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  • Persistent SQL Table lock from C#

    - by Chris
    I'm trying to create a persistent SQL (SQL Server 2005) lock on a table level. I'm not updating/querying the specified table, but I need to prevent a third party application from updating the locked table as a means to prevent transactions from being posted (the table I wish to lock is the key on their transaction that interferes with my processing). From my experience the table is only locked for the time a specific transaction is taking place. Any ideas? The 3rd party developer has logged this feature as an enhancement, but since they are in the middle of rolling out a major release I can expect to wait at least 6 months for this. I know that this isn't a great solution, since their software will fall over but it is of a critical enough nature that we're willing to live with the consequences.

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  • Where is my free space?

    - by Andrey
    A week ago I got a low disk space warning on my Vista x64 Ultimate box - 60 Mb free on the disk C; I cleaned up some downloaded msdn images and got 20 Gb freed up. Three days ago I got another notification, it looked suspicious but I didnt have time to deal with it and just moved some heavy stuff to another drive to free up about 17 Gb.... Today morning - 53Mb left on drive C, again! Now it looks really suspecious, so I downloaded TreeSize to see what's taking up the space, just to see it reporting only 121 GB out of 200 GB used, in other words I suppose to have about 79 Gb free. Then I went to Folder Options, enabled viewing of system and hidden files, rerun teh tool to see another 5 Gb added (which is expected). Then I open disk C in windows explorer, select all and right click Properties, to see it reporting teh same amount of files - 126 Gb. But when I look at Drive C properties, it reports that 200GB of 200 Gb are taken. I just scanned the drive with two different antiviruses - Symantec and AVG and found no viruses... I'm a little confused at this point, any ideas where is my free space, woudl be highly appreciated! Thank you! Andrey

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  • Free desktop recording / screencasting on windows

    - by Mercer Traieste
    I'm a newbie in desktop recording and screencasting. I didn't find a suitable free application to do all the things I want it to do, but I did enjoy using jing. I would expect such an application to have these features: choose the whole desktop, a region, a window to record zoom in an area, and camera move save the recorded movie to a compressed format have basic editing tools have the mouse highlighting feature (either a sonar blip or something similar) highlight window/field on the screen, any trick will do display pressed keys/key combinations (like iphone does) So the question is: Which free desktop recording/screencasting software would you recommend on windows? It doesn't have to have all those features, just tell me your favorable experiences. Please suggest tools that would do mouse/keys/areas highlight tricks. I'm open to commercial software too, but I would prefer a free one. Thank you!

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  • ASP.NET lock thread method

    - by Peter
    Hello, I'm developing an ASP.NET forms webapplication using C#. I have a method which creates a new Order for a customer. It looks similar to this; private string CreateOrder(string userName) { // Fetch current order Order order = FetchOrder(userName); if (order.OrderId == 0) { // Has no order yet, create a new one order.OrderNumber = Utility.GenerateOrderNumber(); order.Save(); } return order; } The problem here is, it is possible that 1 customer in two requests (threads) could cause this method to be called twice while another thread is also inside this method. This can cause two orders to be created. How can I properly lock this method, so it can only be executed by one thread at a time per customer? I tried; Mutex mutex = null; private string CreateOrder(string userName) { if (mutex == null) { mutex = new Mutex(true, userName); } mutex.WaitOne(); // Code from above mutex.ReleaseMutex(); mutex = null; return order; } This works, but on some occasions it hangs on WaitOne and I don't know why. Is there an error, or should I use another method to lock? Thanks

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  • ??ORACLE(?):PMON Release Lock

    - by Liu Maclean(???)
    ?????Oracle????????????PMON???????,??????ORACLE PROCESS,??cleanup dead process????release enqueue lock ,???cleanup latch? ????????????????, ????????????Pmon cleanup dead process?release lock??????????? ??Oracle=> MicroOracle, Maclean???????????Oracle behavior: SQL> select * from v$version; BANNER -------------------------------------------------------------------------------- Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production PL/SQL Release 11.2.0.3.0 - Production CORE    11.2.0.3.0      Production TNS for Linux: Version 11.2.0.3.0 - Production NLSRTL Version 11.2.0.3.0 - Production SQL> select * from global_name; GLOBAL_NAME -------------------------------------------------------------------------------- www.oracledatabase12g.com SQL> select pid,program  from v$process;        PID PROGRAM ---------- ------------------------------------------------          1 PSEUDO          2 [email protected] (PMON)          3 [email protected] (PSP0)          4 [email protected] (VKTM)          5 [email protected] (GEN0)          6 [email protected] (DIAG)          7 [email protected] (DBRM)          8 [email protected] (PING)          9 [email protected] (ACMS)         10 [email protected] (DIA0)         11 [email protected] (LMON)         12 [email protected] (LMD0)         13 [email protected] (LMS0)         14 [email protected] (RMS0)         15 [email protected] (LMHB)         16 [email protected] (MMAN)         17 [email protected] (DBW0)         18 [email protected] (LGWR)         19 [email protected] (CKPT)         20 [email protected] (SMON)         21 [email protected] (RECO)         22 [email protected] (RBAL)         23 [email protected] (ASMB)         24 [email protected] (MMON)         25 [email protected] (MMNL)         26 [email protected] (MARK)         27 [email protected] (D000)         28 [email protected] (SMCO)         29 [email protected] (S000)         30 [email protected] (LCK0)         31 [email protected] (RSMN)         32 [email protected] (TNS V1-V3)         33 [email protected] (W000)         34 [email protected] (TNS V1-V3)         35 [email protected] (TNS V1-V3)         37 [email protected] (ARC0)         38 [email protected] (ARC1)         40 [email protected] (ARC2)         41 [email protected] (ARC3)         43 [email protected] (GTX0)         44 [email protected] (RCBG)         46 [email protected] (QMNC)         47 [email protected] (TNS V1-V3)         48 [email protected] (TNS V1-V3)         49 [email protected] (Q000)         50 [email protected] (Q001)         51 [email protected] (GCR0) SQL> drop table maclean; Table dropped. SQL> create table maclean(t1 int); Table created. SQL> insert into maclean values(1); 1 row created. SQL> commit; Commit complete. ?????????, ?????????:PID=2  PMONPID=11 LMONPID=18 LGWRPID=20 SMONPID=12 LMD ??????2???”enq: TX – row lock contention”?????,???KILL??????,??????PMON?recover dead process?release TX lock: PROCESS A: QL> select addr,spid,pid from v$process where addr = ( select paddr from v$session where sid=(select distinct sid from v$mystat)); ADDR             SPID                            PID ---------------- ------------------------ ---------- 00000000BD516B80 17880                            46 SQL> select distinct sid from v$mystat;        SID ----------         22 SQL> update maclean set t1=t1+1; 1 row updated. PROCESS B SQL> select addr,spid,pid from v$process where addr = ( select paddr from v$session where sid=(select distinct sid from v$mystat)); ADDR             SPID                            PID ---------------- ------------------------ ---------- 00000000BD515AD0 17908                            45 SQL> update maclean set t1=t1+1; HANG.............. PROCESS B ??"enq: TX – row lock contention"?HANG? ????PROCESS C?? ?SMON?10500 event trace ??PMON?KST TRACE: SQL> set linesize 200 pagesize 1400 SQL> select * from v$lock where sid=22; ADDR             KADDR                   SID TY        ID1        ID2      LMODE    REQUEST      CTIME      BLOCK ---------------- ---------------- ---------- -- ---------- ---------- ---------- ---------- ---------- ---------- 00000000BDCD7618 00000000BDCD7670         22 AE        100          0          4          0         48          2 00007F63268A9E28 00007F63268A9E88         22 TM      77902          0          3          0         32          2 00000000B9BB4950 00000000B9BB49C8         22 TX     458765        892          6          0         32          1 PROCESS A holde?ENQUEUE LOCK??? AE?TM?TX SQL> alter system switch logfile; System altered. SQL> alter system checkpoint; System altered. SQL> alter system flush buffer_cache; System altered. SQL> alter system set "_trace_events"='10000-10999:255:2,20,33'; System altered. SQL> ! kill -9 17880 KILL PROCESS A ???PROCESS B??update ?PMON ? PROCESS B ?errorstack ?KST TRACE????? SQL> oradebug setorapid 2; Oracle pid: 2, Unix process pid: 17533, image: [email protected] (PMON) SQL> oradebug dump errorstack 4; Statement processed. SQL> oradebug tracefile_name /s01/orabase/diag/rdbms/vprod/VPROD1/trace/VPROD1_pmon_17533.trc SQL> oradebug setorapid 45; Oracle pid: 45, Unix process pid: 17908, image: [email protected] (TNS V1-V3) SQL> oradebug dump errorstack 4; Statement processed. SQL>oradebug tracefile_name /s01/orabase/diag/rdbms/vprod/VPROD1/trace/VPROD1_ora_17908.trc ??PMON? KST TRACE: 2012-05-18 10:37:34.557225 :8001ECE8:db_trace:ktur.c@5692:ktugru(): [10444:2:1] next rollback uba: 0x00000000.0000.00 2012-05-18 10:37:34.557382 :8001ECE9:db_trace:ksl2.c@16009:ksl_update_post_stats(): [10005:2:1] KSL POST SENT postee=18 num=4 loc='ksa2.h LINE:285 ID:ksasnd' id1=0 id2=0 name=   type=0 2012-05-18 10:37:34.557514 :8001ECEA:db_trace:ksq.c@8540:ksqrcli(): [10704:2:1] ksqrcl: release TX-0007000d-0000037c mode=X 2012-05-18 10:37:34.558819 :8001ECF0:db_trace:ksl2.c@16009:ksl_update_post_stats(): [10005:2:1] KSL POST SENT postee=45 num=5 loc='kji.h LINE:3418 ID:kjata: wake up enqueue owner' id1=0 id2=0 name=   type=0 2012-05-18 10:37:34.559047 :8001ECF8:db_trace:ksl2.c@16009:ksl_update_post_stats(): [10005:2:1] KSL POST SENT postee=12 num=6 loc='kjm.h LINE:1224 ID:kjmpost: post lmd' id1=0 id2=0 name=   type=0 2012-05-18 10:37:34.559271 :8001ECFC:db_trace:ksq.c@8826:ksqrcli(): [10704:2:1] ksqrcl: SUCCESS 2012-05-18 10:37:34.559291 :8001ECFD:db_trace:ktu.c@8652:ktudnx(): [10813:2:1] ktudnx: dec cnt xid:7.13.892 nax:0 nbx:0 2012-05-18 10:37:34.559301 :8001ECFE:db_trace:ktur.c@3198:ktuabt(): [10444:2:1] ABORT TRANSACTION - xid: 0x0007.00d.0000037c 2012-05-18 10:37:34.559327 :8001ECFF:db_trace:ksq.c@8540:ksqrcli(): [10704:2:1] ksqrcl: release TM-0001304e-00000000 mode=SX 2012-05-18 10:37:34.559365 :8001ED00:db_trace:ksq.c@8826:ksqrcli(): [10704:2:1] ksqrcl: SUCCESS 2012-05-18 10:37:34.559908 :8001ED01:db_trace:ksq.c@8540:ksqrcli(): [10704:2:1] ksqrcl: release AE-00000064-00000000 mode=S 2012-05-18 10:37:34.559982 :8001ED02:db_trace:ksq.c@8826:ksqrcli(): [10704:2:1] ksqrcl: SUCCESS 2012-05-18 10:37:34.560217 :8001ED03:db_trace:ksfd.c@15379:ksfdfods(): [10298:2:1] ksfdfods:fob=0xbab87b48 aiopend=0 2012-05-18 10:37:34.560336 :GSIPC:kjcs.c@4876:kjcsombdi(): GSIPC:SOD: 0xbc79e0c8 action 3 state 0 chunk (nil) regq 0xbc79e108 batq 0xbc79e118 2012-05-18 10:37:34.560357 :GSIPC:kjcs.c@5293:kjcsombdi(): GSIPC:SOD: exit cleanup for 0xbc79e0c8 rc: 1, loc: 0x303 2012-05-18 10:37:34.560375 :8001ED04:db_trace:kss.c@1414:kssdch(): [10809:2:1] kssdch(0xbd516b80 = process, 3) 1 0 exit 2012-05-18 10:37:34.560939 :8001ED06:db_trace:kmm.c@10578:kmmlrl(): [10257:2:1] KMMLRL: Entering: flg(0x0) rflg(0x4) 2012-05-18 10:37:34.561091 :8001ED07:db_trace:kmm.c@10472:kmmlrl_process_events(): [10257:2:1] KMMLRL: Events: succ(3) wait(0) fail(0) 2012-05-18 10:37:34.561100 :8001ED08:db_trace:kmm.c@11279:kmmlrl(): [10257:2:1] KMMLRL: Reg/update: flg(0x0) rflg(0x4) 2012-05-18 10:37:34.563325 :8001ED0B:db_trace:kmm.c@12511:kmmlrl(): [10257:2:1] KMMLRL: Update: ret(0) 2012-05-18 10:37:34.563335 :8001ED0C:db_trace:kmm.c@12768:kmmlrl(): [10257:2:1] KMMLRL: Exiting: flg(0x0) rflg(0x4) 2012-05-18 10:37:34.563354 :8001ED0D:db_trace:ksl2.c@2598:kslwtbctx(): [10005:2:1] KSL WAIT BEG [pmon timer] 300/0x12c 0/0x0 0/0x0 wait_id=78 seq_num=79 snap_id=1 PMON??dead process A??????????TX Lock:ksqrcl: release TX-0007000d-0000037c mode=X ?????Post Process B,??Process B ?acquire?TX lock???????:KSL POST SENT postee=45 num=5 loc=’kji.h LINE:3418 ID:kjata: wake up enqueue owner’ id1=0 id2=0 name=   type=0 Process B???PMON??????????ksl2.c@14563:ksliwat(): [10005:45:151] KSL POST RCVD poster=2 num=5 loc=’kji.h LINE:3418 ID:kjata: wake up enqueue owner’ id1=0 id2=0 name=   type=0 fac#=3 posted=0×3 may_be_posted=1kslwtbctx(): [10005:45:151] KSL WAIT BEG [latch: ges resource hash list] 3162668560/0xbc827e10 91/0x5b 0/0×0 wait_id=14 seq_num=15 snap_id=1kslwtectx(): [10005:45:151] KSL WAIT END [latch: ges resource hash list] 3162668560/0xbc827e10 91/0x5b 0/0×0 wait_id=14 seq_num=15 snap_id=1 ?RAC????POST LMD(lock Manager)??,????????GES??:2012-05-18 10:37:34.559047 :8001ECF8:db_trace:ksl2.c@16009:ksl_update_post_stats(): [10005:2:1] KSL POST SENT postee=12 num=6 loc=’kjm.h LINE:1224 ID:kjmpost: post lmd’ id1=0 id2=0 name=   type=0 ??ksqrcl: release TX????????:ksq.c@8826:ksqrcli(): [10704:2:1] ksqrcl: SUCCESS ??PMON abort Process A???Transaction2012-05-18 10:37:34.559291 :8001ECFD:db_trace:ktu.c@8652:ktudnx(): [10813:2:1] ktudnx: dec cnt xid:7.13.892 nax:0 nbx:02012-05-18 10:37:34.559301 :8001ECFE:db_trace:ktur.c@3198:ktuabt(): [10444:2:1] ABORT TRANSACTION – xid: 0×0007.00d.0000037c ??Process A?????maclean??TM lock:ksq.c@8540:ksqrcli(): [10704:2:1] ksqrcl: release TM-0001304e-00000000 mode=SXksq.c@8826:ksqrcli(): [10704:2:1] ksqrcl: SUCCESS ??Process A?????AE ( Prevent Dropping an edition in use) lock:ksq.c@8540:ksqrcli(): [10704:2:1] ksqrcl: release AE-00000064-00000000 mode=Sksq.c@8826:ksqrcli(): [10704:2:1] ksqrcl: SUCCESS ??cleanup process Akjcs.c@4876:kjcsombdi(): GSIPC:SOD: 0xbc79e0c8 action 3 state 0 chunk (nil) regq 0xbc79e108 batq 0xbc79e118GSIPC:kjcs.c@5293:kjcsombdi(): GSIPC:SOD: exit cleanup for 0xbc79e0c8 rc: 1, loc: 0×303kss.c@1414:kssdch(): [10809:2:1] kssdch(0xbd516b80 = process, 3) 1 0 exit 0xbd516b80??PROCESS A ?paddr ???? kssdch???????? ??process???state object SO KSS: delete children of state obj. PMON ??kmmlrl()????instance goodness??update for session drop deltakmmlrl(): [10257:2:1] KMMLRL: Entering: flg(0×0) rflg(0×4)kmmlrl_process_events(): [10257:2:1] KMMLRL: Events: succ(3) wait(0) fail(0)kmmlrl(): [10257:2:1] KMMLRL: Reg/update: flg(0×0) rflg(0×4)kmmlrl(): [10257:2:1] KMMLRL: Update: ret(0)kmmlrl(): [10257:2:1] KMMLRL: Exiting: flg(0×0) rflg(0×4) ????????PMON???? 3s???”pmon timer”??kslwtbctx(): [10005:2:1] KSL WAIT BEG [pmon timer] 300/0x12c 0/0×0 0/0×0 wait_id=78 seq_num=79 snap_id=1

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  • Online Free Accounting Software

    - by Ngu Soon Hui
    I am looking for a free, online-based accounting application, something like a web-version of QuickBooks or MS Money. The catch here is that, of course, it needs to be free. I don't know if any company is philanthropic enough to offer this kind of service to individual users.

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  • Any Free/Opensource billing+timetracking software?

    - by Ian
    I'm looking for a free or even better opensource alternative to many billing sites like GetHarvest.com, Freshbooks.com, Cannybar, The Invoice Machine and stuff like that. Is there any free or open source system that does that? I've looked into SimpleInvoices but it's not really what I'm looking for. Does anyone know of any alternative? Thanks

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  • How do I (quickly) let people know that software I am providing for free is not abandon-ware?

    - by blueberryfields
    As an independent, individual programmer: How do I let people very quickly know that I have not abandoned the software I've written and given away for free? That I am putting in the effort required to maintain and support my software to a professional level? When software written by one or two developers is available for free, or marked as open-source, usually the default assumption is that it's abandon-ware. This is usually a safe assumption - check out the answers to this question if you doubt it: Why do programmers write applications and then make them free?. There are lots of programmers who provide free and/or open-source tools which are not abandon-ware, though. If we're talking about large companies, ie Google, there's no real problem telling the difference between supported, live tools and software, and those which are abandoned or discontinued. A lively git repository isn't quick - users will have to be savvy enough to understand the repository and know where to look for it. Consistent marketing and community management take more time and effort than I can put in on my own. Also, if my software becomes popular/successful, I assume those will grow on their own, and be supported by power users in the community.

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  • Well tested C/C++ lock free queue?

    - by uj
    I am looking for a well-tested, publicly available C/C++ implementation of a lock free queue. I need at least multiple-producers/single-consumer functionality. Multiple-consumers is even better, if exists. I'm targetting VC's _Interlocked... intrinsics, though anything which is straight forward to port would be fine. Could anyone give any pointers?

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  • Do Apple and Google ask for a share if custom payment is done in a free app?

    - by user1590354
    I have a multiplatform game (web/iOS/Android) in the making. In the free version the core game is still fully playable but people who choose to pay will get more social features (and no ads, of course). I was thinking that rather than having a free and a paid version for all the platforms I may release the apps just for free and if the users want more, they have to register and pay a one-time fee (through a payment gateway or PayPal). The extra content would then be available in all the clients they have access to. Theoretically, this means a better value for the players and less maintenance and headache for me (obviously I have to handle all the payment troubles myself). Does it fit into the business model of Apple/Google? Or will they still claim their share of the registration fee?

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  • Lock free multiple readers single writer

    - by dummzeuch
    I have got an in memory data structure that is read by multiple threads and written by only one thread. Currently I am using a critical section to make this access threadsafe. Unfortunately this has the effect of blocking readers even though only another reader is accessing it. There are two options to remedy this: use TMultiReadExclusiveWriteSynchronizer do away with any blocking by using a lock free approach For 2. I have got the following so far (any code that doesn't matter has been left out): type TDataManager = class private FAccessCount: integer; FData: TDataClass; public procedure Read(out _Some: integer; out _Data: double); procedure Write(_Some: integer; _Data: double); end; procedure TDataManager.Read(out _Some: integer; out _Data: double); var Data: TDAtaClass; begin InterlockedIncrement(FAccessCount); try // make sure we get both values from the same TDataClass instance Data := FData; // read the actual data _Some := Data.Some; _Data := Data.Data; finally InterlockedDecrement(FAccessCount); end; end; procedure TDataManager.Write(_Some: integer; _Data: double); var NewData: TDataClass; OldData: TDataClass; ReaderCount: integer; begin NewData := TDataClass.Create(_Some, _Data); InterlockedIncrement(FAccessCount); OldData := TDataClass(InterlockedExchange(integer(FData), integer(NewData)); // now FData points to the new instance but there might still be // readers that got the old one before we exchanged it. ReaderCount := InterlockedDecrement(FAccessCount); if ReaderCount = 0 then // no active readers, so we can safely free the old instance FreeAndNil(OldData) else begin /// here is the problem end; end; Unfortunately there is the small problem of getting rid of the OldData instance after it has been replaced. If no other thread is currently within the Read method (ReaderCount=0), it can safely be disposed and that's it. But what can I do if that's not the case? I could just store it until the next call and dispose it there, but Windows scheduling could in theory let a reader thread sleep while it is within the Read method and still has got a reference to OldData. If you see any other problem with the above code, please tell me about it. This is to be run on computers with multiple cores and the above methods are to be called very frequently. In case this matters: I am using Delphi 2007 with the builtin memory manager. I am aware that the memory manager probably enforces some lock anyway when creating a new class but I want to ignore that for the moment. Edit: It may not have been clear from the above: For the full lifetime of the TDataManager object there is only one thread that writes to the data, not several that might compete for write access. So this is a special case of MREW.

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  • Why lock statements don't scale

    - by Alex.Davies
    We are going to have to stop using lock statements one day. Just like we had to stop using goto statements. The problem is similar, they're pretty easy to follow in small programs, but code with locks isn't composable. That means that small pieces of program that work in isolation can't necessarily be put together and work together. Of course actors scale fine :) Why lock statements don't scale as software gets bigger Deadlocks. You have a program with lots of threads picking up lots of locks. You already know that if two of your threads both try to pick up a lock that the other already has, they will deadlock. Your program will come to a grinding halt, and there will be fire and brimstone. "Easy!" you say, "Just make sure all the threads pick up the locks in the same order." Yes, that works. But you've broken composability. Now, to add a new lock to your code, you have to consider all the other locks already in your code and check that they are taken in the right order. Algorithm buffs will have noticed this approach means it takes quadratic time to write a program. That's bad. Why lock statements don't scale as hardware gets bigger Memory bus contention There's another headache, one that most programmers don't usually need to think about, but is going to bite us in a big way in a few years. Locking needs exclusive use of the entire system's memory bus while taking out the lock. That's not too bad for a single or dual-core system, but already for quad-core systems it's a pretty large overhead. Have a look at this blog about the .NET 4 ThreadPool for some numbers and a weird analogy (see the author's comment). Not too bad yet, but I'm scared my 1000 core machine of the future is going to go slower than my machine today! I don't know the answer to this problem yet. Maybe some kind of per-core work queue system with hierarchical work stealing. Definitely hardware support. But what I do know is that using locks specifically prevents any solution to this. We should be abstracting our code away from the details of locks as soon as possible, so we can swap in whatever solution arrives when it does. NAct uses locks at the moment. But my advice is that you code using actors (which do scale well as software gets bigger). And when there's a better way of implementing actors that'll scale well as hardware gets bigger, only NAct needs to work out how to use it, and your program will go fast on it's own.

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  • (Google AppEngine) Memcache Lock Entry

    - by Friedrich
    Hi, i need a locking in memcache. Since all operations are atomic that should be an easy task. My idea is to use a basic spin-lock mechanism. So every object that needs locking in memcache gets a lock object, which will be polled for access. // pseudo code // try to get a lock int lock; do { lock = Memcache.increment("lock", 1); } while(lock != 1) // ok we got the lock // do something here // and finally unlock Memcache.put("lock", 0); How does such a solution perform? Do you have a better idea how to lock a memcache object? Best regards, Friedrich Schick

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  • Python Locking Implementation (with threading module)

    - by Matty
    This is probably a rudimentary question, but I'm new to threaded programming in Python and am not entirely sure what the correct practice is. Should I be creating a single lock object (either globally or being passed around) and using that everywhere that I need to do locking? Or, should I be creating multiple lock instances in each of the classes where I will be employing them. Take these 2 rudimentary code samples, which direction is best to go? The main difference being that a single lock instance is used in both class A and B in the second, while multiple instances are used in the first. Sample 1 class A(): def __init__(self, theList): self.theList = theList self.lock = threading.Lock() def poll(self): while True: # do some stuff that eventually needs to work with theList self.lock.acquire() try: self.theList.append(something) finally: self.lock.release() class B(threading.Thread): def __init__(self,theList): self.theList = theList self.lock = threading.Lock() self.start() def run(self): while True: # do some stuff that eventually needs to work with theList self.lock.acquire() try: self.theList.remove(something) finally: self.lock.release() if __name__ == "__main__": aList = [] for x in range(10): B(aList) A(aList).poll() Sample 2 class A(): def __init__(self, theList,lock): self.theList = theList self.lock = lock def poll(self): while True: # do some stuff that eventually needs to work with theList self.lock.acquire() try: self.theList.append(something) finally: self.lock.release() class B(threading.Thread): def __init__(self,theList,lock): self.theList = theList self.lock = lock self.start() def run(self): while True: # do some stuff that eventually needs to work with theList self.lock.acquire() try: self.theList.remove(something) finally: self.lock.release() if __name__ == "__main__": lock = threading.Lock() aList = [] for x in range(10): B(aList,lock) A(aList,lock).poll()

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  • Java synchronized method lock on object, or method?

    - by wuntee
    If I have 2 synchronized methods in the same class, but each accessing different variables, can 2 threads access those 2 methods at the same time? Does the lock occur on the object, or does it get as specific as the variables inside the synchronized method? Example: class x{ private int a; private int b; public synchronized void addA(){ a++; } public synchronized void addB(){ b++; } } Can 2 threads access the same instance of class x performing x.addA() and x.addB() at the same time?

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  • How can I lock screen on lxde

    - by maniat1k
    Like gnome Control + alt + L In Lxde how can i do that? What I have to intall to do this? thanks --searching for a solution on my own but... ok if I do alt+f2 and type xscreensaver-command -lock that's a small solution. tryed to do an small script but it's not working.. this is what I do vi lock.sh #!/bin/bash xscreensaver-command -lock exit 0 chmod +x lock.sh but this doesnt work.. ideas?

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