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  • How to prepare for a programming competition? Graphs, Stacks, Trees, oh my! [closed]

    - by Simucal
    Last semester I attended ACM's (Association for Computing Machinery) bi-annual programming competition at a local University. My University sent 2 teams of 3 people and we competed amongst other schools in the mid-west. We got our butts kicked. You are given a packet with about 11 problems (1 problem per page) and you have 4 hours to solve as many as you can. They'll run your program you submit against a set of data and your output must match theirs exactly. In fact, the judging is automated for the most part. In any case.. I went there fairly confident in my programming skills and I left there feeling drained and weak. It was a terribly humbling experience. In 4 hours my team of 3 people completed only one of the problems. The top team completed 4 of them and took 1st place. The problems they asked were like no problems I have ever had to answer before. I later learned that in order to solve them some of them effectively you have to use graphs/graph algorithms, trees, stacks. Some of them were simply "greedy" algo's. My question is, how can I better prepare for this semesters programming competition so I don't leave there feeling like a complete moron? What tips do you have for me to be able to answer these problems that involve graphs, trees, various "well known" algorithms? How can I easily identify the algorithm we should implement for a given problem? I have yet to take Algorithm Design in school so I just feel a little out of my element. Here are some examples of the questions asked at the competitions: ACM Problem Sets Update: Just wanted to update this since the latest competition is over. My team placed 1st for our small region (about 6-7 universities with between 1-5 teams each school) and ~15th for the midwest! So, it is a marked improvement over last years performance for sure. We also had no graduate students on our team and after reviewing the rules we found out that many teams had several! So, that would be a pretty big advantage in my own opinion. Problems this semester ranged from about 1-2 "easy" problems (ie bit manipulation, string manipulation) to hard (graph problems involving fairly complex math and network flow problems). We were able to solve 4 problems in our 5 hours. Just wanted to thank everyone for the resources they provided here, we used them for our weekly team practices and it definitely helped! Some quick tips that I have that aren't suggested below: When you are seated at your computer before the competition starts, quickly type out various data structures that you might need that you won't have access to in your languages libraries. I typed out a Graph data-structure complete with floyd-warshall and dijkstra's algorithm before the competition began. We ended up using it in our 2nd problem that we solved and this is the main reason why we solved this problem before anyone else in the midwest. We had it ready to go from the beginning. Similarly, type out the code to read in a file since this will be required for every problem. Save this answer "template" someplace so you can quickly copy/paste it to your IDE at the beginning of each problem. There are no rules on programming anything before the competition starts so get any boilerplate code out the way. We found it useful to have one person who is on permanent whiteboard duty. This is usually the person who is best at math and at working out solutions to get a head start on future problems you will be doing. One person is on permanent programming duty. Your fastest/most skilled "programmer" (most familiar with the language). This will save debugging time also. The last person has several roles between assessing the packet of problems for the next "easiest" problem, helping the person on the whiteboard work out solutions and helping the person programming work out bugs/issues. This person needs to be flexible and be able to switch between roles easily.

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  • MacBook Pro Late 2009 SATA Resets, Slowness (Is my motherboard dying on both machines?)

    - by A Student at a University
    My MacBook Pro runs slower the longer it's on. I am getting kernel warnings. Some, but not all, resets correlate with AC power connects and disconnects. I don't think the warnings do. (How do I tell?) What are these errors? What causes them? Can this damage the drive or corrupt data? What is it seeing that motivates these? 02:37:16[ 0.791992] ahci 0000:00:0b.0: PCI INT A -> Link[LSI0] -> GSI 20 (level, low) -> IRQ 20 02:37:16[ 0.792047] ahci 0000:00:0b.0: irq 43 for MSI/MSI-X 02:37:16[ 0.792053] ahci 0000:00:0b.0: controller can't do PMP, turning off CAP_PMP 02:37:16[ 0.792104] ahci 0000:00:0b.0: AHCI 0001.0200 32 slots 6 ports 1.5 Gbps 0x3 impl IDE mode 02:37:16[ 0.792107] ahci 0000:00:0b.0: flags: 64bit ncq sntf pm led pio slum part boh 02:37:16[ 0.792111] ahci 0000:00:0b.0: setting latency timer to 64 02:37:16[ 0.813473] scsi0 : ahci 02:37:16[ 0.823340] scsi1 : ahci 02:37:16[ 0.848164] ata1: SATA max UDMA/133 abar m8192@0xe7484000 port 0xe7484100 irq 43 02:37:16[ 0.848166] ata2: SATA max UDMA/133 abar m8192@0xe7484000 port 0xe7484180 irq 43 02:37:16[ 1.190132] ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 300) 02:37:16[ 1.190153] ata2: SATA link up 1.5 Gbps (SStatus 113 SControl 300) 02:37:16[ 1.213568] ata1.00: ATA-8: OCZ-VERTEX2, 1.23, max UDMA/133 02:37:16[ 1.213572] ata1.00: 195371568 sectors, multi 1: LBA48 NCQ (depth 31/32) 02:37:16[ 1.227293] ata2.00: ATA-8: ST9500420ASG, 0002SDM1, max UDMA/133 02:37:16[ 1.227297] ata2.00: 976773168 sectors, multi 16: LBA48 NCQ (depth 31/32) 02:37:16[ 1.229570] ata2.00: configured for UDMA/133 02:37:16[ 1.240120] ata2: exception Emask 0x10 SAct 0x0 SErr 0x5850000 action 0xe frozen 02:37:16[ 1.240123] ata2: irq_stat 0x00000040, connection status changed 02:37:16[ 1.240127] ata2: SError: { PHYRdyChg CommWake LinkSeq TrStaTrns DevExch } 02:37:16[ 1.240133] ata2: hard resetting link 02:37:16[ 1.260738] ata1.00: configured for UDMA/133 02:37:16[ 1.280111] ata1: exception Emask 0x10 SAct 0x0 SErr 0x5850000 action 0xe frozen 02:37:16[ 1.280114] ata1: irq_stat 0x00000040, connection status changed 02:37:16[ 1.280118] ata1: SError: { PHYRdyChg CommWake LinkSeq TrStaTrns DevExch } 02:37:16[ 1.280122] ata1: hard resetting link 02:37:16[ 1.990101] ata2: SATA link up 1.5 Gbps (SStatus 113 SControl 300) 02:37:16[ 1.994215] ata2.00: configured for UDMA/133 02:37:16[ 1.994220] ata2: EH complete 02:37:16[ 2.030097] ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 300) 02:37:16[ 2.090773] ata1.00: configured for UDMA/133 02:37:16[ 2.090778] ata1: EH complete 02:37:16[ 2.090931] scsi 0:0:0:0: Direct-Access ATA OCZ-VERTEX2 1.23 PQ: 0 ANSI: 5 02:37:16[ 2.091045] sd 0:0:0:0: Attached scsi generic sg0 type 0 02:37:16[ 2.091121] sd 0:0:0:0: [sda] 195371568 512-byte logical blocks: (100 GB/93.1 GiB) 02:37:16[ 2.091159] scsi 1:0:0:0: Direct-Access ATA ST9500420ASG 0002 PQ: 0 ANSI: 5 02:37:16[ 2.091163] sd 0:0:0:0: [sda] Write Protect is off 02:37:16[ 2.091165] sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00 02:37:16[ 2.091183] sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA 02:37:16[ 2.091252] sd 1:0:0:0: Attached scsi generic sg1 type 0 02:37:16[ 2.091446] sd 1:0:0:0: [sdb] 976773168 512-byte logical blocks: (500 GB/465 GiB) 02:37:16[ 2.091580] sd 1:0:0:0: [sdb] Write Protect is off 02:37:16[ 2.091582] sd 1:0:0:0: [sdb] Mode Sense: 00 3a 00 00 02:37:16[ 2.091637] sd 1:0:0:0: [sdb] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA 02:37:16[ 2.093140] sd 0:0:0:0: [sda] Attached SCSI disk 02:37:16[ 2.093773] sd 1:0:0:0: [sdb] Attached SCSI disk 02:37:16[ 2.693899] EXT4-fs (dm-0): mounted filesystem with ordered data mode. Opts: (null) 02:37:16[ 5.483492] EXT4-fs (dm-0): re-mounted. Opts: errors=remount-ro 02:37:16[ 7.905040] EXT4-fs (dm-2): mounted filesystem with ordered data mode. Opts: (null) 02:37:25[ 19.553095] EXT4-fs (dm-0): re-mounted. Opts: errors=remount-ro,commit=600 02:37:25[ 19.555266] EXT4-fs (dm-2): re-mounted. Opts: commit=600 02:37:25[ 19.641532] ata1: exception Emask 0x10 SAct 0x0 SErr 0x5950000 action 0xe frozen t4 02:37:25[ 19.641532] ata1: irq_stat 0x00000040, connection status changed 02:37:25[ 19.641532] ata1: SError: { PHYRdyChg CommWake Dispar LinkSeq TrStaTrns DevExch } 02:37:25[ 19.641533] ata1: hard resetting link 02:37:25[ 19.642076] ata2: exception Emask 0x10 SAct 0x0 SErr 0x5950000 action 0xe frozen t4 02:37:25[ 19.642078] ata2: irq_stat 0x00000040, connection status changed 02:37:25[ 19.642081] ata2: SError: { PHYRdyChg CommWake Dispar LinkSeq TrStaTrns DevExch } 02:37:25[ 19.642084] ata2: hard resetting link 02:37:26[ 20.392606] ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 300) 02:37:26[ 20.392610] ata2: SATA link up 1.5 Gbps (SStatus 113 SControl 300) 02:37:26[ 20.396697] ata2.00: configured for UDMA/133 02:37:26[ 20.396703] ata2: EH complete 02:37:26[ 20.451491] ata1.00: configured for UDMA/133 02:37:26[ 20.451498] ata1: EH complete 02:37:30[ 24.563725] EXT4-fs (dm-0): re-mounted. Opts: errors=remount-ro,commit=600 02:37:30[ 24.565939] EXT4-fs (dm-2): re-mounted. Opts: commit=600 02:37:30[ 24.627236] ata1: exception Emask 0x10 SAct 0x0 SErr 0x5900000 action 0xe frozen t4 02:37:30[ 24.627240] ata1: irq_stat 0x00000040, connection status changed 02:37:30[ 24.627242] ata1: SError: { Dispar LinkSeq TrStaTrns DevExch } 02:37:30[ 24.627246] ata1: hard resetting link 02:37:30[ 24.632241] ata2: exception Emask 0x10 SAct 0x0 SErr 0x5950000 action 0xe frozen t4 02:37:30[ 24.632244] ata2: irq_stat 0x00000040, connection status changed 02:37:30[ 24.632247] ata2: SError: { PHYRdyChg CommWake Dispar LinkSeq TrStaTrns DevExch } 02:37:30[ 24.632250] ata2: hard resetting link 02:37:31[ 25.372582] ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 300) 02:37:31[ 25.382615] ata2: SATA link up 1.5 Gbps (SStatus 113 SControl 300) 02:37:31[ 25.386782] ata2.00: configured for UDMA/133 02:37:31[ 25.386788] ata2: EH complete 02:37:31[ 25.431668] ata1.00: configured for UDMA/133 02:37:31[ 25.431674] ata1: EH complete 02:45:54[ 529.141844] EXT4-fs (dm-0): re-mounted. Opts: errors=remount-ro,commit=0 02:45:55[ 529.544529] EXT4-fs (dm-2): re-mounted. Opts: commit=0 02:45:55[ 529.622561] ata1: limiting SATA link speed to 1.5 Gbps 02:45:55[ 529.622568] ata1: exception Emask 0x10 SAct 0x0 SErr 0x5850000 action 0xe frozen 02:45:55[ 529.622572] ata1: irq_stat 0x00400040, connection status changed 02:45:55[ 529.622576] ata1: SError: { PHYRdyChg CommWake LinkSeq TrStaTrns DevExch } 02:45:55[ 529.622583] ata1: hard resetting link 02:45:55[ 529.622609] ata2: limiting SATA link speed to 1.5 Gbps 02:45:55[ 529.622613] ata2: exception Emask 0x10 SAct 0x0 SErr 0x5950000 action 0xe frozen 02:45:55[ 529.622616] ata2: irq_stat 0x00000040, connection status changed 02:45:55[ 529.622620] ata2: SError: { PHYRdyChg CommWake Dispar LinkSeq TrStaTrns DevExch } 02:45:55[ 529.622624] ata2: hard resetting link 02:45:56[ 530.380135] ata2: SATA link up 1.5 Gbps (SStatus 113 SControl 310) 02:45:56[ 530.380157] ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 310) 02:45:56[ 530.384305] ata2.00: configured for UDMA/133 02:45:56[ 530.384314] ata2: EH complete 02:45:56[ 530.399225] ata1.00: configured for UDMA/133 02:45:56[ 530.399233] ata1: EH complete 02:45:58[ 532.395990] EXT4-fs (dm-0): re-mounted. Opts: errors=remount-ro,commit=600 02:45:58[ 532.518270] EXT4-fs (dm-2): re-mounted. Opts: commit=600 02:45:58[ 532.590968] ata1: exception Emask 0x10 SAct 0x0 SErr 0x5840000 action 0xe frozen t4 02:45:58[ 532.590973] ata1: irq_stat 0x00000040, connection status changed 02:45:58[ 532.590977] ata1: SError: { CommWake LinkSeq TrStaTrns DevExch } 02:45:58[ 532.590983] ata1: hard resetting link 02:45:58[ 532.591034] ata2: exception Emask 0x10 SAct 0x0 SErr 0x5950000 action 0xe frozen t4 02:45:58[ 532.591037] ata2: irq_stat 0x00000040, connection status changed 02:45:58[ 532.591041] ata2: SError: { PHYRdyChg CommWake Dispar LinkSeq TrStaTrns DevExch } 02:45:58[ 532.591045] ata2: hard resetting link 02:45:59[ 533.340147] ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 310) 02:45:59[ 533.340168] ata2: SATA link up 1.5 Gbps (SStatus 113 SControl 310) 02:45:59[ 533.344416] ata2.00: configured for UDMA/133 02:45:59[ 533.344424] ata2: EH complete 02:45:59[ 533.360839] ata1.00: configured for UDMA/133 02:45:59[ 533.360847] ata1: EH complete 02:45:59[ 533.584449] EXT4-fs (dm-0): re-mounted. Opts: errors=remount-ro,commit=0 02:45:59[ 533.586999] EXT4-fs (dm-2): re-mounted. Opts: commit=0 02:45:59[ 533.660117] ata2: exception Emask 0x10 SAct 0x0 SErr 0x5950000 action 0xe frozen 02:45:59[ 533.660122] ata2: irq_stat 0x00000040, connection status changed 02:45:59[ 533.660126] ata2: SError: { PHYRdyChg CommWake Dispar LinkSeq TrStaTrns DevExch } 02:45:59[ 533.660132] ata2: hard resetting link 02:45:59[ 533.660141] ata1: exception Emask 0x10 SAct 0x0 SErr 0x5850000 action 0xe frozen 02:45:59[ 533.660143] ata1: irq_stat 0x00000040, connection status changed 02:45:59[ 533.660147] ata1: SError: { PHYRdyChg CommWake LinkSeq TrStaTrns DevExch } 02:45:59[ 533.660151] ata1: hard resetting link 02:46:00[ 534.412536] ata2: SATA link up 1.5 Gbps (SStatus 113 SControl 310) 02:46:00[ 534.412562] ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 310) 02:46:00[ 534.416768] ata2.00: configured for UDMA/133 02:46:00[ 534.416777] ata2: EH complete 02:46:00[ 534.431396] ata1.00: configured for UDMA/133 02:46:00[ 534.431401] ata1: EH complete 02:46:03[ 537.384649] EXT4-fs (dm-0): re-mounted. Opts: errors=remount-ro,commit=600 02:46:03[ 537.504214] EXT4-fs (dm-2): re-mounted. Opts: commit=600 02:46:03[ 537.585992] ata1: exception Emask 0x10 SAct 0x0 SErr 0x5900000 action 0xe frozen t4 02:46:03[ 537.585996] ata1: irq_stat 0x00000040, connection status changed 02:46:03[ 537.585999] ata1: SError: { Dispar LinkSeq TrStaTrns DevExch } 02:46:03[ 537.586002] ata1: hard resetting link 02:46:03[ 537.586028] ata2: exception Emask 0x10 SAct 0x0 SErr 0x5950000 action 0xe frozen t4 02:46:03[ 537.586030] ata2: irq_stat 0x00000040, connection status changed 02:46:03[ 537.586033] ata2: SError: { PHYRdyChg CommWake Dispar LinkSeq TrStaTrns DevExch } 02:46:03[ 537.586036] ata2: hard resetting link 02:46:04[ 538.330147] ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 310) 02:46:04[ 538.330168] ata2: SATA link up 1.5 Gbps (SStatus 113 SControl 310) 02:46:04[ 538.334389] ata2.00: configured for UDMA/133 02:46:04[ 538.334398] ata2: EH complete 02:46:04[ 538.343511] ata1.00: configured for UDMA/133 02:46:04[ 538.343519] ata1: EH complete 02:46:04[ 538.456413] EXT4-fs (dm-0): re-mounted. Opts: errors=remount-ro,commit=0 02:46:04[ 538.459404] EXT4-fs (dm-2): re-mounted. Opts: commit=0 02:46:04[ 538.540138] ata1.00: limiting speed to UDMA/100:PIO4 02:46:04[ 538.540144] ata1: exception Emask 0x10 SAct 0x0 SErr 0x5850000 action 0xe frozen 02:46:04[ 538.540148] ata1: irq_stat 0x00000040, connection status changed 02:46:04[ 538.540153] ata1: SError: { PHYRdyChg CommWake LinkSeq TrStaTrns DevExch } 02:46:04[ 538.540159] ata1: hard resetting link 02:46:04[ 538.540202] ata2.00: limiting speed to UDMA/100:PIO4 02:46:04[ 538.540207] ata2: exception Emask 0x10 SAct 0x0 SErr 0x5950000 action 0xe frozen 02:46:04[ 538.540211] ata2: irq_stat 0x00000040, connection status changed 02:46:04[ 538.540215] ata2: SError: { PHYRdyChg CommWake Dispar LinkSeq TrStaTrns DevExch } 02:46:04[ 538.540220] ata2: hard resetting link 02:46:05[ 539.290054] ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 310) 02:46:05[ 539.290041] ata2: SATA link up 1.5 Gbps (SStatus 113 SControl 310) 02:46:05[ 539.294100] ata2.00: configured for UDMA/100 02:46:05[ 539.294106] ata2: EH complete 02:46:05[ 539.314125] ata1.00: configured for UDMA/100 02:46:05[ 539.314132] ------------[ cut here ]------------ 02:46:05[ 539.314140] WARNING: at /build/buildd/linux-2.6.35/drivers/ata/libata-eh.c:3638 ata_eh_finish+0xdf/0xf0() 02:46:05[ 539.314144] Hardware name: MacBookPro5,3 02:46:05[ 539.314146] Modules linked in: michael_mic arc4 xt_multiport binfmt_misc rfcomm sco bnep l2cap parport_pc ppdev nvidia(P) ipt_REJECT xt_recent snd_hda_codec_cirrus xt_limit xt_tcpudp ipt_addrtype xt_state snd_hda_intel snd_hda_codec snd_hwdep snd_pcm snd_seq_midi applesmc led_class ip6table_filter lib80211_crypt_tkip snd_rawmidi snd_seq_midi_event ip6_tables input_polldev hid_apple snd_seq wl(P) snd_timer snd_seq_device snd joydev bcm5974 usbhid mbp_nvidia_bl uvcvideo btusb videodev v4l1_compat v4l2_compat_ioctl32 nf_nat_irc hid nf_conntrack_irc soundcore snd_page_alloc i2c_nforce2 coretemp lib80211 bluetooth nf_nat_ftp nf_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_conntrack_ftp nf_conntrack lp parport iptable_filter ip_tables x_tables usb_storage firewire_ohci firewire_core forcedeth crc_itu_t ahci libahci 02:46:05[ 539.314221] Pid: 202, comm: scsi_eh_0 Tainted: P 2.6.35-25-generic #44-Ubuntu 02:46:05[ 539.314224] Call Trace: 02:46:05[ 539.314233] [<ffffffff8106091f>] warn_slowpath_common+0x7f/0xc0 02:46:05[ 539.314237] [<ffffffff8106097a>] warn_slowpath_null+0x1a/0x20 02:46:05[ 539.314242] [<ffffffff813dc77f>] ata_eh_finish+0xdf/0xf0 02:46:05[ 539.314246] [<ffffffff813e441e>] sata_pmp_error_handler+0x2e/0x40 02:46:05[ 539.314256] [<ffffffffa00021bf>] ahci_error_handler+0x1f/0x90 [libahci] 02:46:05[ 539.314261] [<ffffffff813dd6d2>] ata_scsi_error+0x492/0x5e0 02:46:05[ 539.314266] [<ffffffff813b24cd>] scsi_error_handler+0x10d/0x190 02:46:05[ 539.314270] [<ffffffff813b23c0>] ? scsi_error_handler+0x0/0x190 02:46:05[ 539.314275] [<ffffffff8107f266>] kthread+0x96/0xa0 02:46:05[ 539.314280] [<ffffffff8100aee4>] kernel_thread_helper+0x4/0x10 02:46:05[ 539.314284] [<ffffffff8107f1d0>] ? kthread+0x0/0xa0 02:46:05[ 539.314288] [<ffffffff8100aee0>] ? kernel_thread_helper+0x0/0x10 02:46:05[ 539.314291] ---[ end trace 76dbffc2d5d49d9b ]--- 02:46:05[ 539.314296] ata1: EH complete 02:46:12[ 547.040091] ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen 02:46:12[ 547.040098] ata1.00: failed command: IDENTIFY DEVICE 02:46:12[ 547.040106] ata1.00: cmd ec/00:00:00:00:00/00:00:00:00:00/40 tag 0 pio 512 in 02:46:12[ 547.040108] res 40/00:01:00:00:00/00:00:00:00:00/e0 Emask 0x4 (timeout) 02:46:12[ 547.040111] ata1.00: status: { DRDY } 02:46:12[ 547.040117] ata1: hard resetting link 02:46:13[ 547.390144] ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 310) 02:46:13[ 547.408430] ata1.00: configured for UDMA/100 02:46:13[ 547.408438] ------------[ cut here ]------------ 02:46:13[ 547.408447] WARNING: at /build/buildd/linux-2.6.35/drivers/ata/libata-eh.c:3638 ata_eh_finish+0xdf/0xf0() 02:46:13[ 547.408451] Hardware name: MacBookPro5,3 02:46:13[ 547.408453] Modules linked in: michael_mic arc4 xt_multiport binfmt_misc rfcomm sco bnep l2cap parport_pc ppdev nvidia(P) ipt_REJECT xt_recent snd_hda_codec_cirrus xt_limit xt_tcpudp ipt_addrtype xt_state snd_hda_intel snd_hda_codec snd_hwdep snd_pcm snd_seq_midi applesmc led_class ip6table_filter lib80211_crypt_tkip snd_rawmidi snd_seq_midi_event ip6_tables input_polldev hid_apple snd_seq wl(P) snd_timer snd_seq_device snd joydev bcm5974 usbhid mbp_nvidia_bl uvcvideo btusb videodev v4l1_compat v4l2_compat_ioctl32 nf_nat_irc hid nf_conntrack_irc soundcore snd_page_alloc i2c_nforce2 coretemp lib80211 bluetooth nf_nat_ftp nf_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_conntrack_ftp nf_conntrack lp parport iptable_filter ip_tables x_tables usb_storage firewire_ohci firewire_core forcedeth crc_itu_t ahci libahci 02:46:13[ 547.408528] Pid: 202, comm: scsi_eh_0 Tainted: P W 2.6.35-25-generic #44-Ubuntu 02:46:13[ 547.408531] Call Trace: 02:46:13[ 547.408540] [<ffffffff8106091f>] warn_slowpath_common+0x7f/0xc0 02:46:13[ 547.408544] [<ffffffff8106097a>] warn_slowpath_null+0x1a/0x20 02:46:13[ 547.408549] [<ffffffff813dc77f>] ata_eh_finish+0xdf/0xf0 02:46:13[ 547.408553] [<ffffffff813e441e>] sata_pmp_error_handler+0x2e/0x40 02:46:13[ 547.408563] [<ffffffffa00021bf>] ahci_error_handler+0x1f/0x90 [libahci] 02:46:13[ 547.408567] [<ffffffff813dd6d2>] ata_scsi_error+0x492/0x5e0 02:46:13[ 547.408572] [<ffffffff813b24cd>] scsi_error_handler+0x10d/0x190 02:46:13[ 547.408577] [<ffffffff813b23c0>] ? scsi_error_handler+0x0/0x190 02:46:13[ 547.408582] [<ffffffff8107f266>] kthread+0x96/0xa0 02:46:13[ 547.408587] [<ffffffff8100aee4>] kernel_thread_helper+0x4/0x10 02:46:13[ 547.408591] [<ffffffff8107f1d0>] ? kthread+0x0/0xa0 02:46:13[ 547.408595] [<ffffffff8100aee0>] ? kernel_thread_helper+0x0/0x10 02:46:13[ 547.408598] ---[ end trace 76dbffc2d5d49d9c ]--- 02:46:13[ 547.408620] ata1: EH complete 02:46:13[ 547.562470] EXT4-fs (dm-0): re-mounted. Opts: errors=remount-ro,commit=600 02:46:13[ 547.671380] EXT4-fs (dm-2): re-mounted. Opts: commit=600 02:46:13[ 547.738198] ata1.00: limiting speed to UDMA/33:PIO4 02:46:13[ 547.738204] ata1: exception Emask 0x10 SAct 0x0 SErr 0x5800000 action 0xe frozen t4 02:46:13[ 547.738208] ata1: irq_stat 0x00000040, connection status changed 02:46:13[ 547.738212] ata1: SError: { LinkSeq TrStaTrns DevExch } 02:46:13[ 547.738218] ata1: hard resetting link 02:46:13[ 547.738262] ata2: exception Emask 0x10 SAct 0x0 SErr 0x5900000 action 0xe frozen t4 02:46:13[ 547.738265] ata2: irq_stat 0x00000040, connection status changed 02:46:13[ 547.738269] ata2: SError: { Dispar LinkSeq TrStaTrns DevExch } 02:46:13[ 547.738274] ata2: hard resetting link 02:46:14[ 548.482561] ata2: SATA link up 1.5 Gbps (SStatus 113 SControl 310) 02:46:14[ 548.484083] ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 310) 02:46:14[ 548.486809] ata2.00: configured for UDMA/100 02:46:14[ 548.486818] ata2: EH complete 02:46:14[ 548.498998] ata1.00: configured for UDMA/33 02:46:14[ 548.499004] ata1: EH complete 02:46:18[ 552.410499] EXT4-fs (dm-0): re-mounted. Opts: errors=remount-ro,commit=600 02:46:18[ 552.522521] EXT4-fs (dm-2): re-mounted. Opts: commit=600 02:46:18[ 552.529674] ata1: exception Emask 0x10 SAct 0x0 SErr 0x5800000 action 0xe frozen t4 02:46:18[ 552.529678] ata1: irq_stat 0x00000040, connection status changed 02:46:18[ 552.529680] ata1: SError: { LinkSeq TrStaTrns DevExch } 02:46:18[ 552.529684] ata1: hard resetting link 02:46:18[ 552.529716] ata2: exception Emask 0x10 SAct 0x0 SErr 0x5800000 action 0xe frozen t4 02:46:18[ 552.529718] ata2: irq_stat 0x00000040, connection status changed 02:46:18[ 552.529720] ata2: SError: { LinkSeq TrStaTrns DevExch } 02:46:18[ 552.529723] ata2: hard resetting link 02:46:19[ 553.280059] ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 310) 02:46:19[ 553.280068] ata2: SATA link up 1.5 Gbps (SStatus 113 SControl 310) 02:46:19[ 553.284141] ata2.00: configured for UDMA/100 02:46:19[ 553.284150] ata2: EH complete 02:46:19[ 553.301629] ata1.00: configured for UDMA/33 02:46:19[ 553.301637] ata1: EH complete

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  • Are there deprecated practices for multithread and multiprocessor programming that I should no longer use?

    - by DeveloperDon
    In the early days of FORTRAN and BASIC, essentially all programs were written with GOTO statements. The result was spaghetti code and the solution was structured programming. Similarly, pointers can have difficult to control characteristics in our programs. C++ started with plenty of pointers, but use of references are recommended. Libraries like STL can reduce some of our dependency. There are also idioms to create smart pointers that have better characteristics, and some version of C++ permit references and managed code. Programming practices like inheritance and polymorphism use a lot of pointers behind the scenes (just as for, while, do structured programming generates code filled with branch instructions). Languages like Java eliminate pointers and use garbage collection to manage dynamically allocated data instead of depending on programmers to match all their new and delete statements. In my reading, I have seen examples of multi-process and multi-thread programming that don't seem to use semaphores. Do they use the same thing with different names or do they have new ways of structuring protection of resources from concurrent use? For example, a specific example of a system for multithread programming with multicore processors is OpenMP. It represents a critical region as follows, without the use of semaphores, which seem not to be included in the environment. th_id = omp_get_thread_num(); #pragma omp critical { cout << "Hello World from thread " << th_id << '\n'; } This example is an excerpt from: http://en.wikipedia.org/wiki/OpenMP Alternatively, similar protection of threads from each other using semaphores with functions wait() and signal() might look like this: wait(sem); th_id = get_thread_num(); cout << "Hello World from thread " << th_id << '\n'; signal(sem); In this example, things are pretty simple, and just a simple review is enough to show the wait() and signal() calls are matched and even with a lot of concurrency, thread safety is provided. But other algorithms are more complicated and use multiple semaphores (both binary and counting) spread across multiple functions with complex conditions that can be called by many threads. The consequences of creating deadlock or failing to make things thread safe can be hard to manage. Do these systems like OpenMP eliminate the problems with semaphores? Do they move the problem somewhere else? How do I transform my favorite semaphore using algorithm to not use semaphores anymore?

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  • MacBook Pro Late 2009 SATA Resets, Slowness (Is my motherboard dying on both machines?)

    - by A Student at a University
    My MacBook Pro runs slower the longer it's on. I am getting kernel warnings. Some, but not all, resets correlate with AC power connects and disconnects. I don't think the warnings do. (How do I tell?) What are these errors? What causes them? Can this damage the drive or corrupt data? What is it seeing that motivates these? 02:37:16[ 0.791992] ahci 0000:00:0b.0: PCI INT A -> Link[LSI0] -> GSI 20 (level, low) -> IRQ 20 02:37:16[ 0.792047] ahci 0000:00:0b.0: irq 43 for MSI/MSI-X 02:37:16[ 0.792053] ahci 0000:00:0b.0: controller can't do PMP, turning off CAP_PMP 02:37:16[ 0.792104] ahci 0000:00:0b.0: AHCI 0001.0200 32 slots 6 ports 1.5 Gbps 0x3 impl IDE mode 02:37:16[ 0.792107] ahci 0000:00:0b.0: flags: 64bit ncq sntf pm led pio slum part boh 02:37:16[ 0.792111] ahci 0000:00:0b.0: setting latency timer to 64 02:37:16[ 0.813473] scsi0 : ahci 02:37:16[ 0.823340] scsi1 : ahci 02:37:16[ 0.848164] ata1: SATA max UDMA/133 abar m8192@0xe7484000 port 0xe7484100 irq 43 02:37:16[ 0.848166] ata2: SATA max UDMA/133 abar m8192@0xe7484000 port 0xe7484180 irq 43 02:37:16[ 1.190132] ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 300) 02:37:16[ 1.190153] ata2: SATA link up 1.5 Gbps (SStatus 113 SControl 300) 02:37:16[ 1.213568] ata1.00: ATA-8: OCZ-VERTEX2, 1.23, max UDMA/133 02:37:16[ 1.213572] ata1.00: 195371568 sectors, multi 1: LBA48 NCQ (depth 31/32) 02:37:16[ 1.227293] ata2.00: ATA-8: ST9500420ASG, 0002SDM1, max UDMA/133 02:37:16[ 1.227297] ata2.00: 976773168 sectors, multi 16: LBA48 NCQ (depth 31/32) 02:37:16[ 1.229570] ata2.00: configured for UDMA/133 02:37:16[ 1.240120] ata2: exception Emask 0x10 SAct 0x0 SErr 0x5850000 action 0xe frozen 02:37:16[ 1.240123] ata2: irq_stat 0x00000040, connection status changed 02:37:16[ 1.240127] ata2: SError: { PHYRdyChg CommWake LinkSeq TrStaTrns DevExch } 02:37:16[ 1.240133] ata2: hard resetting link 02:37:16[ 1.260738] ata1.00: configured for UDMA/133 02:37:16[ 1.280111] ata1: exception Emask 0x10 SAct 0x0 SErr 0x5850000 action 0xe frozen 02:37:16[ 1.280114] ata1: irq_stat 0x00000040, connection status changed 02:37:16[ 1.280118] ata1: SError: { PHYRdyChg CommWake LinkSeq TrStaTrns DevExch } 02:37:16[ 1.280122] ata1: hard resetting link 02:37:16[ 1.990101] ata2: SATA link up 1.5 Gbps (SStatus 113 SControl 300) 02:37:16[ 1.994215] ata2.00: configured for UDMA/133 02:37:16[ 1.994220] ata2: EH complete 02:37:16[ 2.030097] ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 300) 02:37:16[ 2.090773] ata1.00: configured for UDMA/133 02:37:16[ 2.090778] ata1: EH complete 02:37:16[ 2.090931] scsi 0:0:0:0: Direct-Access ATA OCZ-VERTEX2 1.23 PQ: 0 ANSI: 5 02:37:16[ 2.091045] sd 0:0:0:0: Attached scsi generic sg0 type 0 02:37:16[ 2.091121] sd 0:0:0:0: [sda] 195371568 512-byte logical blocks: (100 GB/93.1 GiB) 02:37:16[ 2.091159] scsi 1:0:0:0: Direct-Access ATA ST9500420ASG 0002 PQ: 0 ANSI: 5 02:37:16[ 2.091163] sd 0:0:0:0: [sda] Write Protect is off 02:37:16[ 2.091165] sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00 02:37:16[ 2.091183] sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA 02:37:16[ 2.091252] sd 1:0:0:0: Attached scsi generic sg1 type 0 02:37:16[ 2.091446] sd 1:0:0:0: [sdb] 976773168 512-byte logical blocks: (500 GB/465 GiB) 02:37:16[ 2.091580] sd 1:0:0:0: [sdb] Write Protect is off 02:37:16[ 2.091582] sd 1:0:0:0: [sdb] Mode Sense: 00 3a 00 00 02:37:16[ 2.091637] sd 1:0:0:0: [sdb] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA 02:37:16[ 2.093140] sd 0:0:0:0: [sda] Attached SCSI disk 02:37:16[ 2.093773] sd 1:0:0:0: [sdb] Attached SCSI disk 02:37:16[ 2.693899] EXT4-fs (dm-0): mounted filesystem with ordered data mode. Opts: (null) 02:37:16[ 5.483492] EXT4-fs (dm-0): re-mounted. Opts: errors=remount-ro 02:37:16[ 7.905040] EXT4-fs (dm-2): mounted filesystem with ordered data mode. Opts: (null) 02:37:25[ 19.553095] EXT4-fs (dm-0): re-mounted. Opts: errors=remount-ro,commit=600 02:37:25[ 19.555266] EXT4-fs (dm-2): re-mounted. Opts: commit=600 02:37:25[ 19.641532] ata1: exception Emask 0x10 SAct 0x0 SErr 0x5950000 action 0xe frozen t4 02:37:25[ 19.641532] ata1: irq_stat 0x00000040, connection status changed 02:37:25[ 19.641532] ata1: SError: { PHYRdyChg CommWake Dispar LinkSeq TrStaTrns DevExch } 02:37:25[ 19.641533] ata1: hard resetting link 02:37:25[ 19.642076] ata2: exception Emask 0x10 SAct 0x0 SErr 0x5950000 action 0xe frozen t4 02:37:25[ 19.642078] ata2: irq_stat 0x00000040, connection status changed 02:37:25[ 19.642081] ata2: SError: { PHYRdyChg CommWake Dispar LinkSeq TrStaTrns DevExch } 02:37:25[ 19.642084] ata2: hard resetting link 02:37:26[ 20.392606] ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 300) 02:37:26[ 20.392610] ata2: SATA link up 1.5 Gbps (SStatus 113 SControl 300) 02:37:26[ 20.396697] ata2.00: configured for UDMA/133 02:37:26[ 20.396703] ata2: EH complete 02:37:26[ 20.451491] ata1.00: configured for UDMA/133 02:37:26[ 20.451498] ata1: EH complete 02:37:30[ 24.563725] EXT4-fs (dm-0): re-mounted. Opts: errors=remount-ro,commit=600 02:37:30[ 24.565939] EXT4-fs (dm-2): re-mounted. Opts: commit=600 02:37:30[ 24.627236] ata1: exception Emask 0x10 SAct 0x0 SErr 0x5900000 action 0xe frozen t4 02:37:30[ 24.627240] ata1: irq_stat 0x00000040, connection status changed 02:37:30[ 24.627242] ata1: SError: { Dispar LinkSeq TrStaTrns DevExch } 02:37:30[ 24.627246] ata1: hard resetting link 02:37:30[ 24.632241] ata2: exception Emask 0x10 SAct 0x0 SErr 0x5950000 action 0xe frozen t4 02:37:30[ 24.632244] ata2: irq_stat 0x00000040, connection status changed 02:37:30[ 24.632247] ata2: SError: { PHYRdyChg CommWake Dispar LinkSeq TrStaTrns DevExch } 02:37:30[ 24.632250] ata2: hard resetting link 02:37:31[ 25.372582] ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 300) 02:37:31[ 25.382615] ata2: SATA link up 1.5 Gbps (SStatus 113 SControl 300) 02:37:31[ 25.386782] ata2.00: configured for UDMA/133 02:37:31[ 25.386788] ata2: EH complete 02:37:31[ 25.431668] ata1.00: configured for UDMA/133 02:37:31[ 25.431674] ata1: EH complete 02:45:54[ 529.141844] EXT4-fs (dm-0): re-mounted. Opts: errors=remount-ro,commit=0 02:45:55[ 529.544529] EXT4-fs (dm-2): re-mounted. Opts: commit=0 02:45:55[ 529.622561] ata1: limiting SATA link speed to 1.5 Gbps 02:45:55[ 529.622568] ata1: exception Emask 0x10 SAct 0x0 SErr 0x5850000 action 0xe frozen 02:45:55[ 529.622572] ata1: irq_stat 0x00400040, connection status changed 02:45:55[ 529.622576] ata1: SError: { PHYRdyChg CommWake LinkSeq TrStaTrns DevExch } 02:45:55[ 529.622583] ata1: hard resetting link 02:45:55[ 529.622609] ata2: limiting SATA link speed to 1.5 Gbps 02:45:55[ 529.622613] ata2: exception Emask 0x10 SAct 0x0 SErr 0x5950000 action 0xe frozen 02:45:55[ 529.622616] ata2: irq_stat 0x00000040, connection status changed 02:45:55[ 529.622620] ata2: SError: { PHYRdyChg CommWake Dispar LinkSeq TrStaTrns DevExch } 02:45:55[ 529.622624] ata2: hard resetting link 02:45:56[ 530.380135] ata2: SATA link up 1.5 Gbps (SStatus 113 SControl 310) 02:45:56[ 530.380157] ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 310) 02:45:56[ 530.384305] ata2.00: configured for UDMA/133 02:45:56[ 530.384314] ata2: EH complete 02:45:56[ 530.399225] ata1.00: configured for UDMA/133 02:45:56[ 530.399233] ata1: EH complete 02:45:58[ 532.395990] EXT4-fs (dm-0): re-mounted. Opts: errors=remount-ro,commit=600 02:45:58[ 532.518270] EXT4-fs (dm-2): re-mounted. Opts: commit=600 02:45:58[ 532.590968] ata1: exception Emask 0x10 SAct 0x0 SErr 0x5840000 action 0xe frozen t4 02:45:58[ 532.590973] ata1: irq_stat 0x00000040, connection status changed 02:45:58[ 532.590977] ata1: SError: { CommWake LinkSeq TrStaTrns DevExch } 02:45:58[ 532.590983] ata1: hard resetting link 02:45:58[ 532.591034] ata2: exception Emask 0x10 SAct 0x0 SErr 0x5950000 action 0xe frozen t4 02:45:58[ 532.591037] ata2: irq_stat 0x00000040, connection status changed 02:45:58[ 532.591041] ata2: SError: { PHYRdyChg CommWake Dispar LinkSeq TrStaTrns DevExch } 02:45:58[ 532.591045] ata2: hard resetting link 02:45:59[ 533.340147] ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 310) 02:45:59[ 533.340168] ata2: SATA link up 1.5 Gbps (SStatus 113 SControl 310) 02:45:59[ 533.344416] ata2.00: configured for UDMA/133 02:45:59[ 533.344424] ata2: EH complete 02:45:59[ 533.360839] ata1.00: configured for UDMA/133 02:45:59[ 533.360847] ata1: EH complete 02:45:59[ 533.584449] EXT4-fs (dm-0): re-mounted. Opts: errors=remount-ro,commit=0 02:45:59[ 533.586999] EXT4-fs (dm-2): re-mounted. Opts: commit=0 02:45:59[ 533.660117] ata2: exception Emask 0x10 SAct 0x0 SErr 0x5950000 action 0xe frozen 02:45:59[ 533.660122] ata2: irq_stat 0x00000040, connection status changed 02:45:59[ 533.660126] ata2: SError: { PHYRdyChg CommWake Dispar LinkSeq TrStaTrns DevExch } 02:45:59[ 533.660132] ata2: hard resetting link 02:45:59[ 533.660141] ata1: exception Emask 0x10 SAct 0x0 SErr 0x5850000 action 0xe frozen 02:45:59[ 533.660143] ata1: irq_stat 0x00000040, connection status changed 02:45:59[ 533.660147] ata1: SError: { PHYRdyChg CommWake LinkSeq TrStaTrns DevExch } 02:45:59[ 533.660151] ata1: hard resetting link 02:46:00[ 534.412536] ata2: SATA link up 1.5 Gbps (SStatus 113 SControl 310) 02:46:00[ 534.412562] ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 310) 02:46:00[ 534.416768] ata2.00: configured for UDMA/133 02:46:00[ 534.416777] ata2: EH complete 02:46:00[ 534.431396] ata1.00: configured for UDMA/133 02:46:00[ 534.431401] ata1: EH complete 02:46:03[ 537.384649] EXT4-fs (dm-0): re-mounted. Opts: errors=remount-ro,commit=600 02:46:03[ 537.504214] EXT4-fs (dm-2): re-mounted. Opts: commit=600 02:46:03[ 537.585992] ata1: exception Emask 0x10 SAct 0x0 SErr 0x5900000 action 0xe frozen t4 02:46:03[ 537.585996] ata1: irq_stat 0x00000040, connection status changed 02:46:03[ 537.585999] ata1: SError: { Dispar LinkSeq TrStaTrns DevExch } 02:46:03[ 537.586002] ata1: hard resetting link 02:46:03[ 537.586028] ata2: exception Emask 0x10 SAct 0x0 SErr 0x5950000 action 0xe frozen t4 02:46:03[ 537.586030] ata2: irq_stat 0x00000040, connection status changed 02:46:03[ 537.586033] ata2: SError: { PHYRdyChg CommWake Dispar LinkSeq TrStaTrns DevExch } 02:46:03[ 537.586036] ata2: hard resetting link 02:46:04[ 538.330147] ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 310) 02:46:04[ 538.330168] ata2: SATA link up 1.5 Gbps (SStatus 113 SControl 310) 02:46:04[ 538.334389] ata2.00: configured for UDMA/133 02:46:04[ 538.334398] ata2: EH complete 02:46:04[ 538.343511] ata1.00: configured for UDMA/133 02:46:04[ 538.343519] ata1: EH complete 02:46:04[ 538.456413] EXT4-fs (dm-0): re-mounted. Opts: errors=remount-ro,commit=0 02:46:04[ 538.459404] EXT4-fs (dm-2): re-mounted. Opts: commit=0 02:46:04[ 538.540138] ata1.00: limiting speed to UDMA/100:PIO4 02:46:04[ 538.540144] ata1: exception Emask 0x10 SAct 0x0 SErr 0x5850000 action 0xe frozen 02:46:04[ 538.540148] ata1: irq_stat 0x00000040, connection status changed 02:46:04[ 538.540153] ata1: SError: { PHYRdyChg CommWake LinkSeq TrStaTrns DevExch } 02:46:04[ 538.540159] ata1: hard resetting link 02:46:04[ 538.540202] ata2.00: limiting speed to UDMA/100:PIO4 02:46:04[ 538.540207] ata2: exception Emask 0x10 SAct 0x0 SErr 0x5950000 action 0xe frozen 02:46:04[ 538.540211] ata2: irq_stat 0x00000040, connection status changed 02:46:04[ 538.540215] ata2: SError: { PHYRdyChg CommWake Dispar LinkSeq TrStaTrns DevExch } 02:46:04[ 538.540220] ata2: hard resetting link 02:46:05[ 539.290054] ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 310) 02:46:05[ 539.290041] ata2: SATA link up 1.5 Gbps (SStatus 113 SControl 310) 02:46:05[ 539.294100] ata2.00: configured for UDMA/100 02:46:05[ 539.294106] ata2: EH complete 02:46:05[ 539.314125] ata1.00: configured for UDMA/100 02:46:05[ 539.314132] ------------[ cut here ]------------ 02:46:05[ 539.314140] WARNING: at /build/buildd/linux-2.6.35/drivers/ata/libata-eh.c:3638 ata_eh_finish+0xdf/0xf0() 02:46:05[ 539.314144] Hardware name: MacBookPro5,3 02:46:05[ 539.314146] Modules linked in: michael_mic arc4 xt_multiport binfmt_misc rfcomm sco bnep l2cap parport_pc ppdev nvidia(P) ipt_REJECT xt_recent snd_hda_codec_cirrus xt_limit xt_tcpudp ipt_addrtype xt_state snd_hda_intel snd_hda_codec snd_hwdep snd_pcm snd_seq_midi applesmc led_class ip6table_filter lib80211_crypt_tkip snd_rawmidi snd_seq_midi_event ip6_tables input_polldev hid_apple snd_seq wl(P) snd_timer snd_seq_device snd joydev bcm5974 usbhid mbp_nvidia_bl uvcvideo btusb videodev v4l1_compat v4l2_compat_ioctl32 nf_nat_irc hid nf_conntrack_irc soundcore snd_page_alloc i2c_nforce2 coretemp lib80211 bluetooth nf_nat_ftp nf_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_conntrack_ftp nf_conntrack lp parport iptable_filter ip_tables x_tables usb_storage firewire_ohci firewire_core forcedeth crc_itu_t ahci libahci 02:46:05[ 539.314221] Pid: 202, comm: scsi_eh_0 Tainted: P 2.6.35-25-generic #44-Ubuntu 02:46:05[ 539.314224] Call Trace: 02:46:05[ 539.314233] [<ffffffff8106091f>] warn_slowpath_common+0x7f/0xc0 02:46:05[ 539.314237] [<ffffffff8106097a>] warn_slowpath_null+0x1a/0x20 02:46:05[ 539.314242] [<ffffffff813dc77f>] ata_eh_finish+0xdf/0xf0 02:46:05[ 539.314246] [<ffffffff813e441e>] sata_pmp_error_handler+0x2e/0x40 02:46:05[ 539.314256] [<ffffffffa00021bf>] ahci_error_handler+0x1f/0x90 [libahci] 02:46:05[ 539.314261] [<ffffffff813dd6d2>] ata_scsi_error+0x492/0x5e0 02:46:05[ 539.314266] [<ffffffff813b24cd>] scsi_error_handler+0x10d/0x190 02:46:05[ 539.314270] [<ffffffff813b23c0>] ? scsi_error_handler+0x0/0x190 02:46:05[ 539.314275] [<ffffffff8107f266>] kthread+0x96/0xa0 02:46:05[ 539.314280] [<ffffffff8100aee4>] kernel_thread_helper+0x4/0x10 02:46:05[ 539.314284] [<ffffffff8107f1d0>] ? kthread+0x0/0xa0 02:46:05[ 539.314288] [<ffffffff8100aee0>] ? kernel_thread_helper+0x0/0x10 02:46:05[ 539.314291] ---[ end trace 76dbffc2d5d49d9b ]--- 02:46:05[ 539.314296] ata1: EH complete 02:46:12[ 547.040091] ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen 02:46:12[ 547.040098] ata1.00: failed command: IDENTIFY DEVICE 02:46:12[ 547.040106] ata1.00: cmd ec/00:00:00:00:00/00:00:00:00:00/40 tag 0 pio 512 in 02:46:12[ 547.040108] res 40/00:01:00:00:00/00:00:00:00:00/e0 Emask 0x4 (timeout) 02:46:12[ 547.040111] ata1.00: status: { DRDY } 02:46:12[ 547.040117] ata1: hard resetting link 02:46:13[ 547.390144] ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 310) 02:46:13[ 547.408430] ata1.00: configured for UDMA/100 02:46:13[ 547.408438] ------------[ cut here ]------------ 02:46:13[ 547.408447] WARNING: at /build/buildd/linux-2.6.35/drivers/ata/libata-eh.c:3638 ata_eh_finish+0xdf/0xf0() 02:46:13[ 547.408451] Hardware name: MacBookPro5,3 02:46:13[ 547.408453] Modules linked in: michael_mic arc4 xt_multiport binfmt_misc rfcomm sco bnep l2cap parport_pc ppdev nvidia(P) ipt_REJECT xt_recent snd_hda_codec_cirrus xt_limit xt_tcpudp ipt_addrtype xt_state snd_hda_intel snd_hda_codec snd_hwdep snd_pcm snd_seq_midi applesmc led_class ip6table_filter lib80211_crypt_tkip snd_rawmidi snd_seq_midi_event ip6_tables input_polldev hid_apple snd_seq wl(P) snd_timer snd_seq_device snd joydev bcm5974 usbhid mbp_nvidia_bl uvcvideo btusb videodev v4l1_compat v4l2_compat_ioctl32 nf_nat_irc hid nf_conntrack_irc soundcore snd_page_alloc i2c_nforce2 coretemp lib80211 bluetooth nf_nat_ftp nf_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_conntrack_ftp nf_conntrack lp parport iptable_filter ip_tables x_tables usb_storage firewire_ohci firewire_core forcedeth crc_itu_t ahci libahci 02:46:13[ 547.408528] Pid: 202, comm: scsi_eh_0 Tainted: P W 2.6.35-25-generic #44-Ubuntu 02:46:13[ 547.408531] Call Trace: 02:46:13[ 547.408540] [<ffffffff8106091f>] warn_slowpath_common+0x7f/0xc0 02:46:13[ 547.408544] [<ffffffff8106097a>] warn_slowpath_null+0x1a/0x20 02:46:13[ 547.408549] [<ffffffff813dc77f>] ata_eh_finish+0xdf/0xf0 02:46:13[ 547.408553] [<ffffffff813e441e>] sata_pmp_error_handler+0x2e/0x40 02:46:13[ 547.408563] [<ffffffffa00021bf>] ahci_error_handler+0x1f/0x90 [libahci] 02:46:13[ 547.408567] [<ffffffff813dd6d2>] ata_scsi_error+0x492/0x5e0 02:46:13[ 547.408572] [<ffffffff813b24cd>] scsi_error_handler+0x10d/0x190 02:46:13[ 547.408577] [<ffffffff813b23c0>] ? scsi_error_handler+0x0/0x190 02:46:13[ 547.408582] [<ffffffff8107f266>] kthread+0x96/0xa0 02:46:13[ 547.408587] [<ffffffff8100aee4>] kernel_thread_helper+0x4/0x10 02:46:13[ 547.408591] [<ffffffff8107f1d0>] ? kthread+0x0/0xa0 02:46:13[ 547.408595] [<ffffffff8100aee0>] ? kernel_thread_helper+0x0/0x10 02:46:13[ 547.408598] ---[ end trace 76dbffc2d5d49d9c ]--- 02:46:13[ 547.408620] ata1: EH complete 02:46:13[ 547.562470] EXT4-fs (dm-0): re-mounted. Opts: errors=remount-ro,commit=600 02:46:13[ 547.671380] EXT4-fs (dm-2): re-mounted. Opts: commit=600 02:46:13[ 547.738198] ata1.00: limiting speed to UDMA/33:PIO4 02:46:13[ 547.738204] ata1: exception Emask 0x10 SAct 0x0 SErr 0x5800000 action 0xe frozen t4 02:46:13[ 547.738208] ata1: irq_stat 0x00000040, connection status changed 02:46:13[ 547.738212] ata1: SError: { LinkSeq TrStaTrns DevExch } 02:46:13[ 547.738218] ata1: hard resetting link 02:46:13[ 547.738262] ata2: exception Emask 0x10 SAct 0x0 SErr 0x5900000 action 0xe frozen t4 02:46:13[ 547.738265] ata2: irq_stat 0x00000040, connection status changed 02:46:13[ 547.738269] ata2: SError: { Dispar LinkSeq TrStaTrns DevExch } 02:46:13[ 547.738274] ata2: hard resetting link 02:46:14[ 548.482561] ata2: SATA link up 1.5 Gbps (SStatus 113 SControl 310) 02:46:14[ 548.484083] ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 310) 02:46:14[ 548.486809] ata2.00: configured for UDMA/100 02:46:14[ 548.486818] ata2: EH complete 02:46:14[ 548.498998] ata1.00: configured for UDMA/33 02:46:14[ 548.499004] ata1: EH complete 02:46:18[ 552.410499] EXT4-fs (dm-0): re-mounted. Opts: errors=remount-ro,commit=600 02:46:18[ 552.522521] EXT4-fs (dm-2): re-mounted. Opts: commit=600 02:46:18[ 552.529674] ata1: exception Emask 0x10 SAct 0x0 SErr 0x5800000 action 0xe frozen t4 02:46:18[ 552.529678] ata1: irq_stat 0x00000040, connection status changed 02:46:18[ 552.529680] ata1: SError: { LinkSeq TrStaTrns DevExch } 02:46:18[ 552.529684] ata1: hard resetting link 02:46:18[ 552.529716] ata2: exception Emask 0x10 SAct 0x0 SErr 0x5800000 action 0xe frozen t4 02:46:18[ 552.529718] ata2: irq_stat 0x00000040, connection status changed 02:46:18[ 552.529720] ata2: SError: { LinkSeq TrStaTrns DevExch } 02:46:18[ 552.529723] ata2: hard resetting link 02:46:19[ 553.280059] ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 310) 02:46:19[ 553.280068] ata2: SATA link up 1.5 Gbps (SStatus 113 SControl 310) 02:46:19[ 553.284141] ata2.00: configured for UDMA/100 02:46:19[ 553.284150] ata2: EH complete 02:46:19[ 553.301629] ata1.00: configured for UDMA/33 02:46:19[ 553.301637] ata1: EH complete

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  • What's the fastest and automatic way to transfer 2GB of data between 2 PCs every night?

    - by phan
    While it's fast (less than 2 minutes) I hate having to copy files from PC #1 onto a USB stick, and then manually popping it in PC #2 to copy the files to PC #2. Dropbox is too slow in uploading and then downloading 2GBs (synching), it could take hours. Copying 2GBs over the network is also slow because we're dealing with 10,000 little files that totals 2GBs, and not just one, giant 2gb file. Not sure why, but dealing with 10,000 little files makes the copy process much longer. Is there any other method that I'm missing? Any ideas? I'm using Win7 on both PCs. Edit: These files change every single night.

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  • Why do old programming languages continue to be revised?

    - by SunAvatar
    This question is not, "Why do people still use old programming languages?" I understand that quite well. In fact the two programming languages I know best are C and Scheme, both of which date back to the 70s. Recently I was reading about the changes in C99 and C11 versus C89 (which seems to still be the most-used version of C in practice and the version I learned from K&R). Looking around, it seems like every programming language in heavy use gets a new specification at least once per decade or so. Even Fortran is still getting new revisions, despite the fact that most people using it are still using FORTRAN 77. Contrast this with the approach of, say, the typesetting system TeX. In 1989, with the release of TeX 3.0, Donald Knuth declared that TeX was feature-complete and future releases would contain only bug fixes. Even beyond this, he has stated that upon his death, "all remaining bugs will become features" and absolutely no further updates will be made. Others are free to fork TeX and have done so, but the resulting systems are renamed to indicate that they are different from the official TeX. This is not because Knuth thinks TeX is perfect, but because he understands the value of a stable, predictable system that will do the same thing in fifty years that it does now. Why do most programming language designers not follow the same principle? Of course, when a language is relatively new, it makes sense that it will go through a period of rapid change before settling down. And no one can really object to minor changes that don't do much more than codify existing pseudo-standards or correct unintended readings. But when a language still seems to need improvement after ten or twenty years, why not just fork it or start over, rather than try to change what is already in use? If some people really want to do object-oriented programming in Fortran, why not create "Objective Fortran" for that purpose, and leave Fortran itself alone? I suppose one could say that, regardless of future revisions, C89 is already a standard and nothing stops people from continuing to use it. This is sort of true, but connotations do have consequences. GCC will, in pedantic mode, warn about syntax that is either deprecated or has a subtly different meaning in C99, which means C89 programmers can't just totally ignore the new standard. So there must be some benefit in C99 that is sufficient to impose this overhead on everyone who uses the language. This is a real question, not an invitation to argue. Obviously I do have an opinion on this, but at the moment I'm just trying to understand why this isn't just how things are done already. I suppose the question is: What are the (real or perceived) advantages of updating a language standard, as opposed to creating a new language based on the old?

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  • Will I have internet connection issues next day, if I unplug router at night?

    - by headskracher77
    I did this regularly a few years ago and used to feel like I was 'being punished' by the Interent svc provider for disabling access to my computer, because trying to re-connect the next day became a constant pain. I have the same linksys router, a comcast modem, and hi-speed broadband through their LAN. Question: who or what is at fault for lousy internet connections, slow connections, or no connections: (everybody's tech dept. blames everybody else) The router? 10 year olds, maybe obsolete? The modem? came with the service plan - can connect three devices on a sharedconnection. The ISP: I read they not only even control and completely regulate bandwidth usage, but they also ration it!! (true?) So can I safely 'pull the plug' each night for security or not? thnx

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  • Is it possible to install Ubuntu 10.10 and/or Ubuntu 11.04 on a late 2009 iMac?

    - by Oliver
    I would like to install Ubuntu on my iMac 10,1 (21.5 inch display). I would prefer to instal Natty Narwhal, but would surely settle for Maverick Meerkat (which I have a install dvd of). I have an install of OS X Snow Leopard AND a Bootcamp Partition of Windows 7. I would like to keep all these partitions and setup a triple boot system. If it can work, I'm also wondering if it'd be safe to install all updates from the update manager once it's installed. Thank you in advance. :)

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  • Can I install Ubuntu 12.04 on MacBook 6.1 (Late 2009) on my external hard drive?

    - by tommywinarta
    I have no experience in installing Linux based OS on MacBook, but I already have Windows installed on my Mac. I read some articles saying I can have the Lucid Lynx installed in my Macbook 6.1 and luckily I already got the CD (which was distributed for free back then haha), my question is that can I have the 12.04 installed instead of the 10.04 and what do I need to do that? I also would like to know can I install it on my external hard drive just like installing it on a usb stick? I have viewed the how-to for installing the Lucid Lynx, is it just the same? Thanks in advance!

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  • How do I restore a SQL Server database from last night's full backup and the active transaction log file?

    - by Dylan Beattie
    I have been told that it's good practise to keep your SQL Server data files and log files on physically separate disks, because it'll allow you to recover your data to the point of failure if the data drive fails. So... let's say that mydata.mdf is on drive D:, and my mydata_log.ldf is on drive E:, and it's 16:45, and drive D: has just died horribly. So - I have last night's full backup (mydata.bak). I have hourly transaction-log backups that will bring the data back up to 16:00... but that means I'll lose 45 minutes worth of updates. I still have mydata_log.ldf on the E: drive, which should contain EVERY transaction that was committed right up to the point where the drive failed. How do I go about recreating the database and restoring data from the backup file and the live transaction log, so I don't lose any updates? Is this possible?

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  • Summer Programming Plans

    - by Gabe
    I've wanted to start "hacking" for many months now. But I put it off in favor of school and other things. Now, though, I'm free for the summer and want to learn as much as I can. I have a rough idea of what I want to try my hand at, but need some guidance as to what specifically - and how - I should learn. This is my plan so far: 1) Get good at programming in general. I plan to read up on how to think/work like a programmer. I'm waiting for the Pragmatic Programmer to arrive, which will be the first book I read. Q: What other books/ebooks should I look at? What more can I do here? 2) Learn/Improve at HTML/CSS. My first project will be to make a personal website/blog for myself using HTML and CSS. ----Then I hope to write/design articles like Dustin Curtis. After I finish this (and learn a programming language) I'll try to create user-based a user-focused website. Q: It's my understanding that just trying to design/manage websites is a good way to learn/improve at HTML/CSS. Is that all correct? 3) Try music development. This might be a sort of stretch for stackoverflow, but I'm interested in mixing/making techno songs. (Think Justice, or Daft Punk, or MSTRKRFT.) Q: I have a Mac. Any ideas on how I could start/learn music making? Any programs I should download, for instance? 4) My main goal: Learning a web development language/framework. I'm a year into learning/using C++. But what I really want to do is develop websites and web apps. I've searched online, and there seems to be great debate over which language/framework to learn first (and which is best). I think I've narrowed it down to three: Ruby (Rails), Python (Django), and PHP (?). Q #1: Which should I learn and use first? (Reasons?) Q #2: One reason I was leaning towards PHP is that I'm taking a PHP development course next semester. Learning it now would make that course easy. If PHP was not the answer to Q #1, is it worth learning both? Or, would it be better to just focus on PHP for this summer and next semester, and then transition thereafter to a better language? 5) iPhone/iPad Programming (Maybe). I've a number of simple, useful app ideas that I'd like to eventually get too. I just bought a Mac, as well as a few app development books. Q #1: Am I spreading myself thin trying to learn all of the above, and objective-C? Q #2: How much harder/easier is objective-C compared to the above languages? Also, how easy is it to learn obj-C after learning a web development language (and some C++)? Q #3: Yes or no? Should I go for it, or just keeep with #1-4 for now? Also: If you have any tips on how I should learn (or how you learned to hack), I'm all ears. I'd be especially interested in how you planned out learning: did you just hack whenever you felt like it, or did you "study" the language a few hours a day, or something else? Thanks so much, guys.

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  • Primary language - C++/Qt, C#, Java?

    - by Airjoe
    I'm looking for some input, but let me start with a bit of background (for tl;dr skip to end). I'm an IT major with a concentration in networking. While I'm not a CS major nor do I want to program as a vocation, I do consider myself a programmer and do pretty well with the concepts involved. I've been programming since about 6th grade, started out with a proprietary game creation language that made my transition into C++ at college pretty easy. I like to make programs for myself and friends, and have been paid to program for local businesses. A bit about that- I wrote some programs for a couple local businesses in my senior year in high school. I wrote management systems for local shops (inventory, phone/pos orders, timeclock, customer info, and more stuff I can't remember). It definitely turned out to be over my head, as I had never had any formal programming education. It was a great learning experience, but damn was it crappy code. Oh yeah, by the way, it was all vb6. So, I've used vb6 pretty extensively, I've used c++ in my classes (intro to programming up to algorithms), used Java a little bit in another class (had to write a ping client program, pretty easy) and used Java for some simple Project Euler problems to help learn syntax and such when writing the program for the class. I've also used C# a bit for my own simple personal projects (simple programs, one which would just generate an HTTP request on a list of websites and notify if one responded unexpectedly or not at all, and another which just held a list of things to do and periodically reminded me to do them), things I would've written in vb6 a year or two ago. I've just started using Qt C++ for some undergrad research I'm working on. Now I've had some formal education, I [think I] understand organization in programming a lot better (I didn't even use classes in my vb6 programs where I really should have), how it's important to structure code, split into functions where appropriate, document properly, efficiency both in memory and speed, dynamic and modular programming etc. I was looking for some input on which language to pick up as my "primary". As I'm not a "real programmer", it will be mostly hobby projects, but will include some 'real' projects I'm sure. From my perspective: QtC++ and Java are cross platform, which is cool. Java and C# run in a virtual machine, but I'm not sure if that's a big deal (something extra to distribute, possibly a bit slower? I think Qt would require additional distributables too, right?). I don't really know too much more than this, so I appreciate any help, thanks! TL;DR Am an avocational programmer looking for a language, want quick and straight forward development, liked vb6, will be working with database driven GUI apps- should I go with QtC++, Java, C#, or perhaps something else?

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  • Primary language - QtC++, C#, Java?

    - by Airjoe
    I'm looking for some input, but let me start with a bit of background (for tl;dr skip to end). I'm an IT major with a concentration in networking. While I'm not a CS major nor do I want to program as a vocation, I do consider myself a programmer and do pretty well with the concepts involved. I've been programming since about 6th grade, started out with a proprietary game creation language that made my transition into C++ at college pretty easy. I like to make programs for myself and friends, and have been paid to program for local businesses. A bit about that- I wrote some programs for a couple local businesses in my senior year in high school. I wrote management systems for local shops (inventory, phone/pos orders, timeclock, customer info, and more stuff I can't remember). It definitely turned out to be over my head, as I had never had any formal programming education. It was a great learning experience, but damn was it crappy code. Oh yeah, by the way, it was all vb6. So, I've used vb6 pretty extensively, I've used c++ in my classes (intro to programming up to algorithms), used Java a little bit in another class (had to write a ping client program, pretty easy) and used Java for some simple Project Euler problems to help learn syntax and such when writing the program for the class. I've also used C# a bit for my own simple personal projects (simple programs, one which would just generate an HTTP request on a list of websites and notify if one responded unexpectedly or not at all, and another which just held a list of things to do and periodically reminded me to do them), things I would've written in vb6 a year or two ago. I've just started using Qt C++ for some undergrad research I'm working on. Now I've had some formal education, I [think I] understand organization in programming a lot better (I didn't even use classes in my vb6 programs where I really should have), how it's important to structure code, split into functions where appropriate, document properly, efficiency both in memory and speed, dynamic and modular programming etc. I was looking for some input on which language to pick up as my "primary". As I'm not a "real programmer", it will be mostly hobby projects, but will include some 'real' projects I'm sure. From my perspective: QtC++ and Java are cross platform, which is cool. Java and C# run in a virtual machine, but I'm not sure if that's a big deal (something extra to distribute, possibly a bit slower? I think Qt would require additional distributables too, right?). I don't really know too much more than this, so I appreciate any help, thanks! TL;DR Am an avocational programmer looking for a language, want quick and straight forward development, liked vb6, will be working with database driven GUI apps- should I go with QtC++, Java, C#, or perhaps something else?

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  • Any task-control algorithms programming practices?

    - by NumberFour
    Hi, I was just wondering if there's any field which concerns the task-control programming (or at least that's the way I call it). For a better explanation of task-control consider the following scenario: An application (master-thread) waits for a command - which might be a particular action or a set of actions the application should perform. When a command is received the master-thread creates a task (= spawns an independent thread which actually does the action) and adds a record in it's task-list - thus keeping track of the time of execution, thread handle, task priority...etc. The master-thread awaits for any other incoming commands while taking care of all the tasks - e.g: kills tasks running too long, prioritizes tasks with higher priorities, kills a task on a request of another task, limits the number of currently running tasks, allows task scheduling, cleans finished tasks (threads) and so on. The model is pretty similar to what we can see in OS dealing with running processes. Are there any good practices programming such task-models or is there some theoretical work done in this field? Maybe my question is too generalized, but at least I wanted to know whether there are any experiences working on such models or if there's a better approach. Thanks for any answers.

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  • General Web Programming/designing Question: ?

    - by Prasad
    hi, I have been in web programming for 2 years (Self taught - a biology researcher by profession). I designed a small wiki with needed functionalities and a scientific RTE - ofcourse lot is expected. I used mootools framework and AJAX extensively. I was always curious when ever I saw the query strings passed from URL. Long encrypted query string directly getting passed to the server. Especially Google's design is such. I think this is the start of providing a Web Service to a client - I guess. Now, my question is : is this a special, highly professional, efficient / advanced web design technique to communicate queries via the URL ? I always felt that direct URL based communication is faster. I tried my bit and could send a query through the URL directly. here is the link: http://sgwiki.sdsc.edu/getSGMPage.php?8 By this , the client can directly link to the desired page instead of searching and / or can automate. There are many possibilities. The next request: Can I be pointed to such technique of web programming? oops: I am sorry, If I have not been able to convey my request clearly. Prasad.

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  • Best cubicle toys for programming

    - by dlamblin
    I need some employee/co-worker Christmas gift ideas. Do you have any good cubicle toys that help you to do any of: think about programming problems solve programming problems by representing common abstractions can be directly programmed can interface with a PC based IDE to be programmed. it may present problems that can be solved, to kick start problem solving. Disallowed items are: reference material in book, pamphlet, poster or cheat-sheet form, even if it has kick ass pop-cultural references. edibles. [discuss separately] things that need their own lab-space and/or extensive tools to be worked with. So yes, Lego Mindstorms come to mind, but they aren't cubicle toys because they cost more than cubicle toys would, and they have too many losable parts. comments on the answers so far: The 20 Questions game sounds quite neat as it could get you thinking; The bean balls could be used as tokens in a problem, so I can see that working. The magnetic toys like ball of whacks or the ball-and-stick ones present hands on fun of a structural nature... now can there be a similar hands on fun toy that aids in representing a solution to a problem? The Gui Mags clearly could, but they're quite utility oriented. The AVR Butterfly is less of a toy but definitely priced attractively, cheaper and more responsive than a basic stamp. I'm not going to pick an answer; there's several great suggestions here. Thank you.

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  • How do people know so much about programming?

    - by Luciano
    I see people in this forums with a lot of points, so I assume they know about a lot of different programming stuff. When I was young I knew about basic (commodore) and the turbo pascal (pc). Then in college I learnt about C, memory management, x86 set, loop invariants, graphs, db query optimization, oop, functional, lambda calculus, prolog, concurrency, polymorphism, newton method, simplex, backtracking, dynamic programming, heuristics, np completeness, LR, LALR, neural networks, static & dynamic typing, turing, godel, and more in between. Then in industry I started with Java several years ago and learnt about it, and its variety of frameworks, and also design patterns, architecture patterns, web development, server development, mobile development, tdd, bdd, uml, use cases, bug trackers, process management, people management if you are a tech lead, profiling, security concerns, etc. I started to forget what I learnt in college... And then there is the stuff I don't know yet, like python, .net, perl, JVM stuff like groovy or scala.. Of course Google is a must for rapid documentation access to know if a problem has been solved already and how, and to keep informed about new stuff by blogs and places like this one. It's just too much or I just have a bad memory.. how do you guys manage it?

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  • Programming Technique: How to create a simple card game

    - by Shyam
    Hi, As I am learning the Ruby language, I am getting closer to actual programming. So I was thinking of creating a simple card game. My question isn't Ruby orientated, but I do know want to learn how to solve this problem with a genuine OOP approach. In my card game I want to have four players. Using a standard deck with 52 cards, no jokers/wildcards. In the game I won't use the Ace as a dual card, it is always the highest card. So, the programming problems I wonder about are the following: How can I sort/randomize the deck of cards? There are four types, each having 13 values. Eventually there can be only unique values, so picking random values could generate duplicates. How can I implement a simple AI? As there are tons of card games, someone would have figured this part out already, so references would be great. I am a truly Ruby nuby, and my goal here is to learn to solve problems, so pseudo code would be great, just to understand how to solve the problem programmatically. I apologize for my grammar and writing style if it's unclear, for it is not my native language. Also pointers to sites where such challenges are explained, would be a great resource! Thank you for your comments, answers and feedback!

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  • c# web extracting programming, which libraries, examples samples please

    - by user287745
    I have just started programming and have made a few small applications in C and C#. My understanding is that programming for web and thing related to web is nowadays a very easy task. Please note this is for personnel learning, not for rent a coder or any money making. An application which can run on any Windows platform even Windows 98. The application should start automatically at a scheduled time and do the following. Connect to a site which displays stock prices summary (high low current open). Capture the data (excluding the other things in the site.) And save it to disk (an SQL database) Please note:- Internet connection is assumed to be there always. Do not want to know how to make database schema or database. The stock exchange has no law prohibiting the use of the data provided on its site, but I do not want to mention the name in case I am wrong, but it's for personal private use only. The data of summary of pricing is arranged in a table such that when copied pasted to MS Excel it automatically forms a table. need steps guidance please, examples, lbraries

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  • How do I get an overview and a methodology for programming in Python

    - by Peter Nielsen
    I've started to learn Python and programming from scratch. I have not programmed before so it's a new experience. I do seem to grasp most of the concepts, from variables to definitions and modules. I still need to learn a lot more about what the different libraries and modules do and also I lack knowledge on OOP and classes in Python. I see people who just program in Python like that's all they have ever done and I am still just coming to grips with it. Is there a way, some tools, a logical methodology that would give me an overview or a good hold of how to handle programming problems ? For instance, I'm trying to create a parser which we need at the office . I also need to create a spider that would collect links from various websites. Is there a formidable way of studying the various modules to see what is needed ? Or is it just nose to the grind stone and understand what the documentation says ? Sorry for the lengthy question..

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  • An Ideal Keyboard Layout for Programming

    - by Jon Purdy
    I often hear complaints that programming languages that make heavy use of symbols for brevity, most notably C and C++ (I'm not going to touch APL), are difficult to type because they require frequent use of the shift key. A year or two ago, I got tired of it myself, downloaded Microsoft's Keyboard Layout Creator, made a few changes to my layout, and have not once looked back. The speed difference is astounding; with these few simple changes I am able to type C++ code around 30% faster, depending of course on how hairy it is; best of all, my typing speed in ordinary running text is not compromised. My questions are these: what alternate keyboard layouts have existed for programming, which have gained popularity, are any of them still in modern use, do you personally use any altered layout, and how can my layout be further optimised? I made the following changes to a standard QWERTY layout. (I don't use Dvorak, but there is a programmer Dvorak layout worth mentioning.) Swap numbers with symbols in the top row, because long or repeated literal numbers are typically replaced with named constants; Swap backquote with tilde, because backquotes are rare in many languages but destructors are common in C++; Swap minus with underscore, because underscores are common in identifiers; Swap curly braces with square brackets, because blocks are more common than subscripts; and Swap double quote with single quote, because strings are more common than character literals. I suspect this last is probably going to be the most controversial, as it interferes the most with running text by requiring use of shift to type common contractions. This layout has significantly increased my typing speed in C++, C, Java, and Perl, and somewhat increased it in LISP and Python.

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  • What programming language is this?

    - by Richard M.
    I recently stumbled over a very odd source listing on a rather old programming-related site (lost it somewhere in my browser history as I didn't care about it at first). I think that this is part of a simple (console-based?) snake game. I searched and searched but didn't find a language that looked somwhat like this. This seems like a mix of Python, Ruby and C++. What the hell? What programming-language is the below source listing written in? Maybe you can figure it out? my Snake.hasProps { length parts xDir yDir } & hasMethods { init: length = 0 parts[0].x,y = 5 move: parts[ 0 ].x,y.!add xDir | yDir # Move the head map parts(i,v): parts[ i ] = parts[ i + 1 ] checkBiteSelf checkFeed checkBiteSelf: part } my SnakePart.hasProps { x y } fork SnakePart to !Feed my Game.hasProps { frameTime = 30 } & hasMethods { init: mainloop mainloop: sys.util.sleep frameTime Snake.move Field.getInput -> Snake.xDir | Snake.yDir Field.reDraw with Snake & Feed & Game # For FPS } main.isMethod { game.init }

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  • Non-english domain naming issues in programming

    - by Svend
    Most programming code, I imagine is written in english. But I'm curious how people handling the issue of naming herein. Alot of programming is done within some bussiness domain, usually with well established terms for certain procedures, items. I'm from Denmark for instance, and something I work alot with has a term called "indblikskode", which sorta translates to "insight code". So, do I use the line "string indblikskode = ..." in the C# code for some webservice related to this? Or do I try to use a translation, such as "insightcode"? The bussiness I'm in isn't even consistent in it's language, for instance using the term "organisatorisk enhed" (organizatorical unit), but just as often using the abbreviation "OU", which is obviously abbreviated from the english. How do other people handle this naming issue, while keeping consistent, and sane (in everything from simple variable names in your code, to database tables, to server names)? Duplicates: Should identifiers and comments be always in English or in the native language of the application and developers? Do you use another language instead of english ?

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  • Need an Overview of Possibilities for multicolumn programming

    - by Sam
    Hi folks, From source1 and source2 i gather that IE9 will NOT support multi-column css3!! Since it is still the most popular browser (another thing i cannot understand), i am left but no other choice than to use Programming Power to make multi-columns work. Now, I use three divs that float to left, and which are manually filled with text. Please don't laugh i know its stupid! But I would wish to not to have to worry about the columns and just have a one piece of (un-interrupted) text which all goes into only 1 div, and then have a program smart enough to split it up into X equally wide columns. Question: before i start reinvent the wheel, what methods of programming power have you known that tackle this elegantly? Please suggest your best working multi-column layout sources so I can evaluate which option is the best (I will update the below table). Exploring all possibilities 2011 and further, to enable multi column text user experience: Language Author SourceCodeUsage WorksOnAllMajorBrowser? ================================================================================= html manual labour put text manually in separate left-floating divs "Y" // Upside: control! Downside: few changes necessitates to reflow 3 divs manually! CSS3 w3c css3.info/preview/multi-column-layout/ "N" // {-moz-column-count: 3; -webkit-column-count: 3; } Thats all! javascript a list apart will add url soon ? // php ? ? ? //

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