Reading from SerialPort & Memory Management - C#

Question

I am working on a program that reads in from a serial port, then parses, formats, and displays the information appropriately. This program, however, needs to be run for upwards of 12+ hours - constantly handling a stream of incoming data. I am finding that as I let my app run for a while, the memory usage increases at a linear rate - not good for a 12 hour usage.

I have implemented a logger that writes the raw incoming binary data to a file - is there a way I can utilize this idea to clear my memory cache at regular intervals? I.e. how can I, every so often, write to the log file in such a way that the data doesn't need to be stored in memory?

Also - are there other aspects of a Windows Form Application that would contribute to this? E.g. I print the formatted strings to a textbox, which ends up displaying the entire string. Because this is running for so long, it easily displays hundreds of thousands of lines of text. Should I be writing this to a file and clearing the text? Or something else?

Answer 1

Obviously, if the string grows over time, your app's memory usage will also grow over time. Also, WinForms textboxes can have trouble dealing with very large strings. How large does the string get?

Unless you really want to display the entire string onscreen, you should definitely clear it periodically (depending on your users' expectations); this will save memory and probably improve performance.

Answer 2

I have several serial applications which run either as an application or as a windows service. These are required to be up 24/7-365. The best mechanism I have found to avoid this same problem is two-fold.

1) Write the information out to a log file. For a service, this is the only way of getting the info out. The log file does not increase your memory usage.

2) For the application, write the information out to a log file as well as put it into a listbox. I generally limit the listbox to the last 500 or 1000 entries. With the newer .net controls, the listboxes are virtualized which helps but you also don't run into other memory issues such as the textbox concatenation.

You can take a system down with a textbox by constantly appending the string over a number of hours as it is not intended for that kind of abuse out of the box.