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  • PowerDNS CNAME with multiple A records produces unexpected results

    - by bwight
    This problem from what i can tell is isolated to PowerDNS. The servers are running two packages pdns-static-3.0.1-1.i386.rpm and pdns-recursor-3.3-1.i386.rpm on the most recent version of Amazon Linux. The amazon ec2 loadbalancers are assigned a CNAME with multiple hosts. Below is an example of the actual behavior. Notice how the hosts are always in the same order. [root@localhost ~]# host cache.domain.com cache.domain.com is an alias for xxxxx.us-east-1.elb.amazonaws.com. xxxxx.us-east-1.elb.amazonaws.com has address aaa.aaa.aaa.aaa xxxxx.us-east-1.elb.amazonaws.com has address bbb.bbb.bbb.bbb [root@localhost ~]# host cache.domain.com cache.domain.com is an alias for xxxxx.us-east-1.elb.amazonaws.com. xxxxx.us-east-1.elb.amazonaws.com has address aaa.aaa.aaa.aaa xxxxx.us-east-1.elb.amazonaws.com has address bbb.bbb.bbb.bbb [root@localhost ~]# host cache.domain.com cache.domain.com is an alias for xxxxx.us-east-1.elb.amazonaws.com. xxxxx.us-east-1.elb.amazonaws.com has address aaa.aaa.aaa.aaa xxxxx.us-east-1.elb.amazonaws.com has address bbb.bbb.bbb.bbb Expected behavior is round robin for the hosts [root@localhost ~]# host cache.domain.com cache.domain.com is an alias for xxxxx.us-east-1.elb.amazonaws.com. xxxxx.us-east-1.elb.amazonaws.com has address aaa.aaa.aaa.aaa xxxxx.us-east-1.elb.amazonaws.com has address bbb.bbb.bbb.bbb [root@localhost ~]# host cache.domain.com cache.domain.com is an alias for xxxxx.us-east-1.elb.amazonaws.com. xxxxx.us-east-1.elb.amazonaws.com has address bbb.bbb.bbb.bbb xxxxx.us-east-1.elb.amazonaws.com has address aaa.aaa.aaa.aaa [root@localhost ~]# host cache.domain.com cache.domain.com is an alias for xxxxx.us-east-1.elb.amazonaws.com. xxxxx.us-east-1.elb.amazonaws.com has address aaa.aaa.aaa.aaa xxxxx.us-east-1.elb.amazonaws.com has address bbb.bbb.bbb.bbb The addresses eventually do swap but it seems to be on a 30 minute cache timer changing the TTL of the record doesn't appear to affect anything. It appears as though the resolver has a cache of the response. This adversely affects my application because all of the load is only being sent to one of the loadbalancers (Availability Zones) so if I have servers in two zones then only one zone is under load at a time. Do you know how I can fix this so that each time the host is resolved the order of the addresses is alternating.

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  • Plex won't enter my home directory or other partitions

    - by RobinJ
    I just installed the Plex media server from the Ubuntu Software Center, and opened the web interface. I wanted to start by adding a collection. When it gave me a file browser, I wanted to go to /home/robin/Videos. /home is as far as I got. It showed robin, with an arrow in front of it, but when I tried to expand the directory tree it was empty. The same happened when trying to access /media/Data. For me it's quite useless like this, as all of my media files are inside those 2 directories. Help would be much appreciated. My first guess seemed to be a correct one; It is, as always, a permissions problem. How do I give plex access to my home folder without also giving other users access to it? My home folder is encrypted by the way, so that'll probably complicate things a little. robin@RobinJ:~$ sudo -u plex bash [sudo] password for robin: bash: /home/robin/.bashrc: Permission denied plex@RobinJ:~$ ls -al ls: cannot open directory .: Permission denied plex@RobinJ:~$ cd /home plex@RobinJ:/home$ cd robin bash: cd: robin: Permission denied plex@RobinJ:/home$ ls -al robin ls: cannot open directory robin: Permission denied

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  • Thread scheduling Round Robin / scheduling dispatch

    - by MRP
    #include <pthread.h> #include <stdio.h> #include <stdlib.h> #include <semaphore.h> #define NUM_THREADS 4 #define COUNT_LIMIT 13 int done = 0; int count = 0; int quantum = 2; int thread_ids[4] = {0,1,2,3}; int thread_runtime[4] = {0,5,4,7}; pthread_mutex_t count_mutex; pthread_cond_t count_threshold_cv; void * inc_count(void * arg); static sem_t count_sem; int quit = 0; ///////// Inc_Count//////////////// void *inc_count(void *t) { long my_id = (long)t; int i; sem_wait(&count_sem); /////////////CRIT SECTION////////////////////////////////// printf("run_thread = %d\n",my_id); printf("%d \n",thread_runtime[my_id]); for( i=0; i < thread_runtime[my_id];i++) { printf("runtime= %d\n",thread_runtime[my_id]); pthread_mutex_lock(&count_mutex); count++; if (count == COUNT_LIMIT) { pthread_cond_signal(&count_threshold_cv); printf("inc_count(): thread %ld, count = %d Threshold reached.\n", my_id, count); } printf("inc_count(): thread %ld, count = %d, unlocking mutex\n",my_id, count); pthread_mutex_unlock(&count_mutex); sleep(1) ; }//End For sem_post(&count_sem); // Next Thread Enters Crit Section pthread_exit(NULL); } /////////// Count_Watch //////////////// void *watch_count(void *t) { long my_id = (long)t; printf("Starting watch_count(): thread %ld\n", my_id); pthread_mutex_lock(&count_mutex); if (count<COUNT_LIMIT) { pthread_cond_wait(&count_threshold_cv, &count_mutex); printf("watch_count(): thread %ld Condition signal received.\n", my_id); printf("watch_count(): thread %ld count now = %d.\n", my_id, count); } pthread_mutex_unlock(&count_mutex); pthread_exit(NULL); } ////////////////// Main //////////////// int main (int argc, char *argv[]) { int i; long t1=0, t2=1, t3=2, t4=3; pthread_t threads[4]; pthread_attr_t attr; sem_init(&count_sem, 0, 1); /* Initialize mutex and condition variable objects */ pthread_mutex_init(&count_mutex, NULL); pthread_cond_init (&count_threshold_cv, NULL); /* For portability, explicitly create threads in a joinable state */ pthread_attr_init(&attr); pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE); pthread_create(&threads[0], &attr, watch_count, (void *)t1); pthread_create(&threads[1], &attr, inc_count, (void *)t2); pthread_create(&threads[2], &attr, inc_count, (void *)t3); pthread_create(&threads[3], &attr, inc_count, (void *)t4); /* Wait for all threads to complete */ for (i=0; i<NUM_THREADS; i++) { pthread_join(threads[i], NULL); } printf ("Main(): Waited on %d threads. Done.\n", NUM_THREADS); /* Clean up and exit */ pthread_attr_destroy(&attr); pthread_mutex_destroy(&count_mutex); pthread_cond_destroy(&count_threshold_cv); pthread_exit(NULL); } I am trying to learn thread scheduling, there is a lot of technical coding that I don't know. I do know in theory how it should work, but having trouble getting started in code... I know, at least I think, this program is not real time and its not meant to be. Some how I need to create a scheduler dispatch to control the threads in the order they should run... RR FCFS SJF ect. Right now I don't have a dispatcher. What I do have is semaphores/ mutex to control the threads. This code does run FCFS... and I have been trying to use semaphores to create a RR.. but having a lot of trouble. I believe it would be easier to create a dispatcher but I dont know how. I need help, I am not looking for answers just direction.. some sample code will help to understand a bit more. Thank you.

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  • Setting up multiple servers for one domain

    - by Joseph Torraca
    So I am starting up a new website and I was wondering how to set up 5 servers to host the site. I have already purchased 5 Apple XServes, one will be used as a test server and the other 4 will be for the live site. So I have read some website on the internet and they all reference using one server and installing software onto it and have that server do the load balancing. I have also read that you could use a hardware, rack-mounted system and plug the servers into that. The load balancer would then distribute the load. So I have a few questions about each: 1) How do you set up the software version and have the other servers as "slaves" and have one "master" to direct traffic? 2) Which of the two options above are more reliable, and better suited for a startup that doesn't have many users per month, yet(hopefully)? 3) Is there a theoretical max limit of servers that can be connected to a software load balancing system? Note: Obviously this will change from software to software, but in terms of the server being able to handle it? 4) In your own opinion, what are you using for your sites? Have you had any problems setting up that system or operating it once its running? Are there any things you would stay away from if you had to start over? 5) I also purchased a Apple RAID system, so if you are familiar with it, is there any way to connect it to multiple Xserves so they all serve the same data? I'm a little confused on this, so thanks for all your help and being patient with me. Note: Take it easy on me, I am learning this as I go along, so I may have used terms incorrectly or explained things that don't really make sense. Sorry. P.S. If you need me to supply the specs on the servers to determine which system makes the most sense, I can post them for you.

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  • How to keep groups when pulling with git

    - by mimrock
    I have a staging site that is a working directory of a git repository. How to set up git to let a developer pull out a branch or release without changing the group of the modified files? An example. Let's say I have two developers, robin and david. They are both in git-users group, so initially they can both have write permissions on site.php. -rw-rw-r-- 1 robin git-users 46068 Nov 16 12:12 site.php drwxrwxr-x 8 robin git-users 4096 Nov 16 14:11 .git After robin-server1$ git pull origin master: -rw-rw-r-- 1 robin robin 46068 Nov 16 12:35 site.php drwxrwxr-x 8 robin git-users 4096 Nov 16 14:11 .git And david do not have write permissions on site.php, because the group changed from 'git-users' to 'robin'. From now on, david will get a permission denied, when he tries to pull to this repository.

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  • Multiple data centers and HTTP traffic: DNS Round Robin is the ONLY way to assure instant fail-over?

    - by vmiazzo
    Hi, Multiple A records pointing to the same domain seem to be used almost exclusively to implement DNS Round Robin as a cheap load balancing technique. The usual warning against DNS RR is that it is not good for high availability. When 1 IP goes down clients will continue to use it for minutes. A load balancer is often suggested as a better choice. Both claims are not completely true: When the traffic is HTTP then, most of the HTML browsers are able to automatically try the next A record if the previous is down, without a new DNS look-up. Read here chapter 3.1 and here. When multiple data centers are involved then, DNS RR is the only option to distribute traffic across them. So, is it true that, with multiple data centers and HTTP traffic, the use of DNS RR is the ONLY way to assure instant fail-over when one data center goes down? Thanks, Valentino Edit: Off course each data center has a local Load Balancer with hot spare. It's OK to sacrifice session affinity for an instant fail-over. AFAIK the only way for a DNS to suggest a data center instead of another is to reply with just the IP (or IPs) associated to that data center. If the data center becomes unreachable then all those IP are also unreachables. This means that, even if smart HTML browsers are able to instantly try another A record , all the attempts will fail until the local cache entry expires and a new DNS lookup is done, fetching the new working IPs (I assume DNS automatically suggests to a new data center when one fail). So, "smart DNS" cannot assure instant fail-over. Conversely a DNS round-robin permits it. When one data center fail, the smart HTML browsers (most of them) instantly try the other cached A records jumping to another (working) data center. So, DNS round-robin doesn't assure session affinity or the lowest RTT but seems to be the only way to assure instant fail-over when the clients are "smart" HTML browsers. Edit 2: Some people suggest TCP Anycast as a definitive solution. In this paper (chapter 6) is explained that Anycast fail-over is related to BGP convergence. For this reason Anycast can employ from 15 minutes to 20 seconds to complete. 20 seconds are possible on networks where the topology was optimized for this. Probably just CDN operators can grant such fast fail-overs. Edit 3:* I did some DNS look-ups and traceroutes (maybe some expert can double check) and: The only CDN using TCP Anycast seems to be CacheFly, other operators like CDN networks and BitGravity use CacheFly. Seems that their edges cannot be used as reverse proxies. Therefore, they cannot be used to grant instant failover. Akamai and LimeLight seems to use geo-aware DNS. But! They return multiple A records. From traceroutes seems that the returned IPs are on the same data center. So, I'm puzzled on how they can offer a 100% SLA when one data center goes down.

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  • Load Balancing is unusual in Apache in round-robin mode when one of the tomcat is brought down

    - by srayker
    We are facing a unusual behavior with round-robin load balancing on apache when one of the tomcat server is brought down. Our Setup: we have 2 apache web servers on the front end using mod_jk module for load balancing using round robin for load distribution. We also have enabled session stickyness. This is followed by 4 tomcat servers on which the applications are running. Sometimes under heavy load, if there is a slowness in our DB tier we find that eventually one of the tomcat goes into a hung state and would need a restart. The moment we bounce the tomcat we see a spike in requests in one of the server and this would also go into hung state and need a restart. Eventually all the server will face similar condition. What beats me is why does the Apache transfer the whole load to one server instead of distributing the load. We are now trying the worker.balancer.method=B to see if this helps to resolve our issue. Any thoughts on resolving the issue is greatly appreciated. regards, srayker

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  • Ubuntu 10.04 & IBM DS3524 with FC multipath, inactive path is [failed][faulty] instead of [active][ghost]

    - by Graeme Donaldson
    OK, this is my setup: FC Switches IBM/Brocade, Switch1 and Switch2, independent fabrics. Server IBM x3650 M2, 2x QLogic QLE2460, 1 connected to each FC Switch. Storage IBM DS3524, 2x controllers with 4x FC ports each, but only 2x connected on each. +-----------------------------------------------------------------------+ | HBA1 Server HBA2 | +-----------------------------------------------------------------------+ | | | | | | +-----------------------------+ +------------------------------+ | Switch1 | | Switch2 | +-----------------------------+ +------------------------------+ | | | | | | | | | | | | | | | | | | | | +-----------------------------------+-----------------------------------+ | Contr A, port 3 | Contr A, port 4 | Contr B, port 3 | Contr B, port 4 | +-----------------------------------+-----------------------------------+ | Storage | +-----------------------------------------------------------------------+ My /etc/multipath.conf is from the IBM redbook for the DS3500, except I use a different setting for prio_callout, IBM uses /sbin/mpath_prio_tpc, but according to http://changelogs.ubuntu.com/changelogs/pool/main/m/multipath-tools/multipath-tools_0.4.8-7ubuntu2/changelog, this was renamed to /sbin/mpath_prio_rdac, which I'm using. devices { device { #ds3500 vendor "IBM" product "1746 FAStT" hardware_handler "1 rdac" path_checker rdac failback 0 path_grouping_policy multibus prio_callout "/sbin/mpath_prio_rdac /dev/%n" } } multipaths { multipath { wwid xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx alias array07 path_grouping_policy multibus path_checker readsector0 path_selector "round-robin 0" failback "5" rr_weight priorities no_path_retry "5" } } The output of multipath -ll with controller A as the preferred path: root@db06:~# multipath -ll sdg: checker msg is "directio checker reports path is down" sdh: checker msg is "directio checker reports path is down" array07 (xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx) dm-2 IBM ,1746 FASt [size=4.9T][features=1 queue_if_no_path][hwhandler=0] \_ round-robin 0 [prio=2][active] \_ 5:0:1:0 sdd 8:48 [active][ready] \_ 5:0:2:0 sde 8:64 [active][ready] \_ 6:0:1:0 sdg 8:96 [failed][faulty] \_ 6:0:2:0 sdh 8:112 [failed][faulty] If I change the preferred path using IBM DS Storage Manager to Controller B, the output swaps accordingly: root@db06:~# multipath -ll sdd: checker msg is "directio checker reports path is down" sde: checker msg is "directio checker reports path is down" array07 (xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx) dm-2 IBM ,1746 FASt [size=4.9T][features=1 queue_if_no_path][hwhandler=0] \_ round-robin 0 [prio=2][active] \_ 5:0:1:0 sdd 8:48 [failed][faulty] \_ 5:0:2:0 sde 8:64 [failed][faulty] \_ 6:0:1:0 sdg 8:96 [active][ready] \_ 6:0:2:0 sdh 8:112 [active][ready] According to IBM, the inactive path should be "[active][ghost]", not "[failed][faulty]". Despite this, I don't seem to have any I/O issues, but my syslog is being spammed with this every 5 seconds: Jun 1 15:30:09 db06 multipathd: sdg: directio checker reports path is down Jun 1 15:30:09 db06 kernel: [ 2350.282065] sd 6:0:2:0: [sdh] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE Jun 1 15:30:09 db06 kernel: [ 2350.282071] sd 6:0:2:0: [sdh] Sense Key : Illegal Request [current] Jun 1 15:30:09 db06 kernel: [ 2350.282076] sd 6:0:2:0: [sdh] <<vendor>> ASC=0x94 ASCQ=0x1ASC=0x94 ASCQ=0x1 Jun 1 15:30:09 db06 kernel: [ 2350.282083] sd 6:0:2:0: [sdh] CDB: Read(10): 28 00 00 00 00 00 00 00 08 00 Jun 1 15:30:09 db06 kernel: [ 2350.282092] end_request: I/O error, dev sdh, sector 0 Jun 1 15:30:10 db06 multipathd: sdh: directio checker reports path is down Jun 1 15:30:14 db06 kernel: [ 2355.312270] sd 6:0:1:0: [sdg] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE Jun 1 15:30:14 db06 kernel: [ 2355.312277] sd 6:0:1:0: [sdg] Sense Key : Illegal Request [current] Jun 1 15:30:14 db06 kernel: [ 2355.312282] sd 6:0:1:0: [sdg] <<vendor>> ASC=0x94 ASCQ=0x1ASC=0x94 ASCQ=0x1 Jun 1 15:30:14 db06 kernel: [ 2355.312290] sd 6:0:1:0: [sdg] CDB: Read(10): 28 00 00 00 00 00 00 00 08 00 Jun 1 15:30:14 db06 kernel: [ 2355.312299] end_request: I/O error, dev sdg, sector 0 Does anyone know how I can get the inactive path to show "[active][ghost]" instead of "[failed][faulty]"? I assume that once I can get that right then the spam in my syslog will end as well. One final thing worth mentioning is that the IBM redbook doc targets SLES 11 so I'm assuming there's something a little different under Ubuntu that I just haven't figured out yet. Update: As suggested by Mitch, I've tried removing /etc/multipath.conf, and now the output of multipath -ll looks like this: root@db06:~# multipath -ll sdg: checker msg is "directio checker reports path is down" sdh: checker msg is "directio checker reports path is down" xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxdm-1 IBM ,1746 FASt [size=4.9T][features=0][hwhandler=0] \_ round-robin 0 [prio=1][active] \_ 5:0:2:0 sde 8:64 [active][ready] \_ round-robin 0 [prio=1][enabled] \_ 5:0:1:0 sdd 8:48 [active][ready] \_ round-robin 0 [prio=0][enabled] \_ 6:0:1:0 sdg 8:96 [failed][faulty] \_ round-robin 0 [prio=0][enabled] \_ 6:0:2:0 sdh 8:112 [failed][faulty] So its more or less the same, with the same message in the syslog every 5 minutes as before, but the grouping has changed.

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  • Can't upload project to PPA using Quickly

    - by RobinJ
    I can't get Quickly to upload my project into my PPA. I've set up my PGP key and used it so sign the code of conduct, and the PPA exists. I don't know what other usefull information I can supply. robin@RobinJ:~/Ubuntu One/Python/gtkreddit$ quickly share --ppa robinj/gtkredditGet Launchpad Settings Launchpad connection is ok gpg: WARNING: unsafe permissions on configuration file `/home/robin/.gnupg/gpg.conf' gpg: WARNING: unsafe enclosing directory permissions on configuration file `/home/robin/.gnupg/gpg.conf' gpg: WARNING: unsafe permissions on configuration file `/home/robin/.gnupg/gpg.conf' gpg: WARNING: unsafe enclosing directory permissions on configuration file `/home/robin/.gnupg/gpg.conf' Traceback (most recent call last): File "/usr/share/quickly/templates/ubuntu-application/share.py", line 138, in <module> license.licensing() File "/usr/share/quickly/templates/ubuntu-application/license.py", line 284, in licensing {'translatable': 'yes'}) File "/usr/share/quickly/templates/ubuntu-application/internal/quicklyutils.py", line 166, in change_xml_elem xml_tree.find(parent_node).insert(0, new_node) AttributeError: 'NoneType' object has no attribute 'insert' ERROR: share command failed Aborting I reported this as a bug on Launchpad, because I assume that it is a bug. If you know a quick workaround, please let me know. https://bugs.launchpad.net/ubuntu/+source/quickly/+bug/1018138

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  • HR According to Batman

    - by D'Arcy Lussier
    Any idea who that guy is running alongside the Caped Crusader? That’s Nightwing, but you may know him as Robin…well, the first Robin anyway. There were actually like 5 Robin’s according to Wikipedia: Dick Grayson, the original, who’s parents were circus performers killed by a gangster. Jason Todd, who was caught trying to steal tires off of the Batmobile. Tim Drake, who saw Dick’s parents die and figured out who Batman and Robin were. and a few others that get into recent time travel/altered reality storylines. What does this have to do with HR? Well, it somewhat ties in with an article by Alex Papadimoulis from 2008. In the article he talks about the “Cravath System”. The Craveth system was developed by a law firm called Cravath, Swaine & Moore back in the 19th century. In a nutshell, they believed in hiring the best and brightest straight out of school. These aspiring lawyers would then begin a fight for survival in the firm, with the strong surviving. In what’s termed the “Up and Out” rule, employees needed to be promoted within 3 years or leave the company. They should achieve partner within 7 – 8 years and no later than 10 after initially coming on board (read all about the system on Wikipedia here). Back to Alex’s article, he quotes from a book published in 1947 about the lawfirm: Under the “Cravath system” of taking a substantial number of men annually and keeping a current constantly moving up in the office, and its philosophy of tenure, men are constantly leaving… it is often difficult to keep the best men long enough to determine whether they shall be made partners, for Cravath-trained men are always in demand, usually at premium salaries. And so we see a pattern forming here: 1. Hire a whole whack of smart college graduates 2. Put them to work 3. The ones that stick around should move up the ladder. The ones that don’t stick around served the company well and left to expound the quality of the Cravath firm. Those that didn’t fall into either of those categories were just let go. There’s some interesting undercurrents to these ideas. If you stick around, you better keep your feet moving! I was at a Microsoft shindig a few months back, and was talking to a Microsoft employee. He shared that at MS you have 5 years to achieve a “senior” position within the company. Once you hit that mark, you can stay there for the rest of your career (he told about a guy who’s a “senior” developer and has been for the last 20+ years working on audio drivers for Windows), but you *must* hit that mark within the timeframe. What we see with Microsoft is Cravath’s system in action, whether intentional or not: bring in smart young people and see which ones stick. You need to give people something to work towards. Saying “You must reach this level or else!” is one way to look at it. The other way is to see achieving a higher rank in the organization as something for ambitious employees to reach towards. It’s important for an organization to always have the next generation of executives waiting in the wings, and unless you’re encouraging that early on you may find yourself in a position of needing to fill positions that nobody has been working towards. Now, you might suggest that this isn’t that big of a deal because you could just hire someone from outside the organization, but the Cravath system holds to the tenet of promoting internally; develop your own talent, since your business is the best place for the future leadership to learn teh business from. It’s OK for people to quit. Alex’s article really drives this point home, but its worth noting here also: its OK for your people to quit. In fact its inevitable…and more inevitable that it’ll be good people that leave. Some will stay and work towards the internal awards of promotion, but a number will get experience, serve the organization well, and then move on to something else. This should be expected and treated as a natural business occurrence. The idea of an alumni of an organization begins to come into play here: “That guy used to work for <insert company here>”. There’s a benefit in that: those best and brightest will be drawn to your organization and your reputation will permeate your market through former staff that are sought after because of how well you nurtured them. The Batman Hook All of this brings us back to Batman and his HR practice: when Dick decided he’d had enough of the Robin schtick, he quit and became his own…but he was always associated with Batman and people understood where his training had come from. To the Dark Knight’s credit, he continued training partners under the Robin brand. Luckily he didn’t have to worry about firing any of them (the ship sort of sails when you reveal a secret identity), although there was that unfortunate “quitting” of the second Robin when the Joker blew him up…but regardless, we see the Cravath system at work: bring in talent, expect great things, and be ok with whatever they decide for their careers. It’s an interesting way to approach HR, and luckily for us our business isn’t as dangerous or over-the-top as the caped crusader’s.

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  • Squid on windows loadbalancing only to one server

    - by Martin L.
    After thousands of googles and trying days i cant get the load balancer/failover in squid on windows to work. Iam using squid 2.7. My webservers are 2 single NIC lighttpd and one dual nic lighttpd. server1 in this example is running squid on port 80 and lighttpd on port 8080 (just to test) Requirements: All 3 webservers running lighttpd should be balanced two option for load balancing: Best would be if server1 is busy server2 takes over, if server2 is busy server3 takes over, etc.. Round robin style evenly distributed load. Eg server1 takes first call, server2 second etc.. All requests should be treated the same way (no url rewriting or so on) Sent host headers have to be redirected to every server as http host header, speaking of "server1", "server1.company.internal" and "10.211.1.1". My approach: acl all src all acl manager proto cache_object http_port 80 accel defaultsite=server1.company.internal vhost #reverse proxy entries cache_peer 10.211.2.1 parent 8080 0 no-query originserver round-robin login=PASS name=server1_nic1 cache_peer 10.211.1.2 parent 80 0 no-query originserver round-robin login=PASS name=server2_nic1 cache_peer 10.211.2.3 parent 8080 0 no-query originserver round-robin login=PASS name=server3_nic1 cache_peer 10.211.2.4 parent 8080 0 no-query originserver round-robin login=PASS name=server3_nic2 #decl of names of squid host acl registered_name_hostdomain dstdomain server1.company.internal acl registered_name_host dstdomain server1 #ip of squid host acl registered_name_ip dstdomain 10.211.2.1 # access: redirects the correct squid hostname http_access allow registered_name_hostdomain http_access allow registered_name_host http_access allow registered_name_ip http_access deny all cache_peer_access server1_nic1 allow registered_name_hostdomain cache_peer_access server1_nic1 allow registered_name_host cache_peer_access server1_nic1 allow registered_name_ip cache_peer_access server2_nic1 allow registered_name_hostdomain cache_peer_access server2_nic1 allow registered_name_host cache_peer_access server2_nic1 allow registered_name_ip cache_peer_access server3_nic1 allow registered_name_hostdomain cache_peer_access server3_nic1 allow registered_name_host cache_peer_access server3_nic1 allow registered_name_ip cache_peer_access server3_nic2 allow registered_name_hostdomain cache_peer_access server3_nic2 allow registered_name_host cache_peer_access server3_nic2 allow registered_name_ip cache_peer_access server1_nic1 deny all cache_peer_access server2_nic1 deny all cache_peer_access server3_nic1 deny all cache_peer_access server3_nic2 deny all never_direct allow all Problems: Load balancer does not load balance other than to first server. Only if the first server is killed in any way the second will take over. I have seen the others working at some point, but definitely not as the intended load balancing described above. If the cache_peer_access is not defined sometimes the wrong hostname is sent to the backend webserver and this always depends on the defaultsite= parameter. Probably because the host header on the request to squid is not set and its replaced by defaultsite. Leaving out defaultsite didnt solve the problem. The only workaround i found for this is the current approach with cache_peer_access. Questions: Does the cache_peer_access influence the round-robin? Is there a better workaround to pass the host header to the backed webservers? Which parameters do increase the speed of load balancing or does anyone have a better approach? -Martin

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  • How much a website like bytes.com earning

    - by robin das
    i am running a website similar to bytes.com (IT QnA site) my site attract 600 unique visitors daily. we are planning our self as bytes.com. Atleast any one can tell me that whether we can earn some serious money with this kind of website. websiteoutlook estimate Daily Pageview - 700636 to bytes.com and its using google ads. Can any one please let me know what kind of earning we can expect for dotcom like bytes.com. Please give some light on this topic as a lot of energy, time and money goes in building this kind of website thanks robin Das

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  • How much a website like bytes.com earn

    - by robin das
    i am running a website similar to bytes.com (IT QnA site) my site attract 600 unique visitors daily. we are planning our self as bytes.com. Atleast any one can tell me that whether we can earn some serious money with this kind of website. websiteoutlook estimate Daily Pageview - 700636 to bytes.com Can any one please let me know what kind of earning we can expect for dotcom like bytes.com. Please give some light on this topic as a lot of energy, time and money goes in building this kind of website thanks robin Das

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  • sem_open() error: "undefined reference to sem_open()" on linux (Ubuntu 10.10)

    - by Robin
    So I am getting the error: "undefined reference to sem_open()" even though I have include the semaphore.h header. The same thing is happening for all my pthread function calls (mutex, pthread_create, etc). Any thoughts? I am using the following command to compile: g++ '/home/robin/Desktop/main.cpp' -o '/home/robin/Desktop/main.out' #include <iostream> using namespace std; #include <pthread.h> #include <semaphore.h> #include <fcntl.h> const char *serverControl = "/serverControl"; sem_t* semID; int main ( int argc, char *argv[] ) { //create semaphore used to control servers semID = sem_open(serverControl,O_CREAT,O_RDWR,0); return 0; }

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  • How can I set up OpenVPN to accept more than 60 connections?

    - by Robin
    Greetings! We're using OpenVPN and today hit an unexpected connection limit of 60 - even though max-clients is set to the source code default 1024. Server log: Tue Dec 21 13:49:41 2010 MULTI: new incoming connection would exceed maximum number of clients (60) We're slowly adding new clients to the VPN and expect to hit 200 some time next year, if we can get it working. We're running the server on a Win2003 R2. OpenVPN 2.0.9 Server config as follows: local 192.168.10.211 port 1195 proto tcp dev tun dev-node OpenVPN_Vision ca vision_ca.crt cert vision_server.crt key vision_server.key # This file should be kept secret dh vision_dh1024.pem server 192.168.211.0 255.255.255.0 ifconfig-pool-persist vision_ipp.txt ;server-bridge 10.8.0.4 255.255.255.0 10.8.0.50 10.8.0.100 ;client-to-client keepalive 10 120 comp-lzo ;max-clients 100 # Default in source code is 1024 persist-key persist-tun status openvpn-status-vision.log log vision.log verb 3 I would greatly appreciate any help or input on this one. Thanks! Best regards, Robin

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  • Ram not working in dual dynamic paging mode

    - by Robin Agrahari
    My motherboard is Intel D865GVHZ I m using 512 mb ram and recently i purchased a 512 mb ram of same company same speed(333) and same manufacturer. but my pc is not booting in dual dynamic paging mode . It is not at all booting and the screen freezes on windows logo screen at start up. i checked installing individual rams one by one and the pc is working with either of the ram installed individually. But wen i install both the pc is not working. One more point i found is my one ram has 8 chips on both sides while the other ram has 4 chips on both sides. Is that the root of the problem ?? plz help sir. in hope robin

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  • How do I fix my Ruby installation

    - by Robin Fisher
    Hi all, I rather cleverly (or not in hindsight) installed RVM, which kept hanging whilst compiling Rubies. I have removed the .rvm directory but now my system has reverted to Ruby 1.8.7 i.e. when I type: ruby -v which ruby they both point to 1.8.7. How do I get the ruby command to point to my 1.9.1 installation, which is located in /usr/local/lib/ruby/1.9.1? I'm on OSX 10.6. Thanks Robin

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  • PTLQueue : a scalable bounded-capacity MPMC queue

    - by Dave
    Title: Fast concurrent MPMC queue -- I've used the following concurrent queue algorithm enough that it warrants a blog entry. I'll sketch out the design of a fast and scalable multiple-producer multiple-consumer (MPSC) concurrent queue called PTLQueue. The queue has bounded capacity and is implemented via a circular array. Bounded capacity can be a useful property if there's a mismatch between producer rates and consumer rates where an unbounded queue might otherwise result in excessive memory consumption by virtue of the container nodes that -- in some queue implementations -- are used to hold values. A bounded-capacity queue can provide flow control between components. Beware, however, that bounded collections can also result in resource deadlock if abused. The put() and take() operators are partial and wait for the collection to become non-full or non-empty, respectively. Put() and take() do not allocate memory, and are not vulnerable to the ABA pathologies. The PTLQueue algorithm can be implemented equally well in C/C++ and Java. Partial operators are often more convenient than total methods. In many use cases if the preconditions aren't met, there's nothing else useful the thread can do, so it may as well wait via a partial method. An exception is in the case of work-stealing queues where a thief might scan a set of queues from which it could potentially steal. Total methods return ASAP with a success-failure indication. (It's tempting to describe a queue or API as blocking or non-blocking instead of partial or total, but non-blocking is already an overloaded concurrency term. Perhaps waiting/non-waiting or patient/impatient might be better terms). It's also trivial to construct partial operators by busy-waiting via total operators, but such constructs may be less efficient than an operator explicitly and intentionally designed to wait. A PTLQueue instance contains an array of slots, where each slot has volatile Turn and MailBox fields. The array has power-of-two length allowing mod/div operations to be replaced by masking. We assume sensible padding and alignment to reduce the impact of false sharing. (On x86 I recommend 128-byte alignment and padding because of the adjacent-sector prefetch facility). Each queue also has PutCursor and TakeCursor cursor variables, each of which should be sequestered as the sole occupant of a cache line or sector. You can opt to use 64-bit integers if concerned about wrap-around aliasing in the cursor variables. Put(null) is considered illegal, but the caller or implementation can easily check for and convert null to a distinguished non-null proxy value if null happens to be a value you'd like to pass. Take() will accordingly convert the proxy value back to null. An advantage of PTLQueue is that you can use atomic fetch-and-increment for the partial methods. We initialize each slot at index I with (Turn=I, MailBox=null). Both cursors are initially 0. All shared variables are considered "volatile" and atomics such as CAS and AtomicFetchAndIncrement are presumed to have bidirectional fence semantics. Finally T is the templated type. I've sketched out a total tryTake() method below that allows the caller to poll the queue. tryPut() has an analogous construction. Zebra stripping : alternating row colors for nice-looking code listings. See also google code "prettify" : https://code.google.com/p/google-code-prettify/ Prettify is a javascript module that yields the HTML/CSS/JS equivalent of pretty-print. -- pre:nth-child(odd) { background-color:#ff0000; } pre:nth-child(even) { background-color:#0000ff; } border-left: 11px solid #ccc; margin: 1.7em 0 1.7em 0.3em; background-color:#BFB; font-size:12px; line-height:65%; " // PTLQueue : Put(v) : // producer : partial method - waits as necessary assert v != null assert Mask = 1 && (Mask & (Mask+1)) == 0 // Document invariants // doorway step // Obtain a sequence number -- ticket // As a practical concern the ticket value is temporally unique // The ticket also identifies and selects a slot auto tkt = AtomicFetchIncrement (&PutCursor, 1) slot * s = &Slots[tkt & Mask] // waiting phase : // wait for slot's generation to match the tkt value assigned to this put() invocation. // The "generation" is implicitly encoded as the upper bits in the cursor // above those used to specify the index : tkt div (Mask+1) // The generation serves as an epoch number to identify a cohort of threads // accessing disjoint slots while s-Turn != tkt : Pause assert s-MailBox == null s-MailBox = v // deposit and pass message Take() : // consumer : partial method - waits as necessary auto tkt = AtomicFetchIncrement (&TakeCursor,1) slot * s = &Slots[tkt & Mask] // 2-stage waiting : // First wait for turn for our generation // Acquire exclusive "take" access to slot's MailBox field // Then wait for the slot to become occupied while s-Turn != tkt : Pause // Concurrency in this section of code is now reduced to just 1 producer thread // vs 1 consumer thread. // For a given queue and slot, there will be most one Take() operation running // in this section. // Consumer waits for producer to arrive and make slot non-empty // Extract message; clear mailbox; advance Turn indicator // We have an obvious happens-before relation : // Put(m) happens-before corresponding Take() that returns that same "m" for T v = s-MailBox if v != null : s-MailBox = null ST-ST barrier s-Turn = tkt + Mask + 1 // unlock slot to admit next producer and consumer return v Pause tryTake() : // total method - returns ASAP with failure indication for auto tkt = TakeCursor slot * s = &Slots[tkt & Mask] if s-Turn != tkt : return null T v = s-MailBox // presumptive return value if v == null : return null // ratify tkt and v values and commit by advancing cursor if CAS (&TakeCursor, tkt, tkt+1) != tkt : continue s-MailBox = null ST-ST barrier s-Turn = tkt + Mask + 1 return v The basic idea derives from the Partitioned Ticket Lock "PTL" (US20120240126-A1) and the MultiLane Concurrent Bag (US8689237). The latter is essentially a circular ring-buffer where the elements themselves are queues or concurrent collections. You can think of the PTLQueue as a partitioned ticket lock "PTL" augmented to pass values from lock to unlock via the slots. Alternatively, you could conceptualize of PTLQueue as a degenerate MultiLane bag where each slot or "lane" consists of a simple single-word MailBox instead of a general queue. Each lane in PTLQueue also has a private Turn field which acts like the Turn (Grant) variables found in PTL. Turn enforces strict FIFO ordering and restricts concurrency on the slot mailbox field to at most one simultaneous put() and take() operation. PTL uses a single "ticket" variable and per-slot Turn (grant) fields while MultiLane has distinct PutCursor and TakeCursor cursors and abstract per-slot sub-queues. Both PTL and MultiLane advance their cursor and ticket variables with atomic fetch-and-increment. PTLQueue borrows from both PTL and MultiLane and has distinct put and take cursors and per-slot Turn fields. Instead of a per-slot queues, PTLQueue uses a simple single-word MailBox field. PutCursor and TakeCursor act like a pair of ticket locks, conferring "put" and "take" access to a given slot. PutCursor, for instance, assigns an incoming put() request to a slot and serves as a PTL "Ticket" to acquire "put" permission to that slot's MailBox field. To better explain the operation of PTLQueue we deconstruct the operation of put() and take() as follows. Put() first increments PutCursor obtaining a new unique ticket. That ticket value also identifies a slot. Put() next waits for that slot's Turn field to match that ticket value. This is tantamount to using a PTL to acquire "put" permission on the slot's MailBox field. Finally, having obtained exclusive "put" permission on the slot, put() stores the message value into the slot's MailBox. Take() similarly advances TakeCursor, identifying a slot, and then acquires and secures "take" permission on a slot by waiting for Turn. Take() then waits for the slot's MailBox to become non-empty, extracts the message, and clears MailBox. Finally, take() advances the slot's Turn field, which releases both "put" and "take" access to the slot's MailBox. Note the asymmetry : put() acquires "put" access to the slot, but take() releases that lock. At any given time, for a given slot in a PTLQueue, at most one thread has "put" access and at most one thread has "take" access. This restricts concurrency from general MPMC to 1-vs-1. We have 2 ticket locks -- one for put() and one for take() -- each with its own "ticket" variable in the form of the corresponding cursor, but they share a single "Grant" egress variable in the form of the slot's Turn variable. Advancing the PutCursor, for instance, serves two purposes. First, we obtain a unique ticket which identifies a slot. Second, incrementing the cursor is the doorway protocol step to acquire the per-slot mutual exclusion "put" lock. The cursors and operations to increment those cursors serve double-duty : slot-selection and ticket assignment for locking the slot's MailBox field. At any given time a slot MailBox field can be in one of the following states: empty with no pending operations -- neutral state; empty with one or more waiting take() operations pending -- deficit; occupied with no pending operations; occupied with one or more waiting put() operations -- surplus; empty with a pending put() or pending put() and take() operations -- transitional; or occupied with a pending take() or pending put() and take() operations -- transitional. The partial put() and take() operators can be implemented with an atomic fetch-and-increment operation, which may confer a performance advantage over a CAS-based loop. In addition we have independent PutCursor and TakeCursor cursors. Critically, a put() operation modifies PutCursor but does not access the TakeCursor and a take() operation modifies the TakeCursor cursor but does not access the PutCursor. This acts to reduce coherence traffic relative to some other queue designs. It's worth noting that slow threads or obstruction in one slot (or "lane") does not impede or obstruct operations in other slots -- this gives us some degree of obstruction isolation. PTLQueue is not lock-free, however. The implementation above is expressed with polite busy-waiting (Pause) but it's trivial to implement per-slot parking and unparking to deschedule waiting threads. It's also easy to convert the queue to a more general deque by replacing the PutCursor and TakeCursor cursors with Left/Front and Right/Back cursors that can move either direction. Specifically, to push and pop from the "left" side of the deque we would decrement and increment the Left cursor, respectively, and to push and pop from the "right" side of the deque we would increment and decrement the Right cursor, respectively. We used a variation of PTLQueue for message passing in our recent OPODIS 2013 paper. ul { list-style:none; padding-left:0; padding:0; margin:0; margin-left:0; } ul#myTagID { padding: 0px; margin: 0px; list-style:none; margin-left:0;} -- -- There's quite a bit of related literature in this area. I'll call out a few relevant references: Wilson's NYU Courant Institute UltraComputer dissertation from 1988 is classic and the canonical starting point : Operating System Data Structures for Shared-Memory MIMD Machines with Fetch-and-Add. Regarding provenance and priority, I think PTLQueue or queues effectively equivalent to PTLQueue have been independently rediscovered a number of times. See CB-Queue and BNPBV, below, for instance. But Wilson's dissertation anticipates the basic idea and seems to predate all the others. Gottlieb et al : Basic Techniques for the Efficient Coordination of Very Large Numbers of Cooperating Sequential Processors Orozco et al : CB-Queue in Toward high-throughput algorithms on many-core architectures which appeared in TACO 2012. Meneghin et al : BNPVB family in Performance evaluation of inter-thread communication mechanisms on multicore/multithreaded architecture Dmitry Vyukov : bounded MPMC queue (highly recommended) Alex Otenko : US8607249 (highly related). John Mellor-Crummey : Concurrent queues: Practical fetch-and-phi algorithms. Technical Report 229, Department of Computer Science, University of Rochester Thomasson : FIFO Distributed Bakery Algorithm (very similar to PTLQueue). Scott and Scherer : Dual Data Structures I'll propose an optimization left as an exercise for the reader. Say we wanted to reduce memory usage by eliminating inter-slot padding. Such padding is usually "dark" memory and otherwise unused and wasted. But eliminating the padding leaves us at risk of increased false sharing. Furthermore lets say it was usually the case that the PutCursor and TakeCursor were numerically close to each other. (That's true in some use cases). We might still reduce false sharing by incrementing the cursors by some value other than 1 that is not trivially small and is coprime with the number of slots. Alternatively, we might increment the cursor by one and mask as usual, resulting in a logical index. We then use that logical index value to index into a permutation table, yielding an effective index for use in the slot array. The permutation table would be constructed so that nearby logical indices would map to more distant effective indices. (Open question: what should that permutation look like? Possibly some perversion of a Gray code or De Bruijn sequence might be suitable). As an aside, say we need to busy-wait for some condition as follows : "while C == 0 : Pause". Lets say that C is usually non-zero, so we typically don't wait. But when C happens to be 0 we'll have to spin for some period, possibly brief. We can arrange for the code to be more machine-friendly with respect to the branch predictors by transforming the loop into : "if C == 0 : for { Pause; if C != 0 : break; }". Critically, we want to restructure the loop so there's one branch that controls entry and another that controls loop exit. A concern is that your compiler or JIT might be clever enough to transform this back to "while C == 0 : Pause". You can sometimes avoid this by inserting a call to a some type of very cheap "opaque" method that the compiler can't elide or reorder. On Solaris, for instance, you could use :"if C == 0 : { gethrtime(); for { Pause; if C != 0 : break; }}". It's worth noting the obvious duality between locks and queues. If you have strict FIFO lock implementation with local spinning and succession by direct handoff such as MCS or CLH,then you can usually transform that lock into a queue. Hidden commentary and annotations - invisible : * And of course there's a well-known duality between queues and locks, but I'll leave that topic for another blog post. * Compare and contrast : PTLQ vs PTL and MultiLane * Equivalent : Turn; seq; sequence; pos; position; ticket * Put = Lock; Deposit Take = identify and reserve slot; wait; extract & clear; unlock * conceptualize : Distinct PutLock and TakeLock implemented as ticket lock or PTL Distinct arrival cursors but share per-slot "Turn" variable provides exclusive role-based access to slot's mailbox field put() acquires exclusive access to a slot for purposes of "deposit" assigns slot round-robin and then acquires deposit access rights/perms to that slot take() acquires exclusive access to slot for purposes of "withdrawal" assigns slot round-robin and then acquires withdrawal access rights/perms to that slot At any given time, only one thread can have withdrawal access to a slot at any given time, only one thread can have deposit access to a slot Permissible for T1 to have deposit access and T2 to simultaneously have withdrawal access * round-robin for the purposes of; role-based; access mode; access role mailslot; mailbox; allocate/assign/identify slot rights; permission; license; access permission; * PTL/Ticket hybrid Asymmetric usage ; owner oblivious lock-unlock pairing K-exclusion add Grant cursor pass message m from lock to unlock via Slots[] array Cursor performs 2 functions : + PTL ticket + Assigns request to slot in round-robin fashion Deconstruct protocol : explication put() : allocate slot in round-robin fashion acquire PTL for "put" access store message into slot associated with PTL index take() : Acquire PTL for "take" access // doorway step seq = fetchAdd (&Grant, 1) s = &Slots[seq & Mask] // waiting phase while s-Turn != seq : pause Extract : wait for s-mailbox to be full v = s-mailbox s-mailbox = null Release PTL for both "put" and "take" access s-Turn = seq + Mask + 1 * Slot round-robin assignment and lock "doorway" protocol leverage the same cursor and FetchAdd operation on that cursor FetchAdd (&Cursor,1) + round-robin slot assignment and dispersal + PTL/ticket lock "doorway" step waiting phase is via "Turn" field in slot * PTLQueue uses 2 cursors -- put and take. Acquire "put" access to slot via PTL-like lock Acquire "take" access to slot via PTL-like lock 2 locks : put and take -- at most one thread can access slot's mailbox Both locks use same "turn" field Like multilane : 2 cursors : put and take slot is simple 1-capacity mailbox instead of queue Borrow per-slot turn/grant from PTL Provides strict FIFO Lock slot : put-vs-put take-vs-take at most one put accesses slot at any one time at most one put accesses take at any one time reduction to 1-vs-1 instead of N-vs-M concurrency Per slot locks for put/take Release put/take by advancing turn * is instrumental in ... * P-V Semaphore vs lock vs K-exclusion * See also : FastQueues-excerpt.java dice-etc/queue-mpmc-bounded-blocking-circular-xadd/ * PTLQueue is the same as PTLQB - identical * Expedient return; ASAP; prompt; immediately * Lamport's Bakery algorithm : doorway step then waiting phase Threads arriving at doorway obtain a unique ticket number Threads enter in ticket order * In the terminology of Reed and Kanodia a ticket lock corresponds to the busy-wait implementation of a semaphore using an eventcount and a sequencer It can also be thought of as an optimization of Lamport's bakery lock was designed for fault-tolerance rather than performance Instead of spinning on the release counter, processors using a bakery lock repeatedly examine the tickets of their peers --

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  • Signup form using Braintree Transparent Redirect

    - by Robin Fisher
    Hi, I'm developing an application in Rails and want the user to be able to signup and provide their card details on one form. I'm using the Braintree API and their transparent redirect, which means that the form data is posted directly to Braintree. How can I store and later retrieve the non-payment related information provided by the user from that form e.g. account name, username? These values are not returned in the response provided by Braintree. If you look at the Basecamp signup process, this is the result I want to achieve. Thanks Robin

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  • asp.net rangevalidator for calendar extender entries gives problems in safari

    - by Robin Baralla
    Hi there, I have the following scenario: arrival and departure dates have to be selected on a form, through 2 textboxes with a calendar extender each. I validate the entries to check that no date before today is selected and to check that the departure is after the arrival. I used a rangevalidator and a comparevalidator. In IE, Firefox and Opera it is working fine, in Safari (on windows) however both the validators go off even on entries that should be accepted. It makes me suspect that the date format dd/MM/yyyy causes trouble for Safari. (the dd/MMMM/yyyy also gave the same troubles in the other browsers, probably due to the dependency on UIculture) The code is:   The range validator gets its values in code behind on Page_load RangeValidator1.MinimumValue = DateTime.Now.AddDays(1).ToShortDateString(); RangeValidator1.MaximumValue = DateTime.Now.AddMonths(12).ToShortDateString(); Does anybody have any suggestions on how to solve this problem with safari? best regards, Robin

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  • making arrays from tab-delimited text file column

    - by absolutenewbie
    I was wondering if anyone could help a desperate newbie with perl with the following question. I've been trying all day but with my perl book at work, I can't seem to anything relevant in google...or maybe am genuinely stupid with this. I have a file that looks something like the following: Bob April Bob April Bob March Mary August Robin December Robin April The output file I'm after is: Bob April April March Mary August Robin December April So that it lists each month in the order that it appears for each person. I tried making it into a hash but of course it wouldn't let me have duplicates so I thought I would like to have arrays for each name (in this example, Bob, Mary and Robin). I'm afraid to upload the code I've been trying to tweak because I know it'll be horribly wrong. I think I need to define(?) the array. Would this be correct? Any help would be greatly appreciated and I promise I will be studying more about perl in the meantime. Thank you for your time, patience and help. #!/usr/bin/perl -w while (<>) { chomp; if (defined $old_name) { $name=$1; $month=$2; if ($name eq $old_name) { $array{$month}++; } else { print "$old_name"; foreach (@array) { push (@array, $month); print "\t@array"; } print "\n"; @array=(); $array{$month}++; } } else { $name=$1; $month=$2; $array{month}++; } $old_name=$name; } print "$old_name"; foreach (@array) { push (@array, $month); print "\t@array"; } print "\n";

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  • Suggestions on how to track tag count for a particular object

    - by Robin Fisher
    Hi, I'm looking for suggestions on how to track the number of tags associated with a particular object in Rails. I'm using acts_as_taggable_on and it's working fine. What I would like to be able to do is search for all objects that have no tags, preferably through a scope i.e. Object.untagged.all My first thought was to use an after_save callback to update an attribute called "taggings_count" in my model: def update_taggings_count self.taggings_count = self.tag_list.size self.save end Unfortunately, this does the obvious thing of putting me in an infinite loop. I need to use an after_save callback because the tag_list is not updated until the main object is saved. Would appreciate any suggestions as I'm on the verge of rolling my own tagging system. Regards Robin

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