 CHLD CONT TTOU VTALRM IO RTMIN], SA_RESTART|SA_RESETHAND|0x22302d0}, 8) = 0 rt_sigaction(SIGQUIT, {0x1, [], 0}, {SIG_DFL, ~[HUP INT ILL TRAP KILL SEGV ALRM TERM STKFLT CHLD TSTP TTOU RT_1 RT_2 RT_3 RT_6 RT_9 RT_11 RT_14 RT_15 RT_16 RT_17 RT_20 RT_22], SA_RESTART|SA_RESETHAND|0x22302d0}, 8) = 0 waitpid(20215, [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], 0) = 20215 rt_sigaction(SIGHUP, {SIG_DFL, ~[HUP INT ILL TRAP KILL SEGV ALRM TERM STKFLT CHLD TSTP TTOU RT_1 RT_2 RT_3 RT_6 RT_9 RT_11 RT_14 RT_15 RT_16 RT_17 RT_20 RT_22], SA_NOCLDSTOP|SA_NOCLDWAIT}, NULL, 8) = 0 rt_sigaction(SIGINT, {SIG_DFL, [TRAP BUS FPE USR1 CHLD CONT TTOU VTALRM IO RTMIN], SA_NOCLDSTOP|SA_NOCLDWAIT}, NULL, 8) = 0 rt_sigaction(SIGQUIT, {SIG_DFL, ~[HUP INT ILL TRAP KILL SEGV ALRM TERM STKFLT CHLD TSTP TTOU RT_1 RT_2 RT_3 RT_6 RT_9 RT_11 RT_14 RT_15 RT_16 RT_17 RT_20 RT_22], SA_NOCLDSTOP|SA_NOCLDWAIT}, NULL, 8) = 0 chdir("/usr/lib/.khostd") = 0 pipe([3, 4]) = 0 pipe([5, 6]) = 0 clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0) = 20218 close(6) = 0 close(4) = 0 read(5, "", 4) = 0 close(5) = 0 ioctl(3, SNDCTL_TMR_TIMEBASE or TCGETS, 0xffd61868) = -1 EINVAL (Invalid argument) _llseek(3, 0, 0xffd61890, SEEK_CUR) = -1 ESPIPE (Illegal seek) read(3, "", 4096) = 0 --- SIGCHLD (Child exited) @ 0 (0) --- close(3) = 0 rt_sigaction(SIGHUP, {0x1, [], SA_RESTORER|SA_STACK|SA_RESTART|SA_INTERRUPT|SA_NODEFER|SA_RESETHAND|0x3d61850, (nil)}, {SIG_DFL, ~[HUP INT ILL TRAP KILL SEGV ALRM TERM STKFLT CHLD TSTP TTOU RT_1 RT_2 RT_3 RT_6 RT_9 RT_11 RT_14 RT_15 RT_16 RT_17 RT_20 RT_22], SA_NOCLDSTOP|SA_NOCLDWAIT}, 8) = 0 rt_sigaction(SIGINT, {0x1, [], SA_STACK|0x129b3d8}, {SIG_DFL, [HUP INT], SA_NOCLDSTOP|SA_NOCLDWAIT}, 8) = 0 rt_sigaction(SIGQUIT, {0x1, [], 0}, {SIG_DFL, ~[HUP INT ILL TRAP KILL SEGV ALRM TERM STKFLT CHLD TSTP TTOU RT_1 RT_2 RT_3 RT_6 RT_9 RT_11 RT_14 RT_15 RT_16 RT_17 RT_20 RT_22], SA_NOCLDSTOP|SA_NOCLDWAIT}, 8) = 0 waitpid(20218, [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], 0) = 20218 rt_sigaction(SIGHUP, {SIG_DFL, ~[HUP INT ILL TRAP KILL SEGV ALRM TERM STKFLT CHLD TSTP TTOU RT_1 RT_2 RT_3 RT_6 RT_9 RT_11 RT_14 RT_15 RT_16 RT_17 RT_20 RT_22], SA_NOCLDSTOP|SA_NOCLDWAIT}, NULL, 8) = 0 rt_sigaction(SIGINT, {SIG_DFL, [HUP INT], SA_NOCLDSTOP|SA_NOCLDWAIT}, NULL, 8) = 0 rt_sigaction(SIGQUIT, {SIG_DFL, ~[HUP INT ILL TRAP KILL SEGV ALRM TERM STKFLT CHLD TSTP TTOU RT_1 RT_2 RT_3 RT_6 RT_9 RT_11 RT_14 RT_15 RT_16 RT_17 RT_20 RT_22], SA_NOCLDSTOP|SA_NOCLDWAIT}, NULL, 8) = 0 chdir("/home/deploy") = 0 stat64("/etc/cron.hourly/hichina", {st_mode=S_IFREG|0755, st_size=711660, ...}) = 0 pipe([3, 4]) = 0 pipe([5, 6]) = 0 clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0) = 20230 close(6) = 0 close(4) = 0 read(5, "", 4) = 0 close(5) = 0 ioctl(3, SNDCTL_TMR_TIMEBASE or TCGETS, 0xffd61868) = -1 EINVAL (Invalid argument) _llseek(3, 0, 0xffd61890, SEEK_CUR) = -1 ESPIPE (Illegal seek) read(3, "procps version 3.2.7\n", 4096) = 21 read(3, "", 4096) = 0 --- SIGCHLD (Child exited) @ 0 (0) --- close(3) = 0 rt_sigaction(SIGHUP, {0x1, [], SA_RESTORER|SA_STACK|SA_RESTART|SA_INTERRUPT|SA_NODEFER|SA_RESETHAND|0x3d61850, (nil)}, {SIG_DFL, ~[HUP INT ILL TRAP KILL SEGV ALRM TERM STKFLT CHLD TSTP TTOU RT_1 RT_2 RT_3 RT_6 RT_9 RT_11 RT_14 RT_15 RT_16 RT_17 RT_20 RT_22], SA_NOCLDSTOP|SA_NOCLDWAIT}, 8) = 0 rt_sigaction(SIGINT, {0x1, [], SA_STACK|0x129b3d8}, {SIG_DFL, [HUP INT], SA_NOCLDSTOP|SA_NOCLDWAIT}, 8) = 0 rt_sigaction(SIGQUIT, {0x1, [], 0}, {SIG_DFL, ~[HUP INT ILL TRAP KILL SEGV ALRM TERM STKFLT CHLD TSTP TTOU RT_1 RT_2 RT_3 RT_6 RT_9 RT_11 RT_14 RT_15 RT_16 RT_17 RT_20 RT_22], SA_NOCLDSTOP|SA_NOCLDWAIT}, 8) = 0 waitpid(20230, [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], 0) = 20230 rt_sigaction(SIGHUP, {SIG_DFL, ~[HUP INT ILL TRAP KILL SEGV ALRM TERM STKFLT CHLD TSTP TTOU RT_1 RT_2 RT_3 RT_6 RT_9 RT_11 RT_14 RT_15 RT_16 RT_17 RT_20 RT_22], SA_NOCLDSTOP|SA_NOCLDWAIT}, NULL, 8) = 0 rt_sigaction(SIGINT, {SIG_DFL, [HUP INT], SA_NOCLDSTOP|SA_NOCLDWAIT}, NULL, 8) = 0 rt_sigaction(SIGQUIT, {SIG_DFL, ~[HUP INT ILL TRAP KILL SEGV ALRM TERM STKFLT CHLD TSTP TTOU RT_1 RT_2 RT_3 RT_6 RT_9 RT_11 RT_14 RT_15 RT_16 RT_17 RT_20 RT_22], SA_NOCLDSTOP|SA_NOCLDWAIT}, NULL, 8) = 0 write(1, "procps version 3.2.7\n", 21procps version 3.2.7 ) = 21 munmap(0xf7af1000, 135168) = 0 munmap(0xf7e70000, 630784) = 0 munmap(0xf7f0a000, 634880) = 0 munmap(0xf7d4e000, 1140104) = 0 exit_group(0) = ? [ Process PID=20214 runs in 32 bit mode. ] Thank you very much.

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  • Why does my Sax Parser produce no results after using InputStream Read?

    - by Andy Barlow
    Hello, I have this piece of code which I'm hoping will be able to tell me how much data I have downloaded (and soon put it in a progress bar), and then parse the results through my Sax Parser. If I comment out basically everything above the //xr.parse(new InputSource(request.getInputStream())); line and swap the xr.parse's over, it works fine. But at the moment, my Sax parser tells me I have nothing. Is it something to do with is.read (buffer) section? Also, just as a note, request is a HttpURLConnection with various signatures. /*Input stream to read from our connection*/ InputStream is = request.getInputStream(); /*we make a 2 Kb buffer to accelerate the download, instead of reading the file a byte at once*/ byte [ ] buffer = new byte [ 2048 ] ; /*How many bytes do we have already downloaded*/ int totBytes,bytes,sumBytes = 0; totBytes = request.getContentLength () ; while ( true ) { /*How many bytes we got*/ bytes = is.read (buffer); /*If no more byte, we're done with the download*/ if ( bytes <= 0 ) break; sumBytes+= bytes; Log.v("XML", sumBytes + " of " + totBytes + " " + ( ( float ) sumBytes/ ( float ) totBytes ) *100 + "% done" ); } /* Parse the xml-data from our URL. */ // OLD, and works if comment all the above //xr.parse(new InputSource(request.getInputStream())); xr.parse(new InputSource(is)) /* Parsing has finished. */; Can anyone help me at all?? Kind regards, Andy

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  • Data in linux FIFO seems lost

    - by Utoah
    Hi, I have a bash script which wants to do some work in parallel, I did this by putting each job in an subshell which is run in the background. While the number of job running simultaneously should under some limit, I achieve this by first put some lines in a FIFO, then just before forking the subshell, the parent script is required to read a line from this FIFO. Only after it gets a line can it fork the subshell. Up to now, everything works fine. But when I tried to read a line from the FIFO in the subshell, it seems that only one subshell can get a line, even if there are apparently more lines in the FIFO. So I wonder why cannot other subshell(s) read a line even when there are more lines in the FIFO. My testing code looks something like this: #!/bin/sh fifo_path="/tmp/fy_u_test2.fifo" mkfifo $fifo_path #open fifo for r/w at fd 6 exec 6 $fifo_path process_num=5 #put $process_num lines in the FIFO for ((i=0; i<${process_num}; i++)); do echo "$i" done &6 delay_some(){ local index="$1" echo "This is what u can see. $index \n" sleep 20; } #In each iteration, try to read 2 lines from FIFO, one from this shell, #the other from the subshell for i in 1 2 do date /tmp/fy_date #If a line can be read from FIFO, run a subshell in bk, otherwise, block. read -u6 echo " $$ Read --- $REPLY --- from 6 \n" /tmp/fy_date { delay_some $i #Try to read a line from FIFO read -u6 echo " $$ This is in child # $i, read --- $REPLY --- from 6 \n" /tmp/fy_date } & done And the output file /tmp/fy_date has content of: Mon Apr 26 16:02:18 CST 2010 32561 Read --- 0 --- from 6 \n Mon Apr 26 16:02:18 CST 2010 32561 Read --- 1 --- from 6 \n 32561 This is in child # 1, read --- 2 --- from 6 \n

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  • Unable to aquire image through ImageIO.read(url) because of connection timed out.

    - by Jake Frederix
    Following code always fails URL url = new URL("http://userserve-ak.last.fm/serve/126/8636005.jpg"); Image img = ImageIO.read(url); System.out.println(img); I've manually checked the url, and it is valid, and contains a valid jpg image. The problem I get is; Exception in thread "main" javax.imageio.IIOException: Can't get input stream from URL! at javax.imageio.ImageIO.read(ImageIO.java:1385) at maestro.Main2.main(Main2.java:25) Caused by: java.net.ConnectException: Connection timed out at java.net.PlainSocketImpl.socketConnect(Native Method) at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:310) at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:176) at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:163) at java.net.Socket.connect(Socket.java:546) at java.net.Socket.connect(Socket.java:495) at sun.net.NetworkClient.doConnect(NetworkClient.java:174) at sun.net.www.http.HttpClient.openServer(HttpClient.java:409) at sun.net.www.http.HttpClient.openServer(HttpClient.java:530) at sun.net.www.http.HttpClient.(HttpClient.java:240) at sun.net.www.http.HttpClient.New(HttpClient.java:321) at sun.net.www.http.HttpClient.New(HttpClient.java:338) at sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:814) at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:755) at sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:680) at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1005) at java.net.URL.openStream(URL.java:1029) at javax.imageio.ImageIO.read(ImageIO.java:1383) ... 1 more Java Result: 1 What does this mean? Funny thing is, if I change my internet-connection to that of the neighbour's wireless, it suddenly does work.

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  • Why do my Sax Parser produce no results after using InputStream Read?

    - by Andy Barlow
    Hello, I have this piece of code which I'm hoping will be able to tell me how much data I have downloaded (and soon put it in a progress bar), and then parse the results through my Sax Parser. If I comment out basically everything above the //xr.parse(new InputSource(request.getInputStream())); line and swap the xr.parse's over, it works fine. But at the moment, my Sax parser tells me I have nothing. Is it something to do with is.read (buffer) section? Also, just as a note, request is a HttpURLConnection with various signatures. /*Input stream to read from our connection*/ InputStream is = request.getInputStream(); /*we make a 2 Kb buffer to accelerate the download, instead of reading the file a byte at once*/ byte [ ] buffer = new byte [ 2048 ] ; /*How many bytes do we have already downloaded*/ int totBytes,bytes,sumBytes = 0; totBytes = request.getContentLength () ; while ( true ) { /*How many bytes we got*/ bytes = is.read (buffer); /*If no more byte, we're done with the download*/ if ( bytes <= 0 ) break; sumBytes+= bytes; Log.v("XML", sumBytes + " of " + totBytes + " " + ( ( float ) sumBytes/ ( float ) totBytes ) *100 + "% done" ); } /* Parse the xml-data from our URL. */ // OLD, and works if comment all the above //xr.parse(new InputSource(request.getInputStream())); xr.parse(new InputSource(is)) /* Parsing has finished. */; Can anyone help me at all?? Kind regards, Andy

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  • HttpURLConnection: What's the deal with having to read the whole response?

    - by stormin986
    My current problem is very similar to this one. I have a downloadFile(URL) function that creates a new HttpURLConnection, opens it, reads it, returns the results. When I call this function on the same URL multiple times, the second time around it almost always returns a response code of -1 (But throws no exception!!!). The top answer in that question is very helpful, but there are a few things I'm trying to understand. So, if setting http.keepAlive to false solves the problem, it indicates what exactly? That the server is responding in a way that violates the http protocol? Or more likely, my code is violating the protocol in some way? What will the trace tell me? What should I look for? And what's the deal with this: You need to read everything from error stream. Otherwise, it's going to confuse next connection and that's the cause of -1. Does this mean if the response is some type of error (which would be what response code(s)?), the stream HAS to be fully read? Also, every time I am attempting an http request I am basically creating a new connection, and then disconnect()ing it at the end. However, in my case I'm not getting a 401 or whatever. It's always a 200. But my second connection almost always fails. Does this mean there's some other data I should be reading that I'm not (in a similar manner that the error stream must be fully read)? Please help shed some light on this? I feel like there's some fundamental http protocol understanding I'm missing.

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  • What does the subversion error "Could not read status line" mean?

    - by Jergason
    Exact duplicate: SVN: Could not read status line: connection was closed by server This is not an exact duplicate. The other question was asking about getting the error in a specific situation, and the answer was vauge at best. This is a fairly basic question, but it is driving me nuts. I have set up a brand new repository at beanstalk.com. They give me the url, http://.svn.beanstalkapp.com/blog. They also automatically create the tag, trunk and branches folder in the repository. I have checked out the trunk folder and used svn add to add the new file. I am trying to do my first commit, but I get this error: Commit failed (details follow): CHECKOUT of '/foo/!svn/bln/1': Could not read status line: connection was closed by server. (http://user_name@my_name.svn.beanstalkapp.com) What does this mean, and what causes it? I have googled for a definition of what "Could not read status line" means, but was unable to find anything explaining it. edit: I was getting this error while trying to manipulate my repository from behind a firewall. I still don't know what was causing it, but I don't have this problem at home. Strangeness.

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  • How do I read binary C++ protobuf data using Python protobuf?

    - by nbolton
    The Python version of Google protobuf gives us only: SerializeAsString() Where as the C++ version gives us both: SerializeToArray(...) SerializeAsString() We're writing to our C++ file in binary format, and we'd like to keep it this way. That said, is there a way of reading the binary data into Python and parsing it as if it were a string? Is this the correct way of doing it? binary = get_binary_data() binary_size = get_binary_size() string = None for i in range(len(binary_size)): string += i message = new MyMessage() message.ParseFromString(string) Update: Here's a new example, and a problem: message_length = 512 file = open('foobars.bin', 'rb') eof = False while not eof: data = file.read(message_length) eof = not data if not eof: foo_bar = FooBar() foo_bar.ParseFromString(data) When we get to the foo_bar.ParseFromString(data) line, I get this error: Exception Type: DecodeError Exception Value: Too many bytes when decoding varint. Update 2: It turns out, that the padding on the binary data was throwing protobuf off; too many bytes were being sent in, as the message suggests (in this case it was referring to the padding). This padding comes from using the C++ protobuf function, SerializeToArray on a fixed-length buffer. To eliminate this, I have used this temproary code: message_length = 512 file = open('foobars.bin', 'rb') eof = False while not eof: data = file.read(message_length) eof = not data string = '' for i in range(0, len(data)): byte = data[i] if byte != '\xcc': # yuck! string += data[i] if not eof: foo_bar = FooBar() foo_bar.ParseFromString(string) There is a design flaw here I think. I will re-implement my C++ code so that it writes variable length arrays to the binary file. As advised by the protobuf documentation, I will prefix each message with it's binary size so that I know how much to read when I'm opening the file with Python.

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  • how to read an arraylist from a txt file in java?

    - by lox
    how to read an arraylist from a txt file in java? my arraylist is the form of: public class Account { String username; String password; } i managed to put some "Accounts" in the a txt file, but now i don't know how to read them. this is how my arraylist look in the txt file: username1 password1 | username2 password2 | etc this is a part of the code i came up with, but it doesn't work. it looks logic to me though... :) . public static void RdAc(String args[]) { ArrayList<Account> peoplelist = new ArrayList<Account>(50); int i,i2,i3; String[] theword = null; try { FileReader fr = new FileReader("myfile.txt"); BufferedReader br = new BufferedReader(fr); String line = ""; while ((line = br.readLine()) != null) { String[] theline = line.split(" | "); for (i = 0; i < theline.length; i++) { theword = theline[i].split(" "); } for(i3=0;i3<theline.length;i3++) { Account people = new Account(); for (i2 = 0; i2 < theword.length; i2++) { people.username = theword[i2]; people.password = theword[i2+1]; peoplelist.add(people); } } } } catch (IOException ex) { System.out.println("Could not read from file"); } }

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  • Can threads safely read variables set by VCL events?

    - by Tom1952
    Is it safe for a thread to READ a variable set by a Delphi VCL event? When a user clicks on a VCL TCheckbox, the main thread sets a boolean to the checkbox's Checked state. CheckboxState := CheckBox1.Checked; At any time, a thread reads that variable if CheckBoxState then ... It doesn't matter if the thread "misses" a change to the boolean, because the thread checks the variable in a loop as it does other things. So it will see the state change eventually... Is this safe? Or do I need special code? Is surrounding the read and write of the variable (in the thread and main thread respectively) with critical code calls necessary and sufficient? As I said, it doesn't matter if the thread gets the "wrong" value, but I keep thinking that there might be a low-level problem if one thread tries to read a variable while the main thread is in the middle of writing it, or vice versa. My question is similar to this one: http://stackoverflow.com/questions/1353096/cross-thread-reading-of-a-variable. (Also related to my previous question: http://stackoverflow.com/questions/2449183/using-entercriticalsection-in-thread-to-update-vcl-label)

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  • What is the proper way to code a read-while loop in Scala?

    - by ARKBAN
    What is the "proper" of writing the standard read-while loop in Scala? By proper I mean written in a Scala-like way as opposed to a Java-like way. Here is the code I have in Java: MessageDigest md = MessageDigest.getInstance( "MD5" ); InputStream input = new FileInputStream( "file" ); byte[] buffer = new byte[1024]; int readLen; while( ( readLen = input.read( buffer ) ) != -1 ) md.update( buffer, 0, readLen ); return md.digest(); Here is the code I have in Scala: val md = MessageDigest.getInstance( hashInfo.algorithm ) val input = new FileInputStream( "file" ) val buffer = new Array[ Byte ]( 1024 ) var readLen = 0 while( readLen != -1 ) { readLen = input.read( buffer ) if( readLen != -1 ) md.update( buffer, 0, readLen ) } md.digest The Scala code is correct and works, but feels very un-Scala-ish. For one it is a literal translation of the Java code, taking advantage of none of the advantages of Scala. Further it is actually longer than the Java code! I really feel like I'm missing something, but I can't figure out what. I'm fairly new to Scala, and so I'm asking the question to avoid falling into the pitfall of writing Java-style code in Scala. I'm more interested in the Scala way to solve this kind of problem than in any specific helper method that might be provided by the Scala API to hash a file. (I apologize in advance for my ad hoc Scala adjectives throughout this question.)

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  • How to proceed jpeg Image file size after read--rotate-write operations in Java?

    - by zamska
    Im trying to read a JPEG image as BufferedImage, rotate and save it as another jpeg image from file system. But there is a problem : after these operations I cannot proceed same file size. Here the code //read Image BufferedImage img = ImageIO.read(new File(path)); //rotate Image BufferedImage rotatedImage = new BufferedImage(image.getHeight(), image.getWidth(), BufferedImage.TYPE_3BYTE_BGR); Graphics2D g2d = (Graphics2D) rotatedImage.getGraphics(); g2d.rotate(Math.toRadians(PhotoConstants.ROTATE_LEFT)); int height=-rotatedImage.getHeight(null); g2d.drawImage(image, height, 0, null); g2d.dispose(); //Write Image Iterator iter = ImageIO.getImageWritersByFormatName("jpeg"); ImageWriter writer = (ImageWriter)iter.next(); // instantiate an ImageWriteParam object with default compression options ImageWriteParam iwp = writer.getDefaultWriteParam(); try { FileImageOutputStream output = null; iwp.setCompressionMode(ImageWriteParam.MODE_EXPLICIT); iwp.setCompressionQuality(0.98f); // an integer between 0 and 1 // 1 specifies minimum compression and maximum quality File file = new File(path); output = new FileImageOutputStream(file); writer.setOutput(output); IIOImage iioImage = new IIOImage(image, null, null); writer.write(null, iioImage, iwp); output.flush(); output.close(); writer.dispose(); Is it possible to access compressionQuality parameter of original jpeg image in the beginning. when I set 1 to compression quality, the image gets bigger size. Otherwise I set 0.9 or less the image gets smaller size. How can i proceed the image size after these operations? Thank you,

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  • UI - How I can make users effectively read what my program says?

    - by Magnetic_dud
    I have a simple form that searches through the 2000+ issues of a 3rd party webcomic. (Easy, it's like xkcd: http://url/number That form is as easy as possible, is like this: What number do you want? User writes a number, clicks ok, and goes on the 3rd party website on a new tab Then, my form asks a question: "Did you find that issue memorable? Enter the name here, and we will add it to the "best issues" in home page" When the user will write the name of the issue, it is added to the database (pending moderation by me) So, I supposed this design is the easiest and convenient that users can find. Unfortunately, NONE of the users (maybe a 2% behaved correctly) will actually read what I asked. Some of the issues are offline, and gives a 404. On that issues users will write in the textbox a completely wrong title, and correctly capitalized! It's like if i would name http://xkcd.com/627/ as "The Great Adventures of Jack Smith" Users are from around all over the country, with different browsers, and have a different cookie. I cannot believe that my users will not read what I ask, it is a WHITE PAGE with a button that disappears when clicked and a textbox.... easier than that??? Maybe i should put a checkbox with "I acknowledge that this form is for submitting memorable issues, not for fun"? Oh, who will read that? Or maybe i could enable the textbox only if the user has effectively clicked the link?

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  • Doesn't this defeat the whole purpose of having read-only properties?

    - by flockofcode
    I know how to use properties and I understand that they implicitly call underlying get and set accessors, depending on whether we are writing to or reading from a property. static void Main(string[] args) { A a = new A(); (a.b).i = 100; } class A { private B _b = new B(); public B b { get { return _b; } } } class B { public int i; } What code (a.b).i = 100; essentially does is that first property’s get accessor returns a reference to an object _b, and once we have this reference, we are able to access _b’s members and change their values. Thus, in our example, having read only property only prevents outside code from changing the value of a reference variable _b, but it doesn’t prevent outside code from accessing _b’s members. So it seems that property can only detect whether we are trying to read from or write to a variable ( in our case variable _b ) located on the stack, while it’s not able to detect whether we’re trying to also write to members of an object to which the variable on the stack ( assuming this variable is of reference type ) points to. a) But doesn’t that defeat the whole purpose of having read-only properties? Wouldn’t it be more effective if properties had the ability to also detect whether we’re trying to access members of an object returned by get accessor( assuming backing field is of a reference type )? thank you

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  • why does vector.size() read in one line too little?

    - by ace
    when running the following code, the amount of lines will read on less then there actually is (if the input file is main itself, or otherwise) why is this and how can i change that fact (besides for just adding 1)? #include <fstream> #include <iostream> #include <string> #include <vector> using namespace std; int main() { // open text file for input string file_name; cout << "please enter file name: "; cin >> file_name; // associate the input file stream with a text file ifstream infile(file_name.c_str()); // error checking for a valid filename if ( !infile ) { cerr << "Unable to open file " << file_name << " -- quitting!\n"; return( -1 ); } else cout << "\n"; // some data structures to perform the function vector<string> lines_of_text; string textline; // read in text file, line by line while (getline( infile, textline, '\n' )) { // add the new element to the vector lines_of_text.push_back( textline ); // print the 'back' vector element - see the STL documentation cout << "line read: " << lines_of_text.back() << "\n"; } cout<<lines_of_text.size(); return 0; }

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  • I'm doing hobby programming; what programming methodologies (e.g. XP, Agile...) do you recommend me to read up on?

    - by Anto
    Most of you would probably just call me a kid (I'm 15). I'm doing hobby programming (I started fiddling around with ActionScript 2.0 in Flash 8 when I was 11, now I do mostly C, Python and Java). As I'm 15, I won't get a job for a long period of time (I'm going to spend years in academia before that) and thus this question is not about which programming methodologies you recommend me to read up on for a software engineering job, but instead which methodologies should a hobby programmer read about? What will a hobby developer learn from reading about your recommendation(s)?

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  • Server overloaded with log messages: tty_release_dev: pts0: read/write wait queue active!

    - by Raph
    In the logs, I have this (extract from the full kernel messages logges at 06:01:14): Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.863038] BUG: unable to handle kernel NULL pointer dereference at 0000000000000015 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861081] Process telnet (pid: 20247, threadinfo ffff8800f8598000, task ffff8800024d4500) And then the server logs flooded by this message: Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861547] tty_release_dev: pts0: read/write wait queue active! In the end, 2 hours later, I had to reboot because it had become inaccessible: the load hat grown to 160%. The last command does not show anyone logged on pts0 at that time. I also don't know where this telnet process could come from.... This is an AWS instance running UBUNTU 10.04 LTS And here are the complete logs: Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.863038] BUG: unable to handle kernel NULL pointer dereference at 0000000000000015 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861007] IP: [<ffffffff81363dde>] n_tty_read+0x2ce/0x970 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861019] PGD ee13d067 PUD f8698067 PMD 0 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861025] Oops: 0000 [#1] SMP Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861028] last sysfs file: /sys/devices/xen/vbd-2208/block/sdk/removable Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861032] CPU 0 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861034] Modules linked in: ipv6 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861040] Pid: 20247, comm: telnet Not tainted 2.6.32-312-ec2 #24-Ubuntu Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861042] RIP: e030:[<ffffffff81363dde>] [<ffffffff81363dde>] n_tty_read+0x2ce/0x970 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861047] RSP: e02b:ffff8800f8599d88 EFLAGS: 00010246 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861049] RAX: 0000000000000015 RBX: ffff8800f8598000 RCX: 0000000001aed069 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861052] RDX: 0000000000000000 RSI: ffff8800f8599e67 RDI: ffff8801dd833d1c Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861054] RBP: ffff8800f8599e98 R08: ffffffff8135eb10 R09: 7fffffffffffffff Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861057] R10: 0000000000000000 R11: 0000000000000246 R12: ffff8801dd833800 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861059] R13: 0000000000000000 R14: ffff8801dd833a68 R15: ffff8801dd833d1c Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861065] FS: 00007f90121f6720(0000) GS:ffff880002c40000(0000) knlGS:0000000000000000 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861068] CS: e033 DS: 0000 ES: 0000 CR0: 000000008005003b Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861070] CR2: 0000000000000015 CR3: 0000000032a59000 CR4: 0000000000002660 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861073] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861076] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861081] Process telnet (pid: 20247, threadinfo ffff8800f8598000, task ffff8800024d4500) Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861083] Stack: Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861085] 0000000000000000 0000000001aed069 ffff8801dd8339c8 ffff8800024d4500 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861089] <0> ffff8801dd8339c0 ffff8801dd833c90 0000000001aed027 ffff8800024d4500 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861094] <0> ffff8801dd8338d8 0000000000000000 ffff8800024d4500 0000000000000000 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861099] Call Trace: Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861107] [<ffffffff81034bc0>] ? default_wake_function+0x0/0x10 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861113] [<ffffffff8135ebb6>] tty_read+0xa6/0xf0 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861118] [<ffffffff810ee7e5>] vfs_read+0xb5/0x1a0 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861122] [<ffffffff810ee91c>] sys_read+0x4c/0x80 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861127] [<ffffffff81009ba8>] system_call_fastpath+0x16/0x1b Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861131] [<ffffffff81009b40>] ? system_call+0x0/0x52 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861133] Code: 85 d2 0f 84 92 00 00 00 45 8b ac 24 5c 02 00 00 f0 45 0f b3 2e 45 19 ed 49 63 84 24 5c 02 00 00 49 8b 94 24 50 02 00 00 4c 89 ff <0f> be 1c 02 e8 a9 d3 14 00 41 8b 94 24 5c 02 00 00 41 83 ac 24 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861171] RIP [<ffffffff81363dde>] n_tty_read+0x2ce/0x970 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861175] RSP <ffff8800f8599d88> Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861171] RIP [<ffffffff81363dde>] n_tty_read+0x2ce/0x970 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861175] RSP <ffff8800f8599d88> Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861177] CR2: 0000000000000015 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861205] ---[ end trace f10eee2057ff4f6b ]--- Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861547] tty_release_dev: pts0: read/write wait queue active!

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  • panic! apache2 cannot start due to unable to read error.log !

    - by vvvvvvv
    apache2 fails to start because it cannot open error.log I've checked the syslog, and found something troubling... Jan 20 02:58:18 unassigned sm-mta[3559]: o0FAD04C017861: to=<[email protected]>, delay=4+22:45:18, xdelay=00:06:18, mailer=esmtp, pri=63390823, relay=asdfa$ Jan 20 03:00:01 unassigned /USR/SBIN/CRON[3939]: (root) CMD (if [ -x /usr/bin/vnstat ] && [ `ls /var/lib/vnstat/ | wc -l` -ge 1 ]; then /usr/bin/vnstat -u; f$ Jan 20 03:00:01 unassigned /USR/SBIN/CRON[3944]: (smmsp) CMD (test -x /etc/init.d/sendmail && /usr/share/sendmail/sendmail cron-msp) Jan 20 03:00:01 unassigned /USR/SBIN/CRON[3949]: (www-data) CMD ([ -x /usr/lib/cgi-bin/awstats.pl -a -f /etc/awstats/awstats.conf -a -r /var/log/apache/acces$ Jan 20 03:02:48 unassigned kernel: [371919.642705] ata3.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0 Jan 20 03:02:48 unassigned kernel: [371919.642754] ata3.00: BMDMA stat 0x24 Jan 20 03:02:48 unassigned kernel: [371919.642779] ata3.00: cmd 25/00:08:37:59:e2/00:00:42:00:00/e0 tag 0 dma 4096 in Jan 20 03:02:48 unassigned kernel: [371919.642780] res 51/01:00:37:59:e2/01:00:42:00:00/e0 Emask 0x1 (device error) Jan 20 03:02:48 unassigned kernel: [371919.642824] ata3.00: status: { DRDY ERR } Jan 20 03:02:48 unassigned kernel: [371919.657647] ata3.00: configured for UDMA/133 Jan 20 03:02:48 unassigned kernel: [371919.657661] ata3: EH complete Jan 20 03:02:50 unassigned kernel: [371921.857580] ata3.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0 Jan 20 03:02:50 unassigned kernel: [371921.857620] ata3.00: BMDMA stat 0x24 Jan 20 03:02:50 unassigned kernel: [371921.857645] ata3.00: cmd 25/00:08:37:59:e2/00:00:42:00:00/e0 tag 0 dma 4096 in Jan 20 03:02:50 unassigned kernel: [371921.857646] res 51/01:00:37:59:e2/01:00:42:00:00/e0 Emask 0x1 (device error) Jan 20 03:02:50 unassigned kernel: [371921.857688] ata3.00: status: { DRDY ERR } Jan 20 03:02:50 unassigned kernel: [371921.881468] ata3.00: configured for UDMA/133 Jan 20 03:02:54 unassigned kernel: [371921.881479] ata3: EH complete Jan 20 03:02:54 unassigned kernel: [371924.081382] ata3.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0 Jan 20 03:02:54 unassigned kernel: [371924.081417] ata3.00: BMDMA stat 0x24 Jan 20 03:02:54 unassigned kernel: [371924.081443] ata3.00: cmd 25/00:08:37:59:e2/00:00:42:00:00/e0 tag 0 dma 4096 in Jan 20 03:02:54 unassigned kernel: [371924.081444] res 51/01:00:37:59:e2/01:00:42:00:00/e0 Emask 0x1 (device error) Jan 20 03:02:54 unassigned kernel: [371924.081487] ata3.00: status: { DRDY ERR } Jan 20 03:02:54 unassigned kernel: [371924.105252] ata3.00: configured for UDMA/133 Jan 20 03:02:54 unassigned kernel: [371924.105261] ata3: EH complete Jan 20 03:02:54 unassigned kernel: [371933.656925] sd 2:0:0:0: [sda] 1465149168 512-byte hardware sectors (750156 MB) Jan 20 03:02:54 unassigned kernel: [371933.656941] sd 2:0:0:0: [sda] Write Protect is off Jan 20 03:02:54 unassigned kernel: [371933.656944] sd 2:0:0:0: [sda] Mode Sense: 00 3a 00 00 Jan 20 03:02:54 unassigned kernel: [371933.656956] sd 2:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA Jan 20 03:02:54 unassigned kernel: [371933.656972] sd 2:0:0:0: [sda] 1465149168 512-byte hardware sectors (750156 MB) Jan 20 03:02:54 unassigned kernel: [371933.656979] sd 2:0:0:0: [sda] Write Protect is off Jan 20 03:02:54 unassigned kernel: [371933.656982] sd 2:0:0:0: [sda] Mode Sense: 00 3a 00 00 Jan 20 03:02:54 unassigned kernel: [371933.656993] sd 2:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA Jan 20 03:03:34 unassigned kernel: [371966.060069] ata3.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0 Jan 20 03:05:48 unassigned kernel: [371971.776846] ata3.00: BMDMA stat 0x24 Jan 20 03:05:48 unassigned kernel: [371971.776871] ata3.00: cmd 25/00:18:87:10:ee/00:00:42:00:00/e0 tag 0 dma 12288 in Jan 20 03:05:48 unassigned kernel: [371971.776872] res 51/01:00:87:10:ee/01:00:42:00:00/e0 Emask 0x1 (device error) Jan 20 03:05:48 unassigned kernel: [371971.776914] ata3.00: status: { DRDY ERR } Jan 20 03:05:48 unassigned kernel: [371971.800668] ata3.00: configured for UDMA/133 Jan 20 03:05:48 unassigned kernel: [371971.800687] ata3: EH complete Jan 20 03:05:48 unassigned kernel: [371974.157850] ata3.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0 Jan 20 03:05:48 unassigned kernel: [371974.157885] ata3.00: BMDMA stat 0x24 Jan 20 03:05:48 unassigned kernel: [371974.157911] ata3.00: cmd 25/00:18:87:10:ee/00:00:42:00:00/e0 tag 0 dma 12288 in Jan 20 03:05:48 unassigned kernel: [371974.157912] res 51/01:00:88:10:ee/01:00:42:00:00/e0 Emask 0x1 (device error) Jan 20 03:05:48 unassigned kernel: [371974.157956] ata3.00: status: { DRDY ERR } Jan 20 03:05:48 unassigned kernel: [371974.179773] ata3.00: configured for UDMA/133 Jan 20 03:05:48 unassigned kernel: [371974.179786] ata3: EH complete Jan 20 03:05:48 unassigned kernel: [371976.398570] ata3.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0 Jan 20 03:05:48 unassigned kernel: [371976.398610] ata3.00: BMDMA stat 0x24 Jan 20 03:05:48 unassigned kernel: [371976.398635] ata3.00: cmd 25/00:18:87:10:ee/00:00:42:00:00/e0 tag 0 dma 12288 in Jan 20 03:05:48 unassigned kernel: [371976.398636] res 51/01:00:88:10:ee/01:00:42:00:00/e0 Emask 0x1 (device error) Jan 20 03:05:48 unassigned kernel: [371976.398678] ata3.00: status: { DRDY ERR } Jan 20 03:05:48 unassigned kernel: [371976.423477] ata3.00: configured for UDMA/133 Jan 20 03:05:48 unassigned kernel: [371976.423495] sd 2:0:0:0: [sda] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE,SUGGEST_OK Jan 20 03:05:48 unassigned kernel: [371976.423498] sd 2:0:0:0: [sda] Sense Key : Medium Error [current] [descriptor] Jan 20 03:05:48 unassigned kernel: [371976.423501] Descriptor sense data with sense descriptors (in hex): Jan 20 03:05:48 unassigned kernel: [371976.423503] 72 03 13 00 00 00 00 0c 00 0a 80 00 00 00 00 00 Jan 20 03:05:48 unassigned kernel: [371976.423508] 42 ee 10 88 Jan 20 03:05:48 unassigned kernel: [371976.423510] sd 2:0:0:0: [sda] Add. Sense: Address mark not found for data field Jan 20 03:05:48 unassigned kernel: [371976.423515] end_request: I/O error, dev sda, sector 1122898056 Jan 20 03:05:48 unassigned kernel: [371976.423536] ata3: EH complete Jan 20 03:05:48 unassigned kernel: [371978.630504] ata3.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0 Jan 20 03:05:48 unassigned kernel: [371978.630547] ata3.00: BMDMA stat 0x24

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  • What's the best way to read mailing lists in 2011?

    - by Avdi
    I used to use Emacs/GNUS for reading mailing lists, but that feels very 1990. Plus, it doesn't sync my scoring across PCs. GMail is wonderful, but it kind of sucks for mailing lists. The essential "mute" feature doesn't even work unless the mail is in the Inbox. I'd read my mailing lists on the Google Groups site, but not all of them are Google Groups. Basically, I'm looking for the "Google Reader" of mailing lists. Any suggestions?

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  • How can I grant read-only access to my SQL Server 2008 database?

    - by Adrian Grigore
    Hi, I'm trying to grant read-only access (in other words: select queries only) to a user account on my SQL Server 2008 R2 database. Which rights do I have to grant to the user to make this work? I've tried several kinds of combinations of permissions on the server and the database itself, but in all cases the user could still run update queries or he could not run any queries (not even select) at all. The error message I always got was The server principal "foo" is not able to access the database "bar" under the current security context. Thanks for your help, Adrian

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  • using sed, how to change the text on line seven to read seventh?

    - by Steve
    using sed, how to change the text on line seven to read seventh? Steve Blenheim:238-923-7366:95 Latham Lane, Easton, PA 83755:11/12/56:20300 Betty Boop:245-836-8357:635 Cutesy Lane, Hollywood, CA 91464:6/23/23:14500 Igor Chevsky:385-375-8395:3567 Populus Place, Caldwell, NJ 23875:6/18/68:23400 Norma Corder:397-857-2735:74 Pine Street, Dearborn, MI 23874:3/28/45:245700 Jennifer Cowan:548-834-2348:583 Laurel Ave., Kingsville, TX 83745:10/1/35:58900 Jon DeLoach:408-253-3122:123 Park St., San Jose, CA 04086:7/25/53:85100 Karen Evich:284-758-2857:23 Edgecliff Place, Lincoln, NB 92743:7/25/53:85100 Fred Fardbarkle:674-843-1385:20 Parak Lane, Duluth, MN 23850:4/12/23:780900 Lori Gortz:327-832-5728:3465 Mirlo Street, Peabody, MA 34756:10/2/65:35200 Paco Gutierrez:835-365-1284:454 Easy Street, Decatur, IL 75732:2/28/53:123500 Ephram Hardy:293-259-5395:235 CarltonLane, Joliet, IL 73858:8/12/20:56700

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  • Which is faster for read access on EC2; local drive or EBS?

    - by Phillip Oldham
    Which is faster for read access on an EC2 instance; the "local" drive or an attached EBS volume? I have some data that needs to be persisted so have placed this on an EBS volume. I'm using OpenSolaris, so this volume has been attached as a ZFS pool. However, I have a large chunk of EC2 disk space that's going to go unused, so I'm considering re-purposing this as a ZFS cache volume but I don't want to do this if the disk access is going to be slower than that of the EBS volume as it would potentially have a detrimental effect.

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