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java programmer requests help using ofstream
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Join Date: Dec 2004
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I am a java programmer trying to understand a c++ oddity that I ran into. My c++ program writes a few MB of data using ofstream. Just before the program ends I close the ofstream. However when the program terminates, the amount of free memory on my linux box has decreased by the size of the data that was written. The memory remains lost until the file is deleted. Here is a sample of how I use ofstream:
In my constructor, I have:
ofstream tfile("../../tmp/outputfile.txt", std::ios::app);
a number of prints using tfile occur that are similar to the following line:
tfile << track->GetTrackID() << '\t' << track->GetParentID() << '\t' << pName << '\t';
In the destructor, I have:
tfile.close();
Any ideas would be appreciated![I]
In my constructor, I have:
ofstream tfile("../../tmp/outputfile.txt", std::ios::app);
a number of prints using tfile occur that are similar to the following line:
tfile << track->GetTrackID() << '\t' << track->GetParentID() << '\t' << pName << '\t';
In the destructor, I have:
tfile.close();
Any ideas would be appreciated![I]
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Join Date: Oct 2004
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It looks to me that you are reading data into a buffer that does not get deleted at the end. Check your code for the ever so elusive buffer.
May 'the Google' be with you!
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Join Date: Dec 2004
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Thanks for the quick answer! How does one typically delete/find the buffer? tfile->delete was my first guess, but it causes segmantation faults since the ofstream constructor was not called...
The problematic snippet of code writes the interesting data from my monte carlo sim.
The problematic snippet of code writes the interesting data from my monte carlo sim.
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Originally Posted by santa_barbarian
Thanks for the quick answer! How does one typically delete/find the buffer? tfile->delete was my first guess, but it causes segmantation faults since the ofstream constructor was not called...
The problematic snippet of code writes the interesting data from my monte carlo sim.
Alex Cavnar, aka alc6379
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I am not a Java person, but in C++ you best look at something like "new" and the potentially missing "delete". Here is a typical code segment (commented to the hilt): [php]
// Allocate memory
buffer = new char[length];
// Read data as a block
is.read(buffer, length);
// Close file
is.close();
// Print data
cout << buffer << endl;
// Free memory
delete []buffer;
[/php]
// Allocate memory
buffer = new char[length];
// Read data as a block
is.read(buffer, length);
// Close file
is.close();
// Print data
cout << buffer << endl;
// Free memory
delete []buffer;
[/php]
May 'the Google' be with you!
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Join Date: Dec 2004
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I have a RunAction class which has the following global line:
std::ofstream tfile("../../tmp/outputfile.txt", std::ios::app);
RunAction::~RunAction() {
tfile.close();
}
A second class SD has the following global line:
extern ofstream tfile;
SD:
rocessHits(G4Step* step,G4TouchableHistory* ROhist) {
A couple of other classes use tfile in the same way as the SD class.[INDENT]
std::ofstream tfile("../../tmp/outputfile.txt", std::ios::app);
RunAction::~RunAction() {
tfile.close();
}
A second class SD has the following global line:
extern ofstream tfile;
SD:
rocessHits(G4Step* step,G4TouchableHistory* ROhist) {G4Track* track;}
if(step != NULL)
track = step->GetTrack();
else
track = NULL;
G4double edep = 0;
if(step != NULL)
edep = step->GetTotalEnergyDeposit();
bool write = false;
G4int parentID = track->GetParentID();
G4String pName = (track->GetDefinition())->GetParticleName();
G4double kEnergy = track->GetKineticEnergy();
G4double dEnergy = step->GetTotalEnergyDeposit();
G4String volName = track->GetVolume()->GetName();
if((track != NULL) && (step != NULL) && goodEvent) {// Output to text file.}
if((track->GetDefinition()) != NULL)
if((track->GetVolume()) != NULL)
if((step->GetPostStepPoint()) != NULL)
if((step->GetPostStepPoint()->GetProcessDefinedStep()) != NULL)
tfile << track->GetTrackID() << '\t'
<< track->GetParentID() << '\t'
<< pName << '\t'
<< track->GetCurrentStepNumber() << '\t'
<< kEnergy << '\t'
<< dEnergy << '\t'
<< step->GetStepLength() << '\t'
<< track->GetTrackLength() << '\t'
<< track->GetVolume()->GetName() << '\t'
<< step->GetPostStepPoint()->GetProcessDefinedStep()->GetProcessName() << '\t'
<< track->GetPosition().x() << '\t'
<< track->GetPosition().y() << '\t'
<< track->GetPosition().z() << '\t'
<< track->GetMomentumDirection().x() << '\t'
<< track->GetMomentumDirection().y() << '\t'
<< track->GetMomentumDirection().z() << '\t'
<< track->GetGlobalTime() << '\t'
<< step->GetPreStepPoint()->GetKineticEnergy() << std::endl;
A couple of other classes use tfile in the same way as the SD class.[INDENT]
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My working hypothysis has changed. I now believe that c++ is NOT memory leaking but instead linux is storing the file in cached memory even after the program has terminated. Deleting the file then forces linux to clear it from cached memory...Thanks for your help!
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