Race conditions - can you actually lose the data in memory?

I've seen posts where a race condition can actually destroy the contents of a global memory. I understand about not getting the right information if your read just beats your write, but can it actually lose the data altogether? This would mean you have to semaphore every time you write to a global if you have something polling on it to guarantee the data doesn't get lost. I've never seen this in any example programs - its hard to believe!

I think the idea is merely that when you write to a global (or any)
variable the previous contents are overwritten. If you intended to read the
global before the write but the write ends up happening first then you lose.
"mikema111" wrote in message
news:[email protected]..
> I've seen posts where a race condition can actually destroy the
> contents of a global memory. I understand about not getting the right
> information if your read just beats your write, but can it actually
> lose the data altogether? This would mean you have to semaphore every
> time you write to a global if you have something polling on it to
> guarantee the data doesn't get lost. I've never seen this in any
> example programs - its hard to be
lieve!

Similar Messages

  • I am attempting to have cells use data from a selective month from the year before so that I can show actual from the prio. years each month.

    I am attempting to have cells use data from a selective month from the year before so that I can show actual from the prio. year each month. I need to create a spreedsheet using the the Acutlas from the year-to-date and from last year-to-date, but need to report each month.

    Hi Tony,
    Answering your question would be easier given a screen shot of the source table and one of what you want the summary table to look like.
    Is the data you want for each month in a single cell o the source table, or does the summary table need to collect February's data (for example) from several cells and do some math with those numbers before presenting them on the summary table?
    Regards,
    Barry

  • When insert my lexar USB flash drive I get the message that the disk was not readable by this computer.  It has worked previous to this and I do not want to lose the data by reformatting the drive.  How can I reformat this drive and not lose my data?

    When insert my lexar USB flash drive I get the message that the disk was not readable by this computer.  It has worked previous to this and I do not want to lose the data by reformatting the drive.  How can I reformat this drive and not lose my data?

    You can't reformat it and not wipe everything on it.
    Have you tried a different USB port?
    Only other option, back it up on a different computer.

  • What can i do if i have lose my security question answers and if i have lose the dates of my e-mail adress

    Hello,
    What can i do if i have lose my security question answers and if i have lose the dates of my e-mail adress?

    You need to ask Apple to reset your security questions. To do this, click here and pick a method; if that page doesn't list one for your country or you're unable to call, fill out and submit this form.
    (118800)

  • I ordered iphone 6 on 15 oct and delivery date will be from 3 nov-6nov. i'll travel on 7 nov morning, am worried to receive the order late.. can you please expedite the order?

    i ordered iphone 6 on 15 oct and delivery date will be from 3 nov-6nov. i'll travel on 7 nov morning, am worried to receive the order late.. can you please expedite the order?

    No. Because we are not Apple employees. In fact there is no one from Apple in this forum. Contact Apple directly via phone. Use the "Contact Us" link at the bottom of this page to find the phone listing.

  • I am 19 days from my contract needing to be renewed and I broke my screen.    How far in advance can you renew before the actual renew day?

    I am 19 days from my contract needing to be renewed and I broke my screen.    How far in advance can you renew before the actual renew day?

    Basically it is on the day your contract ends. However some Verizon wireless corporate store managers can over ride that and update possibly a week early. But its iffy.
    Now Verizon will let you upgrade to the Edge program but you have a broken device and they will prey on you since you are desperate for a device. Edge plan is paying full price over 20 months and paying taxes on it up front, you then after paying 60% of the device off can edge up to another device. Now if you pay 60% off at anytime after 30 days you can continue to trade them in for new as much as you want.
    Or you can wait it out get a new free device under contract or reduced cost device again under a 2 year contract.
    The edge plan is no contract.
    Good Luck

  • What is the main benefit of  buying an ipad ? what can you actually do in 16, 32 0r 64 gb when you have 510 gb laptop with you ?

    What is the main benefit of  buying an ipad ? what can you actually do in 16, 32 0r 64 gb when you have 510 gb laptop with you ?

    For me? the advantage of an ipad over a laptop....instant on, instant off, thin and portable. Check your e-mail and put it down, not wait 5 minutes to boot, check your mail, shut it down.
    Is it as fully functional as a laptop? no. Not meant to be. What it lacks in functionality it makes up for in portability.
    Is a necessity? no. But quite handy.

  • Is it possible to view data backed up to iCloud (such as contacts from an old iPhone) without actually restoring the data to a device?

    Can I view contacts backed up to the iCloud from my old iPhone without actually restoring the data on a new device?

    If you have a backup, yes,  You can restore the new device from the old backup.  Without a backup, no.
    Without a backup, and without the device, you no longer have any of your data to put on anything anymore.
    You can redownload purchased content from the iTunes and App stores - just use the same AppleID as you did with the old device.

  • HT2500 Can you categorize archives by date, from or to as you can in outlook?

    Can you categorize archives by date, from or to as you can in outlook? My question actually pertains to Imac but is the same issue on all platforms.

    First we need to sort out what platforum are you using?
    mac, iPhone, ipad
    What version of the OS are you using?
    What app areyou running?
    How about a screen image of the archive you are using?
    How to show us a screen image.  Avoid personal identification.
    command + shift + 3   Will take entire screen.  You hear a click.
    command + shift + 4 Lets you decide what to take.  Mouse pointer changes. Move mouse to upper left corner of desire image.  Hold down left mouse key where to start image.  Drag mouse to lower left of where you want to stop image.  Release mouse.
    You will get a picture n.png file on the desktop.
    one the forum input panel you will see the camera icon.
    click on camera icon.
    another window will appear.
    Make sure you have selected the from your computer tab.
    click on Browse button
    An open file panel appears.  Select the file.
    After selection a file, I have this screen showing.
    You will have to click on Insert Image.  You may have to scroll down to see Insert Image button.

  • How do I delete one of the user accounts on my computer and not lose the data in that account?

    How do I delete one of the user accounts on my computer and not lose the data in that account?

    I actually have the opposite of this problem. haha.
    https://discussions.apple.com/thread/4484354

  • How do you edit out the date and time stamp from a photo

    How do you edit out the date and time stamp from a photo

    You can blur it out with retouch
    The built-in "Retouch" brush in "Edit" mode should suffice, if the background is mostly uniform, and if you set the size of the brush to slightly wider than the bar width of the letters. For example, in this picture I removed the year from the date (in the lower right corner) by using the "retouch" brush and following the contours of the letters. (the screen shot is from iPhoto '11, but iPhoto 9 should give similar results).
    Regards
    Léonie

  • Can you shut off the Internet on a iPhone 4s and still use it with a wifi connection ?

    Can you shut off the Internet on a iPhone 4 and then use the phone as normal

    I assume that you're asking if you can shut off cellular data (as no individual can shut off the Internet! )? Yes, you can turn off cellular data and use the phone features (except for MMS which requires cellular data) and access the Interenet via WiFi.
    Settings>General>Network>Cellular Data>Off

  • I lost my iphone in the woods and it is not connected to the internet. how can i trace it? and if i cant, can i take all the data, such as pictures from my old phone onto a new one?

    so i was walkin in the woods and somehow i droped it. its not conected to the internet. i know because i checked icloud. when i walked around to look for it i used a friends phone to call it so it would ring, but it went straight to voice mail.
    So, how can i trace it? and if i cant, can i take all the data, such as pictures from my old phone onto a new one?

    if you installed find my iphone app on it you can do these things from icloud if it's online
    if not you can't do anything

  • Iam using a table in numbers to plot daily graph lines. If I fill a cell with a text box  at say zero it plots the graph. I can't actually set the cell value until the actual day but the graph plots it at zero when I don't want it to plot anything. Is tho

    I am using a table in Numbers to plot daily graph lines. Mood swings of how I am on the day, i"m a depressive.
    If I fill a cell with a step box at say zero it plots the graph. I can't actually set the cell value until the actual day but the graph plots it at zero when I don't want it to plot anything. Is there a work around. so thatbgraph only plots on the day?

    The answer is (sort of) in your subject, but edited out of the problem statement in the body of your message.
    When you use a stepper or a slider, the value in the cell is always numeric, and is always placed on the chart if that cell is included in the range graphed by the chart.
    But if you use a pop-up menu cell, you can specify numeric or text values in the list of choices for in the menu. Numeric values will be shown on the chart. Text values will not.
    For the example, the values list for the pop-up menu was:
    5
    3
    1
    Choose
    -1
    -3
    -5
    The first pop-up was set to display Choose, then the cell was filled down the rest of the column. Any text value (including a single space, if you want the cell to appear blank) may be used instead of Choose.
    For charts with negative Y values, the X axis will not automatically appear at Y=0. If your value set will include negative values, I would suggest setting the Y axis maximum and minimum to the maximum and minimum values on your menu list, rather than letting Numbers decide what range to include on the chart. Place a line shape across the chart at the zero level, and choose to NOT show the X axis.
    Regards,
    Barry

  • How can I get extract the data between two cursors on an XY graph

    How can I get extract the data between two cursors on an XY graph

    Well, you say xy graph, so this might be a more complicated problem.
    For a waveform graph it's trivial. Simply get the two cursor indices (property: cursor index) and apply them to array subset of the data. Is that all you need?
    Here's how the above code would look like. using cursor.index instead of cursor.x elimnates the need to include scaling information.
    For an xy graph, there could be multiple segments (e.g. imagine a spiral that passes the desired x range multiple times from both sides). This would neeed significantly more code for a general solution.
    Message Edited by altenbach on 11-24-2009 07:53 AM
    LabVIEW Champion . Do more with less code and in less time .
    Attachments:
    cursorsubset.png ‏17 KB

Maybe you are looking for