VirtualAlloc,GlobalAlloc,HeapAlloc,..what to use in my case,...
in [Visual C]
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From: Kerem G�mr�kc� on 7 Mar 2008 19:54 Hi, i have a application that reads a unknown bunch of files to a block of memory, handles them and finally frees the memory. For now, i work with VirtualAlloc, but i get after processing ~250 Files a GetLastError=8 for any memory request, even i know that memory has been released with VirtualFree=TRUE. Why is that the case? The System has 1GB of real physical memory. Sure i know the limitations of user memory space and process space. VirtualAlloc will always be called with MEM_COMMIT and PAGE_READWRITE in my code. I have to read the complete file, not a piece of it, so some files are 205 byte others about 20MB. So what and how can i asure, that my application frees the allocated memory after ist usage and what are the differences on processing impact if i use these functions, better to say: what are the differences between VirtualAlloc, GlobalAlloc and HeapAlloc? The Application is a single threaded app and expects a folder path as input, then it processes the files: FOR EACH FILE IN FOLDER IsFileReadable ReadFileSize VirtualAlloc ReadFileContent DoAnalyzeFileContent WriteToOwnAppFile FlushBuffers VirtualFree NEXT FILE ExitApplication How can i prevent to run into a GetLastError()=8 Subsequent Memory Request fail after a GetLastError=8 Regards K. -- ----------------------- Beste Gr�sse / Best regards / Votre bien devoue Kerem G�mr�kc� Microsoft Live Space: http://kerem-g.spaces.live.com/ Latest Open-Source Projects: http://entwicklung.junetz.de ----------------------- "This reply is provided as is, without warranty express or implied."
From: Kerem G�mr�kc� on 7 Mar 2008 20:13 Hi, i had a look at its resource uttilization/usage with process explorer and it grows exponentially expecially its "Virtual Size" for Virtual Memory, sure for VirtualAlloc and its CPU Usage. At a certail level it slows down the complete system and os starts to work with the pagefile until i kill or stop the process,... Something is wrong here, I think i should not use VirtualAlloc or find a way to 100% give back the allocated memory and then reallocate new memory. How can i force my application to use real physical memory instead virtual? Dow, this belongs to the OS and its internals, i know,... I found this: [Comparing Memory Allocation Methods] http://msdn2.microsoft.com/en-us/library/aa366533.aspx which makey my decision go HeapAlloc, because of the page granularity,... Regards K. -- ----------------------- Beste Gr�sse / Best regards / Votre bien devoue Kerem G�mr�kc� Microsoft Live Space: http://kerem-g.spaces.live.com/ Latest Open-Source Projects: http://entwicklung.junetz.de ----------------------- "This reply is provided as is, without warranty express or implied." "Kerem G�mr�kc�" <kareem114(a)hotmail.com> schrieb im Newsbeitrag news:ObQOrcLgIHA.484(a)TK2MSFTNGP06.phx.gbl... > Hi, > > i have a application that reads a unknown bunch of > files to a block of memory, handles them and finally > frees the memory. For now, i work with VirtualAlloc, > but i get after processing ~250 Files a GetLastError=8 > for any memory request, even i know that memory has > been released with VirtualFree=TRUE. Why is that > the case? The System has 1GB of real physical memory. > Sure i know the limitations of user memory space and > process space. VirtualAlloc will always be called with > MEM_COMMIT and PAGE_READWRITE in my code. > I have to read the complete file, not a piece of it, so > some files are 205 byte others about 20MB. So what > and how can i asure, that my application frees the > allocated memory after ist usage and what are the > differences on processing impact if i use these functions, > better to say: what are the differences between VirtualAlloc, > GlobalAlloc and HeapAlloc? The Application is a single > threaded app and expects a folder path as input, then it > processes the files: > > FOR EACH FILE IN FOLDER > IsFileReadable > ReadFileSize > VirtualAlloc > ReadFileContent > DoAnalyzeFileContent > WriteToOwnAppFile > FlushBuffers > VirtualFree > NEXT FILE > ExitApplication > > How can i prevent to run into a GetLastError()=8 > Subsequent Memory Request fail after a GetLastError=8 > > > Regards > > K. > > -- > ----------------------- > Beste Gr�sse / Best regards / Votre bien devoue > Kerem G�mr�kc� > Microsoft Live Space: http://kerem-g.spaces.live.com/ > Latest Open-Source Projects: http://entwicklung.junetz.de > ----------------------- > "This reply is provided as is, without warranty express or implied." >
From: Alexander Grigoriev on 7 Mar 2008 21:53 What arguments are you passing to VirtualFree? "Kerem G�mr�kc�" <kareem114(a)hotmail.com> wrote in message news:ObQOrcLgIHA.484(a)TK2MSFTNGP06.phx.gbl... > Hi, > > i have a application that reads a unknown bunch of > files to a block of memory, handles them and finally > frees the memory. For now, i work with VirtualAlloc, > but i get after processing ~250 Files a GetLastError=8 > for any memory request, even i know that memory has > been released with VirtualFree=TRUE. Why is that > the case? The System has 1GB of real physical memory. > Sure i know the limitations of user memory space and > process space. VirtualAlloc will always be called with > MEM_COMMIT and PAGE_READWRITE in my code. > I have to read the complete file, not a piece of it, so > some files are 205 byte others about 20MB. So what > and how can i asure, that my application frees the > allocated memory after ist usage and what are the > differences on processing impact if i use these functions, > better to say: what are the differences between VirtualAlloc, > GlobalAlloc and HeapAlloc? The Application is a single > threaded app and expects a folder path as input, then it > processes the files: > > FOR EACH FILE IN FOLDER > IsFileReadable > ReadFileSize > VirtualAlloc > ReadFileContent > DoAnalyzeFileContent > WriteToOwnAppFile > FlushBuffers > VirtualFree > NEXT FILE > ExitApplication > > How can i prevent to run into a GetLastError()=8 > Subsequent Memory Request fail after a GetLastError=8 > > > Regards > > K. > > -- > ----------------------- > Beste Gr�sse / Best regards / Votre bien devoue > Kerem G�mr�kc� > Microsoft Live Space: http://kerem-g.spaces.live.com/ > Latest Open-Source Projects: http://entwicklung.junetz.de > ----------------------- > "This reply is provided as is, without warranty express or implied." >
From: Alex Blekhman on 8 Mar 2008 04:10 "Kerem G�mr�kc�" wrote: > I have several vrapper functions arround the VirtualAlloc and > VirtualFree and i was passing accidentally a MEM_DECOMMIT to a > VirtualFree, not a MEM_RELEASE and also not a zero as second > parameter. This was not clear because of my own flags and > complex wrappers,....dow,... The real question here is why do you need `VirtualAlloc' at all? You always call it with `MEM_COMMIT' and `PAGE_READWRITE' flags making it eventually indistinguishable form regular `operator new' or `malloc'. Actually you're making it worse since you miss all optimizations that CRT may enable (like Low Fragmentation Heap, for example). I suggest you at least to try your code with regular `new' and `delete'. Also, if you want to avoid buffer allocations altogether, then you can use memory mapping to read the files. Alex
From: Alexander Grigoriev on 8 Mar 2008 10:11
He might want certain alignment for non-buffered IO. "Alex Blekhman" <tkfx.REMOVE(a)yahoo.com> wrote in message news:u%23B7IxPgIHA.1132(a)TK2MSFTNGP06.phx.gbl... > "Kerem G�mr�kc�" wrote: >> I have several vrapper functions arround the VirtualAlloc and VirtualFree >> and i was passing accidentally a MEM_DECOMMIT to a VirtualFree, not a >> MEM_RELEASE and also not a zero as second parameter. This was not clear >> because of my own flags and complex wrappers,....dow,... > > The real question here is why do you need `VirtualAlloc' at all? You > always call it with `MEM_COMMIT' and `PAGE_READWRITE' flags making it > eventually indistinguishable form regular `operator new' or `malloc'. > Actually you're making it worse since you miss all optimizations that CRT > may enable (like Low Fragmentation Heap, for example). > > I suggest you at least to try your code with regular `new' and `delete'. > Also, if you want to avoid buffer allocations altogether, then you can use > memory mapping to read the files. > > Alex > |