Strange memory leak in C++[Solved]

[MdaG]

I'm probably doing a real n00b error here, but here goes.

At the beginning of my code I query the user if he/she wants to import data from file, but the code never gets past the cin-part. I have to manually terminate the process from there. The printf-statement never executes and when I look at my system monitor in Gnome it shows a huge memory leakage (from 120Mb to ~730Mb). My DRAM is 768 Mb on my machine. What could be the problem, anyone?

Code:

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int main() {
	float Q[N_STATES][N_ACTIONS];				// State-action pair table
	char	ans;										// Query for save and load data.
	
	/* Seed the random generator */
	srand48(time(0));								
	
	/* Initialize the Q-table */
	cout << "Read data from file? (y/n) : "; <----- I know it get's here
	cin >> ans;
	printf("bajs");     <----- Never gets here
	if (ans == 'y')
		loadData(Q);
	else 
		init(Q);

	/* Do Q-learning algorithm */
	oneStepQ(Q);
	
	/* Store "experience" */
	cout << "Store data on file? (y/n) : ";
	cin >> ans;
	if (ans == 'y')
		saveData(Q);

	return 0;
}
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This is what I get when I try to run the code:

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$ ./detach_left
Read data from file? (y/n) : n

afterwards everything is just painfully slow and I see the memory leakage...

[GordSki]

Could the problem be in init()? One thing to note is that printfs don't always make it to the screen when they are called. It can take time for stdout to get flushed and the text to hit the screen, especially if you go into some memory hungry busy loop......

G.

[MdaG]

My init() looks like this:

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void init(float Q[N_STATES][N_ACTIONS]) {
	int i, j;
	for (i = 0; i < N_STATES; i++)
		for (j = 0; j < N_ACTIONS; j++)
			Q[i][j] = 0.0;
}

[GordSki]

How big are N_STATES and N_ACTIONS?

G.

[MdaG]

constants.h

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#define N_PHI 181								// Number of different angles (degrees)
#define N_DIST 51								// Number of different distances (cm)
#define N_STATES N_DIST*N_PHI				// Number of states equal to nCM * nDeg
#define N_ACTIONS 4							// Number of different actions
#define PRECISION 6							// Floating point precision
#define GAMMA 0.9								// Discount factor for critic
#define ALPHA 0.1								// Learning rate scaling factor
#define LAMBDA 0.9							// Trace decay parameter
#define EPSILON 0.1							// Greedy factor
#define MAX_EPISODES 1000					// Maximum runs before quitting
#define MAX_STEPS 20000						// Maximum steps before failure

[swingman]

Hmmm... output buffering... mixing <iostream> and <stdio.h>

I suggest changing the printf to a cout << msg << endl; or as a minimum add fflush(stdout); after printf.
_
/Bjorn

[GordSki]

init() looks ok too. The other thing you could do is try stepping through the program with gdb and see what's going on.

G.

[MdaG]

Hmmm... output buffering... mixing <iostream> and <stdio.h>

I suggest changing the printf to a cout << msg << endl; or as a minimum add fflush(stdout); after printf.
_
/Bjorn

Thanks. Using printf() together with cout did some strange things. I know now that the memory leak isn't due to cin.

*edit*
I have cornered the problem to a line where I set:

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lastState = thisState;

where lastState and thisState are instances of State. I have overloaded the operator '=' with the following code:

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State State::operator =(const State& s) const {
	return State(s.getDistance(), s.getAngle());
}

[swingman]

init() looks ok too. The other thing you could do is try stepping through the program with gdb and see what's going on.

G.

Or just attach gdb to the currently running process. Just make sure you compile with symbol info, so you can see where the program is stuck.
_
/Bjorn

[MdaG]

init() looks ok too. The other thing you could do is try stepping through the program with gdb and see what's going on.

G.

Or just attach gdb to the currently running process. Just make sure you compile with symbol info, so you can see where the program is stuck.
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/Bjorn

I've never used gdb, what is it? *googling*

*edit*
Nevermind, I think I've figured out how to use gdm. Thanks.

*edit*
I found the error. I had a faulty destructor in the class code of State.