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Java Forum / General / December 2006Files and Memory Usage
>From the perspective of a utility like top, would having a file open and continuously write to it without closing it increase the memory usage? > >From the perspective of a utility like top, would having a file open > and continuously write to it without closing it increase the memory > usage? Note: When I go to reply to your message, my software inserts a character before your text to indicate that I am 'quoting' your words, ..see the '>' above? The stray '>' at the beginning of your *original* message makes it appear that *you* were also quoting someone else! Please leave off the initial '>' in future, to help save the confusion. ( And no, I have no idea what 'top' is, nor its behaviour with Java I/O streams. Yoo might clarify what it is, with a link. ) Andrew T. .. > ( And no, I have no idea what 'top' is, nor its behaviour > with Java I/O streams. Yoo might clarify what it is, with > a link. ) I do not think I said that very clear, so a second attempt.. I suggest you post a link to the 'top' tool that you are using, so others (who may not know what it is) can find out about it, and be able to better answer your question. Andrew T. Well, I believe he is talking about the very very basic *nix tool -- /usr/bin/top. I don't know the answer to the question, but it should be very easy to write a program to test it. Andrew Thompson skrev: >> >From the perspective of a utility like top, would having a file open >> and continuously write to it without closing it increase the memory [quoted text clipped - 6 lines] > The stray '>' at the beginning of your *original* message > makes it appear that *you* were also quoting someone else! Many mail and news agents will put a > in front of From if it starts a line, since a line starting with From may be the start of a new message in some mail/news archive and transport formats. > Andrew Thompson skrev: > >> >From the perspective of a utility like top, would having a file open [quoted text clipped - 11 lines] > line, since a line starting with From may be the start of a new message > in some mail/news archive and transport formats. It took me a few moments to realise the significance of what you were saying, since I'd forgotten the OP's use of the word 'From', and thought you were using it in a more generic sense. It would be interesting to find out if it was the news reader. ..oh wait a second, GG! OK. <http://groups.google.com/group/alt.test/browse_frm/thread/588afb7279a7b824/ec939 3e87967e7fc> Proof you were right Lars, that post by me to alt.test, out of GG, had no leading '>' when I sent it. Andrew T. > > >From the perspective of a utility like top, would having a file open > > and continuously write to it without closing it increase the memory > > usage? > ( And no, I have no idea what 'top' is, nor its behaviour > with Java I/O streams. Yoo might clarify what it is, with > a link. ) > > Andrew T. top is a standard Unix command which is similar to windows task manager. It displays memory and CPU statistics for running applications. I believe the OP is asking if continuously writing to a file will increase the apparent memory usage of a particular application. My short answer is, probably not. Although, the OS might cache some/all of the writes, and therefor allocate memory. Although, generally, if you are going to write to a file throughout the lifetime of an application (say for a log) then keeping the file open DOES make sense. >From the perspective of a utility like top Top is darned handy, but you shouldn't optimize for any given tool. Understand what the tool is measuring and decide if it's important to you (note: top's VIRT and RES numbers probably should be important to you most of the time, but not because they're in top, just because OS memory allocated and resident is important). >would having a file open and continuously write to it without closing it >increase the memory usage? Not usually. You can write many gigs to a file without using any more memory for the VM. There may be files or filesystems where this is not true (some sort of virtual filesystem that lives in the VM, maybe?), but if you're seeing memory grow, it's far more likely you're leaking memory (leaking object references, usually, through a misplaced or hidden static) when reading/generating/writing the data than that the actual write is using memory. -- Mark Rafn dagon@dagon.net <http://www.dagon.net/> >>From the perspective of a utility like top, would having a file open > and continuously write to it without closing it increase the memory > usage? If you are using an ObjectOutputStream, yes, otherwise no. Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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