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  • 5 Reasons You Must Start Capturing Baseline Data

    It is widely acknowledged within the SQL Server community that baselines represent valuable information that DBAs should capture. Unfortunately, very few companies manage to log and report on this information, and DBAs are then forced to troubleshoot from the hip and scramble to find evidence to prove that the database is not the problem. This article will make a compelling argument for why DBAs must start capturing baseline information, and will create a roadmap for subsequent posts.

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  • Webinar: Temporary Tables in Oracle and SQL Server

    Once again Jonathan Lewis (Oracle Ace Director, OakTable Network) and Grant Fritchey (Microsoft SQL Server MVP) will host a live discussion on Oracle and SQL Server, this time in relation to temporary tables. Will they agree on some common ground? Or will it be an out and out argument? Either way, be prepared for a lively exchange that will not only entertain, but will teach you key concepts on Oracle and SQL Server.

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  • Is it possible to access javascript return value outside of function? [on hold]

    - by Kinnard Hockenhull
    How would one access javascript function's return value outside of the function? For example could you tell a function to return something somewhere else in the code? Theoretical example: milkmachine = function(argument){ var r; var k; //do something with arguments and variables return r; } var rainbow = milkmachine(); //rainbow == r milkmachine.return(k); var spectrum = milkmachine(); //spectrum == k

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  • T-SQL Tuesday #34: HELP!

    - by merrillaldrich
    I owe my career to the SQL Server community, specifically the Internet SQL Server community, so this month’s T-SQL Tuesday is especially poignant. I changed careers “cold” about eight years ago, and, while I had some educational background in computer science, I had relatively little real-world DBA experience. Someone gave me a shot in the form of an entry level job, for which I am grateful, but I also had to make the argument to him that I would figure out whatever I needed to do to be successful...(read more)

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  • Open space office for team work? [closed]

    - by pboy
    An argument I often hear to justify open space office layout is that, being open, it contributes to team work and more collaboration between people. Does it really contributes to team work, compared to private offices? Is there hard data that might support this? Edit: I'm interested in that topic in a programmer's context, a bit like the study made in PeopleWare, which focuses on software development.

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  • Java ??????????????

    - by katsumii
    ???????????java?????????????????????????????????? Linux,UNIX??? LANG ? LC_ALL ????????????????????????? Windows ????????????????????????????????????????????????????????????java -Duser.language=en ... ??????????????·??????????????????????????????java.exe????????????jvm.dll ?????????????????????????????????????????????????????java.exe???????????????????????????????????????????Windows: injecting argument to *.exe invocation (INOUE Katsumi @ Tokyo)There are many applications that spawns "java.exe" and there often is no way to pass java flags 

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  • ?????create or replace???PL/SQL??

    - by Liu Maclean(???)
    ????T.Askmaclean.com?????10gR2??????procedure,?????????create or replace ??????????????????,????Oracle???????????????????procedure? ??Maclean ??2?10gR2???????????PL/SQL?????: ??1: ??Flashback Query ????,?????????????flashback database,??????????create or replace???SQL??source$??????????undo data,????????????: SQL> select * from V$version; BANNER ---------------------------------------------------------------- Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bi PL/SQL Release 10.2.0.5.0 - Production CORE 10.2.0.5.0 Production TNS for Linux: Version 10.2.0.5.0 - Production NLSRTL Version 10.2.0.5.0 - Production SQL> select * from global_name; GLOBAL_NAME -------------------------------------------------------------------------------- www.oracledatabase12g.com SQL> create or replace procedure maclean_proc as   2  begin   3  execute immediate 'select 1 from dual';   4  end;   5  / Procedure created. SQL> select * from dba_source where name='MACLEAN_PROC'; OWNER      NAME                           TYPE               LINE TEXT ---------- ------------------------------ ------------ ---------- -------------------------------------------------- SYS        MACLEAN_PROC                   PROCEDURE             1 procedure maclean_proc as SYS        MACLEAN_PROC                   PROCEDURE             2 begin SYS        MACLEAN_PROC                   PROCEDURE             3 execute immediate 'select 1 from dual'; SYS        MACLEAN_PROC                   PROCEDURE             4 end; SQL> select current_scn from v$database; CURRENT_SCN -----------     2660057 create or replace procedure maclean_proc as begin -- I am new procedure execute immediate 'select 2 from dual'; end; / Procedure created. SQL> select current_scn from v$database; CURRENT_SCN -----------     2660113 SQL> select * from dba_source where name='MACLEAN_PROC'; OWNER      NAME                           TYPE               LINE TEXT ---------- ------------------------------ ------------ ---------- -------------------------------------------------- SYS        MACLEAN_PROC                   PROCEDURE             1 procedure maclean_proc as SYS        MACLEAN_PROC                   PROCEDURE             2 begin SYS        MACLEAN_PROC                   PROCEDURE             3 -- I am new procedure SYS        MACLEAN_PROC                   PROCEDURE             4 execute immediate 'select 2 from dual'; SYS        MACLEAN_PROC                   PROCEDURE             5 end; SQL> create table old_source as select * from dba_source as of scn 2660057 where name='MACLEAN_PROC'; Table created. SQL> select * from old_source where name='MACLEAN_PROC'; OWNER      NAME                           TYPE               LINE TEXT ---------- ------------------------------ ------------ ---------- -------------------------------------------------- SYS        MACLEAN_PROC                   PROCEDURE             1 procedure maclean_proc as SYS        MACLEAN_PROC                   PROCEDURE             2 begin SYS        MACLEAN_PROC                   PROCEDURE             3 execute immediate 'select 1 from dual'; SYS        MACLEAN_PROC                   PROCEDURE             4 end; ?????????scn??flashback query????,????????as of timestamp??????????,????PL/SQL????????????????undo??????????,????????????replace/drop ??????PL/SQL??? ??2 ??logminer??replace/drop PL/SQL?????SQL???DELETE??,??logminer?UNDO SQL???PL/SQL?????? ????????????????archivelog????,??????????????? minimal supplemental logging,??????????Unsupported SQLREDO???: create or replace?? ?? procedure???????SQL??????, ??????procedure????????????????, source$??????????????: SQL> ALTER DATABASE ADD SUPPLEMENTAL LOG DATA; Database altered. SQL> create or replace procedure maclean_proc as   2  begin   3  execute immediate 'select 1 from dual';   4  end;   5  / Procedure created. SQL> SQL> oradebug setmypid; Statement processed. SQL> SQL> oradebug event 10046 trace name context forever,level 12; Statement processed. SQL> SQL> create or replace procedure maclean_proc as   2  begin   3  execute immediate 'select 2 from dual';   4  end;   5  / Procedure created. SQL> oradebug tracefile_name /s01/admin/G10R25/udump/g10r25_ora_4305.trc [oracle@vrh8 ~]$ egrep  "update|insert|delete|merge"  /s01/admin/G10R25/udump/g10r25_ora_4305.trc delete from procedureinfo$ where obj#=:1 delete from argument$ where obj#=:1 delete from procedurec$ where obj#=:1 delete from procedureplsql$ where obj#=:1 delete from procedurejava$ where obj#=:1 delete from vtable$ where obj#=:1 insert into procedureinfo$(obj#,procedure#,overload#,procedurename,properties,itypeobj#) values (:1,:2,:3,:4,:5,:6) insert into argument$( obj#,procedure$,procedure#,overload#,position#,sequence#,level#,argument,type#,default#,in_out,length,precision#,scale,radix,charsetid,charsetform,properties,type_owner,type_name,type_subname,type_linkname,pls_type) values (:1,:2,:3,:4,:5,:6,:7,:8,:9,:10,:11,:12,:13,:14,:15,:16,:17,:18,:19,:20,:21,:22,:23) insert into procedureplsql$(obj#,procedure#,entrypoint#) values (:1,:2,:3) update procedure$ set audit$=:2,options=:3 where obj#=:1 delete from source$ where obj#=:1 insert into source$(obj#,line,source) values (:1,:2,:3) delete from idl_ub1$ where obj#=:1 and part=:2 and version<>:3 delete from idl_char$ where obj#=:1 and part=:2 and version<>:3 delete from idl_ub2$ where obj#=:1 and part=:2 and version<>:3 delete from idl_sb4$ where obj#=:1 and part=:2 and version<>:3 delete from ncomp_dll$ where obj#=:1 returning dllname into :2 update idl_sb4$ set piece#=:1 ,length=:2 , piece=:3 where obj#=:4 and part=:5 and piece#=:6 and version=:7 update idl_ub1$ set piece#=:1 ,length=:2 , piece=:3 where obj#=:4 and part=:5 and piece#=:6 and version=:7 update idl_char$ set piece#=:1 ,length=:2 , piece=:3 where obj#=:4 and part=:5 and piece#=:6 and version=:7 update idl_ub2$ set piece#=:1 ,length=:2 , piece=:3 where obj#=:4 and part=:5 and piece#=:6 and version=:7 delete from idl_ub1$ where obj#=:1 and part=:2 and version<>:3 delete from idl_char$ where obj#=:1 and part=:2 and version<>:3 delete from idl_ub2$ where obj#=:1 and part=:2 and version<>:3 delete from idl_sb4$ where obj#=:1 and part=:2 and version<>:3 delete from ncomp_dll$ where obj#=:1 returning dllname into :2 delete from idl_ub1$ where obj#=:1 and part=:2 and (piece#<:3 or piece#>:4) and version=:5 delete from idl_char$ where obj#=:1 and part=:2 and (piece#<:3 or piece#>:4) and version=:5 delete from idl_ub2$ where obj#=:1 and part=:2 and (piece#<:3 or piece#>:4) and version=:5 delete from idl_sb4$ where obj#=:1 and part=:2 and (piece#<:3 or piece#>:4) and version=:5 delete from idl_ub1$ where obj#=:1 and part=:2 and version<>:3 delete from idl_char$ where obj#=:1 and part=:2 and version<>:3 delete from idl_ub2$ where obj#=:1 and part=:2 and version<>:3 delete from idl_sb4$ where obj#=:1 and part=:2 and version<>:3 delete from ncomp_dll$ where obj#=:1 returning dllname into :2 update idl_sb4$ set piece#=:1 ,length=:2 , piece=:3 where obj#=:4 and part=:5 and piece#=:6 and version=:7 update idl_ub1$ set piece#=:1 ,length=:2 , piece=:3 where obj#=:4 and part=:5 and piece#=:6 and version=:7 delete from idl_char$ where obj#=:1 and part=:2 and (piece#<:3 or piece#>:4) and version=:5 delete from idl_ub2$ where obj#=:1 and part=:2 and (piece#<:3 or piece#>:4) and version=:5 delete from error$ where obj#=:1 delete from settings$ where obj# = :1 insert into settings$(obj#, param, value) values (:1, :2, :3) delete from warning_settings$ where obj# = :1 insert into warning_settings$(obj#, warning_num, global_mod, property) values (:1, :2, :3, :4) delete from dependency$ where d_obj#=:1 delete from access$ where d_obj#=:1 insert into dependency$(d_obj#,d_timestamp,order#,p_obj#,p_timestamp, property, d_attrs)values (:1,:2,:3,:4,:5,:6, :7) insert into access$(d_obj#,order#,columns,types) values (:1,:2,:3,:4) update obj$ set obj#=:6,type#=:7,ctime=:8,mtime=:9,stime=:10,status=:11,dataobj#=:13,flags=:14,oid$=:15,spare1=:16, spare2=:17 where owner#=:1 and name=:2 and namespace=:3 and(remoteowner=:4 or remoteowner is null and :4 is null)and(linkname=:5 or linkname is null and :5 is null)and(subname=:12 or subname is null and :12 is null) ?drop procedure??????source$???PL/SQL?????: SQL> oradebug setmypid; Statement processed. SQL> oradebug event 10046 trace name context forever,level 12; Statement processed. SQL> drop procedure maclean_proc; Procedure dropped. SQL> oradebug tracefile_name /s01/admin/G10R25/udump/g10r25_ora_4331.trc delete from context$ where obj#=:1 delete from dir$ where obj#=:1 delete from type_misc$ where obj#=:1 delete from library$ where obj#=:1 delete from procedure$ where obj#=:1 delete from javaobj$ where obj#=:1 delete from operator$ where obj#=:1 delete from opbinding$ where obj#=:1 delete from opancillary$ where obj#=:1 delete from oparg$ where obj# = :1 delete from com$ where obj#=:1 delete from source$ where obj#=:1 delete from idl_ub1$ where obj#=:1 and part=:2 delete from idl_char$ where obj#=:1 and part=:2 delete from idl_ub2$ where obj#=:1 and part=:2 delete from idl_sb4$ where obj#=:1 and part=:2 delete from ncomp_dll$ where obj#=:1 returning dllname into :2 delete from idl_ub1$ where obj#=:1 and part=:2 delete from idl_char$ where obj#=:1 and part=:2 delete from idl_ub2$ where obj#=:1 and part=:2 delete from idl_sb4$ where obj#=:1 and part=:2 delete from ncomp_dll$ where obj#=:1 returning dllname into :2 delete from idl_ub1$ where obj#=:1 and part=:2 delete from idl_char$ where obj#=:1 and part=:2 delete from idl_ub2$ where obj#=:1 and part=:2 delete from idl_sb4$ where obj#=:1 and part=:2 delete from ncomp_dll$ where obj#=:1 returning dllname into :2 delete from error$ where obj#=:1 delete from settings$ where obj# = :1 delete from procedureinfo$ where obj#=:1 delete from argument$ where obj#=:1 delete from procedurec$ where obj#=:1 delete from procedureplsql$ where obj#=:1 delete from procedurejava$ where obj#=:1 delete from vtable$ where obj#=:1 delete from dependency$ where d_obj#=:1 delete from access$ where d_obj#=:1 delete from objauth$ where obj#=:1 update obj$ set obj#=:6,type#=:7,ctime=:8,mtime=:9,stime=:10,status=:11,dataobj#=:13,flags=:14,oid$=:15,spare1=:16, spare2=:17 where owner#=:1 and name=:2 and namespace=:3 and(remoteowner=:4 or remoteowner is null and :4 is null)and(linkname=:5 or linkname is null and :5 is null)and(subname=:12 or subname is null and :12 is null) ??????????source$???redo: SQL> alter system switch logfile; System altered. SQL> select sequence#,name from v$archived_log where sequence#=(select max(sequence#) from v$archived_log);  SEQUENCE# ---------- NAME --------------------------------------------------------------------------------        242 /s01/flash_recovery_area/G10R25/archivelog/2012_05_21/o1_mf_1_242_7vnm13k6_.arc SQL> exec dbms_logmnr.add_logfile ('/s01/flash_recovery_area/G10R25/archivelog/2012_05_21/o1_mf_1_242_7vnm13k6_.arc',options => dbms_logmnr.new); PL/SQL procedure successfully completed. SQL> exec dbms_logmnr.start_logmnr(options => dbms_logmnr.dict_from_online_catalog); PL/SQL procedure successfully completed. SQL> select sql_redo,sql_undo from v$logmnr_contents where seg_name = 'SOURCE$' and operation='DELETE'; delete from "SYS"."SOURCE$" where "OBJ#" = '56059' and "LINE" = '1' and "SOURCE" = 'procedure maclean_proc as ' and ROWID = 'AAAABIAABAAALpyAAN'; insert into "SYS"."SOURCE$"("OBJ#","LINE","SOURCE") values ('56059','1','procedure maclean_proc as '); delete from "SYS"."SOURCE$" where "OBJ#" = '56059' and "LINE" = '2' and "SOURCE" = 'begin ' and ROWID = 'AAAABIAABAAALpyAAO'; insert into "SYS"."SOURCE$"("OBJ#","LINE","SOURCE") values ('56059','2','begin '); delete from "SYS"."SOURCE$" where "OBJ#" = '56059' and "LINE" = '3' and "SOURCE" = 'execute immediate ''select 1 from dual''; ' and ROWID = 'AAAABIAABAAALpyAAP'; insert into "SYS"."SOURCE$"("OBJ#","LINE","SOURCE") values ('56059','3','execute immediate ''select 1 from dual''; '); delete from "SYS"."SOURCE$" where "OBJ#" = '56059' and "LINE" = '4' and "SOURCE" = 'end;' and ROWID = 'AAAABIAABAAALpyAAQ'; insert into "SYS"."SOURCE$"("OBJ#","LINE","SOURCE") values ('56059','4','end;'); delete from "SYS"."SOURCE$" where "OBJ#" = '56059' and "LINE" = '1' and "SOURCE" = 'procedure maclean_proc as ' and ROWID = 'AAAABIAABAAALpyAAJ'; insert into "SYS"."SOURCE$"("OBJ#","LINE","SOURCE") values ('56059','1','procedure maclean_proc as '); delete from "SYS"."SOURCE$" where "OBJ#" = '56059' and "LINE" = '2' and "SOURCE" = 'begin ' and ROWID = 'AAAABIAABAAALpyAAK'; insert into "SYS"."SOURCE$"("OBJ#","LINE","SOURCE") values ('56059','2','begin '); delete from "SYS"."SOURCE$" where "OBJ#" = '56059' and "LINE" = '3' and "SOURCE" = 'execute immediate ''select 2 from dual''; ' and ROWID = 'AAAABIAABAAALpyAAL'; insert into "SYS"."SOURCE$"("OBJ#","LINE","SOURCE") values ('56059','3','execute immediate ''select 2 from dual''; '); delete from "SYS"."SOURCE$" where "OBJ#" = '56059' and "LINE" = '4' and "SOURCE" = 'end;' and ROWID = 'AAAABIAABAAALpyAAM'; insert into "SYS"."SOURCE$"("OBJ#","LINE","SOURCE") values ('56059','4','end;'); ???? logminer???UNDO SQL???????source$????,?DELETE????????????,????SOURCE????????????PL/SQL???DDL???

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  • YUM Update Failed - Error in POSTIN scriptlet in rpm package

    - by Tiffany Walker
    Running "yum update" and it gets to installing and then breaks. Not sure what the problem is. Google shows nothing. Error in POSTIN scriptlet in rpm package gtk2-2.18.9-10.el6.x86_64 error: error creating temporary file /var/tmp/rpm-tmp.NB84HC: Invalid argument error: Couldn't create temporary file for %post(gtk2-2.18.9-10.el6.x86_64): Invalid argument Updating : e2fsprogs-libs-1.41.12-12.el6.x86_64 44/378 Traceback (most recent call last): File "/usr/lib/python2.6/site-packages/yum/rpmtrans.py", line 387, in callback self._instCloseFile( bytes, total, h ) File "/usr/lib/python2.6/site-packages/yum/rpmtrans.py", line 463, in _instCloseFile self.base.history.trans_data_pid_end(pid, state) File "/usr/lib/python2.6/site-packages/yum/history.py", line 858, in trans_data_pid_end """, ('TRUE', self._tid, pid, state)) File "/usr/lib/python2.6/site-packages/yum/sqlutils.py", line 168, in executeSQLQmark return cursor.execute(query, params) sqlite3.OperationalError: unable to open database file error: python callback <bound method RPMTransaction.callback of <yum.rpmtrans.RPMTransaction instance at 0x45c2290>> failed, aborting! With a check all: yum check Loaded plugins: fastestmirror, rhnplugin, security MySQL-client-5.5.27-1.cp.1132.x86_64 is obsoleted by MySQL-client-5.5.27-1.cp.1132.x86_64 MySQL-server-5.5.27-1.cp.1132.x86_64 is obsoleted by MySQL-server-5.5.27-1.cp.1132.x86_64 abrt-libs-2.0.8-6.el6.x86_64 is a duplicate with abrt-libs-2.0.4-14.el6.centos.x86_64 audit-libs-2.2-2.el6.x86_64 is a duplicate with audit-libs-2.1.3-3.el6.x86_64 bandmin-1.6.1-5.noarch has missing requires of perl(bandmin.conf) bandmin-1.6.1-5.noarch has missing requires of perl(bmversion.pl) bandmin-1.6.1-5.noarch has missing requires of perl(services.conf) 32:bind-libs-9.8.2-0.10.rc1.el6_3.3.x86_64 is a duplicate with 32:bind-libs-9.7.3-8.P3.el6_2.2.x86_64 cagefs-safebin-3.6-6.el6.cloudlinux.x86_64 is a duplicate with cagefs-safebin-3.5-1.el6.cloudlinux.x86_64 chkconfig-1.3.49.3-2.el6.x86_64 is a duplicate with chkconfig-1.3.49.3-1.el6_2.x86_64 cloudlinux-release-6-6.3.0.x86_64 is a duplicate with cloudlinux-release-6-6.2.2.x86_64 coreutils-8.4-19.el6.x86_64 is a duplicate with coreutils-8.4-16.el6.x86_64 coreutils-libs-8.4-19.el6.x86_64 is a duplicate with coreutils-libs-8.4-16.el6.x86_64 1:cups-libs-1.4.2-48.el6_3.1.x86_64 is a duplicate with 1:cups-libs-1.4.2-44.el6_2.3.x86_64 1:dbus-libs-1.2.24-7.el6_3.x86_64 is a duplicate with 1:dbus-libs-1.2.24-5.el6_1.x86_64 12:dhcp-common-4.1.1-31.P1.el6_3.1.x86_64 is a duplicate with 12:dhcp-common-4.1.1-25.P1.el6_2.1.x86_64 e2fsprogs-libs-1.41.12-12.el6.x86_64 is a duplicate with e2fsprogs-libs-1.41.12-11.el6.x86_64 exim-4.80-0.x86_64 has missing requires of perl(SafeFile) expat-2.0.1-11.el6_2.x86_64 is a duplicate with expat-2.0.1-9.1.el6.x86_64 frontpage-2002-SR1.2.i386 has missing requires of libexpat.so.0 gawk-3.1.7-10.el6.x86_64 is a duplicate with gawk-3.1.7-9.el6.x86_64 glib2-2.22.5-7.el6.x86_64 is a duplicate with glib2-2.22.5-6.el6.x86_64 glibc-2.12-1.80.el6_3.5.x86_64 is a duplicate with glibc-2.12-1.47.el6_2.12.x86_64 glibc-common-2.12-1.80.el6_3.5.x86_64 is a duplicate with glibc-common-2.12-1.47.el6_2.12.x86_64 gtk2-2.18.9-10.el6.x86_64 is a duplicate with gtk2-2.18.9-6.el6.centos.x86_64 kernel-firmware-2.6.32-320.4.1.lve1.1.4.el6.noarch is obsoleted by kernel-firmware-2.6.32-320.4.1.lve1.1.4.el6.noarch kernel-firmware-2.6.32-320.4.1.lve1.1.4.el6.noarch is obsoleted by kernel-firmware-2.6.32-379.5.1.lve1.1.9.6.1.el6.noarch kernel-firmware-2.6.32-379.5.1.lve1.1.9.6.1.el6.noarch is a duplicate with kernel-firmware-2.6.32-320.4.1.lve1.1.4.el6.noarch kernel-firmware-2.6.32-379.5.1.lve1.1.9.6.1.el6.noarch is obsoleted by kernel-firmware-2.6.32-320.4.1.lve1.1.4.el6.noarch kernel-firmware-2.6.32-379.5.1.lve1.1.9.6.1.el6.noarch is obsoleted by kernel-firmware-2.6.32-379.5.1.lve1.1.9.6.1.el6.noarch kernel-headers-2.6.32-379.5.1.lve1.1.9.6.1.el6.x86_64 is a duplicate with kernel-headers-2.6.32-320.4.1.lve1.1.4.el6.x86_64 keyutils-libs-1.4-4.el6.x86_64 is a duplicate with keyutils-libs-1.4-3.el6.x86_64 krb5-libs-1.9-33.el6_3.3.x86_64 is a duplicate with krb5-libs-1.9-22.el6_2.1.x86_64 libblkid-2.17.2-12.7.el6.x86_64 is a duplicate with libblkid-2.17.2-12.4.el6.x86_64 libcom_err-1.41.12-12.el6.x86_64 is a duplicate with libcom_err-1.41.12-11.el6.x86_64 libgcc-4.4.6-4.el6.x86_64 is a duplicate with libgcc-4.4.6-3.el6.x86_64 libselinux-2.0.94-5.3.el6.x86_64 is a duplicate with libselinux-2.0.94-5.2.el6.x86_64 libstdc++-4.4.6-4.el6.x86_64 is a duplicate with libstdc++-4.4.6-3.el6.x86_64 libtiff-3.9.4-6.el6_3.x86_64 is a duplicate with libtiff-3.9.4-5.el6_2.x86_64 libudev-147-2.42.el6.x86_64 is a duplicate with libudev-147-2.40.el6.x86_64 libuuid-2.17.2-12.7.el6.x86_64 is a duplicate with libuuid-2.17.2-12.4.el6.x86_64 libxml2-2.7.6-8.el6_3.3.x86_64 is a duplicate with libxml2-2.7.6-4.el6_2.4.x86_64 nspr-4.9.1-2.el6_3.x86_64 is a duplicate with nspr-4.8.9-3.el6_2.x86_64 nss-util-3.13.5-1.el6_3.x86_64 is a duplicate with nss-util-3.13.1-3.el6_2.x86_64 openssl-1.0.0-25.el6_3.1.x86_64 is a duplicate with openssl-1.0.0-20.el6_2.5.x86_64 python-2.6.6-29.el6_3.3.x86_64 is a duplicate with python-2.6.6-29.el6.x86_64 python-libs-2.6.6-29.el6_3.3.x86_64 is a duplicate with python-libs-2.6.6-29.el6.x86_64 readline-6.0-4.el6.x86_64 is a duplicate with readline-6.0-3.el6.x86_64 sed-4.2.1-10.el6.x86_64 is a duplicate with sed-4.2.1-7.el6.x86_64 tzdata-2012c-3.el6.noarch is a duplicate with tzdata-2012c-1.el6.noarch xmlrpc-c-1.16.24-1209.1840.el6.x86_64 is a duplicate with xmlrpc-c-1.16.24-1200.1840.el6_1.4.x86_64 xmlrpc-c-client-1.16.24-1209.1840.el6.x86_64 is a duplicate with xmlrpc-c-client-1.16.24-1200.1840.el6_1.4.x86_64 Error: check all Tried: #rm /var/lib/rpm/__db* #rpm --rebuilddb #yum clean all Tried also running yum-complete-transaction still won't finish the update. ls -ld /var/tmp/ drwxrwxrwt. 20 root root 12288 Oct 3 18:44 /var/tmp/ df -h /var/tmp/ Filesystem Size Used Avail Use% Mounted on /tmp 3.9G 1.2G 2.6G 32% /var/tmp Latest errors: Error: Protected multilib versions: libgcc-4.4.6-4.el6.i686 != libgcc-4.4.6-3.el6.x86_64 Error: Protected multilib versions: glibc-2.12-1.80.el6_3.5.i686 != glibc-2.12-1.47.el6_2.12.x86_64 EDITED: yum repolist Loaded plugins: fastestmirror, rhnplugin, security Loading mirror speeds from cached hostfile * cloudlinux-x86_64-server-6: cl.banahosting.com repo id repo name status cloudlinux-x86_64-server-6 CloudLinux Server 6 x86_64 10,948+725 repolist: 10,948 [~]# package-cleanup --dupes Loaded plugins: fastestmirror, rhnplugin xmlrpc-c-client-1.16.24-1209.1840.el6.x86_64 xmlrpc-c-client-1.16.24-1200.1840.el6_1.4.x86_64 bind-libs-9.7.3-8.P3.el6_2.2.x86_64 bind-libs-9.8.2-0.10.rc1.el6_3.3.x86_64 libblkid-2.17.2-12.4.el6.x86_64 libblkid-2.17.2-12.7.el6.x86_64 libtiff-3.9.4-5.el6_2.x86_64 libtiff-3.9.4-6.el6_3.x86_64 audit-libs-2.1.3-3.el6.x86_64 audit-libs-2.2-2.el6.x86_64 libstdc++-4.4.6-3.el6.x86_64 libstdc++-4.4.6-4.el6.x86_64 sed-4.2.1-10.el6.x86_64 sed-4.2.1-7.el6.x86_64 python-libs-2.6.6-29.el6_3.3.x86_64 python-libs-2.6.6-29.el6.x86_64 coreutils-libs-8.4-16.el6.x86_64 coreutils-libs-8.4-19.el6.x86_64 libudev-147-2.40.el6.x86_64 libudev-147-2.42.el6.x86_64 chkconfig-1.3.49.3-2.el6.x86_64 chkconfig-1.3.49.3-1.el6_2.x86_64 keyutils-libs-1.4-4.el6.x86_64 keyutils-libs-1.4-3.el6.x86_64 glibc-2.12-1.47.el6_2.12.x86_64 glibc-2.12-1.80.el6_3.5.x86_64 tzdata-2012c-3.el6.noarch tzdata-2012c-1.el6.noarch coreutils-8.4-19.el6.x86_64 coreutils-8.4-16.el6.x86_64 dbus-libs-1.2.24-7.el6_3.x86_64 dbus-libs-1.2.24-5.el6_1.x86_64 libxml2-2.7.6-4.el6_2.4.x86_64 libxml2-2.7.6-8.el6_3.3.x86_64 abrt-libs-2.0.8-6.el6.x86_64 abrt-libs-2.0.4-14.el6.centos.x86_64 expat-2.0.1-9.1.el6.x86_64 expat-2.0.1-11.el6_2.x86_64 python-2.6.6-29.el6.x86_64 python-2.6.6-29.el6_3.3.x86_64 gtk2-2.18.9-6.el6.centos.x86_64 gtk2-2.18.9-10.el6.x86_64 libcom_err-1.41.12-12.el6.x86_64 libcom_err-1.41.12-11.el6.x86_64 gawk-3.1.7-10.el6.x86_64 gawk-3.1.7-9.el6.x86_64 readline-6.0-4.el6.x86_64 readline-6.0-3.el6.x86_64 glibc-common-2.12-1.80.el6_3.5.x86_64 glibc-common-2.12-1.47.el6_2.12.x86_64 libselinux-2.0.94-5.2.el6.x86_64 libselinux-2.0.94-5.3.el6.x86_64 cups-libs-1.4.2-48.el6_3.1.x86_64 cups-libs-1.4.2-44.el6_2.3.x86_64 nspr-4.9.1-2.el6_3.x86_64 nspr-4.8.9-3.el6_2.x86_64 cagefs-safebin-3.5-1.el6.cloudlinux.x86_64 cagefs-safebin-3.6-6.el6.cloudlinux.x86_64 libuuid-2.17.2-12.4.el6.x86_64 libuuid-2.17.2-12.7.el6.x86_64 xmlrpc-c-1.16.24-1209.1840.el6.x86_64 xmlrpc-c-1.16.24-1200.1840.el6_1.4.x86_64 openssl-1.0.0-20.el6_2.5.x86_64 openssl-1.0.0-25.el6_3.1.x86_64 dhcp-common-4.1.1-25.P1.el6_2.1.x86_64 dhcp-common-4.1.1-31.P1.el6_3.1.x86_64 krb5-libs-1.9-33.el6_3.3.x86_64 krb5-libs-1.9-22.el6_2.1.x86_64 nss-util-3.13.5-1.el6_3.x86_64 nss-util-3.13.1-3.el6_2.x86_64 cloudlinux-release-6-6.2.2.x86_64 cloudlinux-release-6-6.3.0.x86_64 e2fsprogs-libs-1.41.12-11.el6.x86_64 e2fsprogs-libs-1.41.12-12.el6.x86_64 glib2-2.22.5-6.el6.x86_64 glib2-2.22.5-7.el6.x86_64 UPDATE 2 I removed all the dupes and then did update and got this: Updating : sudo-1.7.4p5-13.el6_3.x86_64 79/361 Error in POSTIN scriptlet in rpm package sudo-1.7.4p5-13.el6_3.x86_64 warning: /etc/sudoers created as /etc/sudoers.rpmnew error: error creating temporary file /var/tmp/rpm-tmp.hjTOqJ: Invalid argument error: Couldn't create temporary file for %post(sudo-1.7.4p5-13.el6_3.x86_64): Invalid argument Updating : pcre-7.8-6.el6.x86_64 80/361 Traceback (most recent call last): File "/usr/lib/python2.6/site-packages/yum/rpmtrans.py", line 399, in callback self._instCloseFile( bytes, total, h ) File "/usr/lib/python2.6/site-packages/yum/rpmtrans.py", line 475, in _instCloseFile self.base.history.trans_data_pid_end(pid, state) File "/usr/lib/python2.6/site-packages/yum/history.py", line 858, in trans_data_pid_end """, ('TRUE', self._tid, pid, state)) File "/usr/lib/python2.6/site-packages/yum/sqlutils.py", line 168, in executeSQLQmark return cursor.execute(query, params) sqlite3.OperationalError: unable to open database file error: python callback <bound method RPMTransaction.callback of <yum.rpmtrans.RPMTransaction instance at 0x5c7cfc8>> failed, aborting! - [~]# lsattr /var/tmp/ -------------e- /var/tmp/cache_5b07945563e03aec1c44917886fd99a6 -------------e- /var/tmp/sess_6edfafda1a191f6986bd020ed945eea0 -------------e- /var/tmp/sess_1b837feecdd4c9e6aa6ecd81d41fda75 -------------e- /var/tmp/sess_70bec5f392b4f5f75ac444f5c82db2dc -------------e- /var/tmp/sess_24cd226ba0a370a6d3838a37745b2e15 -------------e- /var/tmp/nginx_proxy -------------e- /var/tmp/sess_19fb1dd060e42c9de8786ef34d7fcf6e -------------e- /var/tmp/sess_b4ac777076c5122a6e27d776de0a2fcb -------------e- /var/tmp/sess_5077441775ef8d07a2185e8fd48a4aa8 -------------e- /var/tmp/cache_4e71d930fe8250e222ae4d1dc39646ff -------------e- /var/tmp/sess_eb6eb29b38b55b85303c3137611f0a2faa15c21d -------------e- /var/tmp/sess_81e7e8d93b395f2c8d7e3fe12cc59e56 -------------e- /var/tmp/sess_05c7f305bdbf9a4c7af251d33ac59766 -------------e- /var/tmp/sess_0ad9369063a37b6b399688a835d69ed2 -------------e- /var/tmp/cache_c780deda617678faeea8f8a34395ac27 -------------e- /var/tmp/sess_9773332e3c99ee18dca0b05e8f02a41e -------------e- /var/tmp/sess_1d9b02b068ea81a3975599ddc12bcfb1 -------------e- /var/tmp/sess_1ffeff444123e924834dc5e80d07571e -------------e- /var/tmp/sess_aa56725471c84d9a06745c56dc499db7 -------------e- /var/tmp/sess_51e19964d7e1a164c63f4c72fa43475c33debbc0 -------------e- /var/tmp/sess_a83c7a05bb189a465b8813ff9e566aa8f9124079 -------------e- /var/tmp/sess_2f506ba5b77c61107871e8cf80393cdb -------------e- /var/tmp/sess_7bfe1578605b259ec5e4fd2200df4cd0 -------------e- /var/tmp/sess_f6e47011789d8d48d56dd78a398d98d5719414a7 -------------e- /var/tmp/sess_b7c43a90a8b8d8f02b0fffca77796ce5 -------------e- /var/tmp/sess_6c3e7103453ad4daba815bd96a903785 -------------e- /var/tmp/sess_86f32a22507d8410b3f0fc7d71a135d5 -------------e- /var/tmp/sess_aaf72d3e8cfb2f27ffdff61323f97e7553855a05 -------------e- /var/tmp/sess_5de4488e2ee03ac0f99ab9494573ccb1 -------------e- /var/tmp/sess_716d97bba4abdb38704a9e4212f6fddc -------------e- /var/tmp/sess_534908a9510a32eda13a5dc95ac022cc -------------e- /var/tmp/sess_626a58203d93427c79621ea4fec0906d -------------e- /var/tmp/sess_827ca92d10d3797f2c187c41764a7036 -------------e- /var/tmp/sess_6282962d77f7bead20e785fbdb9a3d8f -------------e- /var/tmp/cache_b012c8a729fc54a296a700ed92930a0e -------------e- /var/tmp/sess_631e5ba769773da056108d3fbd143963 -------------e- /var/tmp/cache_30bb7f1333ba5f96a229c91a3385d8b5 -------------e- /var/tmp/sess_93e085706b29c3e4e3593bfe39b1079e -------------e- /var/tmp/sess_abd78bd6c285d681c90de8c617747ab3 -------------e- /var/tmp/sess_e144544ed925569018e6607b05f43f253f75e2aa -------------e- /var/tmp/sess_5d3d036c772847a4508d3e100b173d84 -------------e- /var/tmp/sess_f35243d1f40bd8d9ce08940fafc00d93 -------------e- /var/tmp/sess_761c3ffa811b959638ed0b266741eaa4 -------------e- /var/tmp/mm.sem.sNdxjf -------------e- /var/tmp/sess_006d45dbd807291f7bffbd1db3707ed6 -------------e- /var/tmp/cache_2d0162aac9f87c1978ac644923a5e2fe -------------e- /var/tmp/sess_22c534418c380b72d105935b59713dd1 -------------e- /var/tmp/sess_94f72ef408567a15f6287c518e93898e -------------e- /var/tmp/cache_6fe03c83bb87489f3921db1c974dfc0e -------------e- /var/tmp/sess_48bbfa2a2a8793a62c7fd6a389a2763e -------------e- /var/tmp/mm.sem.ERERMV -------------e- /var/tmp/sess_20aba82c03a69b2dc6af66c499c38ee67e27368f -------------e- /var/tmp/sess_f94fe0589a79c934815ef359bcb0a16c7080d937 -------------e- /var/tmp/sess_460390801eb004593b4dee83779f414e -------------e- /var/tmp/spamd-52811-init -------------e- /var/tmp/cache_6427fdb235d59b0b2fbd105bf23d2e87 -------------e- /var/tmp/cache_4ce12d8350d7c0361dc1bf15d552a2d8 -------------e- /var/tmp/sess_039fec2a643340f118b6355e4c836ae8 -------------e- /var/tmp/sess_fa46fa80b26e6cf3d9c7de942d5dbcff -------------e- /var/tmp/cache_664858e614367812148716536e22d030 -------------e- /var/tmp/sess_4c8d4c44fbd828dc17415ce6aa213115 -------------e- /var/tmp/sess_d231a6c0e5dd4d7bacbf9de3d8bb298f -------------e- /var/tmp/sess_a82f8a088a8e37d375f6a9fede4a54d2 -------------e- /var/tmp/sess_604697227ae5359e5783dc9407845338 -------------e- /var/tmp/sess_5b4e623536640abe671b40563d03817d -------------e- /var/tmp/sess_2aba0aff64f3c18f22e0b79d591259e2 -------------e- /var/tmp/sess_bfd52a2d2d80880f8e26ad460739a0494f0d1e9e -------------e- /var/tmp/sess_ba9f3e3a7c7111930d6b801aaa833b46 -------------e- /var/tmp/sess_5cc8c5b620015a465359359a0805fbdd -------------e- /var/tmp/sess_84945c41d604b4653a1bf45d83a1917c -------------e- /var/tmp/sess_5f52569b27430780c07d25cfb8177e5c1ef647f0 -------------e- /var/tmp/sess_45896aef9e77f16be1b3e94b3edb2599 -------------e- /var/tmp/sess_5a67d0ef8f826a2f103b429c8464bdd5f75d6218 -------------e- /var/tmp/sess_1fce98bb32e5b34c79fd5a313de32980 -------------e- /var/tmp/sess_f7ea772ff3fbb1eb2ad8712dd2c49ed8 -------------e- /var/tmp/sess_a9dc16bc5c1eb2768bb2600f0d102fde -------------e- /var/tmp/mm.sem.3zwRTu -------------e- /var/tmp/sess_e2cad140703338a4b8c9254ec6b0a1a2 -------------e- /var/tmp/sess_e7c8e85daf9c5424aecb83e066decf31 -------------e- /var/tmp/sess_800f878fa944370f42e76057e7c033e19520bd41 -------------e- /var/tmp/sess_4fdae64eb18599521ace18679795568b -------------e- /var/tmp/sess_958fb886b97de2e767b059376c4724b5 -------------e- /var/tmp/sess_3c832a31f17744a8bb3c59dde02e561aefbc2e48 -------------e- /var/tmp/sess_6d9d7bf04f34e0d82b101f882196a905 -------------e- /var/tmp/sess_7231c75ae4fad2ca5fbcb6de430a7b13 -------------e- /var/tmp/sess_2eadffa2285def9673ce784395d272d8 -------------e- /var/tmp/cache_2ff353b664d8028df967f807ac18593a -------------e- /var/tmp/sess_4138a267f1f5e3ad93c1d64547c63134ae7c0db3 -------------e- /var/tmp/sess_64cd9fa0d6af8e8041aafffbe3db986a -------------e- /var/tmp/tmpg3ycIG -------------e- /var/tmp/cache_b633ac8283d6de8e39d81160d63fc8cd -------------e- /var/tmp/sess_2cee03cf5eafd3ef55d8efa1b0390436 -------------e- /var/tmp/sess_608066c609e28621f2a29ac04a3a6441 -------------e- /var/tmp/sess_46dfb35cf8266699ba9304e5d8c6869d -------------e- /var/tmp/sess_fb202a0ed54cee8832c5f6e0ca7fc1b3 -------------e- /var/tmp/sess_8fe3c5fd8cdda02855e5f9b5a1ea85a4 -------------e- /var/tmp/sess_941376d5cb51e0ba73f9a27ee259c159 -------------e- /var/tmp/sess_4fa17b1eac1d18341d20d0d8d4991ceb -------------e- /var/tmp/cache_de647c956ca6a1b75744ad194aceaa82 -------------e- /var/tmp/mm.sem.Ugu7Be -------------e- /var/tmp/sess_656e8a50759d5b36b963e7eb85e0bb0d -------------e- /var/tmp/sess_983f77b607bbffa1748d6c49557381e9 -------------e- /var/tmp/sess_632860d092e5e374da522ed2f88e83ce -------------e- /var/tmp/sess_030f900b81cc2a4ad095d53ef3ee0791 -------------e- /var/tmp/yum.log -------------e- /var/tmp/cache_810174993c6a2c0efe2edbe4c39a4a81 -------------e- /var/tmp/sess_29e2c781643434e81d189fc41f47fd34 -------------e- /var/tmp/tmpE12ahd -------------e- /var/tmp/sess_935da512fb077e04610266748b3b77f3 - cat /etc/fstab /tmp as: loop,rw,noexec,nosuid,nodev

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  • Unable to receive emails from Ubuntu postfix mail server

    - by Paddington
    I am unable to receive emails on an Ubuntu 11.04 server running postfix with the Plesk control panel. I can't see the mails even on webmail. I am able to send emails and am not getting any error messages on the email client when I try to receive. Here is the output of the logs: *tail -f /usr/local/psa/var/log/maillog Aug 29 10:38:31 cp9 postfix/tlsmgr[3811]: fatal: open database /var/lib/postfix/smtpd_scache.db: Invalid argument Aug 29 10:38:32 cp9 postfix/master[27738]: warning: process /usr/lib/postfix/tlsmgr pid 3811 exit status 1 Aug 29 10:38:32 cp9 postfix/master[27738]: warning: /usr/lib/postfix/tlsmgr: bad command startup -- throttling Aug 29 10:38:36 cp9 pop3d: Connection, ip=[::ffff:196.201.7.158] Aug 29 10:38:36 cp9 pop3d: IMAP connect from @ [::ffff:196.201.7.158]INFO: LOGIN, [email protected], ip=[::ffff:196.201.7.158] Aug 29 10:38:37 cp9 pop3d: 1346229517.874008 LOGOUT, [email protected], ip=[::ffff:196.201.7.158], top=0, retr=0, time=1, rcvd=24, sent=1716, maildir=/var/qmail/mailnames/essentialhuku.co.za/earle/Maildir Aug 29 10:14:05 cp9 postfix/tlsmgr[1133]: fatal: open database /var/lib/postfix/smtpd_scache.db: Invalid argument Aug 29 10:14:06 cp9 postfix/master[27738]: warning: process /usr/lib/postfix/tlsmgr pid 1133 exit status 1 Aug 29 10:14:06 cp9 postfix/master[27738]: warning: /usr/lib/postfix/tlsmgr: bad command startup -- throttling Aug 29 10:14:08 cp9 pop3d: Connection, ip=[::ffff:196.201.7.158

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  • Managing per-user rc.d init scripts

    - by Steve Schnepp
    I want to delegate SysV init scripts to each user. Like the SysV init, each item in ${HOME}/rc.d starting with S will be launched on server start-up with the start argument. The same for the server shut-down with the one starting with K and with the stop argument. I thought about scripting it myself, but maybe there is already some kind of implementation out there1. In summary it would be a script in /etc/init.d/ that iterates through all the users and launches runparts as the user on the relevant scripts. The platform here is a Linux (Debian flavour), but I think the solution would be quite portable among various Unix-like platforms. Update: The point here is for users to be able to create their own init scripts that should be launch on their behalf when the system boots up. As Dan Carley pointed out, the services won't be able to access any system asset (priviledged ports, system logs, ...). 1. This way I don't have to think that much about all the subtle security implications such as script timeouts for example...

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  • Creating an ec2 image on amazon fails at mkfs.ext3

    - by Dave Orr
    I'm trying to create an image of my ec2 instance in Amazon's cloud. It's been a bit of an adventure so far. I did manage to install Amazon's ec2-api-tools, which was harder than it seemed like it should have been. Then I ran: ec2-bundle-vol -d /mnt -k pk-{key}.pem -c cert-{cert}.pem -u {uid} -s 1536 Which returned: Copying / into the image file /mnt/image... Excluding: /sys/kernel/debug /sys/kernel/security /sys /proc /dev/pts /dev /dev /media /mnt /proc /sys /etc/udev/rules.d/70-persistent-net.rules /etc/udev/rules.d/z25_persistent-net.rules /mnt/image /mnt/img-mnt 1+0 records in 1+0 records out 1048576 bytes (1.0 MB) copied, 0.00677357 s, 155 MB/s mkfs.ext3: option requires an argument -- 'L' Usage: mkfs.ext3 [-c|-l filename] [-b block-size] [-f fragment-size] [-i bytes-per-inode] [-I inode-size] [-J journal-options] [-G meta group size] [-N number-of-inodes] [-m reserved-blocks-percentage] [-o creator-os] [-g blocks-per-group] [-L volume-label] [-M last-mounted-directory] [-O feature[,...]] [-r fs-revision] [-E extended-option[,...]] [-T fs-type] [-U UUID] [-jnqvFKSV] device [blocks-count] ERROR: execution failed: "mkfs.ext3 -F /mnt/image -U 1c001580-9118-4a50-9a25-dcf02be6d25f -L " So mkfs.ext3 wants -L, which is a volume name. But ec2-bundle-vol doesn't seem to take in a volume name as an argument, and the docs (http://docs.amazonwebservices.com/AmazonEC2/gsg/2006-06-26/creating-an-image.html) don't seem to think one should be needed. Certainly their sample command: # ec2-bundle-vol -d /mnt -k ~root/pk-HKZYKTAIG2ECMXYIBH3HXV4ZBZQ55CLO.pem -u 495219933132 -s 1536 doesn't specify anything. So... any help? What am I missing?

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  • Ubuntu 12.04 suddenly cannot connect to WPA2/WPA Personal protected connection. Windows 7 can

    - by d4ryl3
    I have a laptop with Windows 7 and Ubuntu 12.04. I have a Cisco E1200 and when I set it up, it created 2 SSIDs. Let's name them: MyConnection (WPA/WPA2 personal), and MyConnection-Guest (no authentication, guest password entered via web browser). I had no problem connecting to MyConnection before, either in Windows 7 and Ubuntu. But now, I can't access MyConnection on Ubuntu. It just says "connecting..." then disconnects after a while. But I'm able to access the internet (on Ubuntu) when I connect to MyConnection-Guest. MAC filtering is off (even if it's on its MAC address is in the white list). Any idea why I'm unable to connect to MyConnection in Ubuntu? Thanks. Update: My Ubuntu installation can connect to ANY WiFi connection (WPA/WEP/no auth), except for MyConnection. Update2: This is what "The not so easy way" returned: Initializing interface 'eth1' conf '/etc/wpa_supplicant.conf' driver 'default' ctrl_interface 'N/A' bridge 'N/A' Configuration file '/etc/wpa_supplicant.conf' -> '/etc/wpa_supplicant.conf' Reading configuration file '/etc/wpa_supplicant.conf' Priority group 0 id=0 ssid='MyConnection' id=1 ssid='MyConnection' id=2 ssid='MyConnection' id=3 ssid='MyConnection' WEXT: cfg80211-based driver detected SIOCGIWRANGE: WE(compiled)=22 WE(source)=21 enc_capa=0xf capabilities: key_mgmt 0xf enc 0xf flags 0x0 netlink: Operstate: linkmode=1, operstate=5 Own MAC address: xx:xx:xx:xx:xx:xx wpa_driver_wext_set_key: alg=0 key_idx=0 set_tx=0 seq_len=0 key_len=0 wpa_driver_wext_set_key: alg=0 key_idx=1 set_tx=0 seq_len=0 key_len=0 wpa_driver_wext_set_key: alg=0 key_idx=2 set_tx=0 seq_len=0 key_len=0 wpa_driver_wext_set_key: alg=0 key_idx=3 set_tx=0 seq_len=0 key_len=0 wpa_driver_wext_set_key: alg=0 key_idx=4 set_tx=0 seq_len=0 key_len=0 ioctl[SIOCSIWENCODEEXT]: Invalid argument Driver did not support SIOCSIWENCODEEXT wpa_driver_wext_set_key: alg=0 key_idx=5 set_tx=0 seq_len=0 key_len=0 ioctl[SIOCSIWENCODEEXT]: Invalid argument Driver did not support SIOCSIWENCODEEXT wpa_driver_wext_set_countermeasures RSN: flushing PMKID list in the driver Setting scan request: 0 sec 100000 usec WPS: UUID based on MAC address - hexdump(len=16): 16 3b d8 47 9e 24 50 89 96 16 6d 66 35 f3 58 37 EAPOL: SUPP_PAE entering state DISCONNECTED EAPOL: Supplicant port status: Unauthorized EAPOL: KEY_RX entering state NO_KEY_RECEIVE EAPOL: SUPP_BE entering state INITIALIZE EAP: EAP entering state DISABLED EAPOL: Supplicant port status: Unauthorized EAPOL: Supplicant port status: Unauthorized Added interface eth1

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  • WSUS performance for unneeded updates

    - by mhouston100
    We have a WSUS server serving around 300 PC's and a couple of dozen servers and a discussion came up at work as to what products to include. We have a single SQL 2005 instance on one of the servers and it has NEVER been updated. My first thought was to just tick the box for SQL 2005 and let WSUS do it's thing to upgrade to the latest service pack at least. One of the other guys here has the opinion that having updates that are relevant to only a small selection of hosts would effect the performance of WSUS as a whole, claiming that each update does a 'check' against all the hosts or something similar. My argument is that manually updating these servers is obviously not working as the admins are not paying attention to what is needed. So my question is: Do updates that only effect a sub-set of the hosts effect the overall performance of the WSUS server in relation to ALL the hosts? (disk space is not an issue at this point) Is there any performance justification for or against manually updating small amounts of products? Basically I'm needing a rebuttal against his argument and I'm unable to find any concrete documentation to prove him wrong.

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  • SQL Server 2005 Disk Configuration: Single RAID 1+0 or multiple RAID 1+0s?

    - by mfredrickson
    Assuming that the workload for the SQL Server is just a normal OLTP database, and that there are a total of 20 disks available, which configuration would make more sense? A single RAID 1+0, containing all 20 disks. This physical volume would contain both the data files and the transaction log files, but two logical drives would be created from this RAID: one for the data files and one for the log files. Or... Two RAID 1+0s, each containing 10 disks. One physical volume would contain the data files, and the other would contain the log files. The reason for this question is due to a disagreement between me (SQL Developer) and a co-worker (DBA). For every configuration that I've done, or seen others do, the data files and transaction log files were separated at the physical level, and were placed on separate RAIDs. However, my co-workers argument is that by placing all the disks into a single RAID 1+0, then any IO that is done by the server is potentially shared between all 20 disks, instead of just 10 disks in my suggested configuration. Conceptually, his argument makes sense to me. Also, I've found some information from Microsoft that seems to supports his position. http://technet.microsoft.com/en-us/library/cc966414.aspx In the section titled "3. RAID10 Configuration", showing a configuration in which all 20 disks are allocated to a single RAID 1+0, it states: In this scenario, the I/O parallelism can be used to its fullest by all partitions. Therefore, distribution of I/O workload is among 20 physical spindles instead of four at the partition level. But... every other configuration I've seen suggests physically separating the data and log files onto separate RAIDs. Everything I've found here on Server Fault suggests the same. I understand that a log files will be write heavy, and that data files will be a combination of reads and writes, but does this require that the files be placed onto separate RAIDs instead of a single RAID?

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  • How to fix a damaged/corrupted NTFS filesystem/partition without losing the data on it?

    - by Gareth
    I was going to install Fedora 15 along side my Windows 7 Starter on my Acer Apire One D255E and at some point during the resizing of the NTFS partition (the one with Windows on it) the setup failed. Now I cannot access this partition from any OS. When I tried to access it from a Fedora install running on a USB flashdrive I get this error: Error mounting: mount exited with exit code 12: Failed to read last sector (452534271): Invalid argument HINTS: Either the volume is a RAID/LDM but it wasn't setup yet, or it was not setup correctly (e.g. by not using mdadm --build ...), or a wrong device is tried to be mounted, or the partition table is corrupt (partition is smaller than NTFS), or the NTFS boot sector is corrupt (NTFS size is not valid). Failed to mount '/dev/sda5': Invalid argument The device '/dev/sda5' doesn't seem to have a valid NTFS. Maybe the wrong device is used? Or the whole disk instead of a partition (e.g. /dev/sda, not /dev/sda1)? Or the other way around? It doesn't make a lot of sense to me but I was really hoping it would to someone and they can give me a way to restore the partition without losing everything on it (I have a lot of important notes from various classes on there)? Cheers.

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  • ASP.NET exception gives irrelevant stack trace on YSOD, very challenging!

    - by pootow
    Here is the YSOD: Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.Data.SqlClient.SqlException: Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding. Source Error: An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below. Stack Trace: [SqlException (0x80131904): Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding.] System.Data.ProviderBase.DbConnectionPool.GetConnection(DbConnection owningObject) +428 System.Data.ProviderBase.DbConnectionFactory.GetConnection(DbConnection owningConnection) +65 System.Data.ProviderBase.DbConnectionClosed.OpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory) +117 System.Data.SqlClient.SqlConnection.Open() +122 ECommerce.PMethod.Sql.SqlConns.Open() +78 ECommerce.PMethod.Sql.SqlConns..ctor() +120 ECommerce.login.DatasInfo.Proc.UserCenter.IsLogin(String UserGUID, Int32 UserID) +49 ECommerce.login.Rules.Users.UserLogin.isLogin() +44 Config.isUserLogined() +5 Shopping_Shopping.Page_Load(Object sender, EventArgs e) +10 System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +14 System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +35 System.Web.UI.Control.OnLoad(EventArgs e) +99 System.Web.UI.Control.LoadRecursive() +50 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +627 [TypeInitializationException: The type initializer for 'ECommerce.ERP.DAL.DBConn' threw an exception.] ECommerce.ERP.DAL.DBConn.get_ConnString() +0 [ObjectDefinitionStoreException: Factory method 'System.String get_ConnString()' threw an Exception.] Spring.Objects.Factory.Support.SimpleInstantiationStrategy.Instantiate(RootObjectDefinition definition, String name, IObjectFactory factory, MethodInfo factoryMethod, Object[] arguments) +257 Spring.Objects.Factory.Support.ConstructorResolver.InstantiateUsingFactoryMethod(String name, RootObjectDefinition definition, Object[] arguments) +624 Spring.Objects.Factory.Support.AbstractAutowireCapableObjectFactory.InstantiateUsingFactoryMethod(String name, RootObjectDefinition definition, Object[] arguments) +60 Spring.Objects.Factory.Support.AbstractAutowireCapableObjectFactory.CreateObjectInstance(String objectName, RootObjectDefinition objectDefinition, Object[] arguments) +56 Spring.Objects.Factory.Support.AbstractAutowireCapableObjectFactory.InstantiateObject(String name, RootObjectDefinition definition, Object[] arguments, Boolean allowEagerCaching, Boolean suppressConfigure) +436 [ObjectCreationException: Error thrown by a dependency of object 'styleService' defined in 'assembly [ECommerce.Services.Impl, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null], resource [ECommerce.Services.Impl.AppContext.xml] line 56' : Initialization of object failed : Factory method 'System.String get_ConnString()' threw an Exception. while resolving 'constructor argument with name promotionservice' to 'promotionService' defined in 'assembly [ECommerce.Services.Impl, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null], resource [ECommerce.Services.Impl.AppContext.xml] line 31' while resolving 'constructor argument with name domainservice' to 'promotionDomainService' defined in 'assembly [ECommerce.Domain, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null], resource [ECommerce.Domain.AppContext.xml] line 20' while resolving 'constructor argument with name promotionrepos' to 'promotionRepos' defined in 'assembly [ECommerce.Data.AdoNet, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null], resource [ECommerce.Data.AdoNet.AppContext.xml] line 34' while resolving 'constructor argument with name connstr' to 'ECommerce.ERP.DAL.DBConn#389F399' defined in 'assembly [ECommerce.Data.AdoNet, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null], resource [ECommerce.Data.AdoNet.AppContext.xml] line 34'] Spring.Objects.Factory.Support.ObjectDefinitionValueResolver.ResolveReference(IObjectDefinition definition, String name, String argumentName, RuntimeObjectReference reference) +394 Spring.Objects.Factory.Support.ObjectDefinitionValueResolver.ResolvePropertyValue(String name, IObjectDefinition definition, String argumentName, Object argumentValue) +312 Spring.Objects.Factory.Support.ObjectDefinitionValueResolver.ResolveValueIfNecessary(String name, IObjectDefinition definition, String argumentName, Object argumentValue) +17 Spring.Objects.Factory.Support.ConstructorResolver.ResolveConstructorArguments(String objectName, RootObjectDefinition definition, ObjectWrapper wrapper, ConstructorArgumentValues cargs, ConstructorArgumentValues resolvedValues) +993 Spring.Objects.Factory.Support.ConstructorResolver.AutowireConstructor(String objectName, RootObjectDefinition rod, ConstructorInfo[] chosenCtors, Object[] explicitArgs) +171 Spring.Objects.Factory.Support.AbstractAutowireCapableObjectFactory.AutowireConstructor(String name, RootObjectDefinition definition, ConstructorInfo[] ctors, Object[] explicitArgs) +65 Spring.Objects.Factory.Support.AbstractAutowireCapableObjectFactory.CreateObjectInstance(String objectName, RootObjectDefinition objectDefinition, Object[] arguments) +161 Spring.Objects.Factory.Support.AbstractAutowireCapableObjectFactory.InstantiateObject(String name, RootObjectDefinition definition, Object[] arguments, Boolean allowEagerCaching, Boolean suppressConfigure) +636 Spring.Objects.Factory.Support.AbstractObjectFactory.CreateAndCacheSingletonInstance(String objectName, RootObjectDefinition objectDefinition, Object[] arguments) +174 Spring.Objects.Factory.Support.WebObjectFactory.CreateAndCacheSingletonInstance(String objectName, RootObjectDefinition objectDefinition, Object[] arguments) +150 Spring.Objects.Factory.Support.AbstractObjectFactory.GetObjectInternal(String name, Type requiredType, Object[] arguments, Boolean suppressConfigure) +990 Spring.Objects.Factory.Support.AbstractObjectFactory.GetObject(String name) +10 Spring.Context.Support.AbstractApplicationContext.GetObject(String name) +20 ECommerce.Common.ServiceLocator.GetService() +334 ECommerce.Mvc.Controllers.StylesController..ctor() +72 [TargetInvocationException: Exception has been thrown by the target of an invocation.] System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean& canBeCached, RuntimeMethodHandle& ctor, Boolean& bNeedSecurityCheck) +0 System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean fillCache) +86 System.RuntimeType.CreateInstanceImpl(Boolean publicOnly, Boolean skipVisibilityChecks, Boolean fillCache) +230 System.Activator.CreateInstance(Type type, Boolean nonPublic) +67 System.Web.Mvc.DefaultControllerFactory.GetControllerInstance(RequestContext requestContext, Type controllerType) +80 [InvalidOperationException: An error occurred when trying to create a controller of type 'ECommerce.Mvc.Controllers.StylesController'. Make sure that the controller has a parameterless public constructor.] System.Web.Mvc.DefaultControllerFactory.GetControllerInstance(RequestContext requestContext, Type controllerType) +190 System.Web.Mvc.DefaultControllerFactory.CreateController(RequestContext requestContext, String controllerName) +68 System.Web.Mvc.MvcHandler.ProcessRequestInit(HttpContextBase httpContext, IController& controller, IControllerFactory& factory) +118 System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContextBase httpContext, AsyncCallback callback, Object state) +46 System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContext httpContext, AsyncCallback callback, Object state) +63 System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.BeginProcessRequest(HttpContext context, AsyncCallback cb, Object extraData) +13 System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +8677954 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155 Version Information: Microsoft .NET Framework Version:2.0.50727.3082; ASP.NET Version:2.0.50727.3082 Question is: the first stack trace is irrelevant to others, what happened? Any ideas? Let me make this more clear: a MVC page uses the spring part trying to load a lazy-init service which constructor wants a connection string through a static property like this: <object id="promotionRepos" type="ECommerce.Data.AdoNet.Promotions.PromotionRepos, ECommerce.Data.AdoNet" lazy-init="true"> <constructor-arg name="provider"> <null /> </constructor-arg> <constructor-arg name="connStr"> <object type="ECommerce.ERP.DAL.DBConn, ECommerce.ERP.DAL" factory-method="get_ConnString" /> </constructor-arg> <property name="RefreshInterval" value="00:00:10" /> </object> the timeout part is some what irrelevent to all others. see this in the first exception: Shopping_Shopping.Page_Load(Object sender, EventArgs e) +10 it's another page at all. And also, ECommerce.PMethod.Sql.SqlConns.Open() uses its own connection string, not the one loaded by spring, it's different module from diffrent team. And I am sure the connection string is correct. And, this ysod cames up randomly. Sometimes nothing is wrong, and sometimes, it appears. I thought there could be something wrong with my database or the network/firewall, I will check it later, but now I want understand this tricky stack trace.

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  • Save object states in .data or attr - Performance vs CSS?

    - by Neysor
    In response to my answer yesterday about rotating an Image, Jamund told me to use .data() instead of .attr() First I thought that he is right, but then I thought about a bigger context... Is it always better to use .data() instead of .attr()? I looked in some other posts like what-is-better-data-or-attr or jquery-data-vs-attrdata The answers were not satisfactory for me... So I moved on and edited the example by adding CSS. I thought it might be useful to make a different Style on each image if it rotates. My style was the following: .rp[data-rotate="0"] { border:10px solid #FF0000; } .rp[data-rotate="90"] { border:10px solid #00FF00; } .rp[data-rotate="180"] { border:10px solid #0000FF; } .rp[data-rotate="270"] { border:10px solid #00FF00; } Because design and coding are often separated, it could be a nice feature to handle this in CSS instead of adding this functionality into JavaScript. Also in my case the data-rotate is like a special state which the image currently has. So in my opinion it make sense to represent it within the DOM. I also thought this could be a case where it is much better to save with .attr() then with .data(). Never mentioned before in one of the posts I read. But then i thought about performance. Which function is faster? I built my own test following: <!DOCTYPE HTML> <html> <head> <title>test</title> <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script> <script type="text/javascript"> function runfirst(dobj,dname){ console.log("runfirst "+dname); console.time(dname+"-attr"); for(i=0;i<10000;i++){ dobj.attr("data-test","a"+i); } console.timeEnd(dname+"-attr"); console.time(dname+"-data"); for(i=0;i<10000;i++){ dobj.data("data-test","a"+i); } console.timeEnd(dname+"-data"); } function runlast(dobj,dname){ console.log("runlast "+dname); console.time(dname+"-data"); for(i=0;i<10000;i++){ dobj.data("data-test","a"+i); } console.timeEnd(dname+"-data"); console.time(dname+"-attr"); for(i=0;i<10000;i++){ dobj.attr("data-test","a"+i); } console.timeEnd(dname+"-attr"); } $().ready(function() { runfirst($("#rp4"),"#rp4"); runfirst($("#rp3"),"#rp3"); runlast($("#rp2"),"#rp2"); runlast($("#rp1"),"#rp1"); }); </script> </head> <body> <div id="rp1">Testdiv 1</div> <div id="rp2" data-test="1">Testdiv 2</div> <div id="rp3">Testdiv 3</div> <div id="rp4" data-test="1">Testdiv 4</div> </body> </html> It should also show if there is a difference with a predefined data-test or not. One result was this: runfirst #rp4 #rp4-attr: 515ms #rp4-data: 268ms runfirst #rp3 #rp3-attr: 505ms #rp3-data: 264ms runlast #rp2 #rp2-data: 260ms #rp2-attr: 521ms runlast #rp1 #rp1-data: 284ms #rp1-attr: 525ms So the .attr() function did always need more time than the .data() function. This is an argument for .data() I thought. Because performance is always an argument! Then I wanted to post my results here with some questions, and in the act of writing I compared with the questions Stack Overflow showed me (similar titles) And true enough, there was one interesting post about performance I read it and run their example. And now I am confused! This test showed that .data() is slower then .attr() !?!! Why is that so? First I thought it is because of a different jQuery library so I edited it and saved the new one. But the result wasn't changing... So now my questions to you: Why are there some differences in the performance in these two examples? Would you prefer to use data- HTML5 attributes instead of data, if it represents a state? Although it wouldn't be needed at the time of coding? Why - Why not? Now depending on the performance: Would performance be an argument for you using .attr() instead of data, if it shows that .attr() is better? Although data is meant to be used for .data()? UPDATE 1: I did see that without overhead .data() is much faster. Misinterpreted the data :) But I'm more interested in my second question. :) Would you prefer to use data- HTML5 attributes instead of data, if it represents a state? Although it wouldn't be needed at the time of coding? Why - Why not? Are there some other reasons you can think of, to use .attr() and not .data()? e.g. interoperability? because .data() is jquery style and HTML Attributes can be read by all... UPDATE 2: As we see from T.J Crowder's speed test in his answer attr is much faster then data! which is again confusing me :) But please! Performance is an argument, but not the highest! So give answers to my other questions please too!

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  • Did I find a bug in PHP's `crypt()`?

    - by Nathan Long
    I think I may have found a bug in PHP's crypt() function under Windows. However: I recognize that it's probably my fault. PHP is used by millions and worked on by thousands; my code is used by tens and worked on by me. (This argument is best explained on Coding Horror.) So I'm asking for help: show me my fault. I've been trying to find it for a few days now, with no luck. The setup I'm using a Windows server installation with Apache 2.2.14 (Win32) and PHP 5.3.2. My development box runs Windows XP Professional; the 'production' server (this is an intranet setup) runs Windows Storage Server 2003. The problem happens on both. I don't see anything in php.ini related to crypt(), but will happily answer questions about my config. The problem Several scripts in my PHP app occasionally hang: the page sits there on 'waiting for localhost' and never finishes. Each of these scripts uses crypt to hash a user's password before storing it in the database, or, in the case of the login page, to hash the entered password before comparing it to the version stored in the database. Since the login page is the simplest, I focused on it for testing. I repeatedly logged in, and found that it would hang maybe 4 out of 10 times. As an experiment, I changed the login page to use the plain text password and changed my password in the database to its plain text version. The page stopped hanging. I saw that PHP's latest version lists this bugfix: Fixed bug #51059 (crypt crashes when invalid salt are [sic] given). So I created a very simple test script, as follows, using the same salt given in an official example: $foo = crypt('rasmuslerdorf','r1'); echo $foo; This page, too, will hang, if I reload it like crazy. I only see it hanging in Chrome, but regardless of browser, the effect on Apache is the same. Effect on Apache When these pages hang, Apache's server-status page (which I explained here, regarding a different problem) increments the number of requests being processed and decrements the number of idle workers. The requests being processed almost all have a status of 'Sending Reply,' though sometimes for a moment they will show either 'Reading request' or 'keepalive (read).' Eventually, Apache may crash. When it does, the Windows crash report looks like this: szAppName: httpd.exe szAppVer: 2.2.14.0 szModName: php5ts.dll szModVer: 5.3.1.0 // OK, this report was before I upgraded to PHP 5.3.2, // but that didn't fix it offset: 00a2615 Is it my fault? I'm tempted to file a bug report to PHP on this. The argument against it is, as stated above, that bugs are nearly always my fault. However, my argument in favor of 'it's PHP's fault' is: I'm using Windows, whereas most servers use Linux (I don't get to choose this), so the chances are greater that I've found an edge case There was recently a bug with crypt(), so maybe it still has issues I have made the simplest test case I can, and I still have the problem Can anyone duplicate this? Can you suggest where I've gone wrong? Should I file the bug after all? Thanks in advance for any help you may give.

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  • Parallelism in .NET – Part 4, Imperative Data Parallelism: Aggregation

    - by Reed
    In the article on simple data parallelism, I described how to perform an operation on an entire collection of elements in parallel.  Often, this is not adequate, as the parallel operation is going to be performing some form of aggregation. Simple examples of this might include taking the sum of the results of processing a function on each element in the collection, or finding the minimum of the collection given some criteria.  This can be done using the techniques described in simple data parallelism, however, special care needs to be taken into account to synchronize the shared data appropriately.  The Task Parallel Library has tools to assist in this synchronization. The main issue with aggregation when parallelizing a routine is that you need to handle synchronization of data.  Since multiple threads will need to write to a shared portion of data.  Suppose, for example, that we wanted to parallelize a simple loop that looked for the minimum value within a dataset: double min = double.MaxValue; foreach(var item in collection) { double value = item.PerformComputation(); min = System.Math.Min(min, value); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } This seems like a good candidate for parallelization, but there is a problem here.  If we just wrap this into a call to Parallel.ForEach, we’ll introduce a critical race condition, and get the wrong answer.  Let’s look at what happens here: // Buggy code! Do not use! double min = double.MaxValue; Parallel.ForEach(collection, item => { double value = item.PerformComputation(); min = System.Math.Min(min, value); }); This code has a fatal flaw: min will be checked, then set, by multiple threads simultaneously.  Two threads may perform the check at the same time, and set the wrong value for min.  Say we get a value of 1 in thread 1, and a value of 2 in thread 2, and these two elements are the first two to run.  If both hit the min check line at the same time, both will determine that min should change, to 1 and 2 respectively.  If element 1 happens to set the variable first, then element 2 sets the min variable, we’ll detect a min value of 2 instead of 1.  This can lead to wrong answers. Unfortunately, fixing this, with the Parallel.ForEach call we’re using, would require adding locking.  We would need to rewrite this like: // Safe, but slow double min = double.MaxValue; // Make a "lock" object object syncObject = new object(); Parallel.ForEach(collection, item => { double value = item.PerformComputation(); lock(syncObject) min = System.Math.Min(min, value); }); This will potentially add a huge amount of overhead to our calculation.  Since we can potentially block while waiting on the lock for every single iteration, we will most likely slow this down to where it is actually quite a bit slower than our serial implementation.  The problem is the lock statement – any time you use lock(object), you’re almost assuring reduced performance in a parallel situation.  This leads to two observations I’ll make: When parallelizing a routine, try to avoid locks. That being said: Always add any and all required synchronization to avoid race conditions. These two observations tend to be opposing forces – we often need to synchronize our algorithms, but we also want to avoid the synchronization when possible.  Looking at our routine, there is no way to directly avoid this lock, since each element is potentially being run on a separate thread, and this lock is necessary in order for our routine to function correctly every time. However, this isn’t the only way to design this routine to implement this algorithm.  Realize that, although our collection may have thousands or even millions of elements, we have a limited number of Processing Elements (PE).  Processing Element is the standard term for a hardware element which can process and execute instructions.  This typically is a core in your processor, but many modern systems have multiple hardware execution threads per core.  The Task Parallel Library will not execute the work for each item in the collection as a separate work item. Instead, when Parallel.ForEach executes, it will partition the collection into larger “chunks” which get processed on different threads via the ThreadPool.  This helps reduce the threading overhead, and help the overall speed.  In general, the Parallel class will only use one thread per PE in the system. Given the fact that there are typically fewer threads than work items, we can rethink our algorithm design.  We can parallelize our algorithm more effectively by approaching it differently.  Because the basic aggregation we are doing here (Min) is communitive, we do not need to perform this in a given order.  We knew this to be true already – otherwise, we wouldn’t have been able to parallelize this routine in the first place.  With this in mind, we can treat each thread’s work independently, allowing each thread to serially process many elements with no locking, then, after all the threads are complete, “merge” together the results. This can be accomplished via a different set of overloads in the Parallel class: Parallel.ForEach<TSource,TLocal>.  The idea behind these overloads is to allow each thread to begin by initializing some local state (TLocal).  The thread will then process an entire set of items in the source collection, providing that state to the delegate which processes an individual item.  Finally, at the end, a separate delegate is run which allows you to handle merging that local state into your final results. To rewriting our routine using Parallel.ForEach<TSource,TLocal>, we need to provide three delegates instead of one.  The most basic version of this function is declared as: public static ParallelLoopResult ForEach<TSource, TLocal>( IEnumerable<TSource> source, Func<TLocal> localInit, Func<TSource, ParallelLoopState, TLocal, TLocal> body, Action<TLocal> localFinally ) The first delegate (the localInit argument) is defined as Func<TLocal>.  This delegate initializes our local state.  It should return some object we can use to track the results of a single thread’s operations. The second delegate (the body argument) is where our main processing occurs, although now, instead of being an Action<T>, we actually provide a Func<TSource, ParallelLoopState, TLocal, TLocal> delegate.  This delegate will receive three arguments: our original element from the collection (TSource), a ParallelLoopState which we can use for early termination, and the instance of our local state we created (TLocal).  It should do whatever processing you wish to occur per element, then return the value of the local state after processing is completed. The third delegate (the localFinally argument) is defined as Action<TLocal>.  This delegate is passed our local state after it’s been processed by all of the elements this thread will handle.  This is where you can merge your final results together.  This may require synchronization, but now, instead of synchronizing once per element (potentially millions of times), you’ll only have to synchronize once per thread, which is an ideal situation. Now that I’ve explained how this works, lets look at the code: // Safe, and fast! double min = double.MaxValue; // Make a "lock" object object syncObject = new object(); Parallel.ForEach( collection, // First, we provide a local state initialization delegate. () => double.MaxValue, // Next, we supply the body, which takes the original item, loop state, // and local state, and returns a new local state (item, loopState, localState) => { double value = item.PerformComputation(); return System.Math.Min(localState, value); }, // Finally, we provide an Action<TLocal>, to "merge" results together localState => { // This requires locking, but it's only once per used thread lock(syncObj) min = System.Math.Min(min, localState); } ); Although this is a bit more complicated than the previous version, it is now both thread-safe, and has minimal locking.  This same approach can be used by Parallel.For, although now, it’s Parallel.For<TLocal>.  When working with Parallel.For<TLocal>, you use the same triplet of delegates, with the same purpose and results. Also, many times, you can completely avoid locking by using a method of the Interlocked class to perform the final aggregation in an atomic operation.  The MSDN example demonstrating this same technique using Parallel.For uses the Interlocked class instead of a lock, since they are doing a sum operation on a long variable, which is possible via Interlocked.Add. By taking advantage of local state, we can use the Parallel class methods to parallelize algorithms such as aggregation, which, at first, may seem like poor candidates for parallelization.  Doing so requires careful consideration, and often requires a slight redesign of the algorithm, but the performance gains can be significant if handled in a way to avoid excessive synchronization.

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  • C#/.NET Little Wonders: The EventHandler and EventHandler&lt;TEventArgs&gt; delegates

    - by James Michael Hare
    Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. In the last two weeks, we examined the Action family of delegates (and delegates in general), and the Func family of delegates and how they can be used to support generic, reusable algorithms and classes. So this week, we are going to look at a handy pair of delegates that can be used to eliminate the need for defining custom delegates when creating events: the EventHandler and EventHandler<TEventArgs> delegates. Events and delegates Before we begin, let’s quickly consider events in .NET.  According to the MSDN: An event in C# is a way for a class to provide notifications to clients of that class when some interesting thing happens to an object. So, basically, you can create an event in a type so that users of that type can subscribe to notifications of things of interest.  How is this different than some of the delegate programming that we talked about in the last two weeks?  Well, you can think of an event as a special access modifier on a delegate.  Some differences between the two are: Events are a special access case of delegates They behave much like delegates instances inside the type they are declared in, but outside of that type they can only be (un)subscribed to. Events can specify add/remove behavior explicitly If you want to do additional work when someone subscribes or unsubscribes to an event, you can specify the add and remove actions explicitly. Events have access modifiers, but these only specify the access level of those who can (un)subscribe A public event, for example, means anyone can (un)subscribe, but it does not mean that anyone can raise (invoke) the event directly.  Events can only be raised by the type that contains them In contrast, if a delegate is visible, it can be invoked outside of the object (not even in a sub-class!). Events tend to be for notifications only, and should be treated as optional Semantically speaking, events typically don’t perform work on the the class directly, but tend to just notify subscribers when something of note occurs. My basic rule-of-thumb is that if you are just wanting to notify any listeners (who may or may not care) that something has happened, use an event.  However, if you want the caller to provide some function to perform to direct the class about how it should perform work, make it a delegate. Declaring events using custom delegates To declare an event in a type, we simply use the event keyword and specify its delegate type.  For example, let’s say you wanted to create a new TimeOfDayTimer that triggers at a given time of the day (as opposed to on an interval).  We could write something like this: 1: public delegate void TimeOfDayHandler(object source, ElapsedEventArgs e); 2:  3: // A timer that will fire at time of day each day. 4: public class TimeOfDayTimer : IDisposable 5: { 6: // Event that is triggered at time of day. 7: public event TimeOfDayHandler Elapsed; 8:  9: // ... 10: } The first thing to note is that the event is a delegate type, which tells us what types of methods may subscribe to it.  The second thing to note is the signature of the event handler delegate, according to the MSDN: The standard signature of an event handler delegate defines a method that does not return a value, whose first parameter is of type Object and refers to the instance that raises the event, and whose second parameter is derived from type EventArgs and holds the event data. If the event does not generate event data, the second parameter is simply an instance of EventArgs. Otherwise, the second parameter is a custom type derived from EventArgs and supplies any fields or properties needed to hold the event data. So, in a nutshell, the event handler delegates should return void and take two parameters: An object reference to the object that raised the event. An EventArgs (or a subclass of EventArgs) reference to event specific information. Even if your event has no additional information to provide, you are still expected to provide an EventArgs instance.  In this case, feel free to pass the EventArgs.Empty singleton instead of creating new instances of EventArgs (to avoid generating unneeded memory garbage). The EventHandler delegate Because many events have no additional information to pass, and thus do not require custom EventArgs, the signature of the delegates for subscribing to these events is typically: 1: // always takes an object and an EventArgs reference 2: public delegate void EventHandler(object sender, EventArgs e) It would be insane to recreate this delegate for every class that had a basic event with no additional event data, so there already exists a delegate for you called EventHandler that has this very definition!  Feel free to use it to define any events which supply no additional event information: 1: public class Cache 2: { 3: // event that is raised whenever the cache performs a cleanup 4: public event EventHandler OnCleanup; 5:  6: // ... 7: } This will handle any event with the standard EventArgs (no additional information).  But what of events that do need to supply additional information?  Does that mean we’re out of luck for subclasses of EventArgs?  That’s where the generic for of EventHandler comes into play… The generic EventHandler<TEventArgs> delegate Starting with the introduction of generics in .NET 2.0, we have a generic delegate called EventHandler<TEventArgs>.  Its signature is as follows: 1: public delegate void EventHandler<TEventArgs>(object sender, TEventArgs e) 2: where TEventArgs : EventArgs This is similar to EventHandler except it has been made generic to support the more general case.  Thus, it will work for any delegate where the first argument is an object (the sender) and the second argument is a class derived from EventArgs (the event data). For example, let’s say we wanted to create a message receiver, and we wanted it to have a few events such as OnConnected that will tell us when a connection is established (probably with no additional information) and OnMessageReceived that will tell us when a new message arrives (probably with a string for the new message text). So for OnMessageReceived, our MessageReceivedEventArgs might look like this: 1: public sealed class MessageReceivedEventArgs : EventArgs 2: { 3: public string Message { get; set; } 4: } And since OnConnected needs no event argument type defined, our class might look something like this: 1: public class MessageReceiver 2: { 3: // event that is called when the receiver connects with sender 4: public event EventHandler OnConnected; 5:  6: // event that is called when a new message is received. 7: public event EventHandler<MessageReceivedEventArgs> OnMessageReceived; 8:  9: // ... 10: } Notice, nowhere did we have to define a delegate to fit our event definition, the EventHandler and generic EventHandler<TEventArgs> delegates fit almost anything we’d need to do with events. Sidebar: Thread-safety and raising an event When the time comes to raise an event, we should always check to make sure there are subscribers, and then only raise the event if anyone is subscribed.  This is important because if no one is subscribed to the event, then the instance will be null and we will get a NullReferenceException if we attempt to raise the event. 1: // This protects against NullReferenceException... or does it? 2: if (OnMessageReceived != null) 3: { 4: OnMessageReceived(this, new MessageReceivedEventArgs(aMessage)); 5: } The above code seems to handle the null reference if no one is subscribed, but there’s a problem if this is being used in multi-threaded environments.  For example, assume we have thread A which is about to raise the event, and it checks and clears the null check and is about to raise the event.  However, before it can do that thread B unsubscribes to the event, which sets the delegate to null.  Now, when thread A attempts to raise the event, this causes the NullReferenceException that we were hoping to avoid! To counter this, the simplest best-practice method is to copy the event (just a multicast delegate) to a temporary local variable just before we raise it.  Since we are inside the class where this event is being raised, we can copy it to a local variable like this, and it will protect us from multi-threading since multicast delegates are immutable and assignments are atomic: 1: // always make copy of the event multi-cast delegate before checking 2: // for null to avoid race-condition between the null-check and raising it. 3: var handler = OnMessageReceived; 4: 5: if (handler != null) 6: { 7: handler(this, new MessageReceivedEventArgs(aMessage)); 8: } The very slight trade-off is that it’s possible a class may get an event after it unsubscribes in a multi-threaded environment, but this is a small risk and classes should be prepared for this possibility anyway.  For a more detailed discussion on this, check out this excellent Eric Lippert blog post on Events and Races. Summary Generic delegates give us a lot of power to make generic algorithms and classes, and the EventHandler delegate family gives us the flexibility to create events easily, without needing to redefine delegates over and over.  Use them whenever you need to define events with or without specialized EventArgs.   Tweet Technorati Tags: .NET, C#, CSharp, Little Wonders, Generics, Delegates, EventHandler

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  • Refactor This (Ugly Code)!

    - by Alois Kraus
    Ayende has put on his blog some ugly code to refactor. First and foremost it is nearly impossible to reason about other peoples code without knowing the driving forces behind the current code. It is certainly possible to make it much cleaner when potential sources of errors cannot happen in the first place due to good design. I can see what the intention of the code is but I do not know about every brittle detail if I am allowed to reorder things here and there to simplify things. So I decided to make it much simpler by identifying the different responsibilities of the methods and encapsulate it in different classes. The code we need to refactor seems to deal with a handler after a message has been sent to a message queue. The handler does complete the current transaction if there is any and does handle any errors happening there. If during the the completion of the transaction errors occur the transaction is at least disposed. We can enter the handler already in a faulty state where we try to deliver the complete event in any case and signal a failure event and try to resend the message again to the queue if it was not inside a transaction. All is decorated with many try/catch blocks, duplicated code and some state variables to route the program flow. It is hard to understand and difficult to reason about. In other words: This code is a mess and could be written by me if I was under pressure. Here comes to code we want to refactor:         private void HandleMessageCompletion(                                      Message message,                                      TransactionScope tx,                                      OpenedQueue messageQueue,                                      Exception exception,                                      Action<CurrentMessageInformation, Exception> messageCompleted,                                      Action<CurrentMessageInformation> beforeTransactionCommit)         {             var txDisposed = false;             if (exception == null)             {                 try                 {                     if (tx != null)                     {                         if (beforeTransactionCommit != null)                             beforeTransactionCommit(currentMessageInformation);                         tx.Complete();                         tx.Dispose();                         txDisposed = true;                     }                     try                     {                         if (messageCompleted != null)                             messageCompleted(currentMessageInformation, exception);                     }                     catch (Exception e)                     {                         Trace.TraceError("An error occured when raising the MessageCompleted event, the error will NOT affect the message processing"+ e);                     }                     return;                 }                 catch (Exception e)                 {                     Trace.TraceWarning("Failed to complete transaction, moving to error mode"+ e);                     exception = e;                 }             }             try             {                 if (txDisposed == false && tx != null)                 {                     Trace.TraceWarning("Disposing transaction in error mode");                     tx.Dispose();                 }             }             catch (Exception e)             {                 Trace.TraceWarning("Failed to dispose of transaction in error mode."+ e);             }             if (message == null)                 return;                 try             {                 if (messageCompleted != null)                     messageCompleted(currentMessageInformation, exception);             }             catch (Exception e)             {                 Trace.TraceError("An error occured when raising the MessageCompleted event, the error will NOT affect the message processing"+ e);             }               try             {                 var copy = MessageProcessingFailure;                 if (copy != null)                     copy(currentMessageInformation, exception);             }             catch (Exception moduleException)             {                 Trace.TraceError("Module failed to process message failure: " + exception.Message+                                              moduleException);             }               if (messageQueue.IsTransactional == false)// put the item back in the queue             {                 messageQueue.Send(message);             }         }     You can see quite some processing and handling going on there. Yes this looks like real world code one did put together to make things work and he does not trust his callbacks. I guess these are event handlers which are optional and the delegates were extracted from an event to call them back later when necessary.  Lets see what the author of this code did intend:          private void HandleMessageCompletion(             TransactionHandler transactionHandler,             MessageCompletionHandler handler,             CurrentMessageInformation messageInfo,             ErrorCollector errors             )         {               // commit current pending transaction             transactionHandler.CallHandlerAndCommit(messageInfo, errors);               // We have an error for a null message do not send completion event             if (messageInfo.CurrentMessage == null)                 return;               // Send completion event in any case regardless of errors             handler.OnMessageCompleted(messageInfo, errors);               // put message back if queue is not transactional             transactionHandler.ResendMessageOnError(messageInfo.CurrentMessage, errors);         }   I did not bother to write the intention here again since the code should be pretty self explaining by now. I have used comments to explain the still nontrivial procedure step by step revealing the real intention about all this complex program flow. The original complexity of the problem domain does not go away but by applying the techniques of SRP (Single Responsibility Principle) and some functional style but we can abstract the necessary complexity away in useful abstractions which make it much easier to reason about it. Since most of the method seems to deal with errors I thought it was a good idea to encapsulate the error state of our current message in an ErrorCollector object which stores all exceptions in a list along with a description what the error all was about in the exception itself. We can log it later or not depending on the log level or whatever. It is really just a simple list that encapsulates the current error state.          class ErrorCollector          {              List<Exception> _Errors = new List<Exception>();                public void Add(Exception ex, string description)              {                  ex.Data["Description"] = description;                  _Errors.Add(ex);              }                public Exception Last              {                  get                  {                      return _Errors.LastOrDefault();                  }              }                public bool HasError              {                  get                  {                      return _Errors.Count > 0;                  }              }          }   Since the error state is global we have two choices to store a reference in the other helper objects (TransactionHandler and MessageCompletionHandler)or pass it to the method calls when necessary. I did chose the latter one because a second argument does not hurt and makes it easier to reason about the overall state while the helper objects remain stateless and immutable which makes the helper objects much easier to understand and as a bonus thread safe as well. This does not mean that the stored member variables are stateless or thread safe as well but at least our helper classes are it. Most of the complexity is located the transaction handling I consider as a separate responsibility that I delegate to the TransactionHandler which does nothing if there is no transaction or Call the Before Commit Handler Commit Transaction Dispose Transaction if commit did throw In fact it has a second responsibility to resend the message if the transaction did fail. I did see a good fit there since it deals with transaction failures.          class TransactionHandler          {              TransactionScope _Tx;              Action<CurrentMessageInformation> _BeforeCommit;              OpenedQueue _MessageQueue;                public TransactionHandler(TransactionScope tx, Action<CurrentMessageInformation> beforeCommit, OpenedQueue messageQueue)              {                  _Tx = tx;                  _BeforeCommit = beforeCommit;                  _MessageQueue = messageQueue;              }                public void CallHandlerAndCommit(CurrentMessageInformation currentMessageInfo, ErrorCollector errors)              {                  if (_Tx != null && !errors.HasError)                  {                      try                      {                          if (_BeforeCommit != null)                          {                              _BeforeCommit(currentMessageInfo);                          }                            _Tx.Complete();                          _Tx.Dispose();                      }                      catch (Exception ex)                      {                          errors.Add(ex, "Failed to complete transaction, moving to error mode");                          Trace.TraceWarning("Disposing transaction in error mode");                          try                          {                              _Tx.Dispose();                          }                          catch (Exception ex2)                          {                              errors.Add(ex2, "Failed to dispose of transaction in error mode.");                          }                      }                  }              }                public void ResendMessageOnError(Message message, ErrorCollector errors)              {                  if (errors.HasError && !_MessageQueue.IsTransactional)                  {                      _MessageQueue.Send(message);                  }              }          } If we need to change the handling in the future we have a much easier time to reason about our application flow than before. After we did complete our transaction and called our callback we can call the completion handler which is the main purpose of the HandleMessageCompletion method after all. The responsiblity o the MessageCompletionHandler is to call the completion callback and the failure callback when some error has occurred.            class MessageCompletionHandler          {              Action<CurrentMessageInformation, Exception> _MessageCompletedHandler;              Action<CurrentMessageInformation, Exception> _MessageProcessingFailure;                public MessageCompletionHandler(Action<CurrentMessageInformation, Exception> messageCompletedHandler,                                              Action<CurrentMessageInformation, Exception> messageProcessingFailure)              {                  _MessageCompletedHandler = messageCompletedHandler;                  _MessageProcessingFailure = messageProcessingFailure;              }                  public void OnMessageCompleted(CurrentMessageInformation currentMessageInfo, ErrorCollector errors)              {                  try                  {                      if (_MessageCompletedHandler != null)                      {                          _MessageCompletedHandler(currentMessageInfo, errors.Last);                      }                  }                  catch (Exception ex)                  {                      errors.Add(ex, "An error occured when raising the MessageCompleted event, the error will NOT affect the message processing");                  }                    if (errors.HasError)                  {                      SignalFailedMessage(currentMessageInfo, errors);                  }              }                void SignalFailedMessage(CurrentMessageInformation currentMessageInfo, ErrorCollector errors)              {                  try                  {                      if (_MessageProcessingFailure != null)                          _MessageProcessingFailure(currentMessageInfo, errors.Last);                  }                  catch (Exception moduleException)                  {                      errors.Add(moduleException, "Module failed to process message failure");                  }              }            }   If for some reason I did screw up the logic and we need to call the completion handler from our Transaction handler we can simple add to the CallHandlerAndCommit method a third argument to the MessageCompletionHandler and we are fine again. If the logic becomes even more complex and we need to ensure that the completed event is triggered only once we have now one place the completion handler to capture the state. During this refactoring I simple put things together that belong together and came up with useful abstractions. If you look at the original argument list of the HandleMessageCompletion method I have put many things together:   Original Arguments New Arguments Encapsulate Message message CurrentMessageInformation messageInfo         Message message TransactionScope tx Action<CurrentMessageInformation> beforeTransactionCommit OpenedQueue messageQueue TransactionHandler transactionHandler        TransactionScope tx        OpenedQueue messageQueue        Action<CurrentMessageInformation> beforeTransactionCommit Exception exception,             ErrorCollector errors Action<CurrentMessageInformation, Exception> messageCompleted MessageCompletionHandler handler          Action<CurrentMessageInformation, Exception> messageCompleted          Action<CurrentMessageInformation, Exception> messageProcessingFailure The reason is simple: Put the things that have relationships together and you will find nearly automatically useful abstractions. I hope this makes sense to you. If you see a way to make it even more simple you can show Ayende your improved version as well.

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  • A Simple Approach For Presenting With Code Samples

    - by Jesse Taber
    Originally posted on: http://geekswithblogs.net/GruffCode/archive/2013/07/31/a-simple-approach-for-presenting-with-code-samples.aspxI’ve been getting ready for a presentation and have been struggling a bit with the best way to show and execute code samples. I don’t present often (hardly ever), but when I do I like the presentation to have a lot of succinct and executable code snippets to help illustrate the points that I’m making. Depending on what the presentation is about, I might just want to build an entire sample application that I would run during the presentation. In other cases, however, building a full-blown application might not really be the best way to present the code. The presentation I’m working on now is for an open source utility library for dealing with dates and times. I could have probably cooked up a sample app for accepting date and time input and then contrived ways in which it could put the library through its paces, but I had trouble coming up with one app that would illustrate all of the various features of the library that I wanted to highlight. I finally decided that what I really needed was an approach that met the following criteria: Simple: I didn’t want the user interface or overall architecture of a sample application to serve as a distraction from the demonstration of the syntax of the library that the presentation is about. I want to be able to present small bits of code that are focused on accomplishing a single task. Several of these examples will look similar, and that’s OK. I want each sample to “stand on its own” and not rely much on external classes or methods (other than the library that is being presented, of course). “Debuggable” (not really a word, I know): I want to be able to easily run the sample with the debugger attached in Visual Studio should I want to step through any bits of code and show what certain values might be at run time. As far as I know this rules out something like LinqPad, though using LinqPad to present code samples like this is actually a very interesting idea that I might explore another time. Flexible and Selectable: I’m going to have lots of code samples to show, and I want to be able to just package them all up into a single project or module and have an easy way to just run the sample that I want on-demand. Since I’m presenting on a .NET framework library, one of the simplest ways in which I could execute some code samples would be to just create a Console application and use Console.WriteLine to output the pertinent info at run time. This gives me a “no frills” harness from which to run my code samples, and I just hit ‘F5’ to run it with the debugger. This satisfies numbers 1 and 2 from my list of criteria above, but item 3 is a little harder. By default, just running a console application is going to execute the ‘main’ method, and then terminate the program after all code is executed. If I want to have several different code samples and run them one at a time, it would be cumbersome to keep swapping the code I want in and out of the ‘main’ method of the console application. What I really want is an easy way to keep the console app running throughout the whole presentation and just have it run the samples I want when I want. I could setup a simple Windows Forms or WPF desktop application with buttons for the different samples, but then I’m getting away from my first criteria of keeping things as simple as possible. Infinite Loops To The Rescue I found a way to have a simple console application satisfy all three of my requirements above, and it involves using an infinite loop and some Console.ReadLine calls that will give the user an opportunity to break out and exit the program. (All programs that need to run until they are closed explicitly (or crash!) likely use similar constructs behind the scenes. Create a new Windows Forms project, look in the ‘Program.cs’ that gets generated, and then check out the docs for the Application.Run method that it calls.). Here’s how the main method might look: 1: static void Main(string[] args) 2: { 3: do 4: { 5: Console.Write("Enter command or 'exit' to quit: > "); 6: var command = Console.ReadLine(); 7: if ((command ?? string.Empty).Equals("exit", StringComparison.OrdinalIgnoreCase)) 8: { 9: Console.WriteLine("Quitting."); 10: break; 11: } 12: 13: } while (true); 14: } The idea here is the app prompts me for the command I want to run, or I can type in ‘exit’ to break out of the loop and let the application close. The only trick now is to create a set of commands that map to each of the code samples that I’m going to want to run. Each sample is already encapsulated in a single public method in a separate class, so I could just write a big switch statement or create a hashtable/dictionary that maps command text to an Action that will invoke the proper method, but why re-invent the wheel? CLAP For Your Own Presentation I’ve blogged about the CLAP library before, and it turns out that it’s a great fit for satisfying criteria #3 from my list above. CLAP lets you decorate methods in a class with an attribute and then easily invoke those methods from within a console application. CLAP was designed to take the arguments passed into the console app from the command line and parse them to determine which method to run and what arguments to pass to that method, but there’s no reason you can’t re-purpose it to accept command input from within the infinite loop defined above and invoke the corresponding method. Here’s how you might define a couple of different methods to contain two different code samples that you want to run during your presentation: 1: public static class CodeSamples 2: { 3: [Verb(Aliases="one")] 4: public static void SampleOne() 5: { 6: Console.WriteLine("This is sample 1"); 7: } 8:   9: [Verb(Aliases="two")] 10: public static void SampleTwo() 11: { 12: Console.WriteLine("This is sample 2"); 13: } 14: } A couple of things to note about the sample above: I’m using static methods. You don’t actually need to use static methods with CLAP, but the syntax ends up being a bit simpler and static methods happen to lend themselves well to the “one self-contained method per code sample” approach that I want to use. The methods are decorated with a ‘Verb’ attribute. This tells CLAP that they are eligible targets for commands. The “Aliases” argument lets me give them short and easy-to-remember aliases that can be used to invoke them. By default, CLAP just uses the full method name as the command name, but with aliases you can simply the usage a bit. I’m not using any parameters. CLAP’s main feature is its ability to parse out arguments from a command line invocation of a console application and automatically pass them in as parameters to the target methods. My code samples don’t need parameters ,and honestly having them would complicate giving the presentation, so this is a good thing. You could use this same approach to invoke methods with parameters, but you’d have a couple of things to figure out. When you invoke a .NET application from the command line, Windows will parse the arguments and pass them in as a string array (called ‘args’ in the boilerplate console project Program.cs). The parsing that gets done here is smart enough to deal with things like treating strings in double quotes as one argument, and you’d have to re-create that within your infinite loop if you wanted to use parameters. I plan on either submitting a pull request to CLAP to add this capability or maybe just making a small utility class/extension method to do it and posting that here in the future. So I now have a simple class with static methods to contain my code samples, and an infinite loop in my ‘main’ method that can accept text commands. Wiring this all up together is pretty easy: 1: static void Main(string[] args) 2: { 3: do 4: { 5: try 6: { 7: Console.Write("Enter command or 'exit' to quit: > "); 8: var command = Console.ReadLine(); 9: if ((command ?? string.Empty).Equals("exit", StringComparison.OrdinalIgnoreCase)) 10: { 11: Console.WriteLine("Quitting."); 12: break; 13: } 14:   15: Parser.Run<CodeSamples>(new[] { command }); 16: Console.WriteLine("---------------------------------------------------------"); 17: } 18: catch (Exception ex) 19: { 20: Console.Error.WriteLine("Error: " + ex.Message); 21: } 22:   23: } while (true); 24: } Note that I’m now passing the ‘CodeSamples’ class into the CLAP ‘Parser.Run’ as a type argument. This tells CLAP to inspect that class for methods that might be able to handle the commands passed in. I’m also throwing in a little “----“ style line separator and some basic error handling (because I happen to know that some of the samples are going to throw exceptions for demonstration purposes) and I’m good to go. Now during my presentation I can just have the console application running the whole time with the debugger attached and just type in the alias of the code sample method that I want to run when I want to run it.

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