Collect process stat data

def collect(self):
        """
        Collect process stat data
        """
        if not os.access(self.PROC, os.R_OK):
            return False

        # Open PROC file
        file = open(self.PROC, 'r')

        # Get data
        for line in file:

            if line.startswith('ctxt') or line.startswith('processes'):
                data = line.split()
                metric_name = data[0]
                metric_value = int(data[1])
                metric_value = int(self.derivative(metric_name,
                                                   long(metric_value),
                                                   counter))
                self.publish(metric_name, metric_value)

            if line.startswith('procs_') or line.startswith('btime'):
                data = line.split()
                metric_name = data[0]
                metric_value = int(data[1])
                self.publish(metric_name, metric_value)

        # Close file
        file.close()