程序要产生并输出一个100万行左右的JSON数据（大约100MB），按照常规的方法，先在内存中准备好这100万行数据然后输出，服务器用的是Apache + mod_wsgi，一访问服务端就挂了。

查了一下，得知为了避免占用大量的内存导致服务器进程崩溃，最好采用迭代器的方法，如下代码段：

def home(request, epoch=None):
    client_ip = request.META['REMOTE_ADDR']
    if '*' in settings.ALLOWED_IPS or (client_ip and client_ip in settings.ALLOWED_IPS):
        
        # default epoch is 60 seconds ago
        if not epoch:
            epoch = int(time.time() - 60)
        else:
            epoch = int(epoch)
            
        def product_json():
            rows = Details.objects.filter(time_collected__gte=epoch).order_by('auction_id')
            total_number = rows.count()
            yield '{"epoch": %d, "returned_number": %d, "data": [' % (epoch, total_number)
            i = 0
            for row in rows:
                i += 1
                if i < total_number:
                    yield json.dumps(row.to_dict()) + ', '
                else:
                    yield json.dumps(row.to_dict())
            yield ']}'
        
        return HttpResponse(product_json())
    else:
        return HttpResponse(json.dumps({'error': 'Your IP is banned.'}))

参考文章：http://oldj.net/article/django-big-file-response/