Re: moving data from one place to another in a text file

From: Richard (riplin_at_Azonic.co.nz)
Date: 03/03/05

  • Next message: Rick Smith: "Re: moving data from one place to another in a text file" 
    Date: 3 Mar 2005 00:43:04 -0800

    > One concern then would be the correct management and overhead of
    ensuring
    > each word is pulled only once from the queue.

    That is what locks are for. Only one thread can pull a word from the
    queue at a time.

    I did write a printer buffering system nearly 20 years ago which used
    multi-threading (actually it had to use full processes but running in
    the same code and data segments) because it had to monitor multiple
    i/o. It used a circular buffer and had to toggle locks to ensure the
    buffer was kept uncorrupted.

    > Now we're reaching a compromise where we could agree that
    > perhaps RW's thread solution is not so wrong.

    As is usual with RW he vastly overstates and hyperbolises. He states,
    for example, that multi-threading will save resources, but it does this
    only in the very narrow areas where many CPUs are available and
    otherwise unused. In fact as there will be many more cycles used up,
    not just by the extra code but also by the scheduler it will use _more_
    resources. 'Saving' resources when nothing else will use them is
    pointless. Wasting resources when other processes are trying to share
    them is also pointless.

    Most multi-CPU systems are servers and designated to run server
    software and multiple streams. Even desktops are not just running a
    single task, not since MS-DOS of 15 years ago. I have a Linux desktop
    for development and while I am typing here 'top' shows 160 tasks
    running, though the vast majority are sleeping.

    If you have multiple CPUs then run multiple streams. The OS will be
    processing the filesystem cache, the database will use multiple CPUs.
    The servers that I look after have multiple users and run several X
    desktops (to LTSP diskless graphic terminals) plus each user runs
    several copies of applications. Typically there are several hundred
    tasks.

    You may note that RW's machines are corporate servers (not desktops) on
    which he specifically closed down all other services to run his test.

    The idea that one program should grab every resource available should
    have died with MS-DOS.

    There _are_ good reasons for multi-threading, such as having many
    threads having to wait for different responses, and this may apply to
    database systems or web servers.

    RW has made many overstatements about where it can be used and when.

    > forces you to think about problems in a different manner.

    The hard bit is when RW has his steel trap mind closed around a subject
    getting him to think about it in a different manner.

  • Next message: Rick Smith: "Re: moving data from one place to another in a text file"

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